Line data Source code
1 : /*
2 : * Generic process-grouping system.
3 : *
4 : * Based originally on the cpuset system, extracted by Paul Menage
5 : * Copyright (C) 2006 Google, Inc
6 : *
7 : * Notifications support
8 : * Copyright (C) 2009 Nokia Corporation
9 : * Author: Kirill A. Shutemov
10 : *
11 : * Copyright notices from the original cpuset code:
12 : * --------------------------------------------------
13 : * Copyright (C) 2003 BULL SA.
14 : * Copyright (C) 2004-2006 Silicon Graphics, Inc.
15 : *
16 : * Portions derived from Patrick Mochel's sysfs code.
17 : * sysfs is Copyright (c) 2001-3 Patrick Mochel
18 : *
19 : * 2003-10-10 Written by Simon Derr.
20 : * 2003-10-22 Updates by Stephen Hemminger.
21 : * 2004 May-July Rework by Paul Jackson.
22 : * ---------------------------------------------------
23 : *
24 : * This file is subject to the terms and conditions of the GNU General Public
25 : * License. See the file COPYING in the main directory of the Linux
26 : * distribution for more details.
27 : */
28 :
29 : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
30 :
31 : #include "cgroup-internal.h"
32 :
33 : #include <linux/cred.h>
34 : #include <linux/errno.h>
35 : #include <linux/init_task.h>
36 : #include <linux/kernel.h>
37 : #include <linux/magic.h>
38 : #include <linux/mutex.h>
39 : #include <linux/mount.h>
40 : #include <linux/pagemap.h>
41 : #include <linux/proc_fs.h>
42 : #include <linux/rcupdate.h>
43 : #include <linux/sched.h>
44 : #include <linux/sched/task.h>
45 : #include <linux/slab.h>
46 : #include <linux/spinlock.h>
47 : #include <linux/percpu-rwsem.h>
48 : #include <linux/string.h>
49 : #include <linux/hashtable.h>
50 : #include <linux/idr.h>
51 : #include <linux/kthread.h>
52 : #include <linux/atomic.h>
53 : #include <linux/cpuset.h>
54 : #include <linux/proc_ns.h>
55 : #include <linux/nsproxy.h>
56 : #include <linux/file.h>
57 : #include <linux/fs_parser.h>
58 : #include <linux/sched/cputime.h>
59 : #include <linux/psi.h>
60 : #include <net/sock.h>
61 :
62 : #define CREATE_TRACE_POINTS
63 : #include <trace/events/cgroup.h>
64 :
65 : #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
66 : MAX_CFTYPE_NAME + 2)
67 : /* let's not notify more than 100 times per second */
68 : #define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100)
69 :
70 : /*
71 : * cgroup_mutex is the master lock. Any modification to cgroup or its
72 : * hierarchy must be performed while holding it.
73 : *
74 : * css_set_lock protects task->cgroups pointer, the list of css_set
75 : * objects, and the chain of tasks off each css_set.
76 : *
77 : * These locks are exported if CONFIG_PROVE_RCU so that accessors in
78 : * cgroup.h can use them for lockdep annotations.
79 : */
80 : DEFINE_MUTEX(cgroup_mutex);
81 : DEFINE_SPINLOCK(css_set_lock);
82 :
83 : #ifdef CONFIG_PROVE_RCU
84 : EXPORT_SYMBOL_GPL(cgroup_mutex);
85 : EXPORT_SYMBOL_GPL(css_set_lock);
86 : #endif
87 :
88 : DEFINE_SPINLOCK(trace_cgroup_path_lock);
89 : char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
90 : bool cgroup_debug __read_mostly;
91 :
92 : /*
93 : * Protects cgroup_idr and css_idr so that IDs can be released without
94 : * grabbing cgroup_mutex.
95 : */
96 : static DEFINE_SPINLOCK(cgroup_idr_lock);
97 :
98 : /*
99 : * Protects cgroup_file->kn for !self csses. It synchronizes notifications
100 : * against file removal/re-creation across css hiding.
101 : */
102 : static DEFINE_SPINLOCK(cgroup_file_kn_lock);
103 :
104 : DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem);
105 :
106 : #define cgroup_assert_mutex_or_rcu_locked() \
107 : RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
108 : !lockdep_is_held(&cgroup_mutex), \
109 : "cgroup_mutex or RCU read lock required");
110 :
111 : /*
112 : * cgroup destruction makes heavy use of work items and there can be a lot
113 : * of concurrent destructions. Use a separate workqueue so that cgroup
114 : * destruction work items don't end up filling up max_active of system_wq
115 : * which may lead to deadlock.
116 : */
117 : static struct workqueue_struct *cgroup_destroy_wq;
118 :
119 : /* generate an array of cgroup subsystem pointers */
120 : #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
121 : struct cgroup_subsys *cgroup_subsys[] = {
122 : #include <linux/cgroup_subsys.h>
123 : };
124 : #undef SUBSYS
125 :
126 : /* array of cgroup subsystem names */
127 : #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
128 : static const char *cgroup_subsys_name[] = {
129 : #include <linux/cgroup_subsys.h>
130 : };
131 : #undef SUBSYS
132 :
133 : /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
134 : #define SUBSYS(_x) \
135 : DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
136 : DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
137 : EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
138 : EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
139 : #include <linux/cgroup_subsys.h>
140 : #undef SUBSYS
141 :
142 : #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
143 : static struct static_key_true *cgroup_subsys_enabled_key[] = {
144 : #include <linux/cgroup_subsys.h>
145 : };
146 : #undef SUBSYS
147 :
148 : #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
149 : static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
150 : #include <linux/cgroup_subsys.h>
151 : };
152 : #undef SUBSYS
153 :
154 : static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu);
155 :
156 : /* the default hierarchy */
157 : struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu };
158 : EXPORT_SYMBOL_GPL(cgrp_dfl_root);
159 :
160 : /*
161 : * The default hierarchy always exists but is hidden until mounted for the
162 : * first time. This is for backward compatibility.
163 : */
164 : static bool cgrp_dfl_visible;
165 :
166 : /* some controllers are not supported in the default hierarchy */
167 : static u16 cgrp_dfl_inhibit_ss_mask;
168 :
169 : /* some controllers are implicitly enabled on the default hierarchy */
170 : static u16 cgrp_dfl_implicit_ss_mask;
171 :
172 : /* some controllers can be threaded on the default hierarchy */
173 : static u16 cgrp_dfl_threaded_ss_mask;
174 :
175 : /* The list of hierarchy roots */
176 : LIST_HEAD(cgroup_roots);
177 : static int cgroup_root_count;
178 :
179 : /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
180 : static DEFINE_IDR(cgroup_hierarchy_idr);
181 :
182 : /*
183 : * Assign a monotonically increasing serial number to csses. It guarantees
184 : * cgroups with bigger numbers are newer than those with smaller numbers.
185 : * Also, as csses are always appended to the parent's ->children list, it
186 : * guarantees that sibling csses are always sorted in the ascending serial
187 : * number order on the list. Protected by cgroup_mutex.
188 : */
189 : static u64 css_serial_nr_next = 1;
190 :
191 : /*
192 : * These bitmasks identify subsystems with specific features to avoid
193 : * having to do iterative checks repeatedly.
194 : */
195 : static u16 have_fork_callback __read_mostly;
196 : static u16 have_exit_callback __read_mostly;
197 : static u16 have_release_callback __read_mostly;
198 : static u16 have_canfork_callback __read_mostly;
199 :
200 : /* cgroup namespace for init task */
201 : struct cgroup_namespace init_cgroup_ns = {
202 : .ns.count = REFCOUNT_INIT(2),
203 : .user_ns = &init_user_ns,
204 : .ns.ops = &cgroupns_operations,
205 : .ns.inum = PROC_CGROUP_INIT_INO,
206 : .root_cset = &init_css_set,
207 : };
208 :
209 : static struct file_system_type cgroup2_fs_type;
210 : static struct cftype cgroup_base_files[];
211 :
212 : static int cgroup_apply_control(struct cgroup *cgrp);
213 : static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
214 : static void css_task_iter_skip(struct css_task_iter *it,
215 : struct task_struct *task);
216 : static int cgroup_destroy_locked(struct cgroup *cgrp);
217 : static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
218 : struct cgroup_subsys *ss);
219 : static void css_release(struct percpu_ref *ref);
220 : static void kill_css(struct cgroup_subsys_state *css);
221 : static int cgroup_addrm_files(struct cgroup_subsys_state *css,
222 : struct cgroup *cgrp, struct cftype cfts[],
223 : bool is_add);
224 :
225 : /**
226 : * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
227 : * @ssid: subsys ID of interest
228 : *
229 : * cgroup_subsys_enabled() can only be used with literal subsys names which
230 : * is fine for individual subsystems but unsuitable for cgroup core. This
231 : * is slower static_key_enabled() based test indexed by @ssid.
232 : */
233 0 : bool cgroup_ssid_enabled(int ssid)
234 : {
235 0 : if (CGROUP_SUBSYS_COUNT == 0)
236 0 : return false;
237 :
238 : return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
239 : }
240 :
241 : /**
242 : * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
243 : * @cgrp: the cgroup of interest
244 : *
245 : * The default hierarchy is the v2 interface of cgroup and this function
246 : * can be used to test whether a cgroup is on the default hierarchy for
247 : * cases where a subsystem should behave differently depending on the
248 : * interface version.
249 : *
250 : * List of changed behaviors:
251 : *
252 : * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
253 : * and "name" are disallowed.
254 : *
255 : * - When mounting an existing superblock, mount options should match.
256 : *
257 : * - Remount is disallowed.
258 : *
259 : * - rename(2) is disallowed.
260 : *
261 : * - "tasks" is removed. Everything should be at process granularity. Use
262 : * "cgroup.procs" instead.
263 : *
264 : * - "cgroup.procs" is not sorted. pids will be unique unless they got
265 : * recycled in-between reads.
266 : *
267 : * - "release_agent" and "notify_on_release" are removed. Replacement
268 : * notification mechanism will be implemented.
269 : *
270 : * - "cgroup.clone_children" is removed.
271 : *
272 : * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
273 : * and its descendants contain no task; otherwise, 1. The file also
274 : * generates kernfs notification which can be monitored through poll and
275 : * [di]notify when the value of the file changes.
276 : *
277 : * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
278 : * take masks of ancestors with non-empty cpus/mems, instead of being
279 : * moved to an ancestor.
280 : *
281 : * - cpuset: a task can be moved into an empty cpuset, and again it takes
282 : * masks of ancestors.
283 : *
284 : * - blkcg: blk-throttle becomes properly hierarchical.
285 : *
286 : * - debug: disallowed on the default hierarchy.
287 : */
288 2722 : bool cgroup_on_dfl(const struct cgroup *cgrp)
289 : {
290 2722 : return cgrp->root == &cgrp_dfl_root;
291 : }
292 :
293 : /* IDR wrappers which synchronize using cgroup_idr_lock */
294 : static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
295 : gfp_t gfp_mask)
296 : {
297 : int ret;
298 :
299 : idr_preload(gfp_mask);
300 : spin_lock_bh(&cgroup_idr_lock);
301 : ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
302 : spin_unlock_bh(&cgroup_idr_lock);
303 : idr_preload_end();
304 : return ret;
305 : }
306 :
307 0 : static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
308 : {
309 0 : void *ret;
310 :
311 0 : spin_lock_bh(&cgroup_idr_lock);
312 0 : ret = idr_replace(idr, ptr, id);
313 0 : spin_unlock_bh(&cgroup_idr_lock);
314 0 : return ret;
315 : }
316 :
317 0 : static void cgroup_idr_remove(struct idr *idr, int id)
318 : {
319 0 : spin_lock_bh(&cgroup_idr_lock);
320 0 : idr_remove(idr, id);
321 0 : spin_unlock_bh(&cgroup_idr_lock);
322 0 : }
323 :
324 112 : static bool cgroup_has_tasks(struct cgroup *cgrp)
325 : {
326 112 : return cgrp->nr_populated_csets;
327 : }
328 :
329 1133 : bool cgroup_is_threaded(struct cgroup *cgrp)
330 : {
331 1133 : return cgrp->dom_cgrp != cgrp;
332 : }
333 :
334 : /* can @cgrp host both domain and threaded children? */
335 409 : static bool cgroup_is_mixable(struct cgroup *cgrp)
336 : {
337 : /*
338 : * Root isn't under domain level resource control exempting it from
339 : * the no-internal-process constraint, so it can serve as a thread
340 : * root and a parent of resource domains at the same time.
341 : */
342 1128 : return !cgroup_parent(cgrp);
343 : }
344 :
345 : /* can @cgrp become a thread root? Should always be true for a thread root */
346 99 : static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
347 : {
348 : /* mixables don't care */
349 99 : if (cgroup_is_mixable(cgrp))
350 : return true;
351 :
352 : /* domain roots can't be nested under threaded */
353 99 : if (cgroup_is_threaded(cgrp))
354 : return false;
355 :
356 : /* can only have either domain or threaded children */
357 99 : if (cgrp->nr_populated_domain_children)
358 : return false;
359 :
360 : /* and no domain controllers can be enabled */
361 99 : if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
362 0 : return false;
363 :
364 : return true;
365 : }
366 :
367 : /* is @cgrp root of a threaded subtree? */
368 112 : bool cgroup_is_thread_root(struct cgroup *cgrp)
369 : {
370 : /* thread root should be a domain */
371 112 : if (cgroup_is_threaded(cgrp))
372 : return false;
373 :
374 : /* a domain w/ threaded children is a thread root */
375 112 : if (cgrp->nr_threaded_children)
376 : return true;
377 :
378 : /*
379 : * A domain which has tasks and explicit threaded controllers
380 : * enabled is a thread root.
381 : */
382 112 : if (cgroup_has_tasks(cgrp) &&
383 2 : (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask))
384 0 : return true;
385 :
386 : return false;
387 : }
388 :
389 : /* a domain which isn't connected to the root w/o brekage can't be used */
390 99 : static bool cgroup_is_valid_domain(struct cgroup *cgrp)
391 : {
392 : /* the cgroup itself can be a thread root */
393 99 : if (cgroup_is_threaded(cgrp))
394 : return false;
395 :
396 : /* but the ancestors can't be unless mixable */
397 310 : while ((cgrp = cgroup_parent(cgrp))) {
398 211 : if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp))
399 : return false;
400 211 : if (cgroup_is_threaded(cgrp))
401 : return false;
402 : }
403 :
404 : return true;
405 : }
406 :
407 : /* subsystems visibly enabled on a cgroup */
408 147 : static u16 cgroup_control(struct cgroup *cgrp)
409 : {
410 147 : struct cgroup *parent = cgroup_parent(cgrp);
411 147 : u16 root_ss_mask = cgrp->root->subsys_mask;
412 :
413 147 : if (parent) {
414 147 : u16 ss_mask = parent->subtree_control;
415 :
416 : /* threaded cgroups can only have threaded controllers */
417 147 : if (cgroup_is_threaded(cgrp))
418 0 : ss_mask &= cgrp_dfl_threaded_ss_mask;
419 147 : return ss_mask;
420 : }
421 :
422 0 : if (cgroup_on_dfl(cgrp))
423 0 : root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
424 : cgrp_dfl_implicit_ss_mask);
425 : return root_ss_mask;
426 : }
427 :
428 : /* subsystems enabled on a cgroup */
429 98 : static u16 cgroup_ss_mask(struct cgroup *cgrp)
430 : {
431 98 : struct cgroup *parent = cgroup_parent(cgrp);
432 :
433 98 : if (parent) {
434 98 : u16 ss_mask = parent->subtree_ss_mask;
435 :
436 : /* threaded cgroups can only have threaded controllers */
437 98 : if (cgroup_is_threaded(cgrp))
438 0 : ss_mask &= cgrp_dfl_threaded_ss_mask;
439 98 : return ss_mask;
440 : }
441 :
442 0 : return cgrp->root->subsys_mask;
443 : }
444 :
445 : /**
446 : * cgroup_css - obtain a cgroup's css for the specified subsystem
447 : * @cgrp: the cgroup of interest
448 : * @ss: the subsystem of interest (%NULL returns @cgrp->self)
449 : *
450 : * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
451 : * function must be called either under cgroup_mutex or rcu_read_lock() and
452 : * the caller is responsible for pinning the returned css if it wants to
453 : * keep accessing it outside the said locks. This function may return
454 : * %NULL if @cgrp doesn't have @subsys_id enabled.
455 : */
456 444 : static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
457 : struct cgroup_subsys *ss)
458 : {
459 50 : if (ss)
460 0 : return rcu_dereference_check(cgrp->subsys[ss->id],
461 : lockdep_is_held(&cgroup_mutex));
462 : else
463 149 : return &cgrp->self;
464 : }
465 :
466 : /**
467 : * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem
468 : * @cgrp: the cgroup of interest
469 : * @ss: the subsystem of interest
470 : *
471 : * Find and get @cgrp's css assocaited with @ss. If the css doesn't exist
472 : * or is offline, %NULL is returned.
473 : */
474 : static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
475 : struct cgroup_subsys *ss)
476 : {
477 : struct cgroup_subsys_state *css;
478 :
479 : rcu_read_lock();
480 : css = cgroup_css(cgrp, ss);
481 : if (css && !css_tryget_online(css))
482 : css = NULL;
483 : rcu_read_unlock();
484 :
485 : return css;
486 : }
487 :
488 : /**
489 : * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
490 : * @cgrp: the cgroup of interest
491 : * @ss: the subsystem of interest (%NULL returns @cgrp->self)
492 : *
493 : * Similar to cgroup_css() but returns the effective css, which is defined
494 : * as the matching css of the nearest ancestor including self which has @ss
495 : * enabled. If @ss is associated with the hierarchy @cgrp is on, this
496 : * function is guaranteed to return non-NULL css.
497 : */
498 : static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp,
499 : struct cgroup_subsys *ss)
500 : {
501 : lockdep_assert_held(&cgroup_mutex);
502 :
503 : if (!ss)
504 : return &cgrp->self;
505 :
506 : /*
507 : * This function is used while updating css associations and thus
508 : * can't test the csses directly. Test ss_mask.
509 : */
510 : while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) {
511 : cgrp = cgroup_parent(cgrp);
512 : if (!cgrp)
513 : return NULL;
514 : }
515 :
516 : return cgroup_css(cgrp, ss);
517 : }
518 :
519 : /**
520 : * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
521 : * @cgrp: the cgroup of interest
522 : * @ss: the subsystem of interest
523 : *
524 : * Find and get the effective css of @cgrp for @ss. The effective css is
525 : * defined as the matching css of the nearest ancestor including self which
526 : * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
527 : * the root css is returned, so this function always returns a valid css.
528 : *
529 : * The returned css is not guaranteed to be online, and therefore it is the
530 : * callers responsibility to try get a reference for it.
531 : */
532 0 : struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
533 : struct cgroup_subsys *ss)
534 : {
535 0 : struct cgroup_subsys_state *css;
536 :
537 0 : do {
538 0 : css = cgroup_css(cgrp, ss);
539 :
540 0 : if (css)
541 0 : return css;
542 0 : cgrp = cgroup_parent(cgrp);
543 0 : } while (cgrp);
544 :
545 0 : return init_css_set.subsys[ss->id];
546 : }
547 :
548 : /**
549 : * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
550 : * @cgrp: the cgroup of interest
551 : * @ss: the subsystem of interest
552 : *
553 : * Find and get the effective css of @cgrp for @ss. The effective css is
554 : * defined as the matching css of the nearest ancestor including self which
555 : * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
556 : * the root css is returned, so this function always returns a valid css.
557 : * The returned css must be put using css_put().
558 : */
559 0 : struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
560 : struct cgroup_subsys *ss)
561 : {
562 0 : struct cgroup_subsys_state *css;
563 :
564 0 : rcu_read_lock();
565 :
566 0 : do {
567 0 : css = cgroup_css(cgrp, ss);
568 :
569 0 : if (css && css_tryget_online(css))
570 0 : goto out_unlock;
571 0 : cgrp = cgroup_parent(cgrp);
572 0 : } while (cgrp);
573 :
574 0 : css = init_css_set.subsys[ss->id];
575 0 : css_get(css);
576 0 : out_unlock:
577 0 : rcu_read_unlock();
578 0 : return css;
579 : }
580 :
581 294 : static void cgroup_get_live(struct cgroup *cgrp)
582 : {
583 294 : WARN_ON_ONCE(cgroup_is_dead(cgrp));
584 294 : css_get(&cgrp->self);
585 294 : }
586 :
587 : /**
588 : * __cgroup_task_count - count the number of tasks in a cgroup. The caller
589 : * is responsible for taking the css_set_lock.
590 : * @cgrp: the cgroup in question
591 : */
592 0 : int __cgroup_task_count(const struct cgroup *cgrp)
593 : {
594 0 : int count = 0;
595 0 : struct cgrp_cset_link *link;
596 :
597 0 : lockdep_assert_held(&css_set_lock);
598 :
599 0 : list_for_each_entry(link, &cgrp->cset_links, cset_link)
600 0 : count += link->cset->nr_tasks;
601 :
602 0 : return count;
603 : }
604 :
605 : /**
606 : * cgroup_task_count - count the number of tasks in a cgroup.
607 : * @cgrp: the cgroup in question
608 : */
609 0 : int cgroup_task_count(const struct cgroup *cgrp)
610 : {
611 0 : int count;
612 :
613 0 : spin_lock_irq(&css_set_lock);
614 0 : count = __cgroup_task_count(cgrp);
615 0 : spin_unlock_irq(&css_set_lock);
616 :
617 0 : return count;
618 : }
619 :
620 235 : struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
621 : {
622 235 : struct cgroup *cgrp = of->kn->parent->priv;
623 235 : struct cftype *cft = of_cft(of);
624 :
625 : /*
626 : * This is open and unprotected implementation of cgroup_css().
627 : * seq_css() is only called from a kernfs file operation which has
628 : * an active reference on the file. Because all the subsystem
629 : * files are drained before a css is disassociated with a cgroup,
630 : * the matching css from the cgroup's subsys table is guaranteed to
631 : * be and stay valid until the enclosing operation is complete.
632 : */
633 : if (cft->ss)
634 0 : return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
635 : else
636 235 : return &cgrp->self;
637 : }
638 : EXPORT_SYMBOL_GPL(of_css);
639 :
640 : /**
641 : * for_each_css - iterate all css's of a cgroup
642 : * @css: the iteration cursor
643 : * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
644 : * @cgrp: the target cgroup to iterate css's of
645 : *
646 : * Should be called under cgroup_[tree_]mutex.
647 : */
648 : #define for_each_css(css, ssid, cgrp) \
649 : for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
650 : if (!((css) = rcu_dereference_check( \
651 : (cgrp)->subsys[(ssid)], \
652 : lockdep_is_held(&cgroup_mutex)))) { } \
653 : else
654 :
655 : /**
656 : * for_each_e_css - iterate all effective css's of a cgroup
657 : * @css: the iteration cursor
658 : * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
659 : * @cgrp: the target cgroup to iterate css's of
660 : *
661 : * Should be called under cgroup_[tree_]mutex.
662 : */
663 : #define for_each_e_css(css, ssid, cgrp) \
664 : for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
665 : if (!((css) = cgroup_e_css_by_mask(cgrp, \
666 : cgroup_subsys[(ssid)]))) \
667 : ; \
668 : else
669 :
670 : /**
671 : * do_each_subsys_mask - filter for_each_subsys with a bitmask
672 : * @ss: the iteration cursor
673 : * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
674 : * @ss_mask: the bitmask
675 : *
676 : * The block will only run for cases where the ssid-th bit (1 << ssid) of
677 : * @ss_mask is set.
678 : */
679 : #define do_each_subsys_mask(ss, ssid, ss_mask) do { \
680 : unsigned long __ss_mask = (ss_mask); \
681 : if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
682 : (ssid) = 0; \
683 : break; \
684 : } \
685 : for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
686 : (ss) = cgroup_subsys[ssid]; \
687 : {
688 :
689 : #define while_each_subsys_mask() \
690 : } \
691 : } \
692 : } while (false)
693 :
694 : /* iterate over child cgrps, lock should be held throughout iteration */
695 : #define cgroup_for_each_live_child(child, cgrp) \
696 : list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
697 : if (({ lockdep_assert_held(&cgroup_mutex); \
698 : cgroup_is_dead(child); })) \
699 : ; \
700 : else
701 :
702 : /* walk live descendants in pre order */
703 : #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
704 : css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
705 : if (({ lockdep_assert_held(&cgroup_mutex); \
706 : (dsct) = (d_css)->cgroup; \
707 : cgroup_is_dead(dsct); })) \
708 : ; \
709 : else
710 :
711 : /* walk live descendants in postorder */
712 : #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
713 : css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
714 : if (({ lockdep_assert_held(&cgroup_mutex); \
715 : (dsct) = (d_css)->cgroup; \
716 : cgroup_is_dead(dsct); })) \
717 : ; \
718 : else
719 :
720 : /*
721 : * The default css_set - used by init and its children prior to any
722 : * hierarchies being mounted. It contains a pointer to the root state
723 : * for each subsystem. Also used to anchor the list of css_sets. Not
724 : * reference-counted, to improve performance when child cgroups
725 : * haven't been created.
726 : */
727 : struct css_set init_css_set = {
728 : .refcount = REFCOUNT_INIT(1),
729 : .dom_cset = &init_css_set,
730 : .tasks = LIST_HEAD_INIT(init_css_set.tasks),
731 : .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
732 : .dying_tasks = LIST_HEAD_INIT(init_css_set.dying_tasks),
733 : .task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
734 : .threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets),
735 : .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
736 : .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
737 : .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
738 :
739 : /*
740 : * The following field is re-initialized when this cset gets linked
741 : * in cgroup_init(). However, let's initialize the field
742 : * statically too so that the default cgroup can be accessed safely
743 : * early during boot.
744 : */
745 : .dfl_cgrp = &cgrp_dfl_root.cgrp,
746 : };
747 :
748 : static int css_set_count = 1; /* 1 for init_css_set */
749 :
750 81 : static bool css_set_threaded(struct css_set *cset)
751 : {
752 81 : return cset->dom_cset != cset;
753 : }
754 :
755 : /**
756 : * css_set_populated - does a css_set contain any tasks?
757 : * @cset: target css_set
758 : *
759 : * css_set_populated() should be the same as !!cset->nr_tasks at steady
760 : * state. However, css_set_populated() can be called while a task is being
761 : * added to or removed from the linked list before the nr_tasks is
762 : * properly updated. Hence, we can't just look at ->nr_tasks here.
763 : */
764 2456 : static bool css_set_populated(struct css_set *cset)
765 : {
766 7368 : lockdep_assert_held(&css_set_lock);
767 :
768 2456 : return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
769 : }
770 :
771 : /**
772 : * cgroup_update_populated - update the populated count of a cgroup
773 : * @cgrp: the target cgroup
774 : * @populated: inc or dec populated count
775 : *
776 : * One of the css_sets associated with @cgrp is either getting its first
777 : * task or losing the last. Update @cgrp->nr_populated_* accordingly. The
778 : * count is propagated towards root so that a given cgroup's
779 : * nr_populated_children is zero iff none of its descendants contain any
780 : * tasks.
781 : *
782 : * @cgrp's interface file "cgroup.populated" is zero if both
783 : * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and
784 : * 1 otherwise. When the sum changes from or to zero, userland is notified
785 : * that the content of the interface file has changed. This can be used to
786 : * detect when @cgrp and its descendants become populated or empty.
787 : */
788 388 : static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
789 : {
790 388 : struct cgroup *child = NULL;
791 388 : int adj = populated ? 1 : -1;
792 :
793 1164 : lockdep_assert_held(&css_set_lock);
794 :
795 576 : do {
796 576 : bool was_populated = cgroup_is_populated(cgrp);
797 :
798 576 : if (!child) {
799 388 : cgrp->nr_populated_csets += adj;
800 : } else {
801 188 : if (cgroup_is_threaded(child))
802 0 : cgrp->nr_populated_threaded_children += adj;
803 : else
804 188 : cgrp->nr_populated_domain_children += adj;
805 : }
806 :
807 576 : if (was_populated == cgroup_is_populated(cgrp))
808 : break;
809 :
810 190 : cgroup1_check_for_release(cgrp);
811 190 : TRACE_CGROUP_PATH(notify_populated, cgrp,
812 : cgroup_is_populated(cgrp));
813 190 : cgroup_file_notify(&cgrp->events_file);
814 :
815 190 : child = cgrp;
816 578 : cgrp = cgroup_parent(cgrp);
817 : } while (cgrp);
818 388 : }
819 :
820 : /**
821 : * css_set_update_populated - update populated state of a css_set
822 : * @cset: target css_set
823 : * @populated: whether @cset is populated or depopulated
824 : *
825 : * @cset is either getting the first task or losing the last. Update the
826 : * populated counters of all associated cgroups accordingly.
827 : */
828 194 : static void css_set_update_populated(struct css_set *cset, bool populated)
829 : {
830 194 : struct cgrp_cset_link *link;
831 :
832 582 : lockdep_assert_held(&css_set_lock);
833 :
834 581 : list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
835 387 : cgroup_update_populated(link->cgrp, populated);
836 194 : }
837 :
838 : /*
839 : * @task is leaving, advance task iterators which are pointing to it so
840 : * that they can resume at the next position. Advancing an iterator might
841 : * remove it from the list, use safe walk. See css_task_iter_skip() for
842 : * details.
843 : */
844 2272 : static void css_set_skip_task_iters(struct css_set *cset,
845 : struct task_struct *task)
846 : {
847 2272 : struct css_task_iter *it, *pos;
848 :
849 2273 : list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node)
850 1 : css_task_iter_skip(it, task);
851 2272 : }
852 :
853 : /**
854 : * css_set_move_task - move a task from one css_set to another
855 : * @task: task being moved
856 : * @from_cset: css_set @task currently belongs to (may be NULL)
857 : * @to_cset: new css_set @task is being moved to (may be NULL)
858 : * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
859 : *
860 : * Move @task from @from_cset to @to_cset. If @task didn't belong to any
861 : * css_set, @from_cset can be NULL. If @task is being disassociated
862 : * instead of moved, @to_cset can be NULL.
863 : *
864 : * This function automatically handles populated counter updates and
865 : * css_task_iter adjustments but the caller is responsible for managing
866 : * @from_cset and @to_cset's reference counts.
867 : */
868 2348 : static void css_set_move_task(struct task_struct *task,
869 : struct css_set *from_cset, struct css_set *to_cset,
870 : bool use_mg_tasks)
871 : {
872 7044 : lockdep_assert_held(&css_set_lock);
873 :
874 2348 : if (to_cset && !css_set_populated(to_cset))
875 106 : css_set_update_populated(to_cset, true);
876 :
877 2348 : if (from_cset) {
878 1189 : WARN_ON_ONCE(list_empty(&task->cg_list));
879 :
880 1189 : css_set_skip_task_iters(from_cset, task);
881 1189 : list_del_init(&task->cg_list);
882 1189 : if (!css_set_populated(from_cset))
883 88 : css_set_update_populated(from_cset, false);
884 : } else {
885 1159 : WARN_ON_ONCE(!list_empty(&task->cg_list));
886 : }
887 :
888 2348 : if (to_cset) {
889 : /*
890 : * We are synchronized through cgroup_threadgroup_rwsem
891 : * against PF_EXITING setting such that we can't race
892 : * against cgroup_exit()/cgroup_free() dropping the css_set.
893 : */
894 1265 : WARN_ON_ONCE(task->flags & PF_EXITING);
895 :
896 1265 : cgroup_move_task(task, to_cset);
897 1265 : list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
898 : &to_cset->tasks);
899 : }
900 2348 : }
901 :
902 : /*
903 : * hash table for cgroup groups. This improves the performance to find
904 : * an existing css_set. This hash doesn't (currently) take into
905 : * account cgroups in empty hierarchies.
906 : */
907 : #define CSS_SET_HASH_BITS 7
908 : static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
909 :
910 298 : static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
911 : {
912 298 : unsigned long key = 0UL;
913 298 : struct cgroup_subsys *ss;
914 298 : int i;
915 :
916 298 : for_each_subsys(ss, i)
917 : key += (unsigned long)css[i];
918 298 : key = (key >> 16) ^ key;
919 :
920 298 : return key;
921 : }
922 :
923 371 : void put_css_set_locked(struct css_set *cset)
924 : {
925 371 : struct cgrp_cset_link *link, *tmp_link;
926 371 : struct cgroup_subsys *ss;
927 371 : int ssid;
928 :
929 1113 : lockdep_assert_held(&css_set_lock);
930 :
931 371 : if (!refcount_dec_and_test(&cset->refcount))
932 : return;
933 :
934 81 : WARN_ON_ONCE(!list_empty(&cset->threaded_csets));
935 :
936 : /* This css_set is dead. Unlink it and release cgroup and css refs */
937 81 : for_each_subsys(ss, ssid) {
938 : list_del(&cset->e_cset_node[ssid]);
939 : css_put(cset->subsys[ssid]);
940 : }
941 81 : hash_del(&cset->hlist);
942 81 : css_set_count--;
943 :
944 243 : list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
945 162 : list_del(&link->cset_link);
946 162 : list_del(&link->cgrp_link);
947 162 : if (cgroup_parent(link->cgrp))
948 161 : cgroup_put(link->cgrp);
949 162 : kfree(link);
950 : }
951 :
952 81 : if (css_set_threaded(cset)) {
953 0 : list_del(&cset->threaded_csets_node);
954 0 : put_css_set_locked(cset->dom_cset);
955 : }
956 :
957 81 : kfree_rcu(cset, rcu_head);
958 : }
959 :
960 : /**
961 : * compare_css_sets - helper function for find_existing_css_set().
962 : * @cset: candidate css_set being tested
963 : * @old_cset: existing css_set for a task
964 : * @new_cgrp: cgroup that's being entered by the task
965 : * @template: desired set of css pointers in css_set (pre-calculated)
966 : *
967 : * Returns true if "cset" matches "old_cset" except for the hierarchy
968 : * which "new_cgrp" belongs to, for which it should match "new_cgrp".
969 : */
970 1291 : static bool compare_css_sets(struct css_set *cset,
971 : struct css_set *old_cset,
972 : struct cgroup *new_cgrp,
973 : struct cgroup_subsys_state *template[])
974 : {
975 1291 : struct cgroup *new_dfl_cgrp;
976 1291 : struct list_head *l1, *l2;
977 :
978 : /*
979 : * On the default hierarchy, there can be csets which are
980 : * associated with the same set of cgroups but different csses.
981 : * Let's first ensure that csses match.
982 : */
983 1291 : if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
984 : return false;
985 :
986 :
987 : /* @cset's domain should match the default cgroup's */
988 1291 : if (cgroup_on_dfl(new_cgrp))
989 : new_dfl_cgrp = new_cgrp;
990 : else
991 616 : new_dfl_cgrp = old_cset->dfl_cgrp;
992 :
993 1291 : if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp)
994 : return false;
995 :
996 : /*
997 : * Compare cgroup pointers in order to distinguish between
998 : * different cgroups in hierarchies. As different cgroups may
999 : * share the same effective css, this comparison is always
1000 : * necessary.
1001 : */
1002 161 : l1 = &cset->cgrp_links;
1003 161 : l2 = &old_cset->cgrp_links;
1004 422 : while (1) {
1005 422 : struct cgrp_cset_link *link1, *link2;
1006 422 : struct cgroup *cgrp1, *cgrp2;
1007 :
1008 422 : l1 = l1->next;
1009 422 : l2 = l2->next;
1010 : /* See if we reached the end - both lists are equal length. */
1011 422 : if (l1 == &cset->cgrp_links) {
1012 100 : BUG_ON(l2 != &old_cset->cgrp_links);
1013 : break;
1014 : } else {
1015 322 : BUG_ON(l2 == &old_cset->cgrp_links);
1016 : }
1017 : /* Locate the cgroups associated with these links. */
1018 322 : link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
1019 322 : link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
1020 322 : cgrp1 = link1->cgrp;
1021 322 : cgrp2 = link2->cgrp;
1022 : /* Hierarchies should be linked in the same order. */
1023 322 : BUG_ON(cgrp1->root != cgrp2->root);
1024 :
1025 : /*
1026 : * If this hierarchy is the hierarchy of the cgroup
1027 : * that's changing, then we need to check that this
1028 : * css_set points to the new cgroup; if it's any other
1029 : * hierarchy, then this css_set should point to the
1030 : * same cgroup as the old css_set.
1031 : */
1032 322 : if (cgrp1->root == new_cgrp->root) {
1033 161 : if (cgrp1 != new_cgrp)
1034 : return false;
1035 : } else {
1036 161 : if (cgrp1 != cgrp2)
1037 : return false;
1038 : }
1039 : }
1040 : return true;
1041 : }
1042 :
1043 : /**
1044 : * find_existing_css_set - init css array and find the matching css_set
1045 : * @old_cset: the css_set that we're using before the cgroup transition
1046 : * @cgrp: the cgroup that we're moving into
1047 : * @template: out param for the new set of csses, should be clear on entry
1048 : */
1049 198 : static struct css_set *find_existing_css_set(struct css_set *old_cset,
1050 : struct cgroup *cgrp,
1051 : struct cgroup_subsys_state *template[])
1052 : {
1053 198 : struct cgroup_root *root = cgrp->root;
1054 198 : struct cgroup_subsys *ss;
1055 198 : struct css_set *cset;
1056 198 : unsigned long key;
1057 198 : int i;
1058 :
1059 : /*
1060 : * Build the set of subsystem state objects that we want to see in the
1061 : * new css_set. While subsystems can change globally, the entries here
1062 : * won't change, so no need for locking.
1063 : */
1064 198 : for_each_subsys(ss, i) {
1065 : if (root->subsys_mask & (1UL << i)) {
1066 : /*
1067 : * @ss is in this hierarchy, so we want the
1068 : * effective css from @cgrp.
1069 : */
1070 : template[i] = cgroup_e_css_by_mask(cgrp, ss);
1071 : } else {
1072 : /*
1073 : * @ss is not in this hierarchy, so we don't want
1074 : * to change the css.
1075 : */
1076 : template[i] = old_cset->subsys[i];
1077 : }
1078 : }
1079 :
1080 198 : key = css_set_hash(template);
1081 1489 : hash_for_each_possible(css_set_table, cset, hlist, key) {
1082 1291 : if (!compare_css_sets(cset, old_cset, cgrp, template))
1083 1191 : continue;
1084 :
1085 : /* This css_set matches what we need */
1086 : return cset;
1087 : }
1088 :
1089 : /* No existing cgroup group matched */
1090 : return NULL;
1091 : }
1092 :
1093 2 : static void free_cgrp_cset_links(struct list_head *links_to_free)
1094 : {
1095 2 : struct cgrp_cset_link *link, *tmp_link;
1096 :
1097 4 : list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
1098 2 : list_del(&link->cset_link);
1099 2 : kfree(link);
1100 : }
1101 2 : }
1102 :
1103 : /**
1104 : * allocate_cgrp_cset_links - allocate cgrp_cset_links
1105 : * @count: the number of links to allocate
1106 : * @tmp_links: list_head the allocated links are put on
1107 : *
1108 : * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
1109 : * through ->cset_link. Returns 0 on success or -errno.
1110 : */
1111 100 : static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
1112 : {
1113 100 : struct cgrp_cset_link *link;
1114 100 : int i;
1115 :
1116 100 : INIT_LIST_HEAD(tmp_links);
1117 :
1118 300 : for (i = 0; i < count; i++) {
1119 200 : link = kzalloc(sizeof(*link), GFP_KERNEL);
1120 200 : if (!link) {
1121 0 : free_cgrp_cset_links(tmp_links);
1122 0 : return -ENOMEM;
1123 : }
1124 200 : list_add(&link->cset_link, tmp_links);
1125 : }
1126 : return 0;
1127 : }
1128 :
1129 : /**
1130 : * link_css_set - a helper function to link a css_set to a cgroup
1131 : * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
1132 : * @cset: the css_set to be linked
1133 : * @cgrp: the destination cgroup
1134 : */
1135 198 : static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
1136 : struct cgroup *cgrp)
1137 : {
1138 198 : struct cgrp_cset_link *link;
1139 :
1140 198 : BUG_ON(list_empty(tmp_links));
1141 :
1142 198 : if (cgroup_on_dfl(cgrp))
1143 99 : cset->dfl_cgrp = cgrp;
1144 :
1145 198 : link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
1146 198 : link->cset = cset;
1147 198 : link->cgrp = cgrp;
1148 :
1149 : /*
1150 : * Always add links to the tail of the lists so that the lists are
1151 : * in chronological order.
1152 : */
1153 198 : list_move_tail(&link->cset_link, &cgrp->cset_links);
1154 198 : list_add_tail(&link->cgrp_link, &cset->cgrp_links);
1155 :
1156 198 : if (cgroup_parent(cgrp))
1157 195 : cgroup_get_live(cgrp);
1158 198 : }
1159 :
1160 : /**
1161 : * find_css_set - return a new css_set with one cgroup updated
1162 : * @old_cset: the baseline css_set
1163 : * @cgrp: the cgroup to be updated
1164 : *
1165 : * Return a new css_set that's equivalent to @old_cset, but with @cgrp
1166 : * substituted into the appropriate hierarchy.
1167 : */
1168 198 : static struct css_set *find_css_set(struct css_set *old_cset,
1169 : struct cgroup *cgrp)
1170 : {
1171 198 : struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
1172 198 : struct css_set *cset;
1173 198 : struct list_head tmp_links;
1174 198 : struct cgrp_cset_link *link;
1175 198 : struct cgroup_subsys *ss;
1176 198 : unsigned long key;
1177 198 : int ssid;
1178 :
1179 594 : lockdep_assert_held(&cgroup_mutex);
1180 :
1181 : /* First see if we already have a cgroup group that matches
1182 : * the desired set */
1183 198 : spin_lock_irq(&css_set_lock);
1184 198 : cset = find_existing_css_set(old_cset, cgrp, template);
1185 198 : if (cset)
1186 100 : get_css_set(cset);
1187 198 : spin_unlock_irq(&css_set_lock);
1188 :
1189 198 : if (cset)
1190 : return cset;
1191 :
1192 98 : cset = kzalloc(sizeof(*cset), GFP_KERNEL);
1193 98 : if (!cset)
1194 : return NULL;
1195 :
1196 : /* Allocate all the cgrp_cset_link objects that we'll need */
1197 98 : if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
1198 0 : kfree(cset);
1199 0 : return NULL;
1200 : }
1201 :
1202 98 : refcount_set(&cset->refcount, 1);
1203 98 : cset->dom_cset = cset;
1204 98 : INIT_LIST_HEAD(&cset->tasks);
1205 98 : INIT_LIST_HEAD(&cset->mg_tasks);
1206 98 : INIT_LIST_HEAD(&cset->dying_tasks);
1207 98 : INIT_LIST_HEAD(&cset->task_iters);
1208 98 : INIT_LIST_HEAD(&cset->threaded_csets);
1209 98 : INIT_HLIST_NODE(&cset->hlist);
1210 98 : INIT_LIST_HEAD(&cset->cgrp_links);
1211 98 : INIT_LIST_HEAD(&cset->mg_preload_node);
1212 98 : INIT_LIST_HEAD(&cset->mg_node);
1213 :
1214 : /* Copy the set of subsystem state objects generated in
1215 : * find_existing_css_set() */
1216 98 : memcpy(cset->subsys, template, sizeof(cset->subsys));
1217 :
1218 98 : spin_lock_irq(&css_set_lock);
1219 : /* Add reference counts and links from the new css_set. */
1220 294 : list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
1221 196 : struct cgroup *c = link->cgrp;
1222 :
1223 196 : if (c->root == cgrp->root)
1224 98 : c = cgrp;
1225 196 : link_css_set(&tmp_links, cset, c);
1226 : }
1227 :
1228 98 : BUG_ON(!list_empty(&tmp_links));
1229 :
1230 98 : css_set_count++;
1231 :
1232 : /* Add @cset to the hash table */
1233 98 : key = css_set_hash(cset->subsys);
1234 98 : hash_add(css_set_table, &cset->hlist, key);
1235 :
1236 98 : for_each_subsys(ss, ssid) {
1237 : struct cgroup_subsys_state *css = cset->subsys[ssid];
1238 :
1239 : list_add_tail(&cset->e_cset_node[ssid],
1240 : &css->cgroup->e_csets[ssid]);
1241 : css_get(css);
1242 : }
1243 :
1244 98 : spin_unlock_irq(&css_set_lock);
1245 :
1246 : /*
1247 : * If @cset should be threaded, look up the matching dom_cset and
1248 : * link them up. We first fully initialize @cset then look for the
1249 : * dom_cset. It's simpler this way and safe as @cset is guaranteed
1250 : * to stay empty until we return.
1251 : */
1252 98 : if (cgroup_is_threaded(cset->dfl_cgrp)) {
1253 0 : struct css_set *dcset;
1254 :
1255 0 : dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp);
1256 0 : if (!dcset) {
1257 0 : put_css_set(cset);
1258 0 : return NULL;
1259 : }
1260 :
1261 0 : spin_lock_irq(&css_set_lock);
1262 0 : cset->dom_cset = dcset;
1263 0 : list_add_tail(&cset->threaded_csets_node,
1264 : &dcset->threaded_csets);
1265 0 : spin_unlock_irq(&css_set_lock);
1266 : }
1267 :
1268 : return cset;
1269 : }
1270 :
1271 862 : struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
1272 : {
1273 862 : struct cgroup *root_cgrp = kf_root->kn->priv;
1274 :
1275 862 : return root_cgrp->root;
1276 : }
1277 :
1278 2 : static int cgroup_init_root_id(struct cgroup_root *root)
1279 : {
1280 2 : int id;
1281 :
1282 6 : lockdep_assert_held(&cgroup_mutex);
1283 :
1284 2 : id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
1285 2 : if (id < 0)
1286 : return id;
1287 :
1288 2 : root->hierarchy_id = id;
1289 2 : return 0;
1290 : }
1291 :
1292 0 : static void cgroup_exit_root_id(struct cgroup_root *root)
1293 : {
1294 0 : lockdep_assert_held(&cgroup_mutex);
1295 :
1296 0 : idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
1297 0 : }
1298 :
1299 0 : void cgroup_free_root(struct cgroup_root *root)
1300 : {
1301 0 : kfree(root);
1302 0 : }
1303 :
1304 0 : static void cgroup_destroy_root(struct cgroup_root *root)
1305 : {
1306 0 : struct cgroup *cgrp = &root->cgrp;
1307 0 : struct cgrp_cset_link *link, *tmp_link;
1308 :
1309 0 : trace_cgroup_destroy_root(root);
1310 :
1311 0 : cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1312 :
1313 0 : BUG_ON(atomic_read(&root->nr_cgrps));
1314 0 : BUG_ON(!list_empty(&cgrp->self.children));
1315 :
1316 : /* Rebind all subsystems back to the default hierarchy */
1317 0 : WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
1318 :
1319 : /*
1320 : * Release all the links from cset_links to this hierarchy's
1321 : * root cgroup
1322 : */
1323 0 : spin_lock_irq(&css_set_lock);
1324 :
1325 0 : list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
1326 0 : list_del(&link->cset_link);
1327 0 : list_del(&link->cgrp_link);
1328 0 : kfree(link);
1329 : }
1330 :
1331 0 : spin_unlock_irq(&css_set_lock);
1332 :
1333 0 : if (!list_empty(&root->root_list)) {
1334 0 : list_del(&root->root_list);
1335 0 : cgroup_root_count--;
1336 : }
1337 :
1338 0 : cgroup_exit_root_id(root);
1339 :
1340 0 : mutex_unlock(&cgroup_mutex);
1341 :
1342 0 : kernfs_destroy_root(root->kf_root);
1343 0 : cgroup_free_root(root);
1344 0 : }
1345 :
1346 : /*
1347 : * look up cgroup associated with current task's cgroup namespace on the
1348 : * specified hierarchy
1349 : */
1350 : static struct cgroup *
1351 574 : current_cgns_cgroup_from_root(struct cgroup_root *root)
1352 : {
1353 574 : struct cgroup *res = NULL;
1354 574 : struct css_set *cset;
1355 :
1356 1722 : lockdep_assert_held(&css_set_lock);
1357 :
1358 574 : rcu_read_lock();
1359 :
1360 574 : cset = current->nsproxy->cgroup_ns->root_cset;
1361 574 : if (cset == &init_css_set) {
1362 574 : res = &root->cgrp;
1363 0 : } else if (root == &cgrp_dfl_root) {
1364 0 : res = cset->dfl_cgrp;
1365 : } else {
1366 0 : struct cgrp_cset_link *link;
1367 :
1368 0 : list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
1369 0 : struct cgroup *c = link->cgrp;
1370 :
1371 0 : if (c->root == root) {
1372 : res = c;
1373 : break;
1374 : }
1375 : }
1376 : }
1377 574 : rcu_read_unlock();
1378 :
1379 574 : BUG_ON(!res);
1380 574 : return res;
1381 : }
1382 :
1383 : /* look up cgroup associated with given css_set on the specified hierarchy */
1384 953 : static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
1385 : struct cgroup_root *root)
1386 : {
1387 953 : struct cgroup *res = NULL;
1388 :
1389 2859 : lockdep_assert_held(&cgroup_mutex);
1390 2859 : lockdep_assert_held(&css_set_lock);
1391 :
1392 953 : if (cset == &init_css_set) {
1393 318 : res = &root->cgrp;
1394 635 : } else if (root == &cgrp_dfl_root) {
1395 366 : res = cset->dfl_cgrp;
1396 : } else {
1397 269 : struct cgrp_cset_link *link;
1398 :
1399 538 : list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
1400 538 : struct cgroup *c = link->cgrp;
1401 :
1402 538 : if (c->root == root) {
1403 : res = c;
1404 : break;
1405 : }
1406 : }
1407 : }
1408 :
1409 953 : BUG_ON(!res);
1410 953 : return res;
1411 : }
1412 :
1413 : /*
1414 : * Return the cgroup for "task" from the given hierarchy. Must be
1415 : * called with cgroup_mutex and css_set_lock held.
1416 : */
1417 443 : struct cgroup *task_cgroup_from_root(struct task_struct *task,
1418 : struct cgroup_root *root)
1419 : {
1420 : /*
1421 : * No need to lock the task - since we hold css_set_lock the
1422 : * task can't change groups.
1423 : */
1424 443 : return cset_cgroup_from_root(task_css_set(task), root);
1425 : }
1426 :
1427 : /*
1428 : * A task must hold cgroup_mutex to modify cgroups.
1429 : *
1430 : * Any task can increment and decrement the count field without lock.
1431 : * So in general, code holding cgroup_mutex can't rely on the count
1432 : * field not changing. However, if the count goes to zero, then only
1433 : * cgroup_attach_task() can increment it again. Because a count of zero
1434 : * means that no tasks are currently attached, therefore there is no
1435 : * way a task attached to that cgroup can fork (the other way to
1436 : * increment the count). So code holding cgroup_mutex can safely
1437 : * assume that if the count is zero, it will stay zero. Similarly, if
1438 : * a task holds cgroup_mutex on a cgroup with zero count, it
1439 : * knows that the cgroup won't be removed, as cgroup_rmdir()
1440 : * needs that mutex.
1441 : *
1442 : * A cgroup can only be deleted if both its 'count' of using tasks
1443 : * is zero, and its list of 'children' cgroups is empty. Since all
1444 : * tasks in the system use _some_ cgroup, and since there is always at
1445 : * least one task in the system (init, pid == 1), therefore, root cgroup
1446 : * always has either children cgroups and/or using tasks. So we don't
1447 : * need a special hack to ensure that root cgroup cannot be deleted.
1448 : *
1449 : * P.S. One more locking exception. RCU is used to guard the
1450 : * update of a tasks cgroup pointer by cgroup_attach_task()
1451 : */
1452 :
1453 : static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
1454 :
1455 1124 : static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
1456 : char *buf)
1457 : {
1458 1124 : struct cgroup_subsys *ss = cft->ss;
1459 :
1460 1124 : if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
1461 0 : !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
1462 0 : const char *dbg = (cft->flags & CFTYPE_DEBUG) ? ".__DEBUG__." : "";
1463 :
1464 0 : snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s",
1465 0 : dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
1466 0 : cft->name);
1467 : } else {
1468 1124 : strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
1469 : }
1470 1124 : return buf;
1471 : }
1472 :
1473 : /**
1474 : * cgroup_file_mode - deduce file mode of a control file
1475 : * @cft: the control file in question
1476 : *
1477 : * S_IRUGO for read, S_IWUSR for write.
1478 : */
1479 749 : static umode_t cgroup_file_mode(const struct cftype *cft)
1480 : {
1481 749 : umode_t mode = 0;
1482 :
1483 749 : if (cft->read_u64 || cft->read_s64 || cft->seq_show)
1484 749 : mode |= S_IRUGO;
1485 :
1486 749 : if (cft->write_u64 || cft->write_s64 || cft->write) {
1487 549 : if (cft->flags & CFTYPE_WORLD_WRITABLE)
1488 0 : mode |= S_IWUGO;
1489 : else
1490 549 : mode |= S_IWUSR;
1491 : }
1492 :
1493 749 : return mode;
1494 : }
1495 :
1496 : /**
1497 : * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
1498 : * @subtree_control: the new subtree_control mask to consider
1499 : * @this_ss_mask: available subsystems
1500 : *
1501 : * On the default hierarchy, a subsystem may request other subsystems to be
1502 : * enabled together through its ->depends_on mask. In such cases, more
1503 : * subsystems than specified in "cgroup.subtree_control" may be enabled.
1504 : *
1505 : * This function calculates which subsystems need to be enabled if
1506 : * @subtree_control is to be applied while restricted to @this_ss_mask.
1507 : */
1508 98 : static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
1509 : {
1510 98 : u16 cur_ss_mask = subtree_control;
1511 98 : struct cgroup_subsys *ss;
1512 98 : int ssid;
1513 :
1514 294 : lockdep_assert_held(&cgroup_mutex);
1515 :
1516 98 : cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
1517 :
1518 98 : while (true) {
1519 98 : u16 new_ss_mask = cur_ss_mask;
1520 :
1521 98 : do_each_subsys_mask(ss, ssid, cur_ss_mask) {
1522 : new_ss_mask |= ss->depends_on;
1523 98 : } while_each_subsys_mask();
1524 :
1525 : /*
1526 : * Mask out subsystems which aren't available. This can
1527 : * happen only if some depended-upon subsystems were bound
1528 : * to non-default hierarchies.
1529 : */
1530 98 : new_ss_mask &= this_ss_mask;
1531 :
1532 98 : if (new_ss_mask == cur_ss_mask)
1533 : break;
1534 : cur_ss_mask = new_ss_mask;
1535 : }
1536 :
1537 98 : return cur_ss_mask;
1538 : }
1539 :
1540 : /**
1541 : * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
1542 : * @kn: the kernfs_node being serviced
1543 : *
1544 : * This helper undoes cgroup_kn_lock_live() and should be invoked before
1545 : * the method finishes if locking succeeded. Note that once this function
1546 : * returns the cgroup returned by cgroup_kn_lock_live() may become
1547 : * inaccessible any time. If the caller intends to continue to access the
1548 : * cgroup, it should pin it before invoking this function.
1549 : */
1550 347 : void cgroup_kn_unlock(struct kernfs_node *kn)
1551 : {
1552 347 : struct cgroup *cgrp;
1553 :
1554 347 : if (kernfs_type(kn) == KERNFS_DIR)
1555 149 : cgrp = kn->priv;
1556 : else
1557 198 : cgrp = kn->parent->priv;
1558 :
1559 347 : mutex_unlock(&cgroup_mutex);
1560 :
1561 347 : kernfs_unbreak_active_protection(kn);
1562 347 : cgroup_put(cgrp);
1563 347 : }
1564 :
1565 : /**
1566 : * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
1567 : * @kn: the kernfs_node being serviced
1568 : * @drain_offline: perform offline draining on the cgroup
1569 : *
1570 : * This helper is to be used by a cgroup kernfs method currently servicing
1571 : * @kn. It breaks the active protection, performs cgroup locking and
1572 : * verifies that the associated cgroup is alive. Returns the cgroup if
1573 : * alive; otherwise, %NULL. A successful return should be undone by a
1574 : * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
1575 : * cgroup is drained of offlining csses before return.
1576 : *
1577 : * Any cgroup kernfs method implementation which requires locking the
1578 : * associated cgroup should use this helper. It avoids nesting cgroup
1579 : * locking under kernfs active protection and allows all kernfs operations
1580 : * including self-removal.
1581 : */
1582 347 : struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline)
1583 : {
1584 347 : struct cgroup *cgrp;
1585 :
1586 347 : if (kernfs_type(kn) == KERNFS_DIR)
1587 149 : cgrp = kn->priv;
1588 : else
1589 198 : cgrp = kn->parent->priv;
1590 :
1591 : /*
1592 : * We're gonna grab cgroup_mutex which nests outside kernfs
1593 : * active_ref. cgroup liveliness check alone provides enough
1594 : * protection against removal. Ensure @cgrp stays accessible and
1595 : * break the active_ref protection.
1596 : */
1597 347 : if (!cgroup_tryget(cgrp))
1598 : return NULL;
1599 347 : kernfs_break_active_protection(kn);
1600 :
1601 347 : if (drain_offline)
1602 0 : cgroup_lock_and_drain_offline(cgrp);
1603 : else
1604 347 : mutex_lock(&cgroup_mutex);
1605 :
1606 347 : if (!cgroup_is_dead(cgrp))
1607 : return cgrp;
1608 :
1609 0 : cgroup_kn_unlock(kn);
1610 0 : return NULL;
1611 : }
1612 :
1613 375 : static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
1614 : {
1615 375 : char name[CGROUP_FILE_NAME_MAX];
1616 :
1617 1125 : lockdep_assert_held(&cgroup_mutex);
1618 :
1619 375 : if (cft->file_offset) {
1620 50 : struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
1621 50 : struct cgroup_file *cfile = (void *)css + cft->file_offset;
1622 :
1623 50 : spin_lock_irq(&cgroup_file_kn_lock);
1624 50 : cfile->kn = NULL;
1625 50 : spin_unlock_irq(&cgroup_file_kn_lock);
1626 :
1627 50 : del_timer_sync(&cfile->notify_timer);
1628 : }
1629 :
1630 375 : kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
1631 375 : }
1632 :
1633 : /**
1634 : * css_clear_dir - remove subsys files in a cgroup directory
1635 : * @css: taget css
1636 : */
1637 50 : static void css_clear_dir(struct cgroup_subsys_state *css)
1638 : {
1639 50 : struct cgroup *cgrp = css->cgroup;
1640 50 : struct cftype *cfts;
1641 :
1642 50 : if (!(css->flags & CSS_VISIBLE))
1643 : return;
1644 :
1645 50 : css->flags &= ~CSS_VISIBLE;
1646 :
1647 50 : if (!css->ss) {
1648 50 : if (cgroup_on_dfl(cgrp))
1649 : cfts = cgroup_base_files;
1650 : else
1651 25 : cfts = cgroup1_base_files;
1652 :
1653 50 : cgroup_addrm_files(css, cgrp, cfts, false);
1654 : } else {
1655 0 : list_for_each_entry(cfts, &css->ss->cfts, node)
1656 0 : cgroup_addrm_files(css, cgrp, cfts, false);
1657 : }
1658 : }
1659 :
1660 : /**
1661 : * css_populate_dir - create subsys files in a cgroup directory
1662 : * @css: target css
1663 : *
1664 : * On failure, no file is added.
1665 : */
1666 100 : static int css_populate_dir(struct cgroup_subsys_state *css)
1667 : {
1668 100 : struct cgroup *cgrp = css->cgroup;
1669 100 : struct cftype *cfts, *failed_cfts;
1670 100 : int ret;
1671 :
1672 100 : if ((css->flags & CSS_VISIBLE) || !cgrp->kn)
1673 : return 0;
1674 :
1675 100 : if (!css->ss) {
1676 100 : if (cgroup_on_dfl(cgrp))
1677 : cfts = cgroup_base_files;
1678 : else
1679 50 : cfts = cgroup1_base_files;
1680 :
1681 100 : ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
1682 100 : if (ret < 0)
1683 : return ret;
1684 : } else {
1685 0 : list_for_each_entry(cfts, &css->ss->cfts, node) {
1686 0 : ret = cgroup_addrm_files(css, cgrp, cfts, true);
1687 0 : if (ret < 0) {
1688 0 : failed_cfts = cfts;
1689 0 : goto err;
1690 : }
1691 : }
1692 : }
1693 :
1694 100 : css->flags |= CSS_VISIBLE;
1695 :
1696 100 : return 0;
1697 0 : err:
1698 0 : list_for_each_entry(cfts, &css->ss->cfts, node) {
1699 0 : if (cfts == failed_cfts)
1700 : break;
1701 0 : cgroup_addrm_files(css, cgrp, cfts, false);
1702 : }
1703 : return ret;
1704 : }
1705 :
1706 2 : int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
1707 : {
1708 2 : struct cgroup *dcgrp = &dst_root->cgrp;
1709 2 : struct cgroup_subsys *ss;
1710 2 : int ssid, i, ret;
1711 :
1712 6 : lockdep_assert_held(&cgroup_mutex);
1713 :
1714 2 : do_each_subsys_mask(ss, ssid, ss_mask) {
1715 : /*
1716 : * If @ss has non-root csses attached to it, can't move.
1717 : * If @ss is an implicit controller, it is exempt from this
1718 : * rule and can be stolen.
1719 : */
1720 : if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) &&
1721 : !ss->implicit_on_dfl)
1722 : return -EBUSY;
1723 :
1724 : /* can't move between two non-dummy roots either */
1725 : if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
1726 : return -EBUSY;
1727 2 : } while_each_subsys_mask();
1728 :
1729 2 : do_each_subsys_mask(ss, ssid, ss_mask) {
1730 : struct cgroup_root *src_root = ss->root;
1731 : struct cgroup *scgrp = &src_root->cgrp;
1732 : struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
1733 : struct css_set *cset;
1734 :
1735 : WARN_ON(!css || cgroup_css(dcgrp, ss));
1736 :
1737 : /* disable from the source */
1738 : src_root->subsys_mask &= ~(1 << ssid);
1739 : WARN_ON(cgroup_apply_control(scgrp));
1740 : cgroup_finalize_control(scgrp, 0);
1741 :
1742 : /* rebind */
1743 : RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
1744 : rcu_assign_pointer(dcgrp->subsys[ssid], css);
1745 : ss->root = dst_root;
1746 : css->cgroup = dcgrp;
1747 :
1748 : spin_lock_irq(&css_set_lock);
1749 : hash_for_each(css_set_table, i, cset, hlist)
1750 : list_move_tail(&cset->e_cset_node[ss->id],
1751 : &dcgrp->e_csets[ss->id]);
1752 : spin_unlock_irq(&css_set_lock);
1753 :
1754 : /* default hierarchy doesn't enable controllers by default */
1755 : dst_root->subsys_mask |= 1 << ssid;
1756 : if (dst_root == &cgrp_dfl_root) {
1757 : static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
1758 : } else {
1759 : dcgrp->subtree_control |= 1 << ssid;
1760 : static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
1761 : }
1762 :
1763 : ret = cgroup_apply_control(dcgrp);
1764 : if (ret)
1765 : pr_warn("partial failure to rebind %s controller (err=%d)\n",
1766 : ss->name, ret);
1767 :
1768 : if (ss->bind)
1769 : ss->bind(css);
1770 2 : } while_each_subsys_mask();
1771 :
1772 2 : kernfs_activate(dcgrp->kn);
1773 2 : return 0;
1774 : }
1775 :
1776 574 : int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
1777 : struct kernfs_root *kf_root)
1778 : {
1779 574 : int len = 0;
1780 574 : char *buf = NULL;
1781 574 : struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
1782 574 : struct cgroup *ns_cgroup;
1783 :
1784 574 : buf = kmalloc(PATH_MAX, GFP_KERNEL);
1785 574 : if (!buf)
1786 : return -ENOMEM;
1787 :
1788 574 : spin_lock_irq(&css_set_lock);
1789 574 : ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
1790 574 : len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
1791 574 : spin_unlock_irq(&css_set_lock);
1792 :
1793 574 : if (len >= PATH_MAX)
1794 : len = -ERANGE;
1795 574 : else if (len > 0) {
1796 574 : seq_escape(sf, buf, " \t\n\\");
1797 574 : len = 0;
1798 : }
1799 574 : kfree(buf);
1800 574 : return len;
1801 : }
1802 :
1803 : enum cgroup2_param {
1804 : Opt_nsdelegate,
1805 : Opt_memory_localevents,
1806 : Opt_memory_recursiveprot,
1807 : nr__cgroup2_params
1808 : };
1809 :
1810 : static const struct fs_parameter_spec cgroup2_fs_parameters[] = {
1811 : fsparam_flag("nsdelegate", Opt_nsdelegate),
1812 : fsparam_flag("memory_localevents", Opt_memory_localevents),
1813 : fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot),
1814 : {}
1815 : };
1816 :
1817 2 : static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param)
1818 : {
1819 2 : struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1820 2 : struct fs_parse_result result;
1821 2 : int opt;
1822 :
1823 2 : opt = fs_parse(fc, cgroup2_fs_parameters, param, &result);
1824 2 : if (opt < 0)
1825 : return opt;
1826 :
1827 1 : switch (opt) {
1828 1 : case Opt_nsdelegate:
1829 1 : ctx->flags |= CGRP_ROOT_NS_DELEGATE;
1830 1 : return 0;
1831 0 : case Opt_memory_localevents:
1832 0 : ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
1833 0 : return 0;
1834 0 : case Opt_memory_recursiveprot:
1835 0 : ctx->flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
1836 0 : return 0;
1837 : }
1838 : return -EINVAL;
1839 : }
1840 :
1841 1 : static void apply_cgroup_root_flags(unsigned int root_flags)
1842 : {
1843 1 : if (current->nsproxy->cgroup_ns == &init_cgroup_ns) {
1844 1 : if (root_flags & CGRP_ROOT_NS_DELEGATE)
1845 1 : cgrp_dfl_root.flags |= CGRP_ROOT_NS_DELEGATE;
1846 : else
1847 0 : cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE;
1848 :
1849 1 : if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
1850 0 : cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
1851 : else
1852 1 : cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS;
1853 :
1854 1 : if (root_flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
1855 0 : cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
1856 : else
1857 1 : cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_RECURSIVE_PROT;
1858 : }
1859 1 : }
1860 :
1861 288 : static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
1862 : {
1863 288 : if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE)
1864 288 : seq_puts(seq, ",nsdelegate");
1865 289 : if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
1866 0 : seq_puts(seq, ",memory_localevents");
1867 289 : if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
1868 0 : seq_puts(seq, ",memory_recursiveprot");
1869 289 : return 0;
1870 : }
1871 :
1872 0 : static int cgroup_reconfigure(struct fs_context *fc)
1873 : {
1874 0 : struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1875 :
1876 0 : apply_cgroup_root_flags(ctx->flags);
1877 0 : return 0;
1878 : }
1879 :
1880 100 : static void init_cgroup_housekeeping(struct cgroup *cgrp)
1881 : {
1882 100 : struct cgroup_subsys *ss;
1883 100 : int ssid;
1884 :
1885 100 : INIT_LIST_HEAD(&cgrp->self.sibling);
1886 100 : INIT_LIST_HEAD(&cgrp->self.children);
1887 100 : INIT_LIST_HEAD(&cgrp->cset_links);
1888 100 : INIT_LIST_HEAD(&cgrp->pidlists);
1889 100 : mutex_init(&cgrp->pidlist_mutex);
1890 100 : cgrp->self.cgroup = cgrp;
1891 100 : cgrp->self.flags |= CSS_ONLINE;
1892 100 : cgrp->dom_cgrp = cgrp;
1893 100 : cgrp->max_descendants = INT_MAX;
1894 100 : cgrp->max_depth = INT_MAX;
1895 100 : INIT_LIST_HEAD(&cgrp->rstat_css_list);
1896 100 : prev_cputime_init(&cgrp->prev_cputime);
1897 :
1898 100 : for_each_subsys(ss, ssid)
1899 : INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
1900 :
1901 100 : init_waitqueue_head(&cgrp->offline_waitq);
1902 100 : INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);
1903 100 : }
1904 :
1905 2 : void init_cgroup_root(struct cgroup_fs_context *ctx)
1906 : {
1907 2 : struct cgroup_root *root = ctx->root;
1908 2 : struct cgroup *cgrp = &root->cgrp;
1909 :
1910 2 : INIT_LIST_HEAD(&root->root_list);
1911 2 : atomic_set(&root->nr_cgrps, 1);
1912 2 : cgrp->root = root;
1913 2 : init_cgroup_housekeeping(cgrp);
1914 :
1915 2 : root->flags = ctx->flags;
1916 2 : if (ctx->release_agent)
1917 0 : strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX);
1918 2 : if (ctx->name)
1919 1 : strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN);
1920 2 : if (ctx->cpuset_clone_children)
1921 0 : set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
1922 2 : }
1923 :
1924 2 : int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
1925 : {
1926 2 : LIST_HEAD(tmp_links);
1927 2 : struct cgroup *root_cgrp = &root->cgrp;
1928 2 : struct kernfs_syscall_ops *kf_sops;
1929 2 : struct css_set *cset;
1930 2 : int i, ret;
1931 :
1932 6 : lockdep_assert_held(&cgroup_mutex);
1933 :
1934 2 : ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release,
1935 : 0, GFP_KERNEL);
1936 2 : if (ret)
1937 0 : goto out;
1938 :
1939 : /*
1940 : * We're accessing css_set_count without locking css_set_lock here,
1941 : * but that's OK - it can only be increased by someone holding
1942 : * cgroup_lock, and that's us. Later rebinding may disable
1943 : * controllers on the default hierarchy and thus create new csets,
1944 : * which can't be more than the existing ones. Allocate 2x.
1945 : */
1946 2 : ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
1947 2 : if (ret)
1948 0 : goto cancel_ref;
1949 :
1950 2 : ret = cgroup_init_root_id(root);
1951 2 : if (ret)
1952 0 : goto cancel_ref;
1953 :
1954 4 : kf_sops = root == &cgrp_dfl_root ?
1955 2 : &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;
1956 :
1957 2 : root->kf_root = kernfs_create_root(kf_sops,
1958 : KERNFS_ROOT_CREATE_DEACTIVATED |
1959 : KERNFS_ROOT_SUPPORT_EXPORTOP |
1960 : KERNFS_ROOT_SUPPORT_USER_XATTR,
1961 : root_cgrp);
1962 2 : if (IS_ERR(root->kf_root)) {
1963 0 : ret = PTR_ERR(root->kf_root);
1964 0 : goto exit_root_id;
1965 : }
1966 2 : root_cgrp->kn = root->kf_root->kn;
1967 2 : WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1);
1968 2 : root_cgrp->ancestor_ids[0] = cgroup_id(root_cgrp);
1969 :
1970 2 : ret = css_populate_dir(&root_cgrp->self);
1971 2 : if (ret)
1972 0 : goto destroy_root;
1973 :
1974 2 : ret = rebind_subsystems(root, ss_mask);
1975 2 : if (ret)
1976 0 : goto destroy_root;
1977 :
1978 2 : ret = cgroup_bpf_inherit(root_cgrp);
1979 2 : WARN_ON_ONCE(ret);
1980 :
1981 2 : trace_cgroup_setup_root(root);
1982 :
1983 : /*
1984 : * There must be no failure case after here, since rebinding takes
1985 : * care of subsystems' refcounts, which are explicitly dropped in
1986 : * the failure exit path.
1987 : */
1988 2 : list_add(&root->root_list, &cgroup_roots);
1989 2 : cgroup_root_count++;
1990 :
1991 : /*
1992 : * Link the root cgroup in this hierarchy into all the css_set
1993 : * objects.
1994 : */
1995 2 : spin_lock_irq(&css_set_lock);
1996 262 : hash_for_each(css_set_table, i, cset, hlist) {
1997 2 : link_css_set(&tmp_links, cset, root_cgrp);
1998 2 : if (css_set_populated(cset))
1999 1 : cgroup_update_populated(root_cgrp, true);
2000 : }
2001 2 : spin_unlock_irq(&css_set_lock);
2002 :
2003 2 : BUG_ON(!list_empty(&root_cgrp->self.children));
2004 2 : BUG_ON(atomic_read(&root->nr_cgrps) != 1);
2005 :
2006 2 : ret = 0;
2007 2 : goto out;
2008 :
2009 0 : destroy_root:
2010 0 : kernfs_destroy_root(root->kf_root);
2011 0 : root->kf_root = NULL;
2012 0 : exit_root_id:
2013 0 : cgroup_exit_root_id(root);
2014 0 : cancel_ref:
2015 0 : percpu_ref_exit(&root_cgrp->self.refcnt);
2016 2 : out:
2017 2 : free_cgrp_cset_links(&tmp_links);
2018 2 : return ret;
2019 : }
2020 :
2021 2 : int cgroup_do_get_tree(struct fs_context *fc)
2022 : {
2023 2 : struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
2024 2 : int ret;
2025 :
2026 2 : ctx->kfc.root = ctx->root->kf_root;
2027 2 : if (fc->fs_type == &cgroup2_fs_type)
2028 1 : ctx->kfc.magic = CGROUP2_SUPER_MAGIC;
2029 : else
2030 1 : ctx->kfc.magic = CGROUP_SUPER_MAGIC;
2031 2 : ret = kernfs_get_tree(fc);
2032 :
2033 : /*
2034 : * In non-init cgroup namespace, instead of root cgroup's dentry,
2035 : * we return the dentry corresponding to the cgroupns->root_cgrp.
2036 : */
2037 2 : if (!ret && ctx->ns != &init_cgroup_ns) {
2038 0 : struct dentry *nsdentry;
2039 0 : struct super_block *sb = fc->root->d_sb;
2040 0 : struct cgroup *cgrp;
2041 :
2042 0 : mutex_lock(&cgroup_mutex);
2043 0 : spin_lock_irq(&css_set_lock);
2044 :
2045 0 : cgrp = cset_cgroup_from_root(ctx->ns->root_cset, ctx->root);
2046 :
2047 0 : spin_unlock_irq(&css_set_lock);
2048 0 : mutex_unlock(&cgroup_mutex);
2049 :
2050 0 : nsdentry = kernfs_node_dentry(cgrp->kn, sb);
2051 0 : dput(fc->root);
2052 0 : if (IS_ERR(nsdentry)) {
2053 0 : deactivate_locked_super(sb);
2054 0 : ret = PTR_ERR(nsdentry);
2055 0 : nsdentry = NULL;
2056 : }
2057 0 : fc->root = nsdentry;
2058 : }
2059 :
2060 2 : if (!ctx->kfc.new_sb_created)
2061 0 : cgroup_put(&ctx->root->cgrp);
2062 :
2063 2 : return ret;
2064 : }
2065 :
2066 : /*
2067 : * Destroy a cgroup filesystem context.
2068 : */
2069 2 : static void cgroup_fs_context_free(struct fs_context *fc)
2070 : {
2071 2 : struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
2072 :
2073 2 : kfree(ctx->name);
2074 2 : kfree(ctx->release_agent);
2075 2 : put_cgroup_ns(ctx->ns);
2076 2 : kernfs_free_fs_context(fc);
2077 2 : kfree(ctx);
2078 2 : }
2079 :
2080 1 : static int cgroup_get_tree(struct fs_context *fc)
2081 : {
2082 1 : struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
2083 1 : int ret;
2084 :
2085 1 : cgrp_dfl_visible = true;
2086 1 : cgroup_get_live(&cgrp_dfl_root.cgrp);
2087 1 : ctx->root = &cgrp_dfl_root;
2088 :
2089 1 : ret = cgroup_do_get_tree(fc);
2090 1 : if (!ret)
2091 1 : apply_cgroup_root_flags(ctx->flags);
2092 1 : return ret;
2093 : }
2094 :
2095 : static const struct fs_context_operations cgroup_fs_context_ops = {
2096 : .free = cgroup_fs_context_free,
2097 : .parse_param = cgroup2_parse_param,
2098 : .get_tree = cgroup_get_tree,
2099 : .reconfigure = cgroup_reconfigure,
2100 : };
2101 :
2102 : static const struct fs_context_operations cgroup1_fs_context_ops = {
2103 : .free = cgroup_fs_context_free,
2104 : .parse_param = cgroup1_parse_param,
2105 : .get_tree = cgroup1_get_tree,
2106 : .reconfigure = cgroup1_reconfigure,
2107 : };
2108 :
2109 : /*
2110 : * Initialise the cgroup filesystem creation/reconfiguration context. Notably,
2111 : * we select the namespace we're going to use.
2112 : */
2113 2 : static int cgroup_init_fs_context(struct fs_context *fc)
2114 : {
2115 2 : struct cgroup_fs_context *ctx;
2116 :
2117 2 : ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL);
2118 2 : if (!ctx)
2119 : return -ENOMEM;
2120 :
2121 2 : ctx->ns = current->nsproxy->cgroup_ns;
2122 2 : get_cgroup_ns(ctx->ns);
2123 2 : fc->fs_private = &ctx->kfc;
2124 2 : if (fc->fs_type == &cgroup2_fs_type)
2125 1 : fc->ops = &cgroup_fs_context_ops;
2126 : else
2127 1 : fc->ops = &cgroup1_fs_context_ops;
2128 2 : put_user_ns(fc->user_ns);
2129 2 : fc->user_ns = get_user_ns(ctx->ns->user_ns);
2130 2 : fc->global = true;
2131 2 : return 0;
2132 : }
2133 :
2134 0 : static void cgroup_kill_sb(struct super_block *sb)
2135 : {
2136 0 : struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
2137 0 : struct cgroup_root *root = cgroup_root_from_kf(kf_root);
2138 :
2139 : /*
2140 : * If @root doesn't have any children, start killing it.
2141 : * This prevents new mounts by disabling percpu_ref_tryget_live().
2142 : * cgroup_mount() may wait for @root's release.
2143 : *
2144 : * And don't kill the default root.
2145 : */
2146 0 : if (list_empty(&root->cgrp.self.children) && root != &cgrp_dfl_root &&
2147 0 : !percpu_ref_is_dying(&root->cgrp.self.refcnt))
2148 0 : percpu_ref_kill(&root->cgrp.self.refcnt);
2149 0 : cgroup_put(&root->cgrp);
2150 0 : kernfs_kill_sb(sb);
2151 0 : }
2152 :
2153 : struct file_system_type cgroup_fs_type = {
2154 : .name = "cgroup",
2155 : .init_fs_context = cgroup_init_fs_context,
2156 : .parameters = cgroup1_fs_parameters,
2157 : .kill_sb = cgroup_kill_sb,
2158 : .fs_flags = FS_USERNS_MOUNT,
2159 : };
2160 :
2161 : static struct file_system_type cgroup2_fs_type = {
2162 : .name = "cgroup2",
2163 : .init_fs_context = cgroup_init_fs_context,
2164 : .parameters = cgroup2_fs_parameters,
2165 : .kill_sb = cgroup_kill_sb,
2166 : .fs_flags = FS_USERNS_MOUNT,
2167 : };
2168 :
2169 : #ifdef CONFIG_CPUSETS
2170 : static const struct fs_context_operations cpuset_fs_context_ops = {
2171 : .get_tree = cgroup1_get_tree,
2172 : .free = cgroup_fs_context_free,
2173 : };
2174 :
2175 : /*
2176 : * This is ugly, but preserves the userspace API for existing cpuset
2177 : * users. If someone tries to mount the "cpuset" filesystem, we
2178 : * silently switch it to mount "cgroup" instead
2179 : */
2180 : static int cpuset_init_fs_context(struct fs_context *fc)
2181 : {
2182 : char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER);
2183 : struct cgroup_fs_context *ctx;
2184 : int err;
2185 :
2186 : err = cgroup_init_fs_context(fc);
2187 : if (err) {
2188 : kfree(agent);
2189 : return err;
2190 : }
2191 :
2192 : fc->ops = &cpuset_fs_context_ops;
2193 :
2194 : ctx = cgroup_fc2context(fc);
2195 : ctx->subsys_mask = 1 << cpuset_cgrp_id;
2196 : ctx->flags |= CGRP_ROOT_NOPREFIX;
2197 : ctx->release_agent = agent;
2198 :
2199 : get_filesystem(&cgroup_fs_type);
2200 : put_filesystem(fc->fs_type);
2201 : fc->fs_type = &cgroup_fs_type;
2202 :
2203 : return 0;
2204 : }
2205 :
2206 : static struct file_system_type cpuset_fs_type = {
2207 : .name = "cpuset",
2208 : .init_fs_context = cpuset_init_fs_context,
2209 : .fs_flags = FS_USERNS_MOUNT,
2210 : };
2211 : #endif
2212 :
2213 312 : int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
2214 : struct cgroup_namespace *ns)
2215 : {
2216 312 : struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
2217 :
2218 312 : return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
2219 : }
2220 :
2221 0 : int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
2222 : struct cgroup_namespace *ns)
2223 : {
2224 0 : int ret;
2225 :
2226 0 : mutex_lock(&cgroup_mutex);
2227 0 : spin_lock_irq(&css_set_lock);
2228 :
2229 0 : ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
2230 :
2231 0 : spin_unlock_irq(&css_set_lock);
2232 0 : mutex_unlock(&cgroup_mutex);
2233 :
2234 0 : return ret;
2235 : }
2236 : EXPORT_SYMBOL_GPL(cgroup_path_ns);
2237 :
2238 : /**
2239 : * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
2240 : * @task: target task
2241 : * @buf: the buffer to write the path into
2242 : * @buflen: the length of the buffer
2243 : *
2244 : * Determine @task's cgroup on the first (the one with the lowest non-zero
2245 : * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
2246 : * function grabs cgroup_mutex and shouldn't be used inside locks used by
2247 : * cgroup controller callbacks.
2248 : *
2249 : * Return value is the same as kernfs_path().
2250 : */
2251 0 : int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
2252 : {
2253 0 : struct cgroup_root *root;
2254 0 : struct cgroup *cgrp;
2255 0 : int hierarchy_id = 1;
2256 0 : int ret;
2257 :
2258 0 : mutex_lock(&cgroup_mutex);
2259 0 : spin_lock_irq(&css_set_lock);
2260 :
2261 0 : root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
2262 :
2263 0 : if (root) {
2264 0 : cgrp = task_cgroup_from_root(task, root);
2265 0 : ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
2266 : } else {
2267 : /* if no hierarchy exists, everyone is in "/" */
2268 0 : ret = strlcpy(buf, "/", buflen);
2269 : }
2270 :
2271 0 : spin_unlock_irq(&css_set_lock);
2272 0 : mutex_unlock(&cgroup_mutex);
2273 0 : return ret;
2274 : }
2275 : EXPORT_SYMBOL_GPL(task_cgroup_path);
2276 :
2277 : /**
2278 : * cgroup_migrate_add_task - add a migration target task to a migration context
2279 : * @task: target task
2280 : * @mgctx: target migration context
2281 : *
2282 : * Add @task, which is a migration target, to @mgctx->tset. This function
2283 : * becomes noop if @task doesn't need to be migrated. @task's css_set
2284 : * should have been added as a migration source and @task->cg_list will be
2285 : * moved from the css_set's tasks list to mg_tasks one.
2286 : */
2287 198 : static void cgroup_migrate_add_task(struct task_struct *task,
2288 : struct cgroup_mgctx *mgctx)
2289 : {
2290 198 : struct css_set *cset;
2291 :
2292 594 : lockdep_assert_held(&css_set_lock);
2293 :
2294 : /* @task either already exited or can't exit until the end */
2295 198 : if (task->flags & PF_EXITING)
2296 : return;
2297 :
2298 : /* cgroup_threadgroup_rwsem protects racing against forks */
2299 198 : WARN_ON_ONCE(list_empty(&task->cg_list));
2300 :
2301 198 : cset = task_css_set(task);
2302 198 : if (!cset->mg_src_cgrp)
2303 : return;
2304 :
2305 106 : mgctx->tset.nr_tasks++;
2306 :
2307 106 : list_move_tail(&task->cg_list, &cset->mg_tasks);
2308 106 : if (list_empty(&cset->mg_node))
2309 106 : list_add_tail(&cset->mg_node,
2310 : &mgctx->tset.src_csets);
2311 106 : if (list_empty(&cset->mg_dst_cset->mg_node))
2312 106 : list_add_tail(&cset->mg_dst_cset->mg_node,
2313 : &mgctx->tset.dst_csets);
2314 : }
2315 :
2316 : /**
2317 : * cgroup_taskset_first - reset taskset and return the first task
2318 : * @tset: taskset of interest
2319 : * @dst_cssp: output variable for the destination css
2320 : *
2321 : * @tset iteration is initialized and the first task is returned.
2322 : */
2323 0 : struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
2324 : struct cgroup_subsys_state **dst_cssp)
2325 : {
2326 0 : tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
2327 0 : tset->cur_task = NULL;
2328 :
2329 0 : return cgroup_taskset_next(tset, dst_cssp);
2330 : }
2331 :
2332 : /**
2333 : * cgroup_taskset_next - iterate to the next task in taskset
2334 : * @tset: taskset of interest
2335 : * @dst_cssp: output variable for the destination css
2336 : *
2337 : * Return the next task in @tset. Iteration must have been initialized
2338 : * with cgroup_taskset_first().
2339 : */
2340 0 : struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
2341 : struct cgroup_subsys_state **dst_cssp)
2342 : {
2343 0 : struct css_set *cset = tset->cur_cset;
2344 0 : struct task_struct *task = tset->cur_task;
2345 :
2346 0 : while (&cset->mg_node != tset->csets) {
2347 0 : if (!task)
2348 0 : task = list_first_entry(&cset->mg_tasks,
2349 : struct task_struct, cg_list);
2350 : else
2351 0 : task = list_next_entry(task, cg_list);
2352 :
2353 0 : if (&task->cg_list != &cset->mg_tasks) {
2354 0 : tset->cur_cset = cset;
2355 0 : tset->cur_task = task;
2356 :
2357 : /*
2358 : * This function may be called both before and
2359 : * after cgroup_taskset_migrate(). The two cases
2360 : * can be distinguished by looking at whether @cset
2361 : * has its ->mg_dst_cset set.
2362 : */
2363 0 : if (cset->mg_dst_cset)
2364 0 : *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
2365 : else
2366 0 : *dst_cssp = cset->subsys[tset->ssid];
2367 :
2368 0 : return task;
2369 : }
2370 :
2371 0 : cset = list_next_entry(cset, mg_node);
2372 0 : task = NULL;
2373 : }
2374 :
2375 : return NULL;
2376 : }
2377 :
2378 : /**
2379 : * cgroup_taskset_migrate - migrate a taskset
2380 : * @mgctx: migration context
2381 : *
2382 : * Migrate tasks in @mgctx as setup by migration preparation functions.
2383 : * This function fails iff one of the ->can_attach callbacks fails and
2384 : * guarantees that either all or none of the tasks in @mgctx are migrated.
2385 : * @mgctx is consumed regardless of success.
2386 : */
2387 198 : static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
2388 : {
2389 198 : struct cgroup_taskset *tset = &mgctx->tset;
2390 198 : struct cgroup_subsys *ss;
2391 198 : struct task_struct *task, *tmp_task;
2392 198 : struct css_set *cset, *tmp_cset;
2393 198 : int ssid, failed_ssid, ret;
2394 :
2395 : /* check that we can legitimately attach to the cgroup */
2396 198 : if (tset->nr_tasks) {
2397 : do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
2398 : if (ss->can_attach) {
2399 : tset->ssid = ssid;
2400 : ret = ss->can_attach(tset);
2401 : if (ret) {
2402 : failed_ssid = ssid;
2403 : goto out_cancel_attach;
2404 : }
2405 : }
2406 198 : } while_each_subsys_mask();
2407 : }
2408 :
2409 : /*
2410 : * Now that we're guaranteed success, proceed to move all tasks to
2411 : * the new cgroup. There are no failure cases after here, so this
2412 : * is the commit point.
2413 : */
2414 198 : spin_lock_irq(&css_set_lock);
2415 304 : list_for_each_entry(cset, &tset->src_csets, mg_node) {
2416 212 : list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
2417 106 : struct css_set *from_cset = task_css_set(task);
2418 106 : struct css_set *to_cset = cset->mg_dst_cset;
2419 :
2420 106 : get_css_set(to_cset);
2421 106 : to_cset->nr_tasks++;
2422 106 : css_set_move_task(task, from_cset, to_cset, true);
2423 106 : from_cset->nr_tasks--;
2424 : /*
2425 : * If the source or destination cgroup is frozen,
2426 : * the task might require to change its state.
2427 : */
2428 106 : cgroup_freezer_migrate_task(task, from_cset->dfl_cgrp,
2429 : to_cset->dfl_cgrp);
2430 106 : put_css_set_locked(from_cset);
2431 :
2432 : }
2433 : }
2434 198 : spin_unlock_irq(&css_set_lock);
2435 :
2436 : /*
2437 : * Migration is committed, all target tasks are now on dst_csets.
2438 : * Nothing is sensitive to fork() after this point. Notify
2439 : * controllers that migration is complete.
2440 : */
2441 198 : tset->csets = &tset->dst_csets;
2442 :
2443 198 : if (tset->nr_tasks) {
2444 : do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
2445 : if (ss->attach) {
2446 : tset->ssid = ssid;
2447 : ss->attach(tset);
2448 : }
2449 198 : } while_each_subsys_mask();
2450 : }
2451 :
2452 198 : ret = 0;
2453 198 : goto out_release_tset;
2454 :
2455 : out_cancel_attach:
2456 : if (tset->nr_tasks) {
2457 : do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
2458 : if (ssid == failed_ssid)
2459 : break;
2460 : if (ss->cancel_attach) {
2461 : tset->ssid = ssid;
2462 : ss->cancel_attach(tset);
2463 : }
2464 198 : } while_each_subsys_mask();
2465 : }
2466 198 : out_release_tset:
2467 198 : spin_lock_irq(&css_set_lock);
2468 198 : list_splice_init(&tset->dst_csets, &tset->src_csets);
2469 410 : list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
2470 212 : list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
2471 212 : list_del_init(&cset->mg_node);
2472 : }
2473 198 : spin_unlock_irq(&css_set_lock);
2474 :
2475 : /*
2476 : * Re-initialize the cgroup_taskset structure in case it is reused
2477 : * again in another cgroup_migrate_add_task()/cgroup_migrate_execute()
2478 : * iteration.
2479 : */
2480 198 : tset->nr_tasks = 0;
2481 198 : tset->csets = &tset->src_csets;
2482 198 : return ret;
2483 : }
2484 :
2485 : /**
2486 : * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
2487 : * @dst_cgrp: destination cgroup to test
2488 : *
2489 : * On the default hierarchy, except for the mixable, (possible) thread root
2490 : * and threaded cgroups, subtree_control must be zero for migration
2491 : * destination cgroups with tasks so that child cgroups don't compete
2492 : * against tasks.
2493 : */
2494 99 : int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
2495 : {
2496 : /* v1 doesn't have any restriction */
2497 99 : if (!cgroup_on_dfl(dst_cgrp))
2498 : return 0;
2499 :
2500 : /* verify @dst_cgrp can host resources */
2501 99 : if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp))
2502 : return -EOPNOTSUPP;
2503 :
2504 : /* mixables don't care */
2505 99 : if (cgroup_is_mixable(dst_cgrp))
2506 : return 0;
2507 :
2508 : /*
2509 : * If @dst_cgrp is already or can become a thread root or is
2510 : * threaded, it doesn't matter.
2511 : */
2512 99 : if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp))
2513 : return 0;
2514 :
2515 : /* apply no-internal-process constraint */
2516 0 : if (dst_cgrp->subtree_control)
2517 0 : return -EBUSY;
2518 :
2519 : return 0;
2520 : }
2521 :
2522 : /**
2523 : * cgroup_migrate_finish - cleanup after attach
2524 : * @mgctx: migration context
2525 : *
2526 : * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
2527 : * those functions for details.
2528 : */
2529 198 : void cgroup_migrate_finish(struct cgroup_mgctx *mgctx)
2530 : {
2531 198 : LIST_HEAD(preloaded);
2532 198 : struct css_set *cset, *tmp_cset;
2533 :
2534 594 : lockdep_assert_held(&cgroup_mutex);
2535 :
2536 198 : spin_lock_irq(&css_set_lock);
2537 :
2538 198 : list_splice_tail_init(&mgctx->preloaded_src_csets, &preloaded);
2539 198 : list_splice_tail_init(&mgctx->preloaded_dst_csets, &preloaded);
2540 :
2541 410 : list_for_each_entry_safe(cset, tmp_cset, &preloaded, mg_preload_node) {
2542 212 : cset->mg_src_cgrp = NULL;
2543 212 : cset->mg_dst_cgrp = NULL;
2544 212 : cset->mg_dst_cset = NULL;
2545 212 : list_del_init(&cset->mg_preload_node);
2546 212 : put_css_set_locked(cset);
2547 : }
2548 :
2549 198 : spin_unlock_irq(&css_set_lock);
2550 198 : }
2551 :
2552 : /**
2553 : * cgroup_migrate_add_src - add a migration source css_set
2554 : * @src_cset: the source css_set to add
2555 : * @dst_cgrp: the destination cgroup
2556 : * @mgctx: migration context
2557 : *
2558 : * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
2559 : * @src_cset and add it to @mgctx->src_csets, which should later be cleaned
2560 : * up by cgroup_migrate_finish().
2561 : *
2562 : * This function may be called without holding cgroup_threadgroup_rwsem
2563 : * even if the target is a process. Threads may be created and destroyed
2564 : * but as long as cgroup_mutex is not dropped, no new css_set can be put
2565 : * into play and the preloaded css_sets are guaranteed to cover all
2566 : * migrations.
2567 : */
2568 198 : void cgroup_migrate_add_src(struct css_set *src_cset,
2569 : struct cgroup *dst_cgrp,
2570 : struct cgroup_mgctx *mgctx)
2571 : {
2572 198 : struct cgroup *src_cgrp;
2573 :
2574 594 : lockdep_assert_held(&cgroup_mutex);
2575 594 : lockdep_assert_held(&css_set_lock);
2576 :
2577 : /*
2578 : * If ->dead, @src_set is associated with one or more dead cgroups
2579 : * and doesn't contain any migratable tasks. Ignore it early so
2580 : * that the rest of migration path doesn't get confused by it.
2581 : */
2582 198 : if (src_cset->dead)
2583 : return;
2584 :
2585 198 : src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
2586 :
2587 198 : if (!list_empty(&src_cset->mg_preload_node))
2588 : return;
2589 :
2590 198 : WARN_ON(src_cset->mg_src_cgrp);
2591 198 : WARN_ON(src_cset->mg_dst_cgrp);
2592 198 : WARN_ON(!list_empty(&src_cset->mg_tasks));
2593 198 : WARN_ON(!list_empty(&src_cset->mg_node));
2594 :
2595 198 : src_cset->mg_src_cgrp = src_cgrp;
2596 198 : src_cset->mg_dst_cgrp = dst_cgrp;
2597 198 : get_css_set(src_cset);
2598 198 : list_add_tail(&src_cset->mg_preload_node, &mgctx->preloaded_src_csets);
2599 : }
2600 :
2601 : /**
2602 : * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
2603 : * @mgctx: migration context
2604 : *
2605 : * Tasks are about to be moved and all the source css_sets have been
2606 : * preloaded to @mgctx->preloaded_src_csets. This function looks up and
2607 : * pins all destination css_sets, links each to its source, and append them
2608 : * to @mgctx->preloaded_dst_csets.
2609 : *
2610 : * This function must be called after cgroup_migrate_add_src() has been
2611 : * called on each migration source css_set. After migration is performed
2612 : * using cgroup_migrate(), cgroup_migrate_finish() must be called on
2613 : * @mgctx.
2614 : */
2615 198 : int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
2616 : {
2617 198 : struct css_set *src_cset, *tmp_cset;
2618 :
2619 594 : lockdep_assert_held(&cgroup_mutex);
2620 :
2621 : /* look up the dst cset for each src cset and link it to src */
2622 396 : list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets,
2623 : mg_preload_node) {
2624 198 : struct css_set *dst_cset;
2625 198 : struct cgroup_subsys *ss;
2626 198 : int ssid;
2627 :
2628 198 : dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp);
2629 198 : if (!dst_cset)
2630 : return -ENOMEM;
2631 :
2632 396 : WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
2633 :
2634 : /*
2635 : * If src cset equals dst, it's noop. Drop the src.
2636 : * cgroup_migrate() will skip the cset too. Note that we
2637 : * can't handle src == dst as some nodes are used by both.
2638 : */
2639 198 : if (src_cset == dst_cset) {
2640 92 : src_cset->mg_src_cgrp = NULL;
2641 92 : src_cset->mg_dst_cgrp = NULL;
2642 92 : list_del_init(&src_cset->mg_preload_node);
2643 92 : put_css_set(src_cset);
2644 92 : put_css_set(dst_cset);
2645 92 : continue;
2646 : }
2647 :
2648 106 : src_cset->mg_dst_cset = dst_cset;
2649 :
2650 106 : if (list_empty(&dst_cset->mg_preload_node))
2651 198 : list_add_tail(&dst_cset->mg_preload_node,
2652 : &mgctx->preloaded_dst_csets);
2653 : else
2654 0 : put_css_set(dst_cset);
2655 :
2656 : for_each_subsys(ss, ssid)
2657 : if (src_cset->subsys[ssid] != dst_cset->subsys[ssid])
2658 : mgctx->ss_mask |= 1 << ssid;
2659 : }
2660 :
2661 : return 0;
2662 : }
2663 :
2664 : /**
2665 : * cgroup_migrate - migrate a process or task to a cgroup
2666 : * @leader: the leader of the process or the task to migrate
2667 : * @threadgroup: whether @leader points to the whole process or a single task
2668 : * @mgctx: migration context
2669 : *
2670 : * Migrate a process or task denoted by @leader. If migrating a process,
2671 : * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
2672 : * responsible for invoking cgroup_migrate_add_src() and
2673 : * cgroup_migrate_prepare_dst() on the targets before invoking this
2674 : * function and following up with cgroup_migrate_finish().
2675 : *
2676 : * As long as a controller's ->can_attach() doesn't fail, this function is
2677 : * guaranteed to succeed. This means that, excluding ->can_attach()
2678 : * failure, when migrating multiple targets, the success or failure can be
2679 : * decided for all targets by invoking group_migrate_prepare_dst() before
2680 : * actually starting migrating.
2681 : */
2682 198 : int cgroup_migrate(struct task_struct *leader, bool threadgroup,
2683 : struct cgroup_mgctx *mgctx)
2684 : {
2685 198 : struct task_struct *task;
2686 :
2687 : /*
2688 : * Prevent freeing of tasks while we take a snapshot. Tasks that are
2689 : * already PF_EXITING could be freed from underneath us unless we
2690 : * take an rcu_read_lock.
2691 : */
2692 198 : spin_lock_irq(&css_set_lock);
2693 198 : rcu_read_lock();
2694 : task = leader;
2695 198 : do {
2696 198 : cgroup_migrate_add_task(task, mgctx);
2697 198 : if (!threadgroup)
2698 : break;
2699 198 : } while_each_thread(leader, task);
2700 198 : rcu_read_unlock();
2701 198 : spin_unlock_irq(&css_set_lock);
2702 :
2703 198 : return cgroup_migrate_execute(mgctx);
2704 : }
2705 :
2706 : /**
2707 : * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
2708 : * @dst_cgrp: the cgroup to attach to
2709 : * @leader: the task or the leader of the threadgroup to be attached
2710 : * @threadgroup: attach the whole threadgroup?
2711 : *
2712 : * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
2713 : */
2714 198 : int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
2715 : bool threadgroup)
2716 : {
2717 198 : DEFINE_CGROUP_MGCTX(mgctx);
2718 198 : struct task_struct *task;
2719 198 : int ret = 0;
2720 :
2721 : /* look up all src csets */
2722 198 : spin_lock_irq(&css_set_lock);
2723 198 : rcu_read_lock();
2724 : task = leader;
2725 198 : do {
2726 198 : cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx);
2727 198 : if (!threadgroup)
2728 : break;
2729 198 : } while_each_thread(leader, task);
2730 198 : rcu_read_unlock();
2731 198 : spin_unlock_irq(&css_set_lock);
2732 :
2733 : /* prepare dst csets and commit */
2734 198 : ret = cgroup_migrate_prepare_dst(&mgctx);
2735 198 : if (!ret)
2736 198 : ret = cgroup_migrate(leader, threadgroup, &mgctx);
2737 :
2738 198 : cgroup_migrate_finish(&mgctx);
2739 :
2740 198 : if (!ret)
2741 198 : TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup);
2742 :
2743 198 : return ret;
2744 : }
2745 :
2746 198 : struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
2747 : bool *locked)
2748 : __acquires(&cgroup_threadgroup_rwsem)
2749 : {
2750 198 : struct task_struct *tsk;
2751 198 : pid_t pid;
2752 :
2753 198 : if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
2754 198 : return ERR_PTR(-EINVAL);
2755 :
2756 : /*
2757 : * If we migrate a single thread, we don't care about threadgroup
2758 : * stability. If the thread is `current`, it won't exit(2) under our
2759 : * hands or change PID through exec(2). We exclude
2760 : * cgroup_update_dfl_csses and other cgroup_{proc,thread}s_write
2761 : * callers by cgroup_mutex.
2762 : * Therefore, we can skip the global lock.
2763 : */
2764 594 : lockdep_assert_held(&cgroup_mutex);
2765 198 : if (pid || threadgroup) {
2766 198 : percpu_down_write(&cgroup_threadgroup_rwsem);
2767 198 : *locked = true;
2768 : } else {
2769 0 : *locked = false;
2770 : }
2771 :
2772 198 : rcu_read_lock();
2773 198 : if (pid) {
2774 198 : tsk = find_task_by_vpid(pid);
2775 198 : if (!tsk) {
2776 0 : tsk = ERR_PTR(-ESRCH);
2777 0 : goto out_unlock_threadgroup;
2778 : }
2779 : } else {
2780 0 : tsk = current;
2781 : }
2782 :
2783 198 : if (threadgroup)
2784 198 : tsk = tsk->group_leader;
2785 :
2786 : /*
2787 : * kthreads may acquire PF_NO_SETAFFINITY during initialization.
2788 : * If userland migrates such a kthread to a non-root cgroup, it can
2789 : * become trapped in a cpuset, or RT kthread may be born in a
2790 : * cgroup with no rt_runtime allocated. Just say no.
2791 : */
2792 198 : if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) {
2793 0 : tsk = ERR_PTR(-EINVAL);
2794 0 : goto out_unlock_threadgroup;
2795 : }
2796 :
2797 198 : get_task_struct(tsk);
2798 198 : goto out_unlock_rcu;
2799 :
2800 0 : out_unlock_threadgroup:
2801 0 : if (*locked) {
2802 0 : percpu_up_write(&cgroup_threadgroup_rwsem);
2803 0 : *locked = false;
2804 : }
2805 0 : out_unlock_rcu:
2806 198 : rcu_read_unlock();
2807 198 : return tsk;
2808 : }
2809 :
2810 198 : void cgroup_procs_write_finish(struct task_struct *task, bool locked)
2811 : __releases(&cgroup_threadgroup_rwsem)
2812 : {
2813 198 : struct cgroup_subsys *ss;
2814 198 : int ssid;
2815 :
2816 : /* release reference from cgroup_procs_write_start() */
2817 198 : put_task_struct(task);
2818 :
2819 198 : if (locked)
2820 198 : percpu_up_write(&cgroup_threadgroup_rwsem);
2821 198 : for_each_subsys(ss, ssid)
2822 : if (ss->post_attach)
2823 : ss->post_attach();
2824 198 : }
2825 :
2826 0 : static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
2827 : {
2828 0 : struct cgroup_subsys *ss;
2829 0 : bool printed = false;
2830 0 : int ssid;
2831 :
2832 0 : do_each_subsys_mask(ss, ssid, ss_mask) {
2833 : if (printed)
2834 : seq_putc(seq, ' ');
2835 : seq_puts(seq, ss->name);
2836 : printed = true;
2837 0 : } while_each_subsys_mask();
2838 0 : if (printed)
2839 : seq_putc(seq, '\n');
2840 : }
2841 :
2842 : /* show controllers which are enabled from the parent */
2843 0 : static int cgroup_controllers_show(struct seq_file *seq, void *v)
2844 : {
2845 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
2846 :
2847 0 : cgroup_print_ss_mask(seq, cgroup_control(cgrp));
2848 0 : return 0;
2849 : }
2850 :
2851 : /* show controllers which are enabled for a given cgroup's children */
2852 0 : static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
2853 : {
2854 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
2855 :
2856 0 : cgroup_print_ss_mask(seq, cgrp->subtree_control);
2857 0 : return 0;
2858 : }
2859 :
2860 : /**
2861 : * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
2862 : * @cgrp: root of the subtree to update csses for
2863 : *
2864 : * @cgrp's control masks have changed and its subtree's css associations
2865 : * need to be updated accordingly. This function looks up all css_sets
2866 : * which are attached to the subtree, creates the matching updated css_sets
2867 : * and migrates the tasks to the new ones.
2868 : */
2869 0 : static int cgroup_update_dfl_csses(struct cgroup *cgrp)
2870 : {
2871 0 : DEFINE_CGROUP_MGCTX(mgctx);
2872 0 : struct cgroup_subsys_state *d_css;
2873 0 : struct cgroup *dsct;
2874 0 : struct css_set *src_cset;
2875 0 : int ret;
2876 :
2877 0 : lockdep_assert_held(&cgroup_mutex);
2878 :
2879 0 : percpu_down_write(&cgroup_threadgroup_rwsem);
2880 :
2881 : /* look up all csses currently attached to @cgrp's subtree */
2882 0 : spin_lock_irq(&css_set_lock);
2883 0 : cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
2884 0 : struct cgrp_cset_link *link;
2885 :
2886 0 : list_for_each_entry(link, &dsct->cset_links, cset_link)
2887 0 : cgroup_migrate_add_src(link->cset, dsct, &mgctx);
2888 : }
2889 0 : spin_unlock_irq(&css_set_lock);
2890 :
2891 : /* NULL dst indicates self on default hierarchy */
2892 0 : ret = cgroup_migrate_prepare_dst(&mgctx);
2893 0 : if (ret)
2894 0 : goto out_finish;
2895 :
2896 0 : spin_lock_irq(&css_set_lock);
2897 0 : list_for_each_entry(src_cset, &mgctx.preloaded_src_csets, mg_preload_node) {
2898 0 : struct task_struct *task, *ntask;
2899 :
2900 : /* all tasks in src_csets need to be migrated */
2901 0 : list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
2902 0 : cgroup_migrate_add_task(task, &mgctx);
2903 : }
2904 0 : spin_unlock_irq(&css_set_lock);
2905 :
2906 0 : ret = cgroup_migrate_execute(&mgctx);
2907 0 : out_finish:
2908 0 : cgroup_migrate_finish(&mgctx);
2909 0 : percpu_up_write(&cgroup_threadgroup_rwsem);
2910 0 : return ret;
2911 : }
2912 :
2913 : /**
2914 : * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
2915 : * @cgrp: root of the target subtree
2916 : *
2917 : * Because css offlining is asynchronous, userland may try to re-enable a
2918 : * controller while the previous css is still around. This function grabs
2919 : * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
2920 : */
2921 1 : void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
2922 : __acquires(&cgroup_mutex)
2923 : {
2924 1 : struct cgroup *dsct;
2925 1 : struct cgroup_subsys_state *d_css;
2926 1 : struct cgroup_subsys *ss;
2927 1 : int ssid;
2928 :
2929 1 : restart:
2930 1 : mutex_lock(&cgroup_mutex);
2931 :
2932 3 : cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
2933 : for_each_subsys(ss, ssid) {
2934 : struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
2935 : DEFINE_WAIT(wait);
2936 :
2937 : if (!css || !percpu_ref_is_dying(&css->refcnt))
2938 : continue;
2939 :
2940 : cgroup_get_live(dsct);
2941 : prepare_to_wait(&dsct->offline_waitq, &wait,
2942 : TASK_UNINTERRUPTIBLE);
2943 :
2944 : mutex_unlock(&cgroup_mutex);
2945 : schedule();
2946 : finish_wait(&dsct->offline_waitq, &wait);
2947 :
2948 : cgroup_put(dsct);
2949 : goto restart;
2950 : }
2951 : }
2952 1 : }
2953 :
2954 : /**
2955 : * cgroup_save_control - save control masks and dom_cgrp of a subtree
2956 : * @cgrp: root of the target subtree
2957 : *
2958 : * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the
2959 : * respective old_ prefixed fields for @cgrp's subtree including @cgrp
2960 : * itself.
2961 : */
2962 0 : static void cgroup_save_control(struct cgroup *cgrp)
2963 : {
2964 0 : struct cgroup *dsct;
2965 0 : struct cgroup_subsys_state *d_css;
2966 :
2967 0 : cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
2968 0 : dsct->old_subtree_control = dsct->subtree_control;
2969 0 : dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
2970 0 : dsct->old_dom_cgrp = dsct->dom_cgrp;
2971 : }
2972 0 : }
2973 :
2974 : /**
2975 : * cgroup_propagate_control - refresh control masks of a subtree
2976 : * @cgrp: root of the target subtree
2977 : *
2978 : * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
2979 : * ->subtree_control and propagate controller availability through the
2980 : * subtree so that descendants don't have unavailable controllers enabled.
2981 : */
2982 98 : static void cgroup_propagate_control(struct cgroup *cgrp)
2983 : {
2984 98 : struct cgroup *dsct;
2985 98 : struct cgroup_subsys_state *d_css;
2986 :
2987 392 : cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
2988 98 : dsct->subtree_control &= cgroup_control(dsct);
2989 98 : dsct->subtree_ss_mask =
2990 98 : cgroup_calc_subtree_ss_mask(dsct->subtree_control,
2991 98 : cgroup_ss_mask(dsct));
2992 : }
2993 98 : }
2994 :
2995 : /**
2996 : * cgroup_restore_control - restore control masks and dom_cgrp of a subtree
2997 : * @cgrp: root of the target subtree
2998 : *
2999 : * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the
3000 : * respective old_ prefixed fields for @cgrp's subtree including @cgrp
3001 : * itself.
3002 : */
3003 0 : static void cgroup_restore_control(struct cgroup *cgrp)
3004 : {
3005 0 : struct cgroup *dsct;
3006 0 : struct cgroup_subsys_state *d_css;
3007 :
3008 0 : cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
3009 0 : dsct->subtree_control = dsct->old_subtree_control;
3010 0 : dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
3011 0 : dsct->dom_cgrp = dsct->old_dom_cgrp;
3012 : }
3013 0 : }
3014 :
3015 : static bool css_visible(struct cgroup_subsys_state *css)
3016 : {
3017 : struct cgroup_subsys *ss = css->ss;
3018 : struct cgroup *cgrp = css->cgroup;
3019 :
3020 : if (cgroup_control(cgrp) & (1 << ss->id))
3021 : return true;
3022 : if (!(cgroup_ss_mask(cgrp) & (1 << ss->id)))
3023 : return false;
3024 : return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl;
3025 : }
3026 :
3027 : /**
3028 : * cgroup_apply_control_enable - enable or show csses according to control
3029 : * @cgrp: root of the target subtree
3030 : *
3031 : * Walk @cgrp's subtree and create new csses or make the existing ones
3032 : * visible. A css is created invisible if it's being implicitly enabled
3033 : * through dependency. An invisible css is made visible when the userland
3034 : * explicitly enables it.
3035 : *
3036 : * Returns 0 on success, -errno on failure. On failure, csses which have
3037 : * been processed already aren't cleaned up. The caller is responsible for
3038 : * cleaning up with cgroup_apply_control_disable().
3039 : */
3040 98 : static int cgroup_apply_control_enable(struct cgroup *cgrp)
3041 : {
3042 98 : struct cgroup *dsct;
3043 98 : struct cgroup_subsys_state *d_css;
3044 98 : struct cgroup_subsys *ss;
3045 98 : int ssid, ret;
3046 :
3047 294 : cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
3048 : for_each_subsys(ss, ssid) {
3049 : struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
3050 :
3051 : if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
3052 : continue;
3053 :
3054 : if (!css) {
3055 : css = css_create(dsct, ss);
3056 : if (IS_ERR(css))
3057 : return PTR_ERR(css);
3058 : }
3059 :
3060 : WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
3061 :
3062 : if (css_visible(css)) {
3063 : ret = css_populate_dir(css);
3064 : if (ret)
3065 : return ret;
3066 : }
3067 : }
3068 : }
3069 :
3070 98 : return 0;
3071 : }
3072 :
3073 : /**
3074 : * cgroup_apply_control_disable - kill or hide csses according to control
3075 : * @cgrp: root of the target subtree
3076 : *
3077 : * Walk @cgrp's subtree and kill and hide csses so that they match
3078 : * cgroup_ss_mask() and cgroup_visible_mask().
3079 : *
3080 : * A css is hidden when the userland requests it to be disabled while other
3081 : * subsystems are still depending on it. The css must not actively control
3082 : * resources and be in the vanilla state if it's made visible again later.
3083 : * Controllers which may be depended upon should provide ->css_reset() for
3084 : * this purpose.
3085 : */
3086 0 : static void cgroup_apply_control_disable(struct cgroup *cgrp)
3087 : {
3088 0 : struct cgroup *dsct;
3089 0 : struct cgroup_subsys_state *d_css;
3090 0 : struct cgroup_subsys *ss;
3091 0 : int ssid;
3092 :
3093 0 : cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
3094 : for_each_subsys(ss, ssid) {
3095 : struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
3096 :
3097 : if (!css)
3098 : continue;
3099 :
3100 : WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
3101 :
3102 : if (css->parent &&
3103 : !(cgroup_ss_mask(dsct) & (1 << ss->id))) {
3104 : kill_css(css);
3105 : } else if (!css_visible(css)) {
3106 : css_clear_dir(css);
3107 : if (ss->css_reset)
3108 : ss->css_reset(css);
3109 : }
3110 : }
3111 : }
3112 0 : }
3113 :
3114 : /**
3115 : * cgroup_apply_control - apply control mask updates to the subtree
3116 : * @cgrp: root of the target subtree
3117 : *
3118 : * subsystems can be enabled and disabled in a subtree using the following
3119 : * steps.
3120 : *
3121 : * 1. Call cgroup_save_control() to stash the current state.
3122 : * 2. Update ->subtree_control masks in the subtree as desired.
3123 : * 3. Call cgroup_apply_control() to apply the changes.
3124 : * 4. Optionally perform other related operations.
3125 : * 5. Call cgroup_finalize_control() to finish up.
3126 : *
3127 : * This function implements step 3 and propagates the mask changes
3128 : * throughout @cgrp's subtree, updates csses accordingly and perform
3129 : * process migrations.
3130 : */
3131 0 : static int cgroup_apply_control(struct cgroup *cgrp)
3132 : {
3133 0 : int ret;
3134 :
3135 0 : cgroup_propagate_control(cgrp);
3136 :
3137 0 : ret = cgroup_apply_control_enable(cgrp);
3138 0 : if (ret)
3139 : return ret;
3140 :
3141 : /*
3142 : * At this point, cgroup_e_css_by_mask() results reflect the new csses
3143 : * making the following cgroup_update_dfl_csses() properly update
3144 : * css associations of all tasks in the subtree.
3145 : */
3146 0 : ret = cgroup_update_dfl_csses(cgrp);
3147 0 : if (ret)
3148 0 : return ret;
3149 :
3150 : return 0;
3151 : }
3152 :
3153 : /**
3154 : * cgroup_finalize_control - finalize control mask update
3155 : * @cgrp: root of the target subtree
3156 : * @ret: the result of the update
3157 : *
3158 : * Finalize control mask update. See cgroup_apply_control() for more info.
3159 : */
3160 0 : static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
3161 : {
3162 0 : if (ret) {
3163 0 : cgroup_restore_control(cgrp);
3164 0 : cgroup_propagate_control(cgrp);
3165 : }
3166 :
3167 0 : cgroup_apply_control_disable(cgrp);
3168 0 : }
3169 :
3170 : static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable)
3171 : {
3172 : u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask;
3173 :
3174 : /* if nothing is getting enabled, nothing to worry about */
3175 : if (!enable)
3176 : return 0;
3177 :
3178 : /* can @cgrp host any resources? */
3179 : if (!cgroup_is_valid_domain(cgrp->dom_cgrp))
3180 : return -EOPNOTSUPP;
3181 :
3182 : /* mixables don't care */
3183 : if (cgroup_is_mixable(cgrp))
3184 : return 0;
3185 :
3186 : if (domain_enable) {
3187 : /* can't enable domain controllers inside a thread subtree */
3188 : if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp))
3189 : return -EOPNOTSUPP;
3190 : } else {
3191 : /*
3192 : * Threaded controllers can handle internal competitions
3193 : * and are always allowed inside a (prospective) thread
3194 : * subtree.
3195 : */
3196 : if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp))
3197 : return 0;
3198 : }
3199 :
3200 : /*
3201 : * Controllers can't be enabled for a cgroup with tasks to avoid
3202 : * child cgroups competing against tasks.
3203 : */
3204 : if (cgroup_has_tasks(cgrp))
3205 : return -EBUSY;
3206 :
3207 : return 0;
3208 : }
3209 :
3210 : /* change the enabled child controllers for a cgroup in the default hierarchy */
3211 0 : static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
3212 : char *buf, size_t nbytes,
3213 : loff_t off)
3214 : {
3215 0 : u16 enable = 0, disable = 0;
3216 0 : struct cgroup *cgrp, *child;
3217 0 : struct cgroup_subsys *ss;
3218 0 : char *tok;
3219 0 : int ssid, ret;
3220 :
3221 : /*
3222 : * Parse input - space separated list of subsystem names prefixed
3223 : * with either + or -.
3224 : */
3225 0 : buf = strstrip(buf);
3226 0 : while ((tok = strsep(&buf, " "))) {
3227 0 : if (tok[0] == '\0')
3228 0 : continue;
3229 0 : do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
3230 : if (!cgroup_ssid_enabled(ssid) ||
3231 : strcmp(tok + 1, ss->name))
3232 : continue;
3233 :
3234 : if (*tok == '+') {
3235 : enable |= 1 << ssid;
3236 : disable &= ~(1 << ssid);
3237 : } else if (*tok == '-') {
3238 : disable |= 1 << ssid;
3239 : enable &= ~(1 << ssid);
3240 : } else {
3241 : return -EINVAL;
3242 : }
3243 : break;
3244 : } while_each_subsys_mask();
3245 : if (ssid == CGROUP_SUBSYS_COUNT)
3246 : return -EINVAL;
3247 : }
3248 :
3249 0 : cgrp = cgroup_kn_lock_live(of->kn, true);
3250 0 : if (!cgrp)
3251 : return -ENODEV;
3252 :
3253 0 : for_each_subsys(ss, ssid) {
3254 : if (enable & (1 << ssid)) {
3255 : if (cgrp->subtree_control & (1 << ssid)) {
3256 : enable &= ~(1 << ssid);
3257 : continue;
3258 : }
3259 :
3260 : if (!(cgroup_control(cgrp) & (1 << ssid))) {
3261 : ret = -ENOENT;
3262 : goto out_unlock;
3263 : }
3264 : } else if (disable & (1 << ssid)) {
3265 : if (!(cgrp->subtree_control & (1 << ssid))) {
3266 : disable &= ~(1 << ssid);
3267 : continue;
3268 : }
3269 :
3270 : /* a child has it enabled? */
3271 : cgroup_for_each_live_child(child, cgrp) {
3272 : if (child->subtree_control & (1 << ssid)) {
3273 : ret = -EBUSY;
3274 : goto out_unlock;
3275 : }
3276 : }
3277 : }
3278 : }
3279 :
3280 0 : if (!enable && !disable) {
3281 0 : ret = 0;
3282 0 : goto out_unlock;
3283 : }
3284 :
3285 : ret = cgroup_vet_subtree_control_enable(cgrp, enable);
3286 : if (ret)
3287 : goto out_unlock;
3288 :
3289 : /* save and update control masks and prepare csses */
3290 : cgroup_save_control(cgrp);
3291 :
3292 : cgrp->subtree_control |= enable;
3293 : cgrp->subtree_control &= ~disable;
3294 :
3295 : ret = cgroup_apply_control(cgrp);
3296 : cgroup_finalize_control(cgrp, ret);
3297 : if (ret)
3298 : goto out_unlock;
3299 :
3300 : kernfs_activate(cgrp->kn);
3301 0 : out_unlock:
3302 0 : cgroup_kn_unlock(of->kn);
3303 0 : return ret ?: nbytes;
3304 : }
3305 :
3306 : /**
3307 : * cgroup_enable_threaded - make @cgrp threaded
3308 : * @cgrp: the target cgroup
3309 : *
3310 : * Called when "threaded" is written to the cgroup.type interface file and
3311 : * tries to make @cgrp threaded and join the parent's resource domain.
3312 : * This function is never called on the root cgroup as cgroup.type doesn't
3313 : * exist on it.
3314 : */
3315 0 : static int cgroup_enable_threaded(struct cgroup *cgrp)
3316 : {
3317 0 : struct cgroup *parent = cgroup_parent(cgrp);
3318 0 : struct cgroup *dom_cgrp = parent->dom_cgrp;
3319 0 : struct cgroup *dsct;
3320 0 : struct cgroup_subsys_state *d_css;
3321 0 : int ret;
3322 :
3323 0 : lockdep_assert_held(&cgroup_mutex);
3324 :
3325 : /* noop if already threaded */
3326 0 : if (cgroup_is_threaded(cgrp))
3327 : return 0;
3328 :
3329 : /*
3330 : * If @cgroup is populated or has domain controllers enabled, it
3331 : * can't be switched. While the below cgroup_can_be_thread_root()
3332 : * test can catch the same conditions, that's only when @parent is
3333 : * not mixable, so let's check it explicitly.
3334 : */
3335 0 : if (cgroup_is_populated(cgrp) ||
3336 0 : cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
3337 : return -EOPNOTSUPP;
3338 :
3339 : /* we're joining the parent's domain, ensure its validity */
3340 0 : if (!cgroup_is_valid_domain(dom_cgrp) ||
3341 0 : !cgroup_can_be_thread_root(dom_cgrp))
3342 : return -EOPNOTSUPP;
3343 :
3344 : /*
3345 : * The following shouldn't cause actual migrations and should
3346 : * always succeed.
3347 : */
3348 0 : cgroup_save_control(cgrp);
3349 :
3350 0 : cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp)
3351 0 : if (dsct == cgrp || cgroup_is_threaded(dsct))
3352 0 : dsct->dom_cgrp = dom_cgrp;
3353 :
3354 0 : ret = cgroup_apply_control(cgrp);
3355 0 : if (!ret)
3356 0 : parent->nr_threaded_children++;
3357 :
3358 0 : cgroup_finalize_control(cgrp, ret);
3359 0 : return ret;
3360 : }
3361 :
3362 0 : static int cgroup_type_show(struct seq_file *seq, void *v)
3363 : {
3364 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3365 :
3366 0 : if (cgroup_is_threaded(cgrp))
3367 0 : seq_puts(seq, "threaded\n");
3368 0 : else if (!cgroup_is_valid_domain(cgrp))
3369 0 : seq_puts(seq, "domain invalid\n");
3370 0 : else if (cgroup_is_thread_root(cgrp))
3371 0 : seq_puts(seq, "domain threaded\n");
3372 : else
3373 0 : seq_puts(seq, "domain\n");
3374 :
3375 0 : return 0;
3376 : }
3377 :
3378 0 : static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf,
3379 : size_t nbytes, loff_t off)
3380 : {
3381 0 : struct cgroup *cgrp;
3382 0 : int ret;
3383 :
3384 : /* only switching to threaded mode is supported */
3385 0 : if (strcmp(strstrip(buf), "threaded"))
3386 : return -EINVAL;
3387 :
3388 : /* drain dying csses before we re-apply (threaded) subtree control */
3389 0 : cgrp = cgroup_kn_lock_live(of->kn, true);
3390 0 : if (!cgrp)
3391 : return -ENOENT;
3392 :
3393 : /* threaded can only be enabled */
3394 0 : ret = cgroup_enable_threaded(cgrp);
3395 :
3396 0 : cgroup_kn_unlock(of->kn);
3397 0 : return ret ?: nbytes;
3398 : }
3399 :
3400 0 : static int cgroup_max_descendants_show(struct seq_file *seq, void *v)
3401 : {
3402 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3403 0 : int descendants = READ_ONCE(cgrp->max_descendants);
3404 :
3405 0 : if (descendants == INT_MAX)
3406 0 : seq_puts(seq, "max\n");
3407 : else
3408 0 : seq_printf(seq, "%d\n", descendants);
3409 :
3410 0 : return 0;
3411 : }
3412 :
3413 0 : static ssize_t cgroup_max_descendants_write(struct kernfs_open_file *of,
3414 : char *buf, size_t nbytes, loff_t off)
3415 : {
3416 0 : struct cgroup *cgrp;
3417 0 : int descendants;
3418 0 : ssize_t ret;
3419 :
3420 0 : buf = strstrip(buf);
3421 0 : if (!strcmp(buf, "max")) {
3422 0 : descendants = INT_MAX;
3423 : } else {
3424 0 : ret = kstrtoint(buf, 0, &descendants);
3425 0 : if (ret)
3426 : return ret;
3427 : }
3428 :
3429 0 : if (descendants < 0)
3430 : return -ERANGE;
3431 :
3432 0 : cgrp = cgroup_kn_lock_live(of->kn, false);
3433 0 : if (!cgrp)
3434 : return -ENOENT;
3435 :
3436 0 : cgrp->max_descendants = descendants;
3437 :
3438 0 : cgroup_kn_unlock(of->kn);
3439 :
3440 0 : return nbytes;
3441 : }
3442 :
3443 0 : static int cgroup_max_depth_show(struct seq_file *seq, void *v)
3444 : {
3445 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3446 0 : int depth = READ_ONCE(cgrp->max_depth);
3447 :
3448 0 : if (depth == INT_MAX)
3449 0 : seq_puts(seq, "max\n");
3450 : else
3451 0 : seq_printf(seq, "%d\n", depth);
3452 :
3453 0 : return 0;
3454 : }
3455 :
3456 0 : static ssize_t cgroup_max_depth_write(struct kernfs_open_file *of,
3457 : char *buf, size_t nbytes, loff_t off)
3458 : {
3459 0 : struct cgroup *cgrp;
3460 0 : ssize_t ret;
3461 0 : int depth;
3462 :
3463 0 : buf = strstrip(buf);
3464 0 : if (!strcmp(buf, "max")) {
3465 0 : depth = INT_MAX;
3466 : } else {
3467 0 : ret = kstrtoint(buf, 0, &depth);
3468 0 : if (ret)
3469 : return ret;
3470 : }
3471 :
3472 0 : if (depth < 0)
3473 : return -ERANGE;
3474 :
3475 0 : cgrp = cgroup_kn_lock_live(of->kn, false);
3476 0 : if (!cgrp)
3477 : return -ENOENT;
3478 :
3479 0 : cgrp->max_depth = depth;
3480 :
3481 0 : cgroup_kn_unlock(of->kn);
3482 :
3483 0 : return nbytes;
3484 : }
3485 :
3486 62 : static int cgroup_events_show(struct seq_file *seq, void *v)
3487 : {
3488 62 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3489 :
3490 62 : seq_printf(seq, "populated %d\n", cgroup_is_populated(cgrp));
3491 62 : seq_printf(seq, "frozen %d\n", test_bit(CGRP_FROZEN, &cgrp->flags));
3492 :
3493 62 : return 0;
3494 : }
3495 :
3496 0 : static int cgroup_stat_show(struct seq_file *seq, void *v)
3497 : {
3498 0 : struct cgroup *cgroup = seq_css(seq)->cgroup;
3499 :
3500 0 : seq_printf(seq, "nr_descendants %d\n",
3501 : cgroup->nr_descendants);
3502 0 : seq_printf(seq, "nr_dying_descendants %d\n",
3503 : cgroup->nr_dying_descendants);
3504 :
3505 0 : return 0;
3506 : }
3507 :
3508 : static int __maybe_unused cgroup_extra_stat_show(struct seq_file *seq,
3509 : struct cgroup *cgrp, int ssid)
3510 : {
3511 : struct cgroup_subsys *ss = cgroup_subsys[ssid];
3512 : struct cgroup_subsys_state *css;
3513 : int ret;
3514 :
3515 : if (!ss->css_extra_stat_show)
3516 : return 0;
3517 :
3518 : css = cgroup_tryget_css(cgrp, ss);
3519 : if (!css)
3520 : return 0;
3521 :
3522 : ret = ss->css_extra_stat_show(seq, css);
3523 : css_put(css);
3524 : return ret;
3525 : }
3526 :
3527 0 : static int cpu_stat_show(struct seq_file *seq, void *v)
3528 : {
3529 0 : struct cgroup __maybe_unused *cgrp = seq_css(seq)->cgroup;
3530 0 : int ret = 0;
3531 :
3532 0 : cgroup_base_stat_cputime_show(seq);
3533 : #ifdef CONFIG_CGROUP_SCHED
3534 : ret = cgroup_extra_stat_show(seq, cgrp, cpu_cgrp_id);
3535 : #endif
3536 0 : return ret;
3537 : }
3538 :
3539 : #ifdef CONFIG_PSI
3540 : static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
3541 : {
3542 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3543 : struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
3544 :
3545 : return psi_show(seq, psi, PSI_IO);
3546 : }
3547 : static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
3548 : {
3549 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3550 : struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
3551 :
3552 : return psi_show(seq, psi, PSI_MEM);
3553 : }
3554 : static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
3555 : {
3556 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3557 : struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
3558 :
3559 : return psi_show(seq, psi, PSI_CPU);
3560 : }
3561 :
3562 : static ssize_t cgroup_pressure_write(struct kernfs_open_file *of, char *buf,
3563 : size_t nbytes, enum psi_res res)
3564 : {
3565 : struct psi_trigger *new;
3566 : struct cgroup *cgrp;
3567 : struct psi_group *psi;
3568 :
3569 : cgrp = cgroup_kn_lock_live(of->kn, false);
3570 : if (!cgrp)
3571 : return -ENODEV;
3572 :
3573 : cgroup_get(cgrp);
3574 : cgroup_kn_unlock(of->kn);
3575 :
3576 : psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
3577 : new = psi_trigger_create(psi, buf, nbytes, res);
3578 : if (IS_ERR(new)) {
3579 : cgroup_put(cgrp);
3580 : return PTR_ERR(new);
3581 : }
3582 :
3583 : psi_trigger_replace(&of->priv, new);
3584 :
3585 : cgroup_put(cgrp);
3586 :
3587 : return nbytes;
3588 : }
3589 :
3590 : static ssize_t cgroup_io_pressure_write(struct kernfs_open_file *of,
3591 : char *buf, size_t nbytes,
3592 : loff_t off)
3593 : {
3594 : return cgroup_pressure_write(of, buf, nbytes, PSI_IO);
3595 : }
3596 :
3597 : static ssize_t cgroup_memory_pressure_write(struct kernfs_open_file *of,
3598 : char *buf, size_t nbytes,
3599 : loff_t off)
3600 : {
3601 : return cgroup_pressure_write(of, buf, nbytes, PSI_MEM);
3602 : }
3603 :
3604 : static ssize_t cgroup_cpu_pressure_write(struct kernfs_open_file *of,
3605 : char *buf, size_t nbytes,
3606 : loff_t off)
3607 : {
3608 : return cgroup_pressure_write(of, buf, nbytes, PSI_CPU);
3609 : }
3610 :
3611 : static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of,
3612 : poll_table *pt)
3613 : {
3614 : return psi_trigger_poll(&of->priv, of->file, pt);
3615 : }
3616 :
3617 : static void cgroup_pressure_release(struct kernfs_open_file *of)
3618 : {
3619 : psi_trigger_replace(&of->priv, NULL);
3620 : }
3621 : #endif /* CONFIG_PSI */
3622 :
3623 0 : static int cgroup_freeze_show(struct seq_file *seq, void *v)
3624 : {
3625 0 : struct cgroup *cgrp = seq_css(seq)->cgroup;
3626 :
3627 0 : seq_printf(seq, "%d\n", cgrp->freezer.freeze);
3628 :
3629 0 : return 0;
3630 : }
3631 :
3632 0 : static ssize_t cgroup_freeze_write(struct kernfs_open_file *of,
3633 : char *buf, size_t nbytes, loff_t off)
3634 : {
3635 0 : struct cgroup *cgrp;
3636 0 : ssize_t ret;
3637 0 : int freeze;
3638 :
3639 0 : ret = kstrtoint(strstrip(buf), 0, &freeze);
3640 0 : if (ret)
3641 : return ret;
3642 :
3643 0 : if (freeze < 0 || freeze > 1)
3644 : return -ERANGE;
3645 :
3646 0 : cgrp = cgroup_kn_lock_live(of->kn, false);
3647 0 : if (!cgrp)
3648 : return -ENOENT;
3649 :
3650 0 : cgroup_freeze(cgrp, freeze);
3651 :
3652 0 : cgroup_kn_unlock(of->kn);
3653 :
3654 0 : return nbytes;
3655 : }
3656 :
3657 286 : static int cgroup_file_open(struct kernfs_open_file *of)
3658 : {
3659 286 : struct cftype *cft = of_cft(of);
3660 :
3661 286 : if (cft->open)
3662 0 : return cft->open(of);
3663 : return 0;
3664 : }
3665 :
3666 286 : static void cgroup_file_release(struct kernfs_open_file *of)
3667 : {
3668 286 : struct cftype *cft = of_cft(of);
3669 :
3670 286 : if (cft->release)
3671 125 : cft->release(of);
3672 286 : }
3673 :
3674 198 : static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
3675 : size_t nbytes, loff_t off)
3676 : {
3677 198 : struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
3678 198 : struct cgroup *cgrp = of->kn->parent->priv;
3679 198 : struct cftype *cft = of_cft(of);
3680 198 : struct cgroup_subsys_state *css;
3681 198 : int ret;
3682 :
3683 198 : if (!nbytes)
3684 : return 0;
3685 :
3686 : /*
3687 : * If namespaces are delegation boundaries, disallow writes to
3688 : * files in an non-init namespace root from inside the namespace
3689 : * except for the files explicitly marked delegatable -
3690 : * cgroup.procs and cgroup.subtree_control.
3691 : */
3692 198 : if ((cgrp->root->flags & CGRP_ROOT_NS_DELEGATE) &&
3693 99 : !(cft->flags & CFTYPE_NS_DELEGATABLE) &&
3694 0 : ns != &init_cgroup_ns && ns->root_cset->dfl_cgrp == cgrp)
3695 : return -EPERM;
3696 :
3697 198 : if (cft->write)
3698 198 : return cft->write(of, buf, nbytes, off);
3699 :
3700 : /*
3701 : * kernfs guarantees that a file isn't deleted with operations in
3702 : * flight, which means that the matching css is and stays alive and
3703 : * doesn't need to be pinned. The RCU locking is not necessary
3704 : * either. It's just for the convenience of using cgroup_css().
3705 : */
3706 0 : rcu_read_lock();
3707 0 : css = cgroup_css(cgrp, cft->ss);
3708 0 : rcu_read_unlock();
3709 :
3710 0 : if (cft->write_u64) {
3711 0 : unsigned long long v;
3712 0 : ret = kstrtoull(buf, 0, &v);
3713 0 : if (!ret)
3714 0 : ret = cft->write_u64(css, cft, v);
3715 0 : } else if (cft->write_s64) {
3716 0 : long long v;
3717 0 : ret = kstrtoll(buf, 0, &v);
3718 0 : if (!ret)
3719 0 : ret = cft->write_s64(css, cft, v);
3720 : } else {
3721 : ret = -EINVAL;
3722 : }
3723 :
3724 0 : return ret ?: nbytes;
3725 : }
3726 :
3727 0 : static __poll_t cgroup_file_poll(struct kernfs_open_file *of, poll_table *pt)
3728 : {
3729 0 : struct cftype *cft = of_cft(of);
3730 :
3731 0 : if (cft->poll)
3732 0 : return cft->poll(of, pt);
3733 :
3734 0 : return kernfs_generic_poll(of, pt);
3735 : }
3736 :
3737 31 : static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
3738 : {
3739 31 : return seq_cft(seq)->seq_start(seq, ppos);
3740 : }
3741 :
3742 49 : static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
3743 : {
3744 49 : return seq_cft(seq)->seq_next(seq, v, ppos);
3745 : }
3746 :
3747 31 : static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
3748 : {
3749 31 : if (seq_cft(seq)->seq_stop)
3750 0 : seq_cft(seq)->seq_stop(seq, v);
3751 31 : }
3752 :
3753 111 : static int cgroup_seqfile_show(struct seq_file *m, void *arg)
3754 : {
3755 111 : struct cftype *cft = seq_cft(m);
3756 111 : struct cgroup_subsys_state *css = seq_css(m);
3757 :
3758 111 : if (cft->seq_show)
3759 111 : return cft->seq_show(m, arg);
3760 :
3761 0 : if (cft->read_u64)
3762 0 : seq_printf(m, "%llu\n", cft->read_u64(css, cft));
3763 0 : else if (cft->read_s64)
3764 0 : seq_printf(m, "%lld\n", cft->read_s64(css, cft));
3765 : else
3766 : return -EINVAL;
3767 : return 0;
3768 : }
3769 :
3770 : static struct kernfs_ops cgroup_kf_single_ops = {
3771 : .atomic_write_len = PAGE_SIZE,
3772 : .open = cgroup_file_open,
3773 : .release = cgroup_file_release,
3774 : .write = cgroup_file_write,
3775 : .poll = cgroup_file_poll,
3776 : .seq_show = cgroup_seqfile_show,
3777 : };
3778 :
3779 : static struct kernfs_ops cgroup_kf_ops = {
3780 : .atomic_write_len = PAGE_SIZE,
3781 : .open = cgroup_file_open,
3782 : .release = cgroup_file_release,
3783 : .write = cgroup_file_write,
3784 : .poll = cgroup_file_poll,
3785 : .seq_start = cgroup_seqfile_start,
3786 : .seq_next = cgroup_seqfile_next,
3787 : .seq_stop = cgroup_seqfile_stop,
3788 : .seq_show = cgroup_seqfile_show,
3789 : };
3790 :
3791 : /* set uid and gid of cgroup dirs and files to that of the creator */
3792 847 : static int cgroup_kn_set_ugid(struct kernfs_node *kn)
3793 : {
3794 2541 : struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
3795 847 : .ia_uid = current_fsuid(),
3796 847 : .ia_gid = current_fsgid(), };
3797 :
3798 847 : if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
3799 847 : gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
3800 : return 0;
3801 :
3802 0 : return kernfs_setattr(kn, &iattr);
3803 : }
3804 :
3805 0 : static void cgroup_file_notify_timer(struct timer_list *timer)
3806 : {
3807 0 : cgroup_file_notify(container_of(timer, struct cgroup_file,
3808 : notify_timer));
3809 0 : }
3810 :
3811 749 : static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
3812 : struct cftype *cft)
3813 : {
3814 749 : char name[CGROUP_FILE_NAME_MAX];
3815 749 : struct kernfs_node *kn;
3816 749 : struct lock_class_key *key = NULL;
3817 749 : int ret;
3818 :
3819 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
3820 749 : key = &cft->lockdep_key;
3821 : #endif
3822 749 : kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
3823 749 : cgroup_file_mode(cft),
3824 749 : GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
3825 749 : 0, cft->kf_ops, cft,
3826 : NULL, key);
3827 749 : if (IS_ERR(kn))
3828 0 : return PTR_ERR(kn);
3829 :
3830 749 : ret = cgroup_kn_set_ugid(kn);
3831 749 : if (ret) {
3832 0 : kernfs_remove(kn);
3833 0 : return ret;
3834 : }
3835 :
3836 749 : if (cft->file_offset) {
3837 99 : struct cgroup_file *cfile = (void *)css + cft->file_offset;
3838 :
3839 99 : timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
3840 :
3841 99 : spin_lock_irq(&cgroup_file_kn_lock);
3842 99 : cfile->kn = kn;
3843 99 : spin_unlock_irq(&cgroup_file_kn_lock);
3844 : }
3845 :
3846 : return 0;
3847 : }
3848 :
3849 : /**
3850 : * cgroup_addrm_files - add or remove files to a cgroup directory
3851 : * @css: the target css
3852 : * @cgrp: the target cgroup (usually css->cgroup)
3853 : * @cfts: array of cftypes to be added
3854 : * @is_add: whether to add or remove
3855 : *
3856 : * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
3857 : * For removals, this function never fails.
3858 : */
3859 150 : static int cgroup_addrm_files(struct cgroup_subsys_state *css,
3860 : struct cgroup *cgrp, struct cftype cfts[],
3861 : bool is_add)
3862 : {
3863 150 : struct cftype *cft, *cft_end = NULL;
3864 150 : int ret = 0;
3865 :
3866 450 : lockdep_assert_held(&cgroup_mutex);
3867 :
3868 : restart:
3869 1425 : for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
3870 : /* does cft->flags tell us to skip this file on @cgrp? */
3871 1275 : if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
3872 0 : continue;
3873 1275 : if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
3874 0 : continue;
3875 1275 : if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
3876 3 : continue;
3877 1272 : if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
3878 148 : continue;
3879 1124 : if ((cft->flags & CFTYPE_DEBUG) && !cgroup_debug)
3880 0 : continue;
3881 1124 : if (is_add) {
3882 749 : ret = cgroup_add_file(css, cgrp, cft);
3883 749 : if (ret) {
3884 0 : pr_warn("%s: failed to add %s, err=%d\n",
3885 : __func__, cft->name, ret);
3886 0 : cft_end = cft;
3887 0 : is_add = false;
3888 0 : goto restart;
3889 : }
3890 : } else {
3891 375 : cgroup_rm_file(cgrp, cft);
3892 : }
3893 : }
3894 150 : return ret;
3895 : }
3896 :
3897 0 : static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
3898 : {
3899 0 : struct cgroup_subsys *ss = cfts[0].ss;
3900 0 : struct cgroup *root = &ss->root->cgrp;
3901 0 : struct cgroup_subsys_state *css;
3902 0 : int ret = 0;
3903 :
3904 0 : lockdep_assert_held(&cgroup_mutex);
3905 :
3906 : /* add/rm files for all cgroups created before */
3907 0 : css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
3908 0 : struct cgroup *cgrp = css->cgroup;
3909 :
3910 0 : if (!(css->flags & CSS_VISIBLE))
3911 0 : continue;
3912 :
3913 0 : ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
3914 0 : if (ret)
3915 : break;
3916 : }
3917 :
3918 0 : if (is_add && !ret)
3919 0 : kernfs_activate(root->kn);
3920 0 : return ret;
3921 : }
3922 :
3923 0 : static void cgroup_exit_cftypes(struct cftype *cfts)
3924 : {
3925 0 : struct cftype *cft;
3926 :
3927 0 : for (cft = cfts; cft->name[0] != '\0'; cft++) {
3928 : /* free copy for custom atomic_write_len, see init_cftypes() */
3929 0 : if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
3930 0 : kfree(cft->kf_ops);
3931 0 : cft->kf_ops = NULL;
3932 0 : cft->ss = NULL;
3933 :
3934 : /* revert flags set by cgroup core while adding @cfts */
3935 0 : cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
3936 : }
3937 0 : }
3938 :
3939 2 : static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
3940 : {
3941 2 : struct cftype *cft;
3942 :
3943 19 : for (cft = cfts; cft->name[0] != '\0'; cft++) {
3944 17 : struct kernfs_ops *kf_ops;
3945 :
3946 34 : WARN_ON(cft->ss || cft->kf_ops);
3947 :
3948 17 : if (cft->seq_start)
3949 : kf_ops = &cgroup_kf_ops;
3950 : else
3951 13 : kf_ops = &cgroup_kf_single_ops;
3952 :
3953 : /*
3954 : * Ugh... if @cft wants a custom max_write_len, we need to
3955 : * make a copy of kf_ops to set its atomic_write_len.
3956 : */
3957 17 : if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
3958 1 : kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
3959 1 : if (!kf_ops) {
3960 0 : cgroup_exit_cftypes(cfts);
3961 0 : return -ENOMEM;
3962 : }
3963 1 : kf_ops->atomic_write_len = cft->max_write_len;
3964 : }
3965 :
3966 17 : cft->kf_ops = kf_ops;
3967 17 : cft->ss = ss;
3968 : }
3969 :
3970 : return 0;
3971 : }
3972 :
3973 0 : static int cgroup_rm_cftypes_locked(struct cftype *cfts)
3974 : {
3975 0 : lockdep_assert_held(&cgroup_mutex);
3976 :
3977 0 : if (!cfts || !cfts[0].ss)
3978 : return -ENOENT;
3979 :
3980 0 : list_del(&cfts->node);
3981 0 : cgroup_apply_cftypes(cfts, false);
3982 0 : cgroup_exit_cftypes(cfts);
3983 0 : return 0;
3984 : }
3985 :
3986 : /**
3987 : * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
3988 : * @cfts: zero-length name terminated array of cftypes
3989 : *
3990 : * Unregister @cfts. Files described by @cfts are removed from all
3991 : * existing cgroups and all future cgroups won't have them either. This
3992 : * function can be called anytime whether @cfts' subsys is attached or not.
3993 : *
3994 : * Returns 0 on successful unregistration, -ENOENT if @cfts is not
3995 : * registered.
3996 : */
3997 0 : int cgroup_rm_cftypes(struct cftype *cfts)
3998 : {
3999 0 : int ret;
4000 :
4001 0 : mutex_lock(&cgroup_mutex);
4002 0 : ret = cgroup_rm_cftypes_locked(cfts);
4003 0 : mutex_unlock(&cgroup_mutex);
4004 0 : return ret;
4005 : }
4006 :
4007 : /**
4008 : * cgroup_add_cftypes - add an array of cftypes to a subsystem
4009 : * @ss: target cgroup subsystem
4010 : * @cfts: zero-length name terminated array of cftypes
4011 : *
4012 : * Register @cfts to @ss. Files described by @cfts are created for all
4013 : * existing cgroups to which @ss is attached and all future cgroups will
4014 : * have them too. This function can be called anytime whether @ss is
4015 : * attached or not.
4016 : *
4017 : * Returns 0 on successful registration, -errno on failure. Note that this
4018 : * function currently returns 0 as long as @cfts registration is successful
4019 : * even if some file creation attempts on existing cgroups fail.
4020 : */
4021 0 : static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
4022 : {
4023 0 : int ret;
4024 :
4025 0 : if (!cgroup_ssid_enabled(ss->id))
4026 0 : return 0;
4027 :
4028 : if (!cfts || cfts[0].name[0] == '\0')
4029 : return 0;
4030 :
4031 : ret = cgroup_init_cftypes(ss, cfts);
4032 : if (ret)
4033 : return ret;
4034 :
4035 : mutex_lock(&cgroup_mutex);
4036 :
4037 : list_add_tail(&cfts->node, &ss->cfts);
4038 : ret = cgroup_apply_cftypes(cfts, true);
4039 : if (ret)
4040 : cgroup_rm_cftypes_locked(cfts);
4041 :
4042 : mutex_unlock(&cgroup_mutex);
4043 : return ret;
4044 : }
4045 :
4046 : /**
4047 : * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
4048 : * @ss: target cgroup subsystem
4049 : * @cfts: zero-length name terminated array of cftypes
4050 : *
4051 : * Similar to cgroup_add_cftypes() but the added files are only used for
4052 : * the default hierarchy.
4053 : */
4054 0 : int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
4055 : {
4056 0 : struct cftype *cft;
4057 :
4058 0 : for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
4059 0 : cft->flags |= __CFTYPE_ONLY_ON_DFL;
4060 0 : return cgroup_add_cftypes(ss, cfts);
4061 : }
4062 :
4063 : /**
4064 : * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
4065 : * @ss: target cgroup subsystem
4066 : * @cfts: zero-length name terminated array of cftypes
4067 : *
4068 : * Similar to cgroup_add_cftypes() but the added files are only used for
4069 : * the legacy hierarchies.
4070 : */
4071 0 : int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
4072 : {
4073 0 : struct cftype *cft;
4074 :
4075 0 : for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
4076 0 : cft->flags |= __CFTYPE_NOT_ON_DFL;
4077 0 : return cgroup_add_cftypes(ss, cfts);
4078 : }
4079 :
4080 : /**
4081 : * cgroup_file_notify - generate a file modified event for a cgroup_file
4082 : * @cfile: target cgroup_file
4083 : *
4084 : * @cfile must have been obtained by setting cftype->file_offset.
4085 : */
4086 190 : void cgroup_file_notify(struct cgroup_file *cfile)
4087 : {
4088 190 : unsigned long flags;
4089 :
4090 190 : spin_lock_irqsave(&cgroup_file_kn_lock, flags);
4091 190 : if (cfile->kn) {
4092 94 : unsigned long last = cfile->notified_at;
4093 94 : unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
4094 :
4095 94 : if (time_in_range(jiffies, last, next)) {
4096 0 : timer_reduce(&cfile->notify_timer, next);
4097 : } else {
4098 94 : kernfs_notify(cfile->kn);
4099 94 : cfile->notified_at = jiffies;
4100 : }
4101 : }
4102 190 : spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
4103 190 : }
4104 :
4105 : /**
4106 : * css_next_child - find the next child of a given css
4107 : * @pos: the current position (%NULL to initiate traversal)
4108 : * @parent: css whose children to walk
4109 : *
4110 : * This function returns the next child of @parent and should be called
4111 : * under either cgroup_mutex or RCU read lock. The only requirement is
4112 : * that @parent and @pos are accessible. The next sibling is guaranteed to
4113 : * be returned regardless of their states.
4114 : *
4115 : * If a subsystem synchronizes ->css_online() and the start of iteration, a
4116 : * css which finished ->css_online() is guaranteed to be visible in the
4117 : * future iterations and will stay visible until the last reference is put.
4118 : * A css which hasn't finished ->css_online() or already finished
4119 : * ->css_offline() may show up during traversal. It's each subsystem's
4120 : * responsibility to synchronize against on/offlining.
4121 : */
4122 247 : struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
4123 : struct cgroup_subsys_state *parent)
4124 : {
4125 247 : struct cgroup_subsys_state *next;
4126 :
4127 444 : cgroup_assert_mutex_or_rcu_locked();
4128 :
4129 : /*
4130 : * @pos could already have been unlinked from the sibling list.
4131 : * Once a cgroup is removed, its ->sibling.next is no longer
4132 : * updated when its next sibling changes. CSS_RELEASED is set when
4133 : * @pos is taken off list, at which time its next pointer is valid,
4134 : * and, as releases are serialized, the one pointed to by the next
4135 : * pointer is guaranteed to not have started release yet. This
4136 : * implies that if we observe !CSS_RELEASED on @pos in this RCU
4137 : * critical section, the one pointed to by its next pointer is
4138 : * guaranteed to not have finished its RCU grace period even if we
4139 : * have dropped rcu_read_lock() in-between iterations.
4140 : *
4141 : * If @pos has CSS_RELEASED set, its next pointer can't be
4142 : * dereferenced; however, as each css is given a monotonically
4143 : * increasing unique serial number and always appended to the
4144 : * sibling list, the next one can be found by walking the parent's
4145 : * children until the first css with higher serial number than
4146 : * @pos's. While this path can be slower, it happens iff iteration
4147 : * races against release and the race window is very small.
4148 : */
4149 247 : if (!pos) {
4150 247 : next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
4151 0 : } else if (likely(!(pos->flags & CSS_RELEASED))) {
4152 0 : next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
4153 : } else {
4154 0 : list_for_each_entry_rcu(next, &parent->children, sibling,
4155 : lockdep_is_held(&cgroup_mutex))
4156 0 : if (next->serial_nr > pos->serial_nr)
4157 : break;
4158 : }
4159 :
4160 : /*
4161 : * @next, if not pointing to the head, can be dereferenced and is
4162 : * the next sibling.
4163 : */
4164 247 : if (&next->sibling != &parent->children)
4165 0 : return next;
4166 : return NULL;
4167 : }
4168 :
4169 : /**
4170 : * css_next_descendant_pre - find the next descendant for pre-order walk
4171 : * @pos: the current position (%NULL to initiate traversal)
4172 : * @root: css whose descendants to walk
4173 : *
4174 : * To be used by css_for_each_descendant_pre(). Find the next descendant
4175 : * to visit for pre-order traversal of @root's descendants. @root is
4176 : * included in the iteration and the first node to be visited.
4177 : *
4178 : * While this function requires cgroup_mutex or RCU read locking, it
4179 : * doesn't require the whole traversal to be contained in a single critical
4180 : * section. This function will return the correct next descendant as long
4181 : * as both @pos and @root are accessible and @pos is a descendant of @root.
4182 : *
4183 : * If a subsystem synchronizes ->css_online() and the start of iteration, a
4184 : * css which finished ->css_online() is guaranteed to be visible in the
4185 : * future iterations and will stay visible until the last reference is put.
4186 : * A css which hasn't finished ->css_online() or already finished
4187 : * ->css_offline() may show up during traversal. It's each subsystem's
4188 : * responsibility to synchronize against on/offlining.
4189 : */
4190 : struct cgroup_subsys_state *
4191 392 : css_next_descendant_pre(struct cgroup_subsys_state *pos,
4192 : struct cgroup_subsys_state *root)
4193 : {
4194 392 : struct cgroup_subsys_state *next;
4195 :
4196 784 : cgroup_assert_mutex_or_rcu_locked();
4197 :
4198 : /* if first iteration, visit @root */
4199 392 : if (!pos)
4200 : return root;
4201 :
4202 : /* visit the first child if exists */
4203 196 : next = css_next_child(NULL, pos);
4204 196 : if (next)
4205 : return next;
4206 :
4207 : /* no child, visit my or the closest ancestor's next sibling */
4208 196 : while (pos != root) {
4209 0 : next = css_next_child(pos, pos->parent);
4210 0 : if (next)
4211 0 : return next;
4212 0 : pos = pos->parent;
4213 : }
4214 :
4215 : return NULL;
4216 : }
4217 : EXPORT_SYMBOL_GPL(css_next_descendant_pre);
4218 :
4219 : /**
4220 : * css_rightmost_descendant - return the rightmost descendant of a css
4221 : * @pos: css of interest
4222 : *
4223 : * Return the rightmost descendant of @pos. If there's no descendant, @pos
4224 : * is returned. This can be used during pre-order traversal to skip
4225 : * subtree of @pos.
4226 : *
4227 : * While this function requires cgroup_mutex or RCU read locking, it
4228 : * doesn't require the whole traversal to be contained in a single critical
4229 : * section. This function will return the correct rightmost descendant as
4230 : * long as @pos is accessible.
4231 : */
4232 : struct cgroup_subsys_state *
4233 0 : css_rightmost_descendant(struct cgroup_subsys_state *pos)
4234 : {
4235 0 : struct cgroup_subsys_state *last, *tmp;
4236 :
4237 0 : cgroup_assert_mutex_or_rcu_locked();
4238 :
4239 0 : do {
4240 0 : last = pos;
4241 : /* ->prev isn't RCU safe, walk ->next till the end */
4242 0 : pos = NULL;
4243 0 : css_for_each_child(tmp, last)
4244 0 : pos = tmp;
4245 0 : } while (pos);
4246 :
4247 0 : return last;
4248 : }
4249 :
4250 : static struct cgroup_subsys_state *
4251 : css_leftmost_descendant(struct cgroup_subsys_state *pos)
4252 : {
4253 1 : struct cgroup_subsys_state *last;
4254 :
4255 1 : do {
4256 1 : last = pos;
4257 1 : pos = css_next_child(NULL, pos);
4258 1 : } while (pos);
4259 :
4260 1 : return last;
4261 : }
4262 :
4263 : /**
4264 : * css_next_descendant_post - find the next descendant for post-order walk
4265 : * @pos: the current position (%NULL to initiate traversal)
4266 : * @root: css whose descendants to walk
4267 : *
4268 : * To be used by css_for_each_descendant_post(). Find the next descendant
4269 : * to visit for post-order traversal of @root's descendants. @root is
4270 : * included in the iteration and the last node to be visited.
4271 : *
4272 : * While this function requires cgroup_mutex or RCU read locking, it
4273 : * doesn't require the whole traversal to be contained in a single critical
4274 : * section. This function will return the correct next descendant as long
4275 : * as both @pos and @cgroup are accessible and @pos is a descendant of
4276 : * @cgroup.
4277 : *
4278 : * If a subsystem synchronizes ->css_online() and the start of iteration, a
4279 : * css which finished ->css_online() is guaranteed to be visible in the
4280 : * future iterations and will stay visible until the last reference is put.
4281 : * A css which hasn't finished ->css_online() or already finished
4282 : * ->css_offline() may show up during traversal. It's each subsystem's
4283 : * responsibility to synchronize against on/offlining.
4284 : */
4285 : struct cgroup_subsys_state *
4286 2 : css_next_descendant_post(struct cgroup_subsys_state *pos,
4287 : struct cgroup_subsys_state *root)
4288 : {
4289 2 : struct cgroup_subsys_state *next;
4290 :
4291 4 : cgroup_assert_mutex_or_rcu_locked();
4292 :
4293 : /* if first iteration, visit leftmost descendant which may be @root */
4294 2 : if (!pos)
4295 1 : return css_leftmost_descendant(root);
4296 :
4297 : /* if we visited @root, we're done */
4298 1 : if (pos == root)
4299 : return NULL;
4300 :
4301 : /* if there's an unvisited sibling, visit its leftmost descendant */
4302 0 : next = css_next_child(pos, pos->parent);
4303 0 : if (next)
4304 0 : return css_leftmost_descendant(next);
4305 :
4306 : /* no sibling left, visit parent */
4307 0 : return pos->parent;
4308 : }
4309 :
4310 : /**
4311 : * css_has_online_children - does a css have online children
4312 : * @css: the target css
4313 : *
4314 : * Returns %true if @css has any online children; otherwise, %false. This
4315 : * function can be called from any context but the caller is responsible
4316 : * for synchronizing against on/offlining as necessary.
4317 : */
4318 50 : bool css_has_online_children(struct cgroup_subsys_state *css)
4319 : {
4320 50 : struct cgroup_subsys_state *child;
4321 50 : bool ret = false;
4322 :
4323 50 : rcu_read_lock();
4324 50 : css_for_each_child(child, css) {
4325 0 : if (child->flags & CSS_ONLINE) {
4326 : ret = true;
4327 : break;
4328 : }
4329 : }
4330 50 : rcu_read_unlock();
4331 50 : return ret;
4332 : }
4333 :
4334 51 : static struct css_set *css_task_iter_next_css_set(struct css_task_iter *it)
4335 : {
4336 51 : struct list_head *l;
4337 51 : struct cgrp_cset_link *link;
4338 51 : struct css_set *cset;
4339 :
4340 153 : lockdep_assert_held(&css_set_lock);
4341 :
4342 : /* find the next threaded cset */
4343 51 : if (it->tcset_pos) {
4344 25 : l = it->tcset_pos->next;
4345 :
4346 25 : if (l != it->tcset_head) {
4347 0 : it->tcset_pos = l;
4348 0 : return container_of(l, struct css_set,
4349 : threaded_csets_node);
4350 : }
4351 :
4352 25 : it->tcset_pos = NULL;
4353 : }
4354 :
4355 : /* find the next cset */
4356 51 : l = it->cset_pos;
4357 51 : l = l->next;
4358 51 : if (l == it->cset_head) {
4359 26 : it->cset_pos = NULL;
4360 26 : return NULL;
4361 : }
4362 :
4363 25 : if (it->ss) {
4364 0 : cset = container_of(l, struct css_set, e_cset_node[it->ss->id]);
4365 : } else {
4366 25 : link = list_entry(l, struct cgrp_cset_link, cset_link);
4367 25 : cset = link->cset;
4368 : }
4369 :
4370 25 : it->cset_pos = l;
4371 :
4372 : /* initialize threaded css_set walking */
4373 25 : if (it->flags & CSS_TASK_ITER_THREADED) {
4374 25 : if (it->cur_dcset)
4375 0 : put_css_set_locked(it->cur_dcset);
4376 25 : it->cur_dcset = cset;
4377 25 : get_css_set(cset);
4378 :
4379 25 : it->tcset_head = &cset->threaded_csets;
4380 25 : it->tcset_pos = &cset->threaded_csets;
4381 : }
4382 :
4383 : return cset;
4384 : }
4385 :
4386 : /**
4387 : * css_task_iter_advance_css_set - advance a task iterator to the next css_set
4388 : * @it: the iterator to advance
4389 : *
4390 : * Advance @it to the next css_set to walk.
4391 : */
4392 51 : static void css_task_iter_advance_css_set(struct css_task_iter *it)
4393 : {
4394 51 : struct css_set *cset;
4395 :
4396 153 : lockdep_assert_held(&css_set_lock);
4397 :
4398 : /* Advance to the next non-empty css_set and find first non-empty tasks list*/
4399 51 : while ((cset = css_task_iter_next_css_set(it))) {
4400 25 : if (!list_empty(&cset->tasks)) {
4401 5 : it->cur_tasks_head = &cset->tasks;
4402 5 : break;
4403 20 : } else if (!list_empty(&cset->mg_tasks)) {
4404 0 : it->cur_tasks_head = &cset->mg_tasks;
4405 0 : break;
4406 20 : } else if (!list_empty(&cset->dying_tasks)) {
4407 20 : it->cur_tasks_head = &cset->dying_tasks;
4408 20 : break;
4409 : }
4410 : }
4411 51 : if (!cset) {
4412 26 : it->task_pos = NULL;
4413 26 : return;
4414 : }
4415 25 : it->task_pos = it->cur_tasks_head->next;
4416 :
4417 : /*
4418 : * We don't keep css_sets locked across iteration steps and thus
4419 : * need to take steps to ensure that iteration can be resumed after
4420 : * the lock is re-acquired. Iteration is performed at two levels -
4421 : * css_sets and tasks in them.
4422 : *
4423 : * Once created, a css_set never leaves its cgroup lists, so a
4424 : * pinned css_set is guaranteed to stay put and we can resume
4425 : * iteration afterwards.
4426 : *
4427 : * Tasks may leave @cset across iteration steps. This is resolved
4428 : * by registering each iterator with the css_set currently being
4429 : * walked and making css_set_move_task() advance iterators whose
4430 : * next task is leaving.
4431 : */
4432 25 : if (it->cur_cset) {
4433 0 : list_del(&it->iters_node);
4434 0 : put_css_set_locked(it->cur_cset);
4435 : }
4436 25 : get_css_set(cset);
4437 25 : it->cur_cset = cset;
4438 25 : list_add(&it->iters_node, &cset->task_iters);
4439 : }
4440 :
4441 1 : static void css_task_iter_skip(struct css_task_iter *it,
4442 : struct task_struct *task)
4443 : {
4444 3 : lockdep_assert_held(&css_set_lock);
4445 :
4446 1 : if (it->task_pos == &task->cg_list) {
4447 0 : it->task_pos = it->task_pos->next;
4448 0 : it->flags |= CSS_TASK_ITER_SKIPPED;
4449 : }
4450 1 : }
4451 :
4452 75 : static void css_task_iter_advance(struct css_task_iter *it)
4453 : {
4454 75 : struct task_struct *task;
4455 :
4456 225 : lockdep_assert_held(&css_set_lock);
4457 : repeat:
4458 101 : if (it->task_pos) {
4459 : /*
4460 : * Advance iterator to find next entry. We go through cset
4461 : * tasks, mg_tasks and dying_tasks, when consumed we move onto
4462 : * the next cset.
4463 : */
4464 75 : if (it->flags & CSS_TASK_ITER_SKIPPED)
4465 0 : it->flags &= ~CSS_TASK_ITER_SKIPPED;
4466 : else
4467 75 : it->task_pos = it->task_pos->next;
4468 :
4469 75 : if (it->task_pos == &it->cur_cset->tasks) {
4470 5 : it->cur_tasks_head = &it->cur_cset->mg_tasks;
4471 5 : it->task_pos = it->cur_tasks_head->next;
4472 : }
4473 75 : if (it->task_pos == &it->cur_cset->mg_tasks) {
4474 5 : it->cur_tasks_head = &it->cur_cset->dying_tasks;
4475 5 : it->task_pos = it->cur_tasks_head->next;
4476 : }
4477 75 : if (it->task_pos == &it->cur_cset->dying_tasks)
4478 25 : css_task_iter_advance_css_set(it);
4479 : } else {
4480 : /* called from start, proceed to the first cset */
4481 26 : css_task_iter_advance_css_set(it);
4482 : }
4483 :
4484 101 : if (!it->task_pos)
4485 : return;
4486 :
4487 75 : task = list_entry(it->task_pos, struct task_struct, cg_list);
4488 :
4489 75 : if (it->flags & CSS_TASK_ITER_PROCS) {
4490 : /* if PROCS, skip over tasks which aren't group leaders */
4491 75 : if (!thread_group_leader(task))
4492 6 : goto repeat;
4493 :
4494 : /* and dying leaders w/o live member threads */
4495 69 : if (it->cur_tasks_head == &it->cur_cset->dying_tasks &&
4496 20 : !atomic_read(&task->signal->live))
4497 20 : goto repeat;
4498 : } else {
4499 : /* skip all dying ones */
4500 0 : if (it->cur_tasks_head == &it->cur_cset->dying_tasks)
4501 0 : goto repeat;
4502 : }
4503 : }
4504 :
4505 : /**
4506 : * css_task_iter_start - initiate task iteration
4507 : * @css: the css to walk tasks of
4508 : * @flags: CSS_TASK_ITER_* flags
4509 : * @it: the task iterator to use
4510 : *
4511 : * Initiate iteration through the tasks of @css. The caller can call
4512 : * css_task_iter_next() to walk through the tasks until the function
4513 : * returns NULL. On completion of iteration, css_task_iter_end() must be
4514 : * called.
4515 : */
4516 26 : void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
4517 : struct css_task_iter *it)
4518 : {
4519 26 : memset(it, 0, sizeof(*it));
4520 :
4521 26 : spin_lock_irq(&css_set_lock);
4522 :
4523 26 : it->ss = css->ss;
4524 26 : it->flags = flags;
4525 :
4526 26 : if (it->ss)
4527 0 : it->cset_pos = &css->cgroup->e_csets[css->ss->id];
4528 : else
4529 26 : it->cset_pos = &css->cgroup->cset_links;
4530 :
4531 26 : it->cset_head = it->cset_pos;
4532 :
4533 26 : css_task_iter_advance(it);
4534 :
4535 26 : spin_unlock_irq(&css_set_lock);
4536 26 : }
4537 :
4538 : /**
4539 : * css_task_iter_next - return the next task for the iterator
4540 : * @it: the task iterator being iterated
4541 : *
4542 : * The "next" function for task iteration. @it should have been
4543 : * initialized via css_task_iter_start(). Returns NULL when the iteration
4544 : * reaches the end.
4545 : */
4546 75 : struct task_struct *css_task_iter_next(struct css_task_iter *it)
4547 : {
4548 75 : if (it->cur_task) {
4549 49 : put_task_struct(it->cur_task);
4550 49 : it->cur_task = NULL;
4551 : }
4552 :
4553 75 : spin_lock_irq(&css_set_lock);
4554 :
4555 : /* @it may be half-advanced by skips, finish advancing */
4556 75 : if (it->flags & CSS_TASK_ITER_SKIPPED)
4557 0 : css_task_iter_advance(it);
4558 :
4559 75 : if (it->task_pos) {
4560 49 : it->cur_task = list_entry(it->task_pos, struct task_struct,
4561 : cg_list);
4562 49 : get_task_struct(it->cur_task);
4563 49 : css_task_iter_advance(it);
4564 : }
4565 :
4566 75 : spin_unlock_irq(&css_set_lock);
4567 :
4568 75 : return it->cur_task;
4569 : }
4570 :
4571 : /**
4572 : * css_task_iter_end - finish task iteration
4573 : * @it: the task iterator to finish
4574 : *
4575 : * Finish task iteration started by css_task_iter_start().
4576 : */
4577 26 : void css_task_iter_end(struct css_task_iter *it)
4578 : {
4579 26 : if (it->cur_cset) {
4580 25 : spin_lock_irq(&css_set_lock);
4581 25 : list_del(&it->iters_node);
4582 25 : put_css_set_locked(it->cur_cset);
4583 25 : spin_unlock_irq(&css_set_lock);
4584 : }
4585 :
4586 26 : if (it->cur_dcset)
4587 25 : put_css_set(it->cur_dcset);
4588 :
4589 26 : if (it->cur_task)
4590 0 : put_task_struct(it->cur_task);
4591 26 : }
4592 :
4593 125 : static void cgroup_procs_release(struct kernfs_open_file *of)
4594 : {
4595 125 : if (of->priv) {
4596 26 : css_task_iter_end(of->priv);
4597 26 : kfree(of->priv);
4598 : }
4599 125 : }
4600 :
4601 75 : static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
4602 : {
4603 75 : struct kernfs_open_file *of = s->private;
4604 75 : struct css_task_iter *it = of->priv;
4605 :
4606 49 : if (pos)
4607 49 : (*pos)++;
4608 :
4609 49 : return css_task_iter_next(it);
4610 : }
4611 :
4612 31 : static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
4613 : unsigned int iter_flags)
4614 : {
4615 31 : struct kernfs_open_file *of = s->private;
4616 31 : struct cgroup *cgrp = seq_css(s)->cgroup;
4617 31 : struct css_task_iter *it = of->priv;
4618 :
4619 : /*
4620 : * When a seq_file is seeked, it's always traversed sequentially
4621 : * from position 0, so we can simply keep iterating on !0 *pos.
4622 : */
4623 31 : if (!it) {
4624 26 : if (WARN_ON_ONCE((*pos)))
4625 31 : return ERR_PTR(-EINVAL);
4626 :
4627 26 : it = kzalloc(sizeof(*it), GFP_KERNEL);
4628 26 : if (!it)
4629 31 : return ERR_PTR(-ENOMEM);
4630 26 : of->priv = it;
4631 26 : css_task_iter_start(&cgrp->self, iter_flags, it);
4632 5 : } else if (!(*pos)) {
4633 0 : css_task_iter_end(it);
4634 0 : css_task_iter_start(&cgrp->self, iter_flags, it);
4635 : } else
4636 5 : return it->cur_task;
4637 :
4638 26 : return cgroup_procs_next(s, NULL, NULL);
4639 : }
4640 :
4641 31 : static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
4642 : {
4643 31 : struct cgroup *cgrp = seq_css(s)->cgroup;
4644 :
4645 : /*
4646 : * All processes of a threaded subtree belong to the domain cgroup
4647 : * of the subtree. Only threads can be distributed across the
4648 : * subtree. Reject reads on cgroup.procs in the subtree proper.
4649 : * They're always empty anyway.
4650 : */
4651 31 : if (cgroup_is_threaded(cgrp))
4652 31 : return ERR_PTR(-EOPNOTSUPP);
4653 :
4654 31 : return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS |
4655 : CSS_TASK_ITER_THREADED);
4656 : }
4657 :
4658 49 : static int cgroup_procs_show(struct seq_file *s, void *v)
4659 : {
4660 49 : seq_printf(s, "%d\n", task_pid_vnr(v));
4661 49 : return 0;
4662 : }
4663 :
4664 99 : static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb)
4665 : {
4666 99 : int ret;
4667 99 : struct inode *inode;
4668 :
4669 297 : lockdep_assert_held(&cgroup_mutex);
4670 :
4671 99 : inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
4672 99 : if (!inode)
4673 : return -ENOMEM;
4674 :
4675 99 : ret = inode_permission(&init_user_ns, inode, MAY_WRITE);
4676 99 : iput(inode);
4677 99 : return ret;
4678 : }
4679 :
4680 99 : static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
4681 : struct cgroup *dst_cgrp,
4682 : struct super_block *sb)
4683 : {
4684 99 : struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
4685 99 : struct cgroup *com_cgrp = src_cgrp;
4686 99 : int ret;
4687 :
4688 297 : lockdep_assert_held(&cgroup_mutex);
4689 :
4690 : /* find the common ancestor */
4691 153 : while (!cgroup_is_descendant(dst_cgrp, com_cgrp))
4692 207 : com_cgrp = cgroup_parent(com_cgrp);
4693 :
4694 : /* %current should be authorized to migrate to the common ancestor */
4695 99 : ret = cgroup_may_write(com_cgrp, sb);
4696 99 : if (ret)
4697 : return ret;
4698 :
4699 : /*
4700 : * If namespaces are delegation boundaries, %current must be able
4701 : * to see both source and destination cgroups from its namespace.
4702 : */
4703 99 : if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) &&
4704 198 : (!cgroup_is_descendant(src_cgrp, ns->root_cset->dfl_cgrp) ||
4705 198 : !cgroup_is_descendant(dst_cgrp, ns->root_cset->dfl_cgrp)))
4706 0 : return -ENOENT;
4707 :
4708 : return 0;
4709 : }
4710 :
4711 99 : static int cgroup_attach_permissions(struct cgroup *src_cgrp,
4712 : struct cgroup *dst_cgrp,
4713 : struct super_block *sb, bool threadgroup)
4714 : {
4715 99 : int ret = 0;
4716 :
4717 99 : ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb);
4718 99 : if (ret)
4719 : return ret;
4720 :
4721 99 : ret = cgroup_migrate_vet_dst(dst_cgrp);
4722 99 : if (ret)
4723 : return ret;
4724 :
4725 99 : if (!threadgroup && (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp))
4726 0 : ret = -EOPNOTSUPP;
4727 :
4728 : return ret;
4729 : }
4730 :
4731 99 : static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
4732 : bool threadgroup)
4733 : {
4734 99 : struct cgroup *src_cgrp, *dst_cgrp;
4735 99 : struct task_struct *task;
4736 99 : ssize_t ret;
4737 99 : bool locked;
4738 :
4739 99 : dst_cgrp = cgroup_kn_lock_live(of->kn, false);
4740 99 : if (!dst_cgrp)
4741 : return -ENODEV;
4742 :
4743 99 : task = cgroup_procs_write_start(buf, threadgroup, &locked);
4744 99 : ret = PTR_ERR_OR_ZERO(task);
4745 99 : if (ret)
4746 0 : goto out_unlock;
4747 :
4748 : /* find the source cgroup */
4749 99 : spin_lock_irq(&css_set_lock);
4750 99 : src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
4751 99 : spin_unlock_irq(&css_set_lock);
4752 :
4753 : /* process and thread migrations follow same delegation rule */
4754 198 : ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
4755 99 : of->file->f_path.dentry->d_sb, threadgroup);
4756 99 : if (ret)
4757 0 : goto out_finish;
4758 :
4759 99 : ret = cgroup_attach_task(dst_cgrp, task, threadgroup);
4760 :
4761 99 : out_finish:
4762 99 : cgroup_procs_write_finish(task, locked);
4763 99 : out_unlock:
4764 99 : cgroup_kn_unlock(of->kn);
4765 :
4766 99 : return ret;
4767 : }
4768 :
4769 99 : static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
4770 : char *buf, size_t nbytes, loff_t off)
4771 : {
4772 99 : return __cgroup_procs_write(of, buf, true) ?: nbytes;
4773 : }
4774 :
4775 0 : static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
4776 : {
4777 0 : return __cgroup_procs_start(s, pos, 0);
4778 : }
4779 :
4780 0 : static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
4781 : char *buf, size_t nbytes, loff_t off)
4782 : {
4783 0 : return __cgroup_procs_write(of, buf, false) ?: nbytes;
4784 : }
4785 :
4786 : /* cgroup core interface files for the default hierarchy */
4787 : static struct cftype cgroup_base_files[] = {
4788 : {
4789 : .name = "cgroup.type",
4790 : .flags = CFTYPE_NOT_ON_ROOT,
4791 : .seq_show = cgroup_type_show,
4792 : .write = cgroup_type_write,
4793 : },
4794 : {
4795 : .name = "cgroup.procs",
4796 : .flags = CFTYPE_NS_DELEGATABLE,
4797 : .file_offset = offsetof(struct cgroup, procs_file),
4798 : .release = cgroup_procs_release,
4799 : .seq_start = cgroup_procs_start,
4800 : .seq_next = cgroup_procs_next,
4801 : .seq_show = cgroup_procs_show,
4802 : .write = cgroup_procs_write,
4803 : },
4804 : {
4805 : .name = "cgroup.threads",
4806 : .flags = CFTYPE_NS_DELEGATABLE,
4807 : .release = cgroup_procs_release,
4808 : .seq_start = cgroup_threads_start,
4809 : .seq_next = cgroup_procs_next,
4810 : .seq_show = cgroup_procs_show,
4811 : .write = cgroup_threads_write,
4812 : },
4813 : {
4814 : .name = "cgroup.controllers",
4815 : .seq_show = cgroup_controllers_show,
4816 : },
4817 : {
4818 : .name = "cgroup.subtree_control",
4819 : .flags = CFTYPE_NS_DELEGATABLE,
4820 : .seq_show = cgroup_subtree_control_show,
4821 : .write = cgroup_subtree_control_write,
4822 : },
4823 : {
4824 : .name = "cgroup.events",
4825 : .flags = CFTYPE_NOT_ON_ROOT,
4826 : .file_offset = offsetof(struct cgroup, events_file),
4827 : .seq_show = cgroup_events_show,
4828 : },
4829 : {
4830 : .name = "cgroup.max.descendants",
4831 : .seq_show = cgroup_max_descendants_show,
4832 : .write = cgroup_max_descendants_write,
4833 : },
4834 : {
4835 : .name = "cgroup.max.depth",
4836 : .seq_show = cgroup_max_depth_show,
4837 : .write = cgroup_max_depth_write,
4838 : },
4839 : {
4840 : .name = "cgroup.stat",
4841 : .seq_show = cgroup_stat_show,
4842 : },
4843 : {
4844 : .name = "cgroup.freeze",
4845 : .flags = CFTYPE_NOT_ON_ROOT,
4846 : .seq_show = cgroup_freeze_show,
4847 : .write = cgroup_freeze_write,
4848 : },
4849 : {
4850 : .name = "cpu.stat",
4851 : .seq_show = cpu_stat_show,
4852 : },
4853 : #ifdef CONFIG_PSI
4854 : {
4855 : .name = "io.pressure",
4856 : .seq_show = cgroup_io_pressure_show,
4857 : .write = cgroup_io_pressure_write,
4858 : .poll = cgroup_pressure_poll,
4859 : .release = cgroup_pressure_release,
4860 : },
4861 : {
4862 : .name = "memory.pressure",
4863 : .seq_show = cgroup_memory_pressure_show,
4864 : .write = cgroup_memory_pressure_write,
4865 : .poll = cgroup_pressure_poll,
4866 : .release = cgroup_pressure_release,
4867 : },
4868 : {
4869 : .name = "cpu.pressure",
4870 : .seq_show = cgroup_cpu_pressure_show,
4871 : .write = cgroup_cpu_pressure_write,
4872 : .poll = cgroup_pressure_poll,
4873 : .release = cgroup_pressure_release,
4874 : },
4875 : #endif /* CONFIG_PSI */
4876 : { } /* terminate */
4877 : };
4878 :
4879 : /*
4880 : * css destruction is four-stage process.
4881 : *
4882 : * 1. Destruction starts. Killing of the percpu_ref is initiated.
4883 : * Implemented in kill_css().
4884 : *
4885 : * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
4886 : * and thus css_tryget_online() is guaranteed to fail, the css can be
4887 : * offlined by invoking offline_css(). After offlining, the base ref is
4888 : * put. Implemented in css_killed_work_fn().
4889 : *
4890 : * 3. When the percpu_ref reaches zero, the only possible remaining
4891 : * accessors are inside RCU read sections. css_release() schedules the
4892 : * RCU callback.
4893 : *
4894 : * 4. After the grace period, the css can be freed. Implemented in
4895 : * css_free_work_fn().
4896 : *
4897 : * It is actually hairier because both step 2 and 4 require process context
4898 : * and thus involve punting to css->destroy_work adding two additional
4899 : * steps to the already complex sequence.
4900 : */
4901 50 : static void css_free_rwork_fn(struct work_struct *work)
4902 : {
4903 50 : struct cgroup_subsys_state *css = container_of(to_rcu_work(work),
4904 : struct cgroup_subsys_state, destroy_rwork);
4905 50 : struct cgroup_subsys *ss = css->ss;
4906 50 : struct cgroup *cgrp = css->cgroup;
4907 :
4908 50 : percpu_ref_exit(&css->refcnt);
4909 :
4910 50 : if (ss) {
4911 : /* css free path */
4912 0 : struct cgroup_subsys_state *parent = css->parent;
4913 0 : int id = css->id;
4914 :
4915 0 : ss->css_free(css);
4916 0 : cgroup_idr_remove(&ss->css_idr, id);
4917 0 : cgroup_put(cgrp);
4918 :
4919 0 : if (parent)
4920 0 : css_put(parent);
4921 : } else {
4922 : /* cgroup free path */
4923 50 : atomic_dec(&cgrp->root->nr_cgrps);
4924 50 : cgroup1_pidlist_destroy_all(cgrp);
4925 50 : cancel_work_sync(&cgrp->release_agent_work);
4926 :
4927 50 : if (cgroup_parent(cgrp)) {
4928 : /*
4929 : * We get a ref to the parent, and put the ref when
4930 : * this cgroup is being freed, so it's guaranteed
4931 : * that the parent won't be destroyed before its
4932 : * children.
4933 : */
4934 50 : cgroup_put(cgroup_parent(cgrp));
4935 50 : kernfs_put(cgrp->kn);
4936 50 : psi_cgroup_free(cgrp);
4937 50 : if (cgroup_on_dfl(cgrp))
4938 25 : cgroup_rstat_exit(cgrp);
4939 50 : kfree(cgrp);
4940 : } else {
4941 : /*
4942 : * This is root cgroup's refcnt reaching zero,
4943 : * which indicates that the root should be
4944 : * released.
4945 : */
4946 0 : cgroup_destroy_root(cgrp->root);
4947 : }
4948 : }
4949 50 : }
4950 :
4951 50 : static void css_release_work_fn(struct work_struct *work)
4952 : {
4953 50 : struct cgroup_subsys_state *css =
4954 50 : container_of(work, struct cgroup_subsys_state, destroy_work);
4955 50 : struct cgroup_subsys *ss = css->ss;
4956 50 : struct cgroup *cgrp = css->cgroup;
4957 :
4958 50 : mutex_lock(&cgroup_mutex);
4959 :
4960 50 : css->flags |= CSS_RELEASED;
4961 50 : list_del_rcu(&css->sibling);
4962 :
4963 50 : if (ss) {
4964 : /* css release path */
4965 0 : if (!list_empty(&css->rstat_css_node)) {
4966 0 : cgroup_rstat_flush(cgrp);
4967 0 : list_del_rcu(&css->rstat_css_node);
4968 : }
4969 :
4970 0 : cgroup_idr_replace(&ss->css_idr, NULL, css->id);
4971 0 : if (ss->css_released)
4972 0 : ss->css_released(css);
4973 : } else {
4974 50 : struct cgroup *tcgrp;
4975 :
4976 : /* cgroup release path */
4977 50 : TRACE_CGROUP_PATH(release, cgrp);
4978 :
4979 50 : if (cgroup_on_dfl(cgrp))
4980 25 : cgroup_rstat_flush(cgrp);
4981 :
4982 50 : spin_lock_irq(&css_set_lock);
4983 158 : for (tcgrp = cgroup_parent(cgrp); tcgrp;
4984 108 : tcgrp = cgroup_parent(tcgrp))
4985 108 : tcgrp->nr_dying_descendants--;
4986 50 : spin_unlock_irq(&css_set_lock);
4987 :
4988 : /*
4989 : * There are two control paths which try to determine
4990 : * cgroup from dentry without going through kernfs -
4991 : * cgroupstats_build() and css_tryget_online_from_dir().
4992 : * Those are supported by RCU protecting clearing of
4993 : * cgrp->kn->priv backpointer.
4994 : */
4995 50 : if (cgrp->kn)
4996 50 : RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
4997 : NULL);
4998 : }
4999 :
5000 50 : mutex_unlock(&cgroup_mutex);
5001 :
5002 50 : INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
5003 50 : queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
5004 50 : }
5005 :
5006 50 : static void css_release(struct percpu_ref *ref)
5007 : {
5008 50 : struct cgroup_subsys_state *css =
5009 50 : container_of(ref, struct cgroup_subsys_state, refcnt);
5010 :
5011 50 : INIT_WORK(&css->destroy_work, css_release_work_fn);
5012 50 : queue_work(cgroup_destroy_wq, &css->destroy_work);
5013 50 : }
5014 :
5015 : static void init_and_link_css(struct cgroup_subsys_state *css,
5016 : struct cgroup_subsys *ss, struct cgroup *cgrp)
5017 : {
5018 : lockdep_assert_held(&cgroup_mutex);
5019 :
5020 : cgroup_get_live(cgrp);
5021 :
5022 : memset(css, 0, sizeof(*css));
5023 : css->cgroup = cgrp;
5024 : css->ss = ss;
5025 : css->id = -1;
5026 : INIT_LIST_HEAD(&css->sibling);
5027 : INIT_LIST_HEAD(&css->children);
5028 : INIT_LIST_HEAD(&css->rstat_css_node);
5029 : css->serial_nr = css_serial_nr_next++;
5030 : atomic_set(&css->online_cnt, 0);
5031 :
5032 : if (cgroup_parent(cgrp)) {
5033 : css->parent = cgroup_css(cgroup_parent(cgrp), ss);
5034 : css_get(css->parent);
5035 : }
5036 :
5037 : if (cgroup_on_dfl(cgrp) && ss->css_rstat_flush)
5038 : list_add_rcu(&css->rstat_css_node, &cgrp->rstat_css_list);
5039 :
5040 : BUG_ON(cgroup_css(cgrp, ss));
5041 : }
5042 :
5043 : /* invoke ->css_online() on a new CSS and mark it online if successful */
5044 : static int online_css(struct cgroup_subsys_state *css)
5045 : {
5046 : struct cgroup_subsys *ss = css->ss;
5047 : int ret = 0;
5048 :
5049 : lockdep_assert_held(&cgroup_mutex);
5050 :
5051 : if (ss->css_online)
5052 : ret = ss->css_online(css);
5053 : if (!ret) {
5054 : css->flags |= CSS_ONLINE;
5055 : rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
5056 :
5057 : atomic_inc(&css->online_cnt);
5058 : if (css->parent)
5059 : atomic_inc(&css->parent->online_cnt);
5060 : }
5061 : return ret;
5062 : }
5063 :
5064 : /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
5065 : static void offline_css(struct cgroup_subsys_state *css)
5066 : {
5067 : struct cgroup_subsys *ss = css->ss;
5068 :
5069 : lockdep_assert_held(&cgroup_mutex);
5070 :
5071 : if (!(css->flags & CSS_ONLINE))
5072 : return;
5073 :
5074 : if (ss->css_offline)
5075 : ss->css_offline(css);
5076 :
5077 : css->flags &= ~CSS_ONLINE;
5078 : RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
5079 :
5080 : wake_up_all(&css->cgroup->offline_waitq);
5081 : }
5082 :
5083 : /**
5084 : * css_create - create a cgroup_subsys_state
5085 : * @cgrp: the cgroup new css will be associated with
5086 : * @ss: the subsys of new css
5087 : *
5088 : * Create a new css associated with @cgrp - @ss pair. On success, the new
5089 : * css is online and installed in @cgrp. This function doesn't create the
5090 : * interface files. Returns 0 on success, -errno on failure.
5091 : */
5092 : static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
5093 : struct cgroup_subsys *ss)
5094 : {
5095 : struct cgroup *parent = cgroup_parent(cgrp);
5096 : struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
5097 : struct cgroup_subsys_state *css;
5098 : int err;
5099 :
5100 : lockdep_assert_held(&cgroup_mutex);
5101 :
5102 : css = ss->css_alloc(parent_css);
5103 : if (!css)
5104 : css = ERR_PTR(-ENOMEM);
5105 : if (IS_ERR(css))
5106 : return css;
5107 :
5108 : init_and_link_css(css, ss, cgrp);
5109 :
5110 : err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
5111 : if (err)
5112 : goto err_free_css;
5113 :
5114 : err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
5115 : if (err < 0)
5116 : goto err_free_css;
5117 : css->id = err;
5118 :
5119 : /* @css is ready to be brought online now, make it visible */
5120 : list_add_tail_rcu(&css->sibling, &parent_css->children);
5121 : cgroup_idr_replace(&ss->css_idr, css, css->id);
5122 :
5123 : err = online_css(css);
5124 : if (err)
5125 : goto err_list_del;
5126 :
5127 : return css;
5128 :
5129 : err_list_del:
5130 : list_del_rcu(&css->sibling);
5131 : err_free_css:
5132 : list_del_rcu(&css->rstat_css_node);
5133 : INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
5134 : queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
5135 : return ERR_PTR(err);
5136 : }
5137 :
5138 : /*
5139 : * The returned cgroup is fully initialized including its control mask, but
5140 : * it isn't associated with its kernfs_node and doesn't have the control
5141 : * mask applied.
5142 : */
5143 98 : static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
5144 : umode_t mode)
5145 : {
5146 98 : struct cgroup_root *root = parent->root;
5147 98 : struct cgroup *cgrp, *tcgrp;
5148 98 : struct kernfs_node *kn;
5149 98 : int level = parent->level + 1;
5150 98 : int ret;
5151 :
5152 : /* allocate the cgroup and its ID, 0 is reserved for the root */
5153 196 : cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)),
5154 : GFP_KERNEL);
5155 98 : if (!cgrp)
5156 98 : return ERR_PTR(-ENOMEM);
5157 :
5158 98 : ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
5159 98 : if (ret)
5160 0 : goto out_free_cgrp;
5161 :
5162 98 : if (cgroup_on_dfl(parent)) {
5163 49 : ret = cgroup_rstat_init(cgrp);
5164 49 : if (ret)
5165 0 : goto out_cancel_ref;
5166 : }
5167 :
5168 : /* create the directory */
5169 98 : kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
5170 98 : if (IS_ERR(kn)) {
5171 0 : ret = PTR_ERR(kn);
5172 0 : goto out_stat_exit;
5173 : }
5174 98 : cgrp->kn = kn;
5175 :
5176 98 : init_cgroup_housekeeping(cgrp);
5177 :
5178 98 : cgrp->self.parent = &parent->self;
5179 98 : cgrp->root = root;
5180 98 : cgrp->level = level;
5181 :
5182 98 : ret = psi_cgroup_alloc(cgrp);
5183 98 : if (ret)
5184 : goto out_kernfs_remove;
5185 :
5186 98 : ret = cgroup_bpf_inherit(cgrp);
5187 98 : if (ret)
5188 : goto out_psi_free;
5189 :
5190 : /*
5191 : * New cgroup inherits effective freeze counter, and
5192 : * if the parent has to be frozen, the child has too.
5193 : */
5194 98 : cgrp->freezer.e_freeze = parent->freezer.e_freeze;
5195 98 : if (cgrp->freezer.e_freeze) {
5196 : /*
5197 : * Set the CGRP_FREEZE flag, so when a process will be
5198 : * attached to the child cgroup, it will become frozen.
5199 : * At this point the new cgroup is unpopulated, so we can
5200 : * consider it frozen immediately.
5201 : */
5202 0 : set_bit(CGRP_FREEZE, &cgrp->flags);
5203 0 : set_bit(CGRP_FROZEN, &cgrp->flags);
5204 : }
5205 :
5206 98 : spin_lock_irq(&css_set_lock);
5207 502 : for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
5208 306 : cgrp->ancestor_ids[tcgrp->level] = cgroup_id(tcgrp);
5209 :
5210 306 : if (tcgrp != cgrp) {
5211 208 : tcgrp->nr_descendants++;
5212 :
5213 : /*
5214 : * If the new cgroup is frozen, all ancestor cgroups
5215 : * get a new frozen descendant, but their state can't
5216 : * change because of this.
5217 : */
5218 208 : if (cgrp->freezer.e_freeze)
5219 0 : tcgrp->freezer.nr_frozen_descendants++;
5220 : }
5221 : }
5222 98 : spin_unlock_irq(&css_set_lock);
5223 :
5224 98 : if (notify_on_release(parent))
5225 0 : set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
5226 :
5227 98 : if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
5228 0 : set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
5229 :
5230 98 : cgrp->self.serial_nr = css_serial_nr_next++;
5231 :
5232 : /* allocation complete, commit to creation */
5233 196 : list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
5234 98 : atomic_inc(&root->nr_cgrps);
5235 98 : cgroup_get_live(parent);
5236 :
5237 : /*
5238 : * On the default hierarchy, a child doesn't automatically inherit
5239 : * subtree_control from the parent. Each is configured manually.
5240 : */
5241 98 : if (!cgroup_on_dfl(cgrp))
5242 49 : cgrp->subtree_control = cgroup_control(cgrp);
5243 :
5244 98 : cgroup_propagate_control(cgrp);
5245 :
5246 98 : return cgrp;
5247 :
5248 : out_psi_free:
5249 : psi_cgroup_free(cgrp);
5250 : out_kernfs_remove:
5251 : kernfs_remove(cgrp->kn);
5252 0 : out_stat_exit:
5253 0 : if (cgroup_on_dfl(parent))
5254 0 : cgroup_rstat_exit(cgrp);
5255 0 : out_cancel_ref:
5256 0 : percpu_ref_exit(&cgrp->self.refcnt);
5257 0 : out_free_cgrp:
5258 0 : kfree(cgrp);
5259 0 : return ERR_PTR(ret);
5260 : }
5261 :
5262 98 : static bool cgroup_check_hierarchy_limits(struct cgroup *parent)
5263 : {
5264 98 : struct cgroup *cgroup;
5265 98 : int ret = false;
5266 98 : int level = 1;
5267 :
5268 294 : lockdep_assert_held(&cgroup_mutex);
5269 :
5270 306 : for (cgroup = parent; cgroup; cgroup = cgroup_parent(cgroup)) {
5271 208 : if (cgroup->nr_descendants >= cgroup->max_descendants)
5272 0 : goto fail;
5273 :
5274 208 : if (level > cgroup->max_depth)
5275 0 : goto fail;
5276 :
5277 208 : level++;
5278 : }
5279 :
5280 : ret = true;
5281 98 : fail:
5282 98 : return ret;
5283 : }
5284 :
5285 98 : int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
5286 : {
5287 98 : struct cgroup *parent, *cgrp;
5288 98 : int ret;
5289 :
5290 : /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
5291 98 : if (strchr(name, '\n'))
5292 : return -EINVAL;
5293 :
5294 98 : parent = cgroup_kn_lock_live(parent_kn, false);
5295 98 : if (!parent)
5296 : return -ENODEV;
5297 :
5298 98 : if (!cgroup_check_hierarchy_limits(parent)) {
5299 0 : ret = -EAGAIN;
5300 0 : goto out_unlock;
5301 : }
5302 :
5303 98 : cgrp = cgroup_create(parent, name, mode);
5304 98 : if (IS_ERR(cgrp)) {
5305 0 : ret = PTR_ERR(cgrp);
5306 0 : goto out_unlock;
5307 : }
5308 :
5309 : /*
5310 : * This extra ref will be put in cgroup_free_fn() and guarantees
5311 : * that @cgrp->kn is always accessible.
5312 : */
5313 98 : kernfs_get(cgrp->kn);
5314 :
5315 98 : ret = cgroup_kn_set_ugid(cgrp->kn);
5316 98 : if (ret)
5317 0 : goto out_destroy;
5318 :
5319 98 : ret = css_populate_dir(&cgrp->self);
5320 98 : if (ret)
5321 0 : goto out_destroy;
5322 :
5323 98 : ret = cgroup_apply_control_enable(cgrp);
5324 98 : if (ret)
5325 0 : goto out_destroy;
5326 :
5327 98 : TRACE_CGROUP_PATH(mkdir, cgrp);
5328 :
5329 : /* let's create and online css's */
5330 98 : kernfs_activate(cgrp->kn);
5331 :
5332 98 : ret = 0;
5333 98 : goto out_unlock;
5334 :
5335 0 : out_destroy:
5336 0 : cgroup_destroy_locked(cgrp);
5337 98 : out_unlock:
5338 98 : cgroup_kn_unlock(parent_kn);
5339 98 : return ret;
5340 : }
5341 :
5342 : /*
5343 : * This is called when the refcnt of a css is confirmed to be killed.
5344 : * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
5345 : * initate destruction and put the css ref from kill_css().
5346 : */
5347 : static void css_killed_work_fn(struct work_struct *work)
5348 : {
5349 : struct cgroup_subsys_state *css =
5350 : container_of(work, struct cgroup_subsys_state, destroy_work);
5351 :
5352 : mutex_lock(&cgroup_mutex);
5353 :
5354 : do {
5355 : offline_css(css);
5356 : css_put(css);
5357 : /* @css can't go away while we're holding cgroup_mutex */
5358 : css = css->parent;
5359 : } while (css && atomic_dec_and_test(&css->online_cnt));
5360 :
5361 : mutex_unlock(&cgroup_mutex);
5362 : }
5363 :
5364 : /* css kill confirmation processing requires process context, bounce */
5365 : static void css_killed_ref_fn(struct percpu_ref *ref)
5366 : {
5367 : struct cgroup_subsys_state *css =
5368 : container_of(ref, struct cgroup_subsys_state, refcnt);
5369 :
5370 : if (atomic_dec_and_test(&css->online_cnt)) {
5371 : INIT_WORK(&css->destroy_work, css_killed_work_fn);
5372 : queue_work(cgroup_destroy_wq, &css->destroy_work);
5373 : }
5374 : }
5375 :
5376 : /**
5377 : * kill_css - destroy a css
5378 : * @css: css to destroy
5379 : *
5380 : * This function initiates destruction of @css by removing cgroup interface
5381 : * files and putting its base reference. ->css_offline() will be invoked
5382 : * asynchronously once css_tryget_online() is guaranteed to fail and when
5383 : * the reference count reaches zero, @css will be released.
5384 : */
5385 : static void kill_css(struct cgroup_subsys_state *css)
5386 : {
5387 : lockdep_assert_held(&cgroup_mutex);
5388 :
5389 : if (css->flags & CSS_DYING)
5390 : return;
5391 :
5392 : css->flags |= CSS_DYING;
5393 :
5394 : /*
5395 : * This must happen before css is disassociated with its cgroup.
5396 : * See seq_css() for details.
5397 : */
5398 : css_clear_dir(css);
5399 :
5400 : /*
5401 : * Killing would put the base ref, but we need to keep it alive
5402 : * until after ->css_offline().
5403 : */
5404 : css_get(css);
5405 :
5406 : /*
5407 : * cgroup core guarantees that, by the time ->css_offline() is
5408 : * invoked, no new css reference will be given out via
5409 : * css_tryget_online(). We can't simply call percpu_ref_kill() and
5410 : * proceed to offlining css's because percpu_ref_kill() doesn't
5411 : * guarantee that the ref is seen as killed on all CPUs on return.
5412 : *
5413 : * Use percpu_ref_kill_and_confirm() to get notifications as each
5414 : * css is confirmed to be seen as killed on all CPUs.
5415 : */
5416 : percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
5417 : }
5418 :
5419 : /**
5420 : * cgroup_destroy_locked - the first stage of cgroup destruction
5421 : * @cgrp: cgroup to be destroyed
5422 : *
5423 : * css's make use of percpu refcnts whose killing latency shouldn't be
5424 : * exposed to userland and are RCU protected. Also, cgroup core needs to
5425 : * guarantee that css_tryget_online() won't succeed by the time
5426 : * ->css_offline() is invoked. To satisfy all the requirements,
5427 : * destruction is implemented in the following two steps.
5428 : *
5429 : * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
5430 : * userland visible parts and start killing the percpu refcnts of
5431 : * css's. Set up so that the next stage will be kicked off once all
5432 : * the percpu refcnts are confirmed to be killed.
5433 : *
5434 : * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
5435 : * rest of destruction. Once all cgroup references are gone, the
5436 : * cgroup is RCU-freed.
5437 : *
5438 : * This function implements s1. After this step, @cgrp is gone as far as
5439 : * the userland is concerned and a new cgroup with the same name may be
5440 : * created. As cgroup doesn't care about the names internally, this
5441 : * doesn't cause any problem.
5442 : */
5443 51 : static int cgroup_destroy_locked(struct cgroup *cgrp)
5444 : __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
5445 : {
5446 51 : struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);
5447 51 : struct cgroup_subsys_state *css;
5448 51 : struct cgrp_cset_link *link;
5449 51 : int ssid;
5450 :
5451 153 : lockdep_assert_held(&cgroup_mutex);
5452 :
5453 : /*
5454 : * Only migration can raise populated from zero and we're already
5455 : * holding cgroup_mutex.
5456 : */
5457 51 : if (cgroup_is_populated(cgrp))
5458 : return -EBUSY;
5459 :
5460 : /*
5461 : * Make sure there's no live children. We can't test emptiness of
5462 : * ->self.children as dead children linger on it while being
5463 : * drained; otherwise, "rmdir parent/child parent" may fail.
5464 : */
5465 50 : if (css_has_online_children(&cgrp->self))
5466 : return -EBUSY;
5467 :
5468 : /*
5469 : * Mark @cgrp and the associated csets dead. The former prevents
5470 : * further task migration and child creation by disabling
5471 : * cgroup_lock_live_group(). The latter makes the csets ignored by
5472 : * the migration path.
5473 : */
5474 50 : cgrp->self.flags &= ~CSS_ONLINE;
5475 :
5476 50 : spin_lock_irq(&css_set_lock);
5477 100 : list_for_each_entry(link, &cgrp->cset_links, cset_link)
5478 50 : link->cset->dead = true;
5479 50 : spin_unlock_irq(&css_set_lock);
5480 :
5481 : /* initiate massacre of all css's */
5482 50 : for_each_css(css, ssid, cgrp)
5483 : kill_css(css);
5484 :
5485 : /* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */
5486 50 : css_clear_dir(&cgrp->self);
5487 50 : kernfs_remove(cgrp->kn);
5488 :
5489 50 : if (parent && cgroup_is_threaded(cgrp))
5490 0 : parent->nr_threaded_children--;
5491 :
5492 50 : spin_lock_irq(&css_set_lock);
5493 208 : for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) {
5494 108 : tcgrp->nr_descendants--;
5495 108 : tcgrp->nr_dying_descendants++;
5496 : /*
5497 : * If the dying cgroup is frozen, decrease frozen descendants
5498 : * counters of ancestor cgroups.
5499 : */
5500 108 : if (test_bit(CGRP_FROZEN, &cgrp->flags))
5501 0 : tcgrp->freezer.nr_frozen_descendants--;
5502 : }
5503 50 : spin_unlock_irq(&css_set_lock);
5504 :
5505 50 : cgroup1_check_for_release(parent);
5506 :
5507 50 : cgroup_bpf_offline(cgrp);
5508 :
5509 : /* put the base reference */
5510 50 : percpu_ref_kill(&cgrp->self.refcnt);
5511 :
5512 50 : return 0;
5513 : };
5514 :
5515 51 : int cgroup_rmdir(struct kernfs_node *kn)
5516 : {
5517 51 : struct cgroup *cgrp;
5518 51 : int ret = 0;
5519 :
5520 51 : cgrp = cgroup_kn_lock_live(kn, false);
5521 51 : if (!cgrp)
5522 : return 0;
5523 :
5524 51 : ret = cgroup_destroy_locked(cgrp);
5525 51 : if (!ret)
5526 50 : TRACE_CGROUP_PATH(rmdir, cgrp);
5527 :
5528 51 : cgroup_kn_unlock(kn);
5529 51 : return ret;
5530 : }
5531 :
5532 : static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
5533 : .show_options = cgroup_show_options,
5534 : .mkdir = cgroup_mkdir,
5535 : .rmdir = cgroup_rmdir,
5536 : .show_path = cgroup_show_path,
5537 : };
5538 :
5539 : static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
5540 : {
5541 : struct cgroup_subsys_state *css;
5542 :
5543 : pr_debug("Initializing cgroup subsys %s\n", ss->name);
5544 :
5545 : mutex_lock(&cgroup_mutex);
5546 :
5547 : idr_init(&ss->css_idr);
5548 : INIT_LIST_HEAD(&ss->cfts);
5549 :
5550 : /* Create the root cgroup state for this subsystem */
5551 : ss->root = &cgrp_dfl_root;
5552 : css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
5553 : /* We don't handle early failures gracefully */
5554 : BUG_ON(IS_ERR(css));
5555 : init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
5556 :
5557 : /*
5558 : * Root csses are never destroyed and we can't initialize
5559 : * percpu_ref during early init. Disable refcnting.
5560 : */
5561 : css->flags |= CSS_NO_REF;
5562 :
5563 : if (early) {
5564 : /* allocation can't be done safely during early init */
5565 : css->id = 1;
5566 : } else {
5567 : css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
5568 : BUG_ON(css->id < 0);
5569 : }
5570 :
5571 : /* Update the init_css_set to contain a subsys
5572 : * pointer to this state - since the subsystem is
5573 : * newly registered, all tasks and hence the
5574 : * init_css_set is in the subsystem's root cgroup. */
5575 : init_css_set.subsys[ss->id] = css;
5576 :
5577 : have_fork_callback |= (bool)ss->fork << ss->id;
5578 : have_exit_callback |= (bool)ss->exit << ss->id;
5579 : have_release_callback |= (bool)ss->release << ss->id;
5580 : have_canfork_callback |= (bool)ss->can_fork << ss->id;
5581 :
5582 : /* At system boot, before all subsystems have been
5583 : * registered, no tasks have been forked, so we don't
5584 : * need to invoke fork callbacks here. */
5585 : BUG_ON(!list_empty(&init_task.tasks));
5586 :
5587 : BUG_ON(online_css(css));
5588 :
5589 : mutex_unlock(&cgroup_mutex);
5590 : }
5591 :
5592 : /**
5593 : * cgroup_init_early - cgroup initialization at system boot
5594 : *
5595 : * Initialize cgroups at system boot, and initialize any
5596 : * subsystems that request early init.
5597 : */
5598 1 : int __init cgroup_init_early(void)
5599 : {
5600 1 : static struct cgroup_fs_context __initdata ctx;
5601 1 : struct cgroup_subsys *ss;
5602 1 : int i;
5603 :
5604 1 : ctx.root = &cgrp_dfl_root;
5605 1 : init_cgroup_root(&ctx);
5606 1 : cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
5607 :
5608 1 : RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
5609 :
5610 1 : for_each_subsys(ss, i) {
5611 : WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
5612 : "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
5613 : i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
5614 : ss->id, ss->name);
5615 : WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
5616 : "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
5617 :
5618 : ss->id = i;
5619 : ss->name = cgroup_subsys_name[i];
5620 : if (!ss->legacy_name)
5621 : ss->legacy_name = cgroup_subsys_name[i];
5622 :
5623 : if (ss->early_init)
5624 : cgroup_init_subsys(ss, true);
5625 : }
5626 1 : return 0;
5627 : }
5628 :
5629 : static u16 cgroup_disable_mask __initdata;
5630 :
5631 : /**
5632 : * cgroup_init - cgroup initialization
5633 : *
5634 : * Register cgroup filesystem and /proc file, and initialize
5635 : * any subsystems that didn't request early init.
5636 : */
5637 1 : int __init cgroup_init(void)
5638 : {
5639 1 : struct cgroup_subsys *ss;
5640 1 : int ssid;
5641 :
5642 1 : BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
5643 1 : BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
5644 1 : BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
5645 :
5646 1 : cgroup_rstat_boot();
5647 :
5648 : /*
5649 : * The latency of the synchronize_rcu() is too high for cgroups,
5650 : * avoid it at the cost of forcing all readers into the slow path.
5651 : */
5652 1 : rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss);
5653 :
5654 1 : get_user_ns(init_cgroup_ns.user_ns);
5655 :
5656 1 : mutex_lock(&cgroup_mutex);
5657 :
5658 : /*
5659 : * Add init_css_set to the hash table so that dfl_root can link to
5660 : * it during init.
5661 : */
5662 1 : hash_add(css_set_table, &init_css_set.hlist,
5663 : css_set_hash(init_css_set.subsys));
5664 :
5665 1 : BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
5666 :
5667 1 : mutex_unlock(&cgroup_mutex);
5668 :
5669 1 : for_each_subsys(ss, ssid) {
5670 : if (ss->early_init) {
5671 : struct cgroup_subsys_state *css =
5672 : init_css_set.subsys[ss->id];
5673 :
5674 : css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
5675 : GFP_KERNEL);
5676 : BUG_ON(css->id < 0);
5677 : } else {
5678 : cgroup_init_subsys(ss, false);
5679 : }
5680 :
5681 : list_add_tail(&init_css_set.e_cset_node[ssid],
5682 : &cgrp_dfl_root.cgrp.e_csets[ssid]);
5683 :
5684 : /*
5685 : * Setting dfl_root subsys_mask needs to consider the
5686 : * disabled flag and cftype registration needs kmalloc,
5687 : * both of which aren't available during early_init.
5688 : */
5689 : if (cgroup_disable_mask & (1 << ssid)) {
5690 : static_branch_disable(cgroup_subsys_enabled_key[ssid]);
5691 : printk(KERN_INFO "Disabling %s control group subsystem\n",
5692 : ss->name);
5693 : continue;
5694 : }
5695 :
5696 : if (cgroup1_ssid_disabled(ssid))
5697 : printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
5698 : ss->name);
5699 :
5700 : cgrp_dfl_root.subsys_mask |= 1 << ss->id;
5701 :
5702 : /* implicit controllers must be threaded too */
5703 : WARN_ON(ss->implicit_on_dfl && !ss->threaded);
5704 :
5705 : if (ss->implicit_on_dfl)
5706 : cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
5707 : else if (!ss->dfl_cftypes)
5708 : cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
5709 :
5710 : if (ss->threaded)
5711 : cgrp_dfl_threaded_ss_mask |= 1 << ss->id;
5712 :
5713 : if (ss->dfl_cftypes == ss->legacy_cftypes) {
5714 : WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
5715 : } else {
5716 : WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
5717 : WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
5718 : }
5719 :
5720 : if (ss->bind)
5721 : ss->bind(init_css_set.subsys[ssid]);
5722 :
5723 : mutex_lock(&cgroup_mutex);
5724 : css_populate_dir(init_css_set.subsys[ssid]);
5725 : mutex_unlock(&cgroup_mutex);
5726 : }
5727 :
5728 : /* init_css_set.subsys[] has been updated, re-hash */
5729 1 : hash_del(&init_css_set.hlist);
5730 1 : hash_add(css_set_table, &init_css_set.hlist,
5731 : css_set_hash(init_css_set.subsys));
5732 :
5733 1 : WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
5734 1 : WARN_ON(register_filesystem(&cgroup_fs_type));
5735 1 : WARN_ON(register_filesystem(&cgroup2_fs_type));
5736 1 : WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show));
5737 : #ifdef CONFIG_CPUSETS
5738 : WARN_ON(register_filesystem(&cpuset_fs_type));
5739 : #endif
5740 :
5741 1 : return 0;
5742 : }
5743 :
5744 1 : static int __init cgroup_wq_init(void)
5745 : {
5746 : /*
5747 : * There isn't much point in executing destruction path in
5748 : * parallel. Good chunk is serialized with cgroup_mutex anyway.
5749 : * Use 1 for @max_active.
5750 : *
5751 : * We would prefer to do this in cgroup_init() above, but that
5752 : * is called before init_workqueues(): so leave this until after.
5753 : */
5754 1 : cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
5755 1 : BUG_ON(!cgroup_destroy_wq);
5756 1 : return 0;
5757 : }
5758 : core_initcall(cgroup_wq_init);
5759 :
5760 0 : void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
5761 : {
5762 0 : struct kernfs_node *kn;
5763 :
5764 0 : kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);
5765 0 : if (!kn)
5766 : return;
5767 0 : kernfs_path(kn, buf, buflen);
5768 0 : kernfs_put(kn);
5769 : }
5770 :
5771 : /*
5772 : * proc_cgroup_show()
5773 : * - Print task's cgroup paths into seq_file, one line for each hierarchy
5774 : * - Used for /proc/<pid>/cgroup.
5775 : */
5776 172 : int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
5777 : struct pid *pid, struct task_struct *tsk)
5778 : {
5779 172 : char *buf;
5780 172 : int retval;
5781 172 : struct cgroup_root *root;
5782 :
5783 172 : retval = -ENOMEM;
5784 172 : buf = kmalloc(PATH_MAX, GFP_KERNEL);
5785 172 : if (!buf)
5786 0 : goto out;
5787 :
5788 172 : mutex_lock(&cgroup_mutex);
5789 172 : spin_lock_irq(&css_set_lock);
5790 :
5791 516 : for_each_root(root) {
5792 344 : struct cgroup_subsys *ss;
5793 344 : struct cgroup *cgrp;
5794 344 : int ssid, count = 0;
5795 :
5796 344 : if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
5797 0 : continue;
5798 :
5799 344 : seq_printf(m, "%d:", root->hierarchy_id);
5800 344 : if (root != &cgrp_dfl_root)
5801 : for_each_subsys(ss, ssid)
5802 : if (root->subsys_mask & (1 << ssid))
5803 : seq_printf(m, "%s%s", count++ ? "," : "",
5804 : ss->legacy_name);
5805 344 : if (strlen(root->name))
5806 172 : seq_printf(m, "%sname=%s", count ? "," : "",
5807 172 : root->name);
5808 344 : seq_putc(m, ':');
5809 :
5810 344 : cgrp = task_cgroup_from_root(tsk, root);
5811 :
5812 : /*
5813 : * On traditional hierarchies, all zombie tasks show up as
5814 : * belonging to the root cgroup. On the default hierarchy,
5815 : * while a zombie doesn't show up in "cgroup.procs" and
5816 : * thus can't be migrated, its /proc/PID/cgroup keeps
5817 : * reporting the cgroup it belonged to before exiting. If
5818 : * the cgroup is removed before the zombie is reaped,
5819 : * " (deleted)" is appended to the cgroup path.
5820 : */
5821 344 : if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
5822 312 : retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
5823 312 : current->nsproxy->cgroup_ns);
5824 312 : if (retval >= PATH_MAX)
5825 : retval = -ENAMETOOLONG;
5826 312 : if (retval < 0)
5827 0 : goto out_unlock;
5828 :
5829 312 : seq_puts(m, buf);
5830 : } else {
5831 32 : seq_puts(m, "/");
5832 : }
5833 :
5834 344 : if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
5835 0 : seq_puts(m, " (deleted)\n");
5836 : else
5837 344 : seq_putc(m, '\n');
5838 : }
5839 :
5840 : retval = 0;
5841 172 : out_unlock:
5842 172 : spin_unlock_irq(&css_set_lock);
5843 172 : mutex_unlock(&cgroup_mutex);
5844 172 : kfree(buf);
5845 172 : out:
5846 172 : return retval;
5847 : }
5848 :
5849 : /**
5850 : * cgroup_fork - initialize cgroup related fields during copy_process()
5851 : * @child: pointer to task_struct of forking parent process.
5852 : *
5853 : * A task is associated with the init_css_set until cgroup_post_fork()
5854 : * attaches it to the target css_set.
5855 : */
5856 1162 : void cgroup_fork(struct task_struct *child)
5857 : {
5858 1162 : RCU_INIT_POINTER(child->cgroups, &init_css_set);
5859 1162 : INIT_LIST_HEAD(&child->cg_list);
5860 1162 : }
5861 :
5862 0 : static struct cgroup *cgroup_get_from_file(struct file *f)
5863 : {
5864 0 : struct cgroup_subsys_state *css;
5865 0 : struct cgroup *cgrp;
5866 :
5867 0 : css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
5868 0 : if (IS_ERR(css))
5869 0 : return ERR_CAST(css);
5870 :
5871 0 : cgrp = css->cgroup;
5872 0 : if (!cgroup_on_dfl(cgrp)) {
5873 0 : cgroup_put(cgrp);
5874 0 : return ERR_PTR(-EBADF);
5875 : }
5876 :
5877 : return cgrp;
5878 : }
5879 :
5880 : /**
5881 : * cgroup_css_set_fork - find or create a css_set for a child process
5882 : * @kargs: the arguments passed to create the child process
5883 : *
5884 : * This functions finds or creates a new css_set which the child
5885 : * process will be attached to in cgroup_post_fork(). By default,
5886 : * the child process will be given the same css_set as its parent.
5887 : *
5888 : * If CLONE_INTO_CGROUP is specified this function will try to find an
5889 : * existing css_set which includes the requested cgroup and if not create
5890 : * a new css_set that the child will be attached to later. If this function
5891 : * succeeds it will hold cgroup_threadgroup_rwsem on return. If
5892 : * CLONE_INTO_CGROUP is requested this function will grab cgroup mutex
5893 : * before grabbing cgroup_threadgroup_rwsem and will hold a reference
5894 : * to the target cgroup.
5895 : */
5896 1162 : static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
5897 : __acquires(&cgroup_mutex) __acquires(&cgroup_threadgroup_rwsem)
5898 : {
5899 1162 : int ret;
5900 1162 : struct cgroup *dst_cgrp = NULL;
5901 1162 : struct css_set *cset;
5902 1162 : struct super_block *sb;
5903 1162 : struct file *f;
5904 :
5905 1162 : if (kargs->flags & CLONE_INTO_CGROUP)
5906 0 : mutex_lock(&cgroup_mutex);
5907 :
5908 1162 : cgroup_threadgroup_change_begin(current);
5909 :
5910 1162 : spin_lock_irq(&css_set_lock);
5911 1162 : cset = task_css_set(current);
5912 1162 : get_css_set(cset);
5913 1162 : spin_unlock_irq(&css_set_lock);
5914 :
5915 1162 : if (!(kargs->flags & CLONE_INTO_CGROUP)) {
5916 1162 : kargs->cset = cset;
5917 1162 : return 0;
5918 : }
5919 :
5920 0 : f = fget_raw(kargs->cgroup);
5921 0 : if (!f) {
5922 0 : ret = -EBADF;
5923 0 : goto err;
5924 : }
5925 0 : sb = f->f_path.dentry->d_sb;
5926 :
5927 0 : dst_cgrp = cgroup_get_from_file(f);
5928 0 : if (IS_ERR(dst_cgrp)) {
5929 0 : ret = PTR_ERR(dst_cgrp);
5930 0 : dst_cgrp = NULL;
5931 0 : goto err;
5932 : }
5933 :
5934 0 : if (cgroup_is_dead(dst_cgrp)) {
5935 0 : ret = -ENODEV;
5936 0 : goto err;
5937 : }
5938 :
5939 : /*
5940 : * Verify that we the target cgroup is writable for us. This is
5941 : * usually done by the vfs layer but since we're not going through
5942 : * the vfs layer here we need to do it "manually".
5943 : */
5944 0 : ret = cgroup_may_write(dst_cgrp, sb);
5945 0 : if (ret)
5946 0 : goto err;
5947 :
5948 0 : ret = cgroup_attach_permissions(cset->dfl_cgrp, dst_cgrp, sb,
5949 0 : !(kargs->flags & CLONE_THREAD));
5950 0 : if (ret)
5951 0 : goto err;
5952 :
5953 0 : kargs->cset = find_css_set(cset, dst_cgrp);
5954 0 : if (!kargs->cset) {
5955 0 : ret = -ENOMEM;
5956 0 : goto err;
5957 : }
5958 :
5959 0 : put_css_set(cset);
5960 0 : fput(f);
5961 0 : kargs->cgrp = dst_cgrp;
5962 0 : return ret;
5963 :
5964 0 : err:
5965 0 : cgroup_threadgroup_change_end(current);
5966 0 : mutex_unlock(&cgroup_mutex);
5967 0 : if (f)
5968 0 : fput(f);
5969 0 : if (dst_cgrp)
5970 0 : cgroup_put(dst_cgrp);
5971 0 : put_css_set(cset);
5972 0 : if (kargs->cset)
5973 0 : put_css_set(kargs->cset);
5974 : return ret;
5975 : }
5976 :
5977 : /**
5978 : * cgroup_css_set_put_fork - drop references we took during fork
5979 : * @kargs: the arguments passed to create the child process
5980 : *
5981 : * Drop references to the prepared css_set and target cgroup if
5982 : * CLONE_INTO_CGROUP was requested.
5983 : */
5984 1162 : static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs)
5985 : __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
5986 : {
5987 1162 : cgroup_threadgroup_change_end(current);
5988 :
5989 1162 : if (kargs->flags & CLONE_INTO_CGROUP) {
5990 0 : struct cgroup *cgrp = kargs->cgrp;
5991 0 : struct css_set *cset = kargs->cset;
5992 :
5993 0 : mutex_unlock(&cgroup_mutex);
5994 :
5995 0 : if (cset) {
5996 0 : put_css_set(cset);
5997 0 : kargs->cset = NULL;
5998 : }
5999 :
6000 0 : if (cgrp) {
6001 0 : cgroup_put(cgrp);
6002 0 : kargs->cgrp = NULL;
6003 : }
6004 : }
6005 1162 : }
6006 :
6007 : /**
6008 : * cgroup_can_fork - called on a new task before the process is exposed
6009 : * @child: the child process
6010 : *
6011 : * This prepares a new css_set for the child process which the child will
6012 : * be attached to in cgroup_post_fork().
6013 : * This calls the subsystem can_fork() callbacks. If the cgroup_can_fork()
6014 : * callback returns an error, the fork aborts with that error code. This
6015 : * allows for a cgroup subsystem to conditionally allow or deny new forks.
6016 : */
6017 1162 : int cgroup_can_fork(struct task_struct *child, struct kernel_clone_args *kargs)
6018 : {
6019 1162 : struct cgroup_subsys *ss;
6020 1162 : int i, j, ret;
6021 :
6022 1162 : ret = cgroup_css_set_fork(kargs);
6023 1162 : if (ret)
6024 0 : return ret;
6025 :
6026 1162 : do_each_subsys_mask(ss, i, have_canfork_callback) {
6027 : ret = ss->can_fork(child, kargs->cset);
6028 : if (ret)
6029 : goto out_revert;
6030 : } while_each_subsys_mask();
6031 :
6032 : return 0;
6033 :
6034 : out_revert:
6035 : for_each_subsys(ss, j) {
6036 : if (j >= i)
6037 : break;
6038 : if (ss->cancel_fork)
6039 : ss->cancel_fork(child, kargs->cset);
6040 : }
6041 :
6042 : cgroup_css_set_put_fork(kargs);
6043 :
6044 : return ret;
6045 : }
6046 :
6047 : /**
6048 : * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
6049 : * @child: the child process
6050 : * @kargs: the arguments passed to create the child process
6051 : *
6052 : * This calls the cancel_fork() callbacks if a fork failed *after*
6053 : * cgroup_can_fork() succeded and cleans up references we took to
6054 : * prepare a new css_set for the child process in cgroup_can_fork().
6055 : */
6056 0 : void cgroup_cancel_fork(struct task_struct *child,
6057 : struct kernel_clone_args *kargs)
6058 : {
6059 0 : struct cgroup_subsys *ss;
6060 0 : int i;
6061 :
6062 0 : for_each_subsys(ss, i)
6063 : if (ss->cancel_fork)
6064 : ss->cancel_fork(child, kargs->cset);
6065 :
6066 0 : cgroup_css_set_put_fork(kargs);
6067 0 : }
6068 :
6069 : /**
6070 : * cgroup_post_fork - finalize cgroup setup for the child process
6071 : * @child: the child process
6072 : *
6073 : * Attach the child process to its css_set calling the subsystem fork()
6074 : * callbacks.
6075 : */
6076 1162 : void cgroup_post_fork(struct task_struct *child,
6077 : struct kernel_clone_args *kargs)
6078 : __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
6079 : {
6080 1162 : struct cgroup_subsys *ss;
6081 1162 : struct css_set *cset;
6082 1162 : int i;
6083 :
6084 1162 : cset = kargs->cset;
6085 1162 : kargs->cset = NULL;
6086 :
6087 1162 : spin_lock_irq(&css_set_lock);
6088 :
6089 : /* init tasks are special, only link regular threads */
6090 1162 : if (likely(child->pid)) {
6091 1159 : WARN_ON_ONCE(!list_empty(&child->cg_list));
6092 1159 : cset->nr_tasks++;
6093 1159 : css_set_move_task(child, NULL, cset, false);
6094 : } else {
6095 3 : put_css_set(cset);
6096 3 : cset = NULL;
6097 : }
6098 :
6099 : /*
6100 : * If the cgroup has to be frozen, the new task has too. Let's set
6101 : * the JOBCTL_TRAP_FREEZE jobctl bit to get the task into the
6102 : * frozen state.
6103 : */
6104 1162 : if (unlikely(cgroup_task_freeze(child))) {
6105 0 : spin_lock(&child->sighand->siglock);
6106 0 : WARN_ON_ONCE(child->frozen);
6107 0 : child->jobctl |= JOBCTL_TRAP_FREEZE;
6108 0 : spin_unlock(&child->sighand->siglock);
6109 :
6110 : /*
6111 : * Calling cgroup_update_frozen() isn't required here,
6112 : * because it will be called anyway a bit later from
6113 : * do_freezer_trap(). So we avoid cgroup's transient switch
6114 : * from the frozen state and back.
6115 : */
6116 : }
6117 :
6118 1162 : spin_unlock_irq(&css_set_lock);
6119 :
6120 : /*
6121 : * Call ss->fork(). This must happen after @child is linked on
6122 : * css_set; otherwise, @child might change state between ->fork()
6123 : * and addition to css_set.
6124 : */
6125 1162 : do_each_subsys_mask(ss, i, have_fork_callback) {
6126 : ss->fork(child);
6127 1162 : } while_each_subsys_mask();
6128 :
6129 : /* Make the new cset the root_cset of the new cgroup namespace. */
6130 1162 : if (kargs->flags & CLONE_NEWCGROUP) {
6131 0 : struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset;
6132 :
6133 0 : get_css_set(cset);
6134 0 : child->nsproxy->cgroup_ns->root_cset = cset;
6135 0 : put_css_set(rcset);
6136 : }
6137 :
6138 1162 : cgroup_css_set_put_fork(kargs);
6139 1162 : }
6140 :
6141 : /**
6142 : * cgroup_exit - detach cgroup from exiting task
6143 : * @tsk: pointer to task_struct of exiting process
6144 : *
6145 : * Description: Detach cgroup from @tsk.
6146 : *
6147 : */
6148 1083 : void cgroup_exit(struct task_struct *tsk)
6149 : {
6150 1083 : struct cgroup_subsys *ss;
6151 1083 : struct css_set *cset;
6152 1083 : int i;
6153 :
6154 1083 : spin_lock_irq(&css_set_lock);
6155 :
6156 1083 : WARN_ON_ONCE(list_empty(&tsk->cg_list));
6157 1083 : cset = task_css_set(tsk);
6158 1083 : css_set_move_task(tsk, cset, NULL, false);
6159 1083 : list_add_tail(&tsk->cg_list, &cset->dying_tasks);
6160 1083 : cset->nr_tasks--;
6161 :
6162 1083 : WARN_ON_ONCE(cgroup_task_frozen(tsk));
6163 1083 : if (unlikely(cgroup_task_freeze(tsk)))
6164 0 : cgroup_update_frozen(task_dfl_cgroup(tsk));
6165 :
6166 1083 : spin_unlock_irq(&css_set_lock);
6167 :
6168 : /* see cgroup_post_fork() for details */
6169 1083 : do_each_subsys_mask(ss, i, have_exit_callback) {
6170 : ss->exit(tsk);
6171 1083 : } while_each_subsys_mask();
6172 1083 : }
6173 :
6174 1083 : void cgroup_release(struct task_struct *task)
6175 : {
6176 1083 : struct cgroup_subsys *ss;
6177 1083 : int ssid;
6178 :
6179 1083 : do_each_subsys_mask(ss, ssid, have_release_callback) {
6180 : ss->release(task);
6181 1083 : } while_each_subsys_mask();
6182 :
6183 1083 : spin_lock_irq(&css_set_lock);
6184 1083 : css_set_skip_task_iters(task_css_set(task), task);
6185 1083 : list_del_init(&task->cg_list);
6186 1083 : spin_unlock_irq(&css_set_lock);
6187 1083 : }
6188 :
6189 1083 : void cgroup_free(struct task_struct *task)
6190 : {
6191 1083 : struct css_set *cset = task_css_set(task);
6192 1083 : put_css_set(cset);
6193 1083 : }
6194 :
6195 0 : static int __init cgroup_disable(char *str)
6196 : {
6197 0 : struct cgroup_subsys *ss;
6198 0 : char *token;
6199 0 : int i;
6200 :
6201 0 : while ((token = strsep(&str, ",")) != NULL) {
6202 : if (!*token)
6203 : continue;
6204 :
6205 : for_each_subsys(ss, i) {
6206 : if (strcmp(token, ss->name) &&
6207 : strcmp(token, ss->legacy_name))
6208 : continue;
6209 : cgroup_disable_mask |= 1 << i;
6210 : }
6211 : }
6212 0 : return 1;
6213 : }
6214 : __setup("cgroup_disable=", cgroup_disable);
6215 :
6216 0 : void __init __weak enable_debug_cgroup(void) { }
6217 :
6218 0 : static int __init enable_cgroup_debug(char *str)
6219 : {
6220 0 : cgroup_debug = true;
6221 0 : enable_debug_cgroup();
6222 0 : return 1;
6223 : }
6224 : __setup("cgroup_debug", enable_cgroup_debug);
6225 :
6226 : /**
6227 : * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
6228 : * @dentry: directory dentry of interest
6229 : * @ss: subsystem of interest
6230 : *
6231 : * If @dentry is a directory for a cgroup which has @ss enabled on it, try
6232 : * to get the corresponding css and return it. If such css doesn't exist
6233 : * or can't be pinned, an ERR_PTR value is returned.
6234 : */
6235 0 : struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
6236 : struct cgroup_subsys *ss)
6237 : {
6238 0 : struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
6239 0 : struct file_system_type *s_type = dentry->d_sb->s_type;
6240 0 : struct cgroup_subsys_state *css = NULL;
6241 0 : struct cgroup *cgrp;
6242 :
6243 : /* is @dentry a cgroup dir? */
6244 0 : if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
6245 0 : !kn || kernfs_type(kn) != KERNFS_DIR)
6246 0 : return ERR_PTR(-EBADF);
6247 :
6248 0 : rcu_read_lock();
6249 :
6250 : /*
6251 : * This path doesn't originate from kernfs and @kn could already
6252 : * have been or be removed at any point. @kn->priv is RCU
6253 : * protected for this access. See css_release_work_fn() for details.
6254 : */
6255 0 : cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
6256 0 : if (cgrp)
6257 0 : css = cgroup_css(cgrp, ss);
6258 :
6259 0 : if (!css || !css_tryget_online(css))
6260 0 : css = ERR_PTR(-ENOENT);
6261 :
6262 0 : rcu_read_unlock();
6263 0 : return css;
6264 : }
6265 :
6266 : /**
6267 : * css_from_id - lookup css by id
6268 : * @id: the cgroup id
6269 : * @ss: cgroup subsys to be looked into
6270 : *
6271 : * Returns the css if there's valid one with @id, otherwise returns NULL.
6272 : * Should be called under rcu_read_lock().
6273 : */
6274 0 : struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
6275 : {
6276 0 : WARN_ON_ONCE(!rcu_read_lock_held());
6277 0 : return idr_find(&ss->css_idr, id);
6278 : }
6279 :
6280 : /**
6281 : * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
6282 : * @path: path on the default hierarchy
6283 : *
6284 : * Find the cgroup at @path on the default hierarchy, increment its
6285 : * reference count and return it. Returns pointer to the found cgroup on
6286 : * success, ERR_PTR(-ENOENT) if @path doesn't exist and ERR_PTR(-ENOTDIR)
6287 : * if @path points to a non-directory.
6288 : */
6289 0 : struct cgroup *cgroup_get_from_path(const char *path)
6290 : {
6291 0 : struct kernfs_node *kn;
6292 0 : struct cgroup *cgrp;
6293 :
6294 0 : mutex_lock(&cgroup_mutex);
6295 :
6296 0 : kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path);
6297 0 : if (kn) {
6298 0 : if (kernfs_type(kn) == KERNFS_DIR) {
6299 0 : cgrp = kn->priv;
6300 0 : cgroup_get_live(cgrp);
6301 : } else {
6302 0 : cgrp = ERR_PTR(-ENOTDIR);
6303 : }
6304 0 : kernfs_put(kn);
6305 : } else {
6306 0 : cgrp = ERR_PTR(-ENOENT);
6307 : }
6308 :
6309 0 : mutex_unlock(&cgroup_mutex);
6310 0 : return cgrp;
6311 : }
6312 : EXPORT_SYMBOL_GPL(cgroup_get_from_path);
6313 :
6314 : /**
6315 : * cgroup_get_from_fd - get a cgroup pointer from a fd
6316 : * @fd: fd obtained by open(cgroup2_dir)
6317 : *
6318 : * Find the cgroup from a fd which should be obtained
6319 : * by opening a cgroup directory. Returns a pointer to the
6320 : * cgroup on success. ERR_PTR is returned if the cgroup
6321 : * cannot be found.
6322 : */
6323 0 : struct cgroup *cgroup_get_from_fd(int fd)
6324 : {
6325 0 : struct cgroup *cgrp;
6326 0 : struct file *f;
6327 :
6328 0 : f = fget_raw(fd);
6329 0 : if (!f)
6330 0 : return ERR_PTR(-EBADF);
6331 :
6332 0 : cgrp = cgroup_get_from_file(f);
6333 0 : fput(f);
6334 0 : return cgrp;
6335 : }
6336 : EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
6337 :
6338 0 : static u64 power_of_ten(int power)
6339 : {
6340 0 : u64 v = 1;
6341 0 : while (power--)
6342 0 : v *= 10;
6343 0 : return v;
6344 : }
6345 :
6346 : /**
6347 : * cgroup_parse_float - parse a floating number
6348 : * @input: input string
6349 : * @dec_shift: number of decimal digits to shift
6350 : * @v: output
6351 : *
6352 : * Parse a decimal floating point number in @input and store the result in
6353 : * @v with decimal point right shifted @dec_shift times. For example, if
6354 : * @input is "12.3456" and @dec_shift is 3, *@v will be set to 12345.
6355 : * Returns 0 on success, -errno otherwise.
6356 : *
6357 : * There's nothing cgroup specific about this function except that it's
6358 : * currently the only user.
6359 : */
6360 0 : int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v)
6361 : {
6362 0 : s64 whole, frac = 0;
6363 0 : int fstart = 0, fend = 0, flen;
6364 :
6365 0 : if (!sscanf(input, "%lld.%n%lld%n", &whole, &fstart, &frac, &fend))
6366 : return -EINVAL;
6367 0 : if (frac < 0)
6368 : return -EINVAL;
6369 :
6370 0 : flen = fend > fstart ? fend - fstart : 0;
6371 0 : if (flen < dec_shift)
6372 0 : frac *= power_of_ten(dec_shift - flen);
6373 : else
6374 0 : frac = DIV_ROUND_CLOSEST_ULL(frac, power_of_ten(flen - dec_shift));
6375 :
6376 0 : *v = whole * power_of_ten(dec_shift) + frac;
6377 0 : return 0;
6378 : }
6379 :
6380 : /*
6381 : * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
6382 : * definition in cgroup-defs.h.
6383 : */
6384 : #ifdef CONFIG_SOCK_CGROUP_DATA
6385 :
6386 : #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
6387 :
6388 : DEFINE_SPINLOCK(cgroup_sk_update_lock);
6389 : static bool cgroup_sk_alloc_disabled __read_mostly;
6390 :
6391 : void cgroup_sk_alloc_disable(void)
6392 : {
6393 : if (cgroup_sk_alloc_disabled)
6394 : return;
6395 : pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
6396 : cgroup_sk_alloc_disabled = true;
6397 : }
6398 :
6399 : #else
6400 :
6401 : #define cgroup_sk_alloc_disabled false
6402 :
6403 : #endif
6404 :
6405 : void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
6406 : {
6407 : if (cgroup_sk_alloc_disabled) {
6408 : skcd->no_refcnt = 1;
6409 : return;
6410 : }
6411 :
6412 : /* Don't associate the sock with unrelated interrupted task's cgroup. */
6413 : if (in_interrupt())
6414 : return;
6415 :
6416 : rcu_read_lock();
6417 :
6418 : while (true) {
6419 : struct css_set *cset;
6420 :
6421 : cset = task_css_set(current);
6422 : if (likely(cgroup_tryget(cset->dfl_cgrp))) {
6423 : skcd->val = (unsigned long)cset->dfl_cgrp;
6424 : cgroup_bpf_get(cset->dfl_cgrp);
6425 : break;
6426 : }
6427 : cpu_relax();
6428 : }
6429 :
6430 : rcu_read_unlock();
6431 : }
6432 :
6433 : void cgroup_sk_clone(struct sock_cgroup_data *skcd)
6434 : {
6435 : if (skcd->val) {
6436 : if (skcd->no_refcnt)
6437 : return;
6438 : /*
6439 : * We might be cloning a socket which is left in an empty
6440 : * cgroup and the cgroup might have already been rmdir'd.
6441 : * Don't use cgroup_get_live().
6442 : */
6443 : cgroup_get(sock_cgroup_ptr(skcd));
6444 : cgroup_bpf_get(sock_cgroup_ptr(skcd));
6445 : }
6446 : }
6447 :
6448 : void cgroup_sk_free(struct sock_cgroup_data *skcd)
6449 : {
6450 : struct cgroup *cgrp = sock_cgroup_ptr(skcd);
6451 :
6452 : if (skcd->no_refcnt)
6453 : return;
6454 : cgroup_bpf_put(cgrp);
6455 : cgroup_put(cgrp);
6456 : }
6457 :
6458 : #endif /* CONFIG_SOCK_CGROUP_DATA */
6459 :
6460 : #ifdef CONFIG_CGROUP_BPF
6461 : int cgroup_bpf_attach(struct cgroup *cgrp,
6462 : struct bpf_prog *prog, struct bpf_prog *replace_prog,
6463 : struct bpf_cgroup_link *link,
6464 : enum bpf_attach_type type,
6465 : u32 flags)
6466 : {
6467 : int ret;
6468 :
6469 : mutex_lock(&cgroup_mutex);
6470 : ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link, type, flags);
6471 : mutex_unlock(&cgroup_mutex);
6472 : return ret;
6473 : }
6474 :
6475 : int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
6476 : enum bpf_attach_type type)
6477 : {
6478 : int ret;
6479 :
6480 : mutex_lock(&cgroup_mutex);
6481 : ret = __cgroup_bpf_detach(cgrp, prog, NULL, type);
6482 : mutex_unlock(&cgroup_mutex);
6483 : return ret;
6484 : }
6485 :
6486 : int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
6487 : union bpf_attr __user *uattr)
6488 : {
6489 : int ret;
6490 :
6491 : mutex_lock(&cgroup_mutex);
6492 : ret = __cgroup_bpf_query(cgrp, attr, uattr);
6493 : mutex_unlock(&cgroup_mutex);
6494 : return ret;
6495 : }
6496 : #endif /* CONFIG_CGROUP_BPF */
6497 :
6498 : #ifdef CONFIG_SYSFS
6499 0 : static ssize_t show_delegatable_files(struct cftype *files, char *buf,
6500 : ssize_t size, const char *prefix)
6501 : {
6502 0 : struct cftype *cft;
6503 0 : ssize_t ret = 0;
6504 :
6505 0 : for (cft = files; cft && cft->name[0] != '\0'; cft++) {
6506 0 : if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
6507 0 : continue;
6508 :
6509 0 : if (prefix)
6510 0 : ret += snprintf(buf + ret, size - ret, "%s.", prefix);
6511 :
6512 0 : ret += snprintf(buf + ret, size - ret, "%s\n", cft->name);
6513 :
6514 0 : if (WARN_ON(ret >= size))
6515 : break;
6516 : }
6517 :
6518 0 : return ret;
6519 : }
6520 :
6521 0 : static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr,
6522 : char *buf)
6523 : {
6524 0 : struct cgroup_subsys *ss;
6525 0 : int ssid;
6526 0 : ssize_t ret = 0;
6527 :
6528 0 : ret = show_delegatable_files(cgroup_base_files, buf, PAGE_SIZE - ret,
6529 : NULL);
6530 :
6531 0 : for_each_subsys(ss, ssid)
6532 : ret += show_delegatable_files(ss->dfl_cftypes, buf + ret,
6533 : PAGE_SIZE - ret,
6534 : cgroup_subsys_name[ssid]);
6535 :
6536 0 : return ret;
6537 : }
6538 : static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate);
6539 :
6540 0 : static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr,
6541 : char *buf)
6542 : {
6543 0 : return snprintf(buf, PAGE_SIZE,
6544 : "nsdelegate\n"
6545 : "memory_localevents\n"
6546 : "memory_recursiveprot\n");
6547 : }
6548 : static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features);
6549 :
6550 : static struct attribute *cgroup_sysfs_attrs[] = {
6551 : &cgroup_delegate_attr.attr,
6552 : &cgroup_features_attr.attr,
6553 : NULL,
6554 : };
6555 :
6556 : static const struct attribute_group cgroup_sysfs_attr_group = {
6557 : .attrs = cgroup_sysfs_attrs,
6558 : .name = "cgroup",
6559 : };
6560 :
6561 1 : static int __init cgroup_sysfs_init(void)
6562 : {
6563 1 : return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group);
6564 : }
6565 : subsys_initcall(cgroup_sysfs_init);
6566 :
6567 : #endif /* CONFIG_SYSFS */
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