Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * linux/kernel/exit.c
4 : *
5 : * Copyright (C) 1991, 1992 Linus Torvalds
6 : */
7 :
8 : #include <linux/mm.h>
9 : #include <linux/slab.h>
10 : #include <linux/sched/autogroup.h>
11 : #include <linux/sched/mm.h>
12 : #include <linux/sched/stat.h>
13 : #include <linux/sched/task.h>
14 : #include <linux/sched/task_stack.h>
15 : #include <linux/sched/cputime.h>
16 : #include <linux/interrupt.h>
17 : #include <linux/module.h>
18 : #include <linux/capability.h>
19 : #include <linux/completion.h>
20 : #include <linux/personality.h>
21 : #include <linux/tty.h>
22 : #include <linux/iocontext.h>
23 : #include <linux/key.h>
24 : #include <linux/cpu.h>
25 : #include <linux/acct.h>
26 : #include <linux/tsacct_kern.h>
27 : #include <linux/file.h>
28 : #include <linux/fdtable.h>
29 : #include <linux/freezer.h>
30 : #include <linux/binfmts.h>
31 : #include <linux/nsproxy.h>
32 : #include <linux/pid_namespace.h>
33 : #include <linux/ptrace.h>
34 : #include <linux/profile.h>
35 : #include <linux/mount.h>
36 : #include <linux/proc_fs.h>
37 : #include <linux/kthread.h>
38 : #include <linux/mempolicy.h>
39 : #include <linux/taskstats_kern.h>
40 : #include <linux/delayacct.h>
41 : #include <linux/cgroup.h>
42 : #include <linux/syscalls.h>
43 : #include <linux/signal.h>
44 : #include <linux/posix-timers.h>
45 : #include <linux/cn_proc.h>
46 : #include <linux/mutex.h>
47 : #include <linux/futex.h>
48 : #include <linux/pipe_fs_i.h>
49 : #include <linux/audit.h> /* for audit_free() */
50 : #include <linux/resource.h>
51 : #include <linux/blkdev.h>
52 : #include <linux/task_io_accounting_ops.h>
53 : #include <linux/tracehook.h>
54 : #include <linux/fs_struct.h>
55 : #include <linux/init_task.h>
56 : #include <linux/perf_event.h>
57 : #include <trace/events/sched.h>
58 : #include <linux/hw_breakpoint.h>
59 : #include <linux/oom.h>
60 : #include <linux/writeback.h>
61 : #include <linux/shm.h>
62 : #include <linux/kcov.h>
63 : #include <linux/random.h>
64 : #include <linux/rcuwait.h>
65 : #include <linux/compat.h>
66 : #include <linux/io_uring.h>
67 :
68 : #include <linux/uaccess.h>
69 : #include <asm/unistd.h>
70 : #include <asm/mmu_context.h>
71 :
72 0 : static void __unhash_process(struct task_struct *p, bool group_dead)
73 : {
74 0 : nr_threads--;
75 0 : detach_pid(p, PIDTYPE_PID);
76 0 : if (group_dead) {
77 0 : detach_pid(p, PIDTYPE_TGID);
78 0 : detach_pid(p, PIDTYPE_PGID);
79 0 : detach_pid(p, PIDTYPE_SID);
80 :
81 0 : list_del_rcu(&p->tasks);
82 0 : list_del_init(&p->sibling);
83 0 : __this_cpu_dec(process_counts);
84 : }
85 0 : list_del_rcu(&p->thread_group);
86 0 : list_del_rcu(&p->thread_node);
87 0 : }
88 :
89 : /*
90 : * This function expects the tasklist_lock write-locked.
91 : */
92 0 : static void __exit_signal(struct task_struct *tsk)
93 : {
94 0 : struct signal_struct *sig = tsk->signal;
95 0 : bool group_dead = thread_group_leader(tsk);
96 0 : struct sighand_struct *sighand;
97 0 : struct tty_struct *tty;
98 0 : u64 utime, stime;
99 :
100 0 : sighand = rcu_dereference_check(tsk->sighand,
101 : lockdep_tasklist_lock_is_held());
102 0 : spin_lock(&sighand->siglock);
103 :
104 : #ifdef CONFIG_POSIX_TIMERS
105 0 : posix_cpu_timers_exit(tsk);
106 0 : if (group_dead)
107 0 : posix_cpu_timers_exit_group(tsk);
108 : #endif
109 :
110 0 : if (group_dead) {
111 0 : tty = sig->tty;
112 0 : sig->tty = NULL;
113 : } else {
114 : /*
115 : * If there is any task waiting for the group exit
116 : * then notify it:
117 : */
118 0 : if (sig->notify_count > 0 && !--sig->notify_count)
119 0 : wake_up_process(sig->group_exit_task);
120 :
121 0 : if (tsk == sig->curr_target)
122 0 : sig->curr_target = next_thread(tsk);
123 : }
124 :
125 0 : add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
126 : sizeof(unsigned long long));
127 :
128 : /*
129 : * Accumulate here the counters for all threads as they die. We could
130 : * skip the group leader because it is the last user of signal_struct,
131 : * but we want to avoid the race with thread_group_cputime() which can
132 : * see the empty ->thread_head list.
133 : */
134 0 : task_cputime(tsk, &utime, &stime);
135 0 : write_seqlock(&sig->stats_lock);
136 0 : sig->utime += utime;
137 0 : sig->stime += stime;
138 0 : sig->gtime += task_gtime(tsk);
139 0 : sig->min_flt += tsk->min_flt;
140 0 : sig->maj_flt += tsk->maj_flt;
141 0 : sig->nvcsw += tsk->nvcsw;
142 0 : sig->nivcsw += tsk->nivcsw;
143 0 : sig->inblock += task_io_get_inblock(tsk);
144 0 : sig->oublock += task_io_get_oublock(tsk);
145 0 : task_io_accounting_add(&sig->ioac, &tsk->ioac);
146 0 : sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
147 0 : sig->nr_threads--;
148 0 : __unhash_process(tsk, group_dead);
149 0 : write_sequnlock(&sig->stats_lock);
150 :
151 : /*
152 : * Do this under ->siglock, we can race with another thread
153 : * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
154 : */
155 0 : flush_sigqueue(&tsk->pending);
156 0 : tsk->sighand = NULL;
157 0 : spin_unlock(&sighand->siglock);
158 :
159 0 : __cleanup_sighand(sighand);
160 0 : clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
161 0 : if (group_dead) {
162 0 : flush_sigqueue(&sig->shared_pending);
163 0 : tty_kref_put(tty);
164 : }
165 0 : }
166 :
167 0 : static void delayed_put_task_struct(struct rcu_head *rhp)
168 : {
169 0 : struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
170 :
171 0 : perf_event_delayed_put(tsk);
172 0 : trace_sched_process_free(tsk);
173 0 : put_task_struct(tsk);
174 0 : }
175 :
176 0 : void put_task_struct_rcu_user(struct task_struct *task)
177 : {
178 0 : if (refcount_dec_and_test(&task->rcu_users))
179 0 : call_rcu(&task->rcu, delayed_put_task_struct);
180 0 : }
181 :
182 0 : void release_task(struct task_struct *p)
183 : {
184 0 : struct task_struct *leader;
185 0 : struct pid *thread_pid;
186 0 : int zap_leader;
187 0 : repeat:
188 : /* don't need to get the RCU readlock here - the process is dead and
189 : * can't be modifying its own credentials. But shut RCU-lockdep up */
190 0 : rcu_read_lock();
191 0 : atomic_dec(&__task_cred(p)->user->processes);
192 0 : rcu_read_unlock();
193 :
194 0 : cgroup_release(p);
195 :
196 0 : write_lock_irq(&tasklist_lock);
197 0 : ptrace_release_task(p);
198 0 : thread_pid = get_pid(p->thread_pid);
199 0 : __exit_signal(p);
200 :
201 : /*
202 : * If we are the last non-leader member of the thread
203 : * group, and the leader is zombie, then notify the
204 : * group leader's parent process. (if it wants notification.)
205 : */
206 0 : zap_leader = 0;
207 0 : leader = p->group_leader;
208 0 : if (leader != p && thread_group_empty(leader)
209 0 : && leader->exit_state == EXIT_ZOMBIE) {
210 : /*
211 : * If we were the last child thread and the leader has
212 : * exited already, and the leader's parent ignores SIGCHLD,
213 : * then we are the one who should release the leader.
214 : */
215 0 : zap_leader = do_notify_parent(leader, leader->exit_signal);
216 0 : if (zap_leader)
217 0 : leader->exit_state = EXIT_DEAD;
218 : }
219 :
220 0 : write_unlock_irq(&tasklist_lock);
221 0 : seccomp_filter_release(p);
222 0 : proc_flush_pid(thread_pid);
223 0 : put_pid(thread_pid);
224 0 : release_thread(p);
225 0 : put_task_struct_rcu_user(p);
226 :
227 0 : p = leader;
228 0 : if (unlikely(zap_leader))
229 0 : goto repeat;
230 0 : }
231 :
232 0 : int rcuwait_wake_up(struct rcuwait *w)
233 : {
234 0 : int ret = 0;
235 0 : struct task_struct *task;
236 :
237 0 : rcu_read_lock();
238 :
239 : /*
240 : * Order condition vs @task, such that everything prior to the load
241 : * of @task is visible. This is the condition as to why the user called
242 : * rcuwait_wake() in the first place. Pairs with set_current_state()
243 : * barrier (A) in rcuwait_wait_event().
244 : *
245 : * WAIT WAKE
246 : * [S] tsk = current [S] cond = true
247 : * MB (A) MB (B)
248 : * [L] cond [L] tsk
249 : */
250 0 : smp_mb(); /* (B) */
251 :
252 0 : task = rcu_dereference(w->task);
253 0 : if (task)
254 0 : ret = wake_up_process(task);
255 0 : rcu_read_unlock();
256 :
257 0 : return ret;
258 : }
259 : EXPORT_SYMBOL_GPL(rcuwait_wake_up);
260 :
261 : /*
262 : * Determine if a process group is "orphaned", according to the POSIX
263 : * definition in 2.2.2.52. Orphaned process groups are not to be affected
264 : * by terminal-generated stop signals. Newly orphaned process groups are
265 : * to receive a SIGHUP and a SIGCONT.
266 : *
267 : * "I ask you, have you ever known what it is to be an orphan?"
268 : */
269 0 : static int will_become_orphaned_pgrp(struct pid *pgrp,
270 : struct task_struct *ignored_task)
271 : {
272 0 : struct task_struct *p;
273 :
274 0 : do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
275 0 : if ((p == ignored_task) ||
276 0 : (p->exit_state && thread_group_empty(p)) ||
277 0 : is_global_init(p->real_parent))
278 0 : continue;
279 :
280 0 : if (task_pgrp(p->real_parent) != pgrp &&
281 0 : task_session(p->real_parent) == task_session(p))
282 : return 0;
283 : } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
284 :
285 : return 1;
286 : }
287 :
288 0 : int is_current_pgrp_orphaned(void)
289 : {
290 0 : int retval;
291 :
292 0 : read_lock(&tasklist_lock);
293 0 : retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
294 0 : read_unlock(&tasklist_lock);
295 :
296 0 : return retval;
297 : }
298 :
299 0 : static bool has_stopped_jobs(struct pid *pgrp)
300 : {
301 0 : struct task_struct *p;
302 :
303 0 : do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
304 0 : if (p->signal->flags & SIGNAL_STOP_STOPPED)
305 : return true;
306 0 : } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
307 :
308 : return false;
309 : }
310 :
311 : /*
312 : * Check to see if any process groups have become orphaned as
313 : * a result of our exiting, and if they have any stopped jobs,
314 : * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
315 : */
316 : static void
317 0 : kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
318 : {
319 0 : struct pid *pgrp = task_pgrp(tsk);
320 0 : struct task_struct *ignored_task = tsk;
321 :
322 0 : if (!parent)
323 : /* exit: our father is in a different pgrp than
324 : * we are and we were the only connection outside.
325 : */
326 0 : parent = tsk->real_parent;
327 : else
328 : /* reparent: our child is in a different pgrp than
329 : * we are, and it was the only connection outside.
330 : */
331 : ignored_task = NULL;
332 :
333 0 : if (task_pgrp(parent) != pgrp &&
334 0 : task_session(parent) == task_session(tsk) &&
335 0 : will_become_orphaned_pgrp(pgrp, ignored_task) &&
336 0 : has_stopped_jobs(pgrp)) {
337 0 : __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
338 0 : __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
339 : }
340 0 : }
341 :
342 : #ifdef CONFIG_MEMCG
343 : /*
344 : * A task is exiting. If it owned this mm, find a new owner for the mm.
345 : */
346 : void mm_update_next_owner(struct mm_struct *mm)
347 : {
348 : struct task_struct *c, *g, *p = current;
349 :
350 : retry:
351 : /*
352 : * If the exiting or execing task is not the owner, it's
353 : * someone else's problem.
354 : */
355 : if (mm->owner != p)
356 : return;
357 : /*
358 : * The current owner is exiting/execing and there are no other
359 : * candidates. Do not leave the mm pointing to a possibly
360 : * freed task structure.
361 : */
362 : if (atomic_read(&mm->mm_users) <= 1) {
363 : WRITE_ONCE(mm->owner, NULL);
364 : return;
365 : }
366 :
367 : read_lock(&tasklist_lock);
368 : /*
369 : * Search in the children
370 : */
371 : list_for_each_entry(c, &p->children, sibling) {
372 : if (c->mm == mm)
373 : goto assign_new_owner;
374 : }
375 :
376 : /*
377 : * Search in the siblings
378 : */
379 : list_for_each_entry(c, &p->real_parent->children, sibling) {
380 : if (c->mm == mm)
381 : goto assign_new_owner;
382 : }
383 :
384 : /*
385 : * Search through everything else, we should not get here often.
386 : */
387 : for_each_process(g) {
388 : if (g->flags & PF_KTHREAD)
389 : continue;
390 : for_each_thread(g, c) {
391 : if (c->mm == mm)
392 : goto assign_new_owner;
393 : if (c->mm)
394 : break;
395 : }
396 : }
397 : read_unlock(&tasklist_lock);
398 : /*
399 : * We found no owner yet mm_users > 1: this implies that we are
400 : * most likely racing with swapoff (try_to_unuse()) or /proc or
401 : * ptrace or page migration (get_task_mm()). Mark owner as NULL.
402 : */
403 : WRITE_ONCE(mm->owner, NULL);
404 : return;
405 :
406 : assign_new_owner:
407 : BUG_ON(c == p);
408 : get_task_struct(c);
409 : /*
410 : * The task_lock protects c->mm from changing.
411 : * We always want mm->owner->mm == mm
412 : */
413 : task_lock(c);
414 : /*
415 : * Delay read_unlock() till we have the task_lock()
416 : * to ensure that c does not slip away underneath us
417 : */
418 : read_unlock(&tasklist_lock);
419 : if (c->mm != mm) {
420 : task_unlock(c);
421 : put_task_struct(c);
422 : goto retry;
423 : }
424 : WRITE_ONCE(mm->owner, c);
425 : task_unlock(c);
426 : put_task_struct(c);
427 : }
428 : #endif /* CONFIG_MEMCG */
429 :
430 : /*
431 : * Turn us into a lazy TLB process if we
432 : * aren't already..
433 : */
434 0 : static void exit_mm(void)
435 : {
436 0 : struct mm_struct *mm = current->mm;
437 0 : struct core_state *core_state;
438 :
439 0 : exit_mm_release(current, mm);
440 0 : if (!mm)
441 : return;
442 0 : sync_mm_rss(mm);
443 : /*
444 : * Serialize with any possible pending coredump.
445 : * We must hold mmap_lock around checking core_state
446 : * and clearing tsk->mm. The core-inducing thread
447 : * will increment ->nr_threads for each thread in the
448 : * group with ->mm != NULL.
449 : */
450 0 : mmap_read_lock(mm);
451 0 : core_state = mm->core_state;
452 0 : if (core_state) {
453 0 : struct core_thread self;
454 :
455 0 : mmap_read_unlock(mm);
456 :
457 0 : self.task = current;
458 0 : if (self.task->flags & PF_SIGNALED)
459 0 : self.next = xchg(&core_state->dumper.next, &self);
460 : else
461 0 : self.task = NULL;
462 : /*
463 : * Implies mb(), the result of xchg() must be visible
464 : * to core_state->dumper.
465 : */
466 0 : if (atomic_dec_and_test(&core_state->nr_threads))
467 0 : complete(&core_state->startup);
468 :
469 0 : for (;;) {
470 0 : set_current_state(TASK_UNINTERRUPTIBLE);
471 0 : if (!self.task) /* see coredump_finish() */
472 : break;
473 0 : freezable_schedule();
474 : }
475 0 : __set_current_state(TASK_RUNNING);
476 0 : mmap_read_lock(mm);
477 : }
478 0 : mmgrab(mm);
479 0 : BUG_ON(mm != current->active_mm);
480 : /* more a memory barrier than a real lock */
481 0 : task_lock(current);
482 : /*
483 : * When a thread stops operating on an address space, the loop
484 : * in membarrier_private_expedited() may not observe that
485 : * tsk->mm, and the loop in membarrier_global_expedited() may
486 : * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
487 : * rq->membarrier_state, so those would not issue an IPI.
488 : * Membarrier requires a memory barrier after accessing
489 : * user-space memory, before clearing tsk->mm or the
490 : * rq->membarrier_state.
491 : */
492 0 : smp_mb__after_spinlock();
493 0 : local_irq_disable();
494 0 : current->mm = NULL;
495 0 : membarrier_update_current_mm(NULL);
496 0 : enter_lazy_tlb(mm, current);
497 0 : local_irq_enable();
498 0 : task_unlock(current);
499 0 : mmap_read_unlock(mm);
500 0 : mm_update_next_owner(mm);
501 0 : mmput(mm);
502 0 : if (test_thread_flag(TIF_MEMDIE))
503 0 : exit_oom_victim();
504 : }
505 :
506 0 : static struct task_struct *find_alive_thread(struct task_struct *p)
507 : {
508 0 : struct task_struct *t;
509 :
510 0 : for_each_thread(p, t) {
511 0 : if (!(t->flags & PF_EXITING))
512 0 : return t;
513 : }
514 : return NULL;
515 : }
516 :
517 0 : static struct task_struct *find_child_reaper(struct task_struct *father,
518 : struct list_head *dead)
519 : __releases(&tasklist_lock)
520 : __acquires(&tasklist_lock)
521 : {
522 0 : struct pid_namespace *pid_ns = task_active_pid_ns(father);
523 0 : struct task_struct *reaper = pid_ns->child_reaper;
524 0 : struct task_struct *p, *n;
525 :
526 0 : if (likely(reaper != father))
527 : return reaper;
528 :
529 0 : reaper = find_alive_thread(father);
530 0 : if (reaper) {
531 0 : pid_ns->child_reaper = reaper;
532 0 : return reaper;
533 : }
534 :
535 0 : write_unlock_irq(&tasklist_lock);
536 :
537 0 : list_for_each_entry_safe(p, n, dead, ptrace_entry) {
538 0 : list_del_init(&p->ptrace_entry);
539 0 : release_task(p);
540 : }
541 :
542 0 : zap_pid_ns_processes(pid_ns);
543 : write_lock_irq(&tasklist_lock);
544 :
545 : return father;
546 : }
547 :
548 : /*
549 : * When we die, we re-parent all our children, and try to:
550 : * 1. give them to another thread in our thread group, if such a member exists
551 : * 2. give it to the first ancestor process which prctl'd itself as a
552 : * child_subreaper for its children (like a service manager)
553 : * 3. give it to the init process (PID 1) in our pid namespace
554 : */
555 0 : static struct task_struct *find_new_reaper(struct task_struct *father,
556 : struct task_struct *child_reaper)
557 : {
558 0 : struct task_struct *thread, *reaper;
559 :
560 0 : thread = find_alive_thread(father);
561 0 : if (thread)
562 : return thread;
563 :
564 0 : if (father->signal->has_child_subreaper) {
565 0 : unsigned int ns_level = task_pid(father)->level;
566 : /*
567 : * Find the first ->is_child_subreaper ancestor in our pid_ns.
568 : * We can't check reaper != child_reaper to ensure we do not
569 : * cross the namespaces, the exiting parent could be injected
570 : * by setns() + fork().
571 : * We check pid->level, this is slightly more efficient than
572 : * task_active_pid_ns(reaper) != task_active_pid_ns(father).
573 : */
574 0 : for (reaper = father->real_parent;
575 0 : task_pid(reaper)->level == ns_level;
576 0 : reaper = reaper->real_parent) {
577 0 : if (reaper == &init_task)
578 : break;
579 0 : if (!reaper->signal->is_child_subreaper)
580 0 : continue;
581 0 : thread = find_alive_thread(reaper);
582 0 : if (thread)
583 0 : return thread;
584 : }
585 : }
586 :
587 : return child_reaper;
588 : }
589 :
590 : /*
591 : * Any that need to be release_task'd are put on the @dead list.
592 : */
593 0 : static void reparent_leader(struct task_struct *father, struct task_struct *p,
594 : struct list_head *dead)
595 : {
596 0 : if (unlikely(p->exit_state == EXIT_DEAD))
597 : return;
598 :
599 : /* We don't want people slaying init. */
600 0 : p->exit_signal = SIGCHLD;
601 :
602 : /* If it has exited notify the new parent about this child's death. */
603 0 : if (!p->ptrace &&
604 0 : p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
605 0 : if (do_notify_parent(p, p->exit_signal)) {
606 0 : p->exit_state = EXIT_DEAD;
607 0 : list_add(&p->ptrace_entry, dead);
608 : }
609 : }
610 :
611 0 : kill_orphaned_pgrp(p, father);
612 : }
613 :
614 : /*
615 : * This does two things:
616 : *
617 : * A. Make init inherit all the child processes
618 : * B. Check to see if any process groups have become orphaned
619 : * as a result of our exiting, and if they have any stopped
620 : * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
621 : */
622 0 : static void forget_original_parent(struct task_struct *father,
623 : struct list_head *dead)
624 : {
625 0 : struct task_struct *p, *t, *reaper;
626 :
627 0 : if (unlikely(!list_empty(&father->ptraced)))
628 0 : exit_ptrace(father, dead);
629 :
630 : /* Can drop and reacquire tasklist_lock */
631 0 : reaper = find_child_reaper(father, dead);
632 0 : if (list_empty(&father->children))
633 : return;
634 :
635 0 : reaper = find_new_reaper(father, reaper);
636 0 : list_for_each_entry(p, &father->children, sibling) {
637 0 : for_each_thread(p, t) {
638 0 : RCU_INIT_POINTER(t->real_parent, reaper);
639 0 : BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
640 0 : if (likely(!t->ptrace))
641 0 : t->parent = t->real_parent;
642 0 : if (t->pdeath_signal)
643 0 : group_send_sig_info(t->pdeath_signal,
644 : SEND_SIG_NOINFO, t,
645 : PIDTYPE_TGID);
646 : }
647 : /*
648 : * If this is a threaded reparent there is no need to
649 : * notify anyone anything has happened.
650 : */
651 0 : if (!same_thread_group(reaper, father))
652 0 : reparent_leader(father, p, dead);
653 : }
654 0 : list_splice_tail_init(&father->children, &reaper->children);
655 : }
656 :
657 : /*
658 : * Send signals to all our closest relatives so that they know
659 : * to properly mourn us..
660 : */
661 0 : static void exit_notify(struct task_struct *tsk, int group_dead)
662 : {
663 0 : bool autoreap;
664 0 : struct task_struct *p, *n;
665 0 : LIST_HEAD(dead);
666 :
667 0 : write_lock_irq(&tasklist_lock);
668 0 : forget_original_parent(tsk, &dead);
669 :
670 0 : if (group_dead)
671 0 : kill_orphaned_pgrp(tsk->group_leader, NULL);
672 :
673 0 : tsk->exit_state = EXIT_ZOMBIE;
674 0 : if (unlikely(tsk->ptrace)) {
675 0 : int sig = thread_group_leader(tsk) &&
676 0 : thread_group_empty(tsk) &&
677 0 : !ptrace_reparented(tsk) ?
678 0 : tsk->exit_signal : SIGCHLD;
679 0 : autoreap = do_notify_parent(tsk, sig);
680 0 : } else if (thread_group_leader(tsk)) {
681 0 : autoreap = thread_group_empty(tsk) &&
682 0 : do_notify_parent(tsk, tsk->exit_signal);
683 : } else {
684 : autoreap = true;
685 : }
686 :
687 0 : if (autoreap) {
688 0 : tsk->exit_state = EXIT_DEAD;
689 0 : list_add(&tsk->ptrace_entry, &dead);
690 : }
691 :
692 : /* mt-exec, de_thread() is waiting for group leader */
693 0 : if (unlikely(tsk->signal->notify_count < 0))
694 0 : wake_up_process(tsk->signal->group_exit_task);
695 0 : write_unlock_irq(&tasklist_lock);
696 :
697 0 : list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
698 0 : list_del_init(&p->ptrace_entry);
699 0 : release_task(p);
700 : }
701 0 : }
702 :
703 : #ifdef CONFIG_DEBUG_STACK_USAGE
704 : static void check_stack_usage(void)
705 : {
706 : static DEFINE_SPINLOCK(low_water_lock);
707 : static int lowest_to_date = THREAD_SIZE;
708 : unsigned long free;
709 :
710 : free = stack_not_used(current);
711 :
712 : if (free >= lowest_to_date)
713 : return;
714 :
715 : spin_lock(&low_water_lock);
716 : if (free < lowest_to_date) {
717 : pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
718 : current->comm, task_pid_nr(current), free);
719 : lowest_to_date = free;
720 : }
721 : spin_unlock(&low_water_lock);
722 : }
723 : #else
724 0 : static inline void check_stack_usage(void) {}
725 : #endif
726 :
727 0 : void __noreturn do_exit(long code)
728 : {
729 0 : struct task_struct *tsk = current;
730 0 : int group_dead;
731 :
732 : /*
733 : * We can get here from a kernel oops, sometimes with preemption off.
734 : * Start by checking for critical errors.
735 : * Then fix up important state like USER_DS and preemption.
736 : * Then do everything else.
737 : */
738 :
739 0 : WARN_ON(blk_needs_flush_plug(tsk));
740 :
741 0 : if (unlikely(in_interrupt()))
742 0 : panic("Aiee, killing interrupt handler!");
743 0 : if (unlikely(!tsk->pid))
744 0 : panic("Attempted to kill the idle task!");
745 :
746 : /*
747 : * If do_exit is called because this processes oopsed, it's possible
748 : * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
749 : * continuing. Amongst other possible reasons, this is to prevent
750 : * mm_release()->clear_child_tid() from writing to a user-controlled
751 : * kernel address.
752 : */
753 0 : force_uaccess_begin();
754 :
755 0 : if (unlikely(in_atomic())) {
756 0 : pr_info("note: %s[%d] exited with preempt_count %d\n",
757 : current->comm, task_pid_nr(current),
758 : preempt_count());
759 0 : preempt_count_set(PREEMPT_ENABLED);
760 : }
761 :
762 0 : profile_task_exit(tsk);
763 0 : kcov_task_exit(tsk);
764 :
765 0 : ptrace_event(PTRACE_EVENT_EXIT, code);
766 :
767 0 : validate_creds_for_do_exit(tsk);
768 :
769 : /*
770 : * We're taking recursive faults here in do_exit. Safest is to just
771 : * leave this task alone and wait for reboot.
772 : */
773 0 : if (unlikely(tsk->flags & PF_EXITING)) {
774 0 : pr_alert("Fixing recursive fault but reboot is needed!\n");
775 0 : futex_exit_recursive(tsk);
776 0 : set_current_state(TASK_UNINTERRUPTIBLE);
777 0 : schedule();
778 : }
779 :
780 0 : io_uring_files_cancel(tsk->files);
781 0 : exit_signals(tsk); /* sets PF_EXITING */
782 :
783 : /* sync mm's RSS info before statistics gathering */
784 0 : if (tsk->mm)
785 0 : sync_mm_rss(tsk->mm);
786 0 : acct_update_integrals(tsk);
787 0 : group_dead = atomic_dec_and_test(&tsk->signal->live);
788 0 : if (group_dead) {
789 : /*
790 : * If the last thread of global init has exited, panic
791 : * immediately to get a useable coredump.
792 : */
793 0 : if (unlikely(is_global_init(tsk)))
794 0 : panic("Attempted to kill init! exitcode=0x%08x\n",
795 0 : tsk->signal->group_exit_code ?: (int)code);
796 :
797 : #ifdef CONFIG_POSIX_TIMERS
798 0 : hrtimer_cancel(&tsk->signal->real_timer);
799 0 : exit_itimers(tsk->signal);
800 : #endif
801 0 : if (tsk->mm)
802 0 : setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
803 : }
804 0 : acct_collect(code, group_dead);
805 0 : if (group_dead)
806 : tty_audit_exit();
807 0 : audit_free(tsk);
808 :
809 0 : tsk->exit_code = code;
810 0 : taskstats_exit(tsk, group_dead);
811 :
812 0 : exit_mm();
813 :
814 0 : if (group_dead)
815 0 : acct_process();
816 0 : trace_sched_process_exit(tsk);
817 :
818 0 : exit_sem(tsk);
819 0 : exit_shm(tsk);
820 0 : exit_files(tsk);
821 0 : exit_fs(tsk);
822 0 : if (group_dead)
823 0 : disassociate_ctty(1);
824 0 : exit_task_namespaces(tsk);
825 0 : exit_task_work(tsk);
826 0 : exit_thread(tsk);
827 :
828 : /*
829 : * Flush inherited counters to the parent - before the parent
830 : * gets woken up by child-exit notifications.
831 : *
832 : * because of cgroup mode, must be called before cgroup_exit()
833 : */
834 0 : perf_event_exit_task(tsk);
835 :
836 0 : sched_autogroup_exit_task(tsk);
837 0 : cgroup_exit(tsk);
838 :
839 : /*
840 : * FIXME: do that only when needed, using sched_exit tracepoint
841 : */
842 0 : flush_ptrace_hw_breakpoint(tsk);
843 :
844 0 : exit_tasks_rcu_start();
845 0 : exit_notify(tsk, group_dead);
846 0 : proc_exit_connector(tsk);
847 0 : mpol_put_task_policy(tsk);
848 : #ifdef CONFIG_FUTEX
849 0 : if (unlikely(current->pi_state_cache))
850 0 : kfree(current->pi_state_cache);
851 : #endif
852 : /*
853 : * Make sure we are holding no locks:
854 : */
855 0 : debug_check_no_locks_held();
856 :
857 0 : if (tsk->io_context)
858 0 : exit_io_context(tsk);
859 :
860 0 : if (tsk->splice_pipe)
861 0 : free_pipe_info(tsk->splice_pipe);
862 :
863 0 : if (tsk->task_frag.page)
864 0 : put_page(tsk->task_frag.page);
865 :
866 0 : validate_creds_for_do_exit(tsk);
867 :
868 0 : check_stack_usage();
869 0 : preempt_disable();
870 0 : if (tsk->nr_dirtied)
871 0 : __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
872 0 : exit_rcu();
873 0 : exit_tasks_rcu_finish();
874 :
875 0 : lockdep_free_task(tsk);
876 0 : do_task_dead();
877 : }
878 : EXPORT_SYMBOL_GPL(do_exit);
879 :
880 0 : void complete_and_exit(struct completion *comp, long code)
881 : {
882 0 : if (comp)
883 0 : complete(comp);
884 :
885 0 : do_exit(code);
886 : }
887 : EXPORT_SYMBOL(complete_and_exit);
888 :
889 0 : SYSCALL_DEFINE1(exit, int, error_code)
890 : {
891 0 : do_exit((error_code&0xff)<<8);
892 : }
893 :
894 : /*
895 : * Take down every thread in the group. This is called by fatal signals
896 : * as well as by sys_exit_group (below).
897 : */
898 : void
899 0 : do_group_exit(int exit_code)
900 : {
901 0 : struct signal_struct *sig = current->signal;
902 :
903 0 : BUG_ON(exit_code & 0x80); /* core dumps don't get here */
904 :
905 0 : if (signal_group_exit(sig))
906 0 : exit_code = sig->group_exit_code;
907 0 : else if (!thread_group_empty(current)) {
908 0 : struct sighand_struct *const sighand = current->sighand;
909 :
910 0 : spin_lock_irq(&sighand->siglock);
911 0 : if (signal_group_exit(sig))
912 : /* Another thread got here before we took the lock. */
913 0 : exit_code = sig->group_exit_code;
914 : else {
915 0 : sig->group_exit_code = exit_code;
916 0 : sig->flags = SIGNAL_GROUP_EXIT;
917 0 : zap_other_threads(current);
918 : }
919 0 : spin_unlock_irq(&sighand->siglock);
920 : }
921 :
922 0 : do_exit(exit_code);
923 : /* NOTREACHED */
924 : }
925 :
926 : /*
927 : * this kills every thread in the thread group. Note that any externally
928 : * wait4()-ing process will get the correct exit code - even if this
929 : * thread is not the thread group leader.
930 : */
931 0 : SYSCALL_DEFINE1(exit_group, int, error_code)
932 : {
933 0 : do_group_exit((error_code & 0xff) << 8);
934 : /* NOTREACHED */
935 : return 0;
936 : }
937 :
938 : struct waitid_info {
939 : pid_t pid;
940 : uid_t uid;
941 : int status;
942 : int cause;
943 : };
944 :
945 : struct wait_opts {
946 : enum pid_type wo_type;
947 : int wo_flags;
948 : struct pid *wo_pid;
949 :
950 : struct waitid_info *wo_info;
951 : int wo_stat;
952 : struct rusage *wo_rusage;
953 :
954 : wait_queue_entry_t child_wait;
955 : int notask_error;
956 : };
957 :
958 0 : static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
959 : {
960 0 : return wo->wo_type == PIDTYPE_MAX ||
961 0 : task_pid_type(p, wo->wo_type) == wo->wo_pid;
962 : }
963 :
964 : static int
965 0 : eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
966 : {
967 0 : if (!eligible_pid(wo, p))
968 : return 0;
969 :
970 : /*
971 : * Wait for all children (clone and not) if __WALL is set or
972 : * if it is traced by us.
973 : */
974 0 : if (ptrace || (wo->wo_flags & __WALL))
975 : return 1;
976 :
977 : /*
978 : * Otherwise, wait for clone children *only* if __WCLONE is set;
979 : * otherwise, wait for non-clone children *only*.
980 : *
981 : * Note: a "clone" child here is one that reports to its parent
982 : * using a signal other than SIGCHLD, or a non-leader thread which
983 : * we can only see if it is traced by us.
984 : */
985 0 : if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
986 0 : return 0;
987 :
988 : return 1;
989 : }
990 :
991 : /*
992 : * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
993 : * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
994 : * the lock and this task is uninteresting. If we return nonzero, we have
995 : * released the lock and the system call should return.
996 : */
997 0 : static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
998 : {
999 0 : int state, status;
1000 0 : pid_t pid = task_pid_vnr(p);
1001 0 : uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1002 0 : struct waitid_info *infop;
1003 :
1004 0 : if (!likely(wo->wo_flags & WEXITED))
1005 : return 0;
1006 :
1007 0 : if (unlikely(wo->wo_flags & WNOWAIT)) {
1008 0 : status = p->exit_code;
1009 0 : get_task_struct(p);
1010 0 : read_unlock(&tasklist_lock);
1011 0 : sched_annotate_sleep();
1012 0 : if (wo->wo_rusage)
1013 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1014 0 : put_task_struct(p);
1015 0 : goto out_info;
1016 : }
1017 : /*
1018 : * Move the task's state to DEAD/TRACE, only one thread can do this.
1019 : */
1020 0 : state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1021 0 : EXIT_TRACE : EXIT_DEAD;
1022 0 : if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1023 : return 0;
1024 : /*
1025 : * We own this thread, nobody else can reap it.
1026 : */
1027 0 : read_unlock(&tasklist_lock);
1028 0 : sched_annotate_sleep();
1029 :
1030 : /*
1031 : * Check thread_group_leader() to exclude the traced sub-threads.
1032 : */
1033 0 : if (state == EXIT_DEAD && thread_group_leader(p)) {
1034 0 : struct signal_struct *sig = p->signal;
1035 0 : struct signal_struct *psig = current->signal;
1036 0 : unsigned long maxrss;
1037 0 : u64 tgutime, tgstime;
1038 :
1039 : /*
1040 : * The resource counters for the group leader are in its
1041 : * own task_struct. Those for dead threads in the group
1042 : * are in its signal_struct, as are those for the child
1043 : * processes it has previously reaped. All these
1044 : * accumulate in the parent's signal_struct c* fields.
1045 : *
1046 : * We don't bother to take a lock here to protect these
1047 : * p->signal fields because the whole thread group is dead
1048 : * and nobody can change them.
1049 : *
1050 : * psig->stats_lock also protects us from our sub-theads
1051 : * which can reap other children at the same time. Until
1052 : * we change k_getrusage()-like users to rely on this lock
1053 : * we have to take ->siglock as well.
1054 : *
1055 : * We use thread_group_cputime_adjusted() to get times for
1056 : * the thread group, which consolidates times for all threads
1057 : * in the group including the group leader.
1058 : */
1059 0 : thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1060 0 : spin_lock_irq(¤t->sighand->siglock);
1061 0 : write_seqlock(&psig->stats_lock);
1062 0 : psig->cutime += tgutime + sig->cutime;
1063 0 : psig->cstime += tgstime + sig->cstime;
1064 0 : psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1065 0 : psig->cmin_flt +=
1066 0 : p->min_flt + sig->min_flt + sig->cmin_flt;
1067 0 : psig->cmaj_flt +=
1068 0 : p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1069 0 : psig->cnvcsw +=
1070 0 : p->nvcsw + sig->nvcsw + sig->cnvcsw;
1071 0 : psig->cnivcsw +=
1072 0 : p->nivcsw + sig->nivcsw + sig->cnivcsw;
1073 0 : psig->cinblock +=
1074 0 : task_io_get_inblock(p) +
1075 0 : sig->inblock + sig->cinblock;
1076 0 : psig->coublock +=
1077 0 : task_io_get_oublock(p) +
1078 0 : sig->oublock + sig->coublock;
1079 0 : maxrss = max(sig->maxrss, sig->cmaxrss);
1080 0 : if (psig->cmaxrss < maxrss)
1081 0 : psig->cmaxrss = maxrss;
1082 0 : task_io_accounting_add(&psig->ioac, &p->ioac);
1083 0 : task_io_accounting_add(&psig->ioac, &sig->ioac);
1084 0 : write_sequnlock(&psig->stats_lock);
1085 0 : spin_unlock_irq(¤t->sighand->siglock);
1086 : }
1087 :
1088 0 : if (wo->wo_rusage)
1089 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1090 0 : status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1091 0 : ? p->signal->group_exit_code : p->exit_code;
1092 0 : wo->wo_stat = status;
1093 :
1094 0 : if (state == EXIT_TRACE) {
1095 0 : write_lock_irq(&tasklist_lock);
1096 : /* We dropped tasklist, ptracer could die and untrace */
1097 0 : ptrace_unlink(p);
1098 :
1099 : /* If parent wants a zombie, don't release it now */
1100 0 : state = EXIT_ZOMBIE;
1101 0 : if (do_notify_parent(p, p->exit_signal))
1102 0 : state = EXIT_DEAD;
1103 0 : p->exit_state = state;
1104 0 : write_unlock_irq(&tasklist_lock);
1105 : }
1106 0 : if (state == EXIT_DEAD)
1107 0 : release_task(p);
1108 :
1109 0 : out_info:
1110 0 : infop = wo->wo_info;
1111 0 : if (infop) {
1112 0 : if ((status & 0x7f) == 0) {
1113 0 : infop->cause = CLD_EXITED;
1114 0 : infop->status = status >> 8;
1115 : } else {
1116 0 : infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1117 0 : infop->status = status & 0x7f;
1118 : }
1119 0 : infop->pid = pid;
1120 0 : infop->uid = uid;
1121 : }
1122 :
1123 : return pid;
1124 : }
1125 :
1126 0 : static int *task_stopped_code(struct task_struct *p, bool ptrace)
1127 : {
1128 0 : if (ptrace) {
1129 0 : if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1130 0 : return &p->exit_code;
1131 : } else {
1132 0 : if (p->signal->flags & SIGNAL_STOP_STOPPED)
1133 0 : return &p->signal->group_exit_code;
1134 : }
1135 : return NULL;
1136 : }
1137 :
1138 : /**
1139 : * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1140 : * @wo: wait options
1141 : * @ptrace: is the wait for ptrace
1142 : * @p: task to wait for
1143 : *
1144 : * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1145 : *
1146 : * CONTEXT:
1147 : * read_lock(&tasklist_lock), which is released if return value is
1148 : * non-zero. Also, grabs and releases @p->sighand->siglock.
1149 : *
1150 : * RETURNS:
1151 : * 0 if wait condition didn't exist and search for other wait conditions
1152 : * should continue. Non-zero return, -errno on failure and @p's pid on
1153 : * success, implies that tasklist_lock is released and wait condition
1154 : * search should terminate.
1155 : */
1156 0 : static int wait_task_stopped(struct wait_opts *wo,
1157 : int ptrace, struct task_struct *p)
1158 : {
1159 0 : struct waitid_info *infop;
1160 0 : int exit_code, *p_code, why;
1161 0 : uid_t uid = 0; /* unneeded, required by compiler */
1162 0 : pid_t pid;
1163 :
1164 : /*
1165 : * Traditionally we see ptrace'd stopped tasks regardless of options.
1166 : */
1167 0 : if (!ptrace && !(wo->wo_flags & WUNTRACED))
1168 : return 0;
1169 :
1170 0 : if (!task_stopped_code(p, ptrace))
1171 : return 0;
1172 :
1173 0 : exit_code = 0;
1174 0 : spin_lock_irq(&p->sighand->siglock);
1175 :
1176 0 : p_code = task_stopped_code(p, ptrace);
1177 0 : if (unlikely(!p_code))
1178 0 : goto unlock_sig;
1179 :
1180 0 : exit_code = *p_code;
1181 0 : if (!exit_code)
1182 0 : goto unlock_sig;
1183 :
1184 0 : if (!unlikely(wo->wo_flags & WNOWAIT))
1185 0 : *p_code = 0;
1186 :
1187 0 : uid = from_kuid_munged(current_user_ns(), task_uid(p));
1188 0 : unlock_sig:
1189 0 : spin_unlock_irq(&p->sighand->siglock);
1190 0 : if (!exit_code)
1191 : return 0;
1192 :
1193 : /*
1194 : * Now we are pretty sure this task is interesting.
1195 : * Make sure it doesn't get reaped out from under us while we
1196 : * give up the lock and then examine it below. We don't want to
1197 : * keep holding onto the tasklist_lock while we call getrusage and
1198 : * possibly take page faults for user memory.
1199 : */
1200 0 : get_task_struct(p);
1201 0 : pid = task_pid_vnr(p);
1202 0 : why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1203 0 : read_unlock(&tasklist_lock);
1204 0 : sched_annotate_sleep();
1205 0 : if (wo->wo_rusage)
1206 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1207 0 : put_task_struct(p);
1208 :
1209 0 : if (likely(!(wo->wo_flags & WNOWAIT)))
1210 0 : wo->wo_stat = (exit_code << 8) | 0x7f;
1211 :
1212 0 : infop = wo->wo_info;
1213 0 : if (infop) {
1214 0 : infop->cause = why;
1215 0 : infop->status = exit_code;
1216 0 : infop->pid = pid;
1217 0 : infop->uid = uid;
1218 : }
1219 : return pid;
1220 : }
1221 :
1222 : /*
1223 : * Handle do_wait work for one task in a live, non-stopped state.
1224 : * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1225 : * the lock and this task is uninteresting. If we return nonzero, we have
1226 : * released the lock and the system call should return.
1227 : */
1228 0 : static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1229 : {
1230 0 : struct waitid_info *infop;
1231 0 : pid_t pid;
1232 0 : uid_t uid;
1233 :
1234 0 : if (!unlikely(wo->wo_flags & WCONTINUED))
1235 : return 0;
1236 :
1237 0 : if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1238 : return 0;
1239 :
1240 0 : spin_lock_irq(&p->sighand->siglock);
1241 : /* Re-check with the lock held. */
1242 0 : if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1243 0 : spin_unlock_irq(&p->sighand->siglock);
1244 0 : return 0;
1245 : }
1246 0 : if (!unlikely(wo->wo_flags & WNOWAIT))
1247 0 : p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1248 0 : uid = from_kuid_munged(current_user_ns(), task_uid(p));
1249 0 : spin_unlock_irq(&p->sighand->siglock);
1250 :
1251 0 : pid = task_pid_vnr(p);
1252 0 : get_task_struct(p);
1253 0 : read_unlock(&tasklist_lock);
1254 0 : sched_annotate_sleep();
1255 0 : if (wo->wo_rusage)
1256 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1257 0 : put_task_struct(p);
1258 :
1259 0 : infop = wo->wo_info;
1260 0 : if (!infop) {
1261 0 : wo->wo_stat = 0xffff;
1262 : } else {
1263 0 : infop->cause = CLD_CONTINUED;
1264 0 : infop->pid = pid;
1265 0 : infop->uid = uid;
1266 0 : infop->status = SIGCONT;
1267 : }
1268 : return pid;
1269 : }
1270 :
1271 : /*
1272 : * Consider @p for a wait by @parent.
1273 : *
1274 : * -ECHILD should be in ->notask_error before the first call.
1275 : * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1276 : * Returns zero if the search for a child should continue;
1277 : * then ->notask_error is 0 if @p is an eligible child,
1278 : * or still -ECHILD.
1279 : */
1280 0 : static int wait_consider_task(struct wait_opts *wo, int ptrace,
1281 : struct task_struct *p)
1282 : {
1283 : /*
1284 : * We can race with wait_task_zombie() from another thread.
1285 : * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1286 : * can't confuse the checks below.
1287 : */
1288 0 : int exit_state = READ_ONCE(p->exit_state);
1289 0 : int ret;
1290 :
1291 0 : if (unlikely(exit_state == EXIT_DEAD))
1292 : return 0;
1293 :
1294 0 : ret = eligible_child(wo, ptrace, p);
1295 0 : if (!ret)
1296 : return ret;
1297 :
1298 0 : if (unlikely(exit_state == EXIT_TRACE)) {
1299 : /*
1300 : * ptrace == 0 means we are the natural parent. In this case
1301 : * we should clear notask_error, debugger will notify us.
1302 : */
1303 0 : if (likely(!ptrace))
1304 0 : wo->notask_error = 0;
1305 0 : return 0;
1306 : }
1307 :
1308 0 : if (likely(!ptrace) && unlikely(p->ptrace)) {
1309 : /*
1310 : * If it is traced by its real parent's group, just pretend
1311 : * the caller is ptrace_do_wait() and reap this child if it
1312 : * is zombie.
1313 : *
1314 : * This also hides group stop state from real parent; otherwise
1315 : * a single stop can be reported twice as group and ptrace stop.
1316 : * If a ptracer wants to distinguish these two events for its
1317 : * own children it should create a separate process which takes
1318 : * the role of real parent.
1319 : */
1320 0 : if (!ptrace_reparented(p))
1321 0 : ptrace = 1;
1322 : }
1323 :
1324 : /* slay zombie? */
1325 0 : if (exit_state == EXIT_ZOMBIE) {
1326 : /* we don't reap group leaders with subthreads */
1327 0 : if (!delay_group_leader(p)) {
1328 : /*
1329 : * A zombie ptracee is only visible to its ptracer.
1330 : * Notification and reaping will be cascaded to the
1331 : * real parent when the ptracer detaches.
1332 : */
1333 0 : if (unlikely(ptrace) || likely(!p->ptrace))
1334 0 : return wait_task_zombie(wo, p);
1335 : }
1336 :
1337 : /*
1338 : * Allow access to stopped/continued state via zombie by
1339 : * falling through. Clearing of notask_error is complex.
1340 : *
1341 : * When !@ptrace:
1342 : *
1343 : * If WEXITED is set, notask_error should naturally be
1344 : * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1345 : * so, if there are live subthreads, there are events to
1346 : * wait for. If all subthreads are dead, it's still safe
1347 : * to clear - this function will be called again in finite
1348 : * amount time once all the subthreads are released and
1349 : * will then return without clearing.
1350 : *
1351 : * When @ptrace:
1352 : *
1353 : * Stopped state is per-task and thus can't change once the
1354 : * target task dies. Only continued and exited can happen.
1355 : * Clear notask_error if WCONTINUED | WEXITED.
1356 : */
1357 0 : if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1358 0 : wo->notask_error = 0;
1359 : } else {
1360 : /*
1361 : * @p is alive and it's gonna stop, continue or exit, so
1362 : * there always is something to wait for.
1363 : */
1364 0 : wo->notask_error = 0;
1365 : }
1366 :
1367 : /*
1368 : * Wait for stopped. Depending on @ptrace, different stopped state
1369 : * is used and the two don't interact with each other.
1370 : */
1371 0 : ret = wait_task_stopped(wo, ptrace, p);
1372 0 : if (ret)
1373 : return ret;
1374 :
1375 : /*
1376 : * Wait for continued. There's only one continued state and the
1377 : * ptracer can consume it which can confuse the real parent. Don't
1378 : * use WCONTINUED from ptracer. You don't need or want it.
1379 : */
1380 0 : return wait_task_continued(wo, p);
1381 : }
1382 :
1383 : /*
1384 : * Do the work of do_wait() for one thread in the group, @tsk.
1385 : *
1386 : * -ECHILD should be in ->notask_error before the first call.
1387 : * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1388 : * Returns zero if the search for a child should continue; then
1389 : * ->notask_error is 0 if there were any eligible children,
1390 : * or still -ECHILD.
1391 : */
1392 0 : static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1393 : {
1394 0 : struct task_struct *p;
1395 :
1396 0 : list_for_each_entry(p, &tsk->children, sibling) {
1397 0 : int ret = wait_consider_task(wo, 0, p);
1398 :
1399 0 : if (ret)
1400 0 : return ret;
1401 : }
1402 :
1403 : return 0;
1404 : }
1405 :
1406 0 : static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1407 : {
1408 0 : struct task_struct *p;
1409 :
1410 0 : list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1411 0 : int ret = wait_consider_task(wo, 1, p);
1412 :
1413 0 : if (ret)
1414 0 : return ret;
1415 : }
1416 :
1417 : return 0;
1418 : }
1419 :
1420 0 : static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1421 : int sync, void *key)
1422 : {
1423 0 : struct wait_opts *wo = container_of(wait, struct wait_opts,
1424 : child_wait);
1425 0 : struct task_struct *p = key;
1426 :
1427 0 : if (!eligible_pid(wo, p))
1428 : return 0;
1429 :
1430 0 : if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1431 : return 0;
1432 :
1433 0 : return default_wake_function(wait, mode, sync, key);
1434 : }
1435 :
1436 0 : void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1437 : {
1438 0 : __wake_up_sync_key(&parent->signal->wait_chldexit,
1439 : TASK_INTERRUPTIBLE, p);
1440 0 : }
1441 :
1442 0 : static long do_wait(struct wait_opts *wo)
1443 : {
1444 0 : struct task_struct *tsk;
1445 0 : int retval;
1446 :
1447 0 : trace_sched_process_wait(wo->wo_pid);
1448 :
1449 0 : init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1450 0 : wo->child_wait.private = current;
1451 0 : add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1452 0 : repeat:
1453 : /*
1454 : * If there is nothing that can match our criteria, just get out.
1455 : * We will clear ->notask_error to zero if we see any child that
1456 : * might later match our criteria, even if we are not able to reap
1457 : * it yet.
1458 : */
1459 0 : wo->notask_error = -ECHILD;
1460 0 : if ((wo->wo_type < PIDTYPE_MAX) &&
1461 0 : (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1462 0 : goto notask;
1463 :
1464 0 : set_current_state(TASK_INTERRUPTIBLE);
1465 0 : read_lock(&tasklist_lock);
1466 0 : tsk = current;
1467 0 : do {
1468 0 : retval = do_wait_thread(wo, tsk);
1469 0 : if (retval)
1470 0 : goto end;
1471 :
1472 0 : retval = ptrace_do_wait(wo, tsk);
1473 0 : if (retval)
1474 0 : goto end;
1475 :
1476 0 : if (wo->wo_flags & __WNOTHREAD)
1477 : break;
1478 0 : } while_each_thread(current, tsk);
1479 0 : read_unlock(&tasklist_lock);
1480 :
1481 0 : notask:
1482 0 : retval = wo->notask_error;
1483 0 : if (!retval && !(wo->wo_flags & WNOHANG)) {
1484 0 : retval = -ERESTARTSYS;
1485 0 : if (!signal_pending(current)) {
1486 0 : schedule();
1487 0 : goto repeat;
1488 : }
1489 : }
1490 0 : end:
1491 0 : __set_current_state(TASK_RUNNING);
1492 0 : remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1493 0 : return retval;
1494 : }
1495 :
1496 0 : static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1497 : int options, struct rusage *ru)
1498 : {
1499 0 : struct wait_opts wo;
1500 0 : struct pid *pid = NULL;
1501 0 : enum pid_type type;
1502 0 : long ret;
1503 0 : unsigned int f_flags = 0;
1504 :
1505 0 : if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1506 : __WNOTHREAD|__WCLONE|__WALL))
1507 : return -EINVAL;
1508 0 : if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1509 : return -EINVAL;
1510 :
1511 0 : switch (which) {
1512 : case P_ALL:
1513 : type = PIDTYPE_MAX;
1514 : break;
1515 0 : case P_PID:
1516 0 : type = PIDTYPE_PID;
1517 0 : if (upid <= 0)
1518 : return -EINVAL;
1519 :
1520 0 : pid = find_get_pid(upid);
1521 0 : break;
1522 0 : case P_PGID:
1523 0 : type = PIDTYPE_PGID;
1524 0 : if (upid < 0)
1525 : return -EINVAL;
1526 :
1527 0 : if (upid)
1528 0 : pid = find_get_pid(upid);
1529 : else
1530 0 : pid = get_task_pid(current, PIDTYPE_PGID);
1531 : break;
1532 0 : case P_PIDFD:
1533 0 : type = PIDTYPE_PID;
1534 0 : if (upid < 0)
1535 : return -EINVAL;
1536 :
1537 0 : pid = pidfd_get_pid(upid, &f_flags);
1538 0 : if (IS_ERR(pid))
1539 0 : return PTR_ERR(pid);
1540 :
1541 : break;
1542 : default:
1543 : return -EINVAL;
1544 : }
1545 :
1546 0 : wo.wo_type = type;
1547 0 : wo.wo_pid = pid;
1548 0 : wo.wo_flags = options;
1549 0 : wo.wo_info = infop;
1550 0 : wo.wo_rusage = ru;
1551 0 : if (f_flags & O_NONBLOCK)
1552 0 : wo.wo_flags |= WNOHANG;
1553 :
1554 0 : ret = do_wait(&wo);
1555 0 : if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
1556 0 : ret = -EAGAIN;
1557 :
1558 0 : put_pid(pid);
1559 0 : return ret;
1560 : }
1561 :
1562 0 : SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1563 : infop, int, options, struct rusage __user *, ru)
1564 : {
1565 0 : struct rusage r;
1566 0 : struct waitid_info info = {.status = 0};
1567 0 : long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1568 0 : int signo = 0;
1569 :
1570 0 : if (err > 0) {
1571 0 : signo = SIGCHLD;
1572 0 : err = 0;
1573 0 : if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1574 : return -EFAULT;
1575 : }
1576 0 : if (!infop)
1577 : return err;
1578 :
1579 0 : if (!user_write_access_begin(infop, sizeof(*infop)))
1580 : return -EFAULT;
1581 :
1582 0 : unsafe_put_user(signo, &infop->si_signo, Efault);
1583 0 : unsafe_put_user(0, &infop->si_errno, Efault);
1584 0 : unsafe_put_user(info.cause, &infop->si_code, Efault);
1585 0 : unsafe_put_user(info.pid, &infop->si_pid, Efault);
1586 0 : unsafe_put_user(info.uid, &infop->si_uid, Efault);
1587 0 : unsafe_put_user(info.status, &infop->si_status, Efault);
1588 0 : user_write_access_end();
1589 0 : return err;
1590 0 : Efault:
1591 : user_write_access_end();
1592 : return -EFAULT;
1593 : }
1594 :
1595 0 : long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1596 : struct rusage *ru)
1597 : {
1598 0 : struct wait_opts wo;
1599 0 : struct pid *pid = NULL;
1600 0 : enum pid_type type;
1601 0 : long ret;
1602 :
1603 0 : if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1604 : __WNOTHREAD|__WCLONE|__WALL))
1605 : return -EINVAL;
1606 :
1607 : /* -INT_MIN is not defined */
1608 0 : if (upid == INT_MIN)
1609 : return -ESRCH;
1610 :
1611 0 : if (upid == -1)
1612 : type = PIDTYPE_MAX;
1613 0 : else if (upid < 0) {
1614 0 : type = PIDTYPE_PGID;
1615 0 : pid = find_get_pid(-upid);
1616 0 : } else if (upid == 0) {
1617 0 : type = PIDTYPE_PGID;
1618 0 : pid = get_task_pid(current, PIDTYPE_PGID);
1619 : } else /* upid > 0 */ {
1620 0 : type = PIDTYPE_PID;
1621 0 : pid = find_get_pid(upid);
1622 : }
1623 :
1624 0 : wo.wo_type = type;
1625 0 : wo.wo_pid = pid;
1626 0 : wo.wo_flags = options | WEXITED;
1627 0 : wo.wo_info = NULL;
1628 0 : wo.wo_stat = 0;
1629 0 : wo.wo_rusage = ru;
1630 0 : ret = do_wait(&wo);
1631 0 : put_pid(pid);
1632 0 : if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1633 0 : ret = -EFAULT;
1634 :
1635 : return ret;
1636 : }
1637 :
1638 0 : int kernel_wait(pid_t pid, int *stat)
1639 : {
1640 0 : struct wait_opts wo = {
1641 : .wo_type = PIDTYPE_PID,
1642 0 : .wo_pid = find_get_pid(pid),
1643 : .wo_flags = WEXITED,
1644 : };
1645 0 : int ret;
1646 :
1647 0 : ret = do_wait(&wo);
1648 0 : if (ret > 0 && wo.wo_stat)
1649 0 : *stat = wo.wo_stat;
1650 0 : put_pid(wo.wo_pid);
1651 0 : return ret;
1652 : }
1653 :
1654 0 : SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1655 : int, options, struct rusage __user *, ru)
1656 : {
1657 0 : struct rusage r;
1658 0 : long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1659 :
1660 0 : if (err > 0) {
1661 0 : if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1662 0 : return -EFAULT;
1663 : }
1664 : return err;
1665 : }
1666 :
1667 : #ifdef __ARCH_WANT_SYS_WAITPID
1668 :
1669 : /*
1670 : * sys_waitpid() remains for compatibility. waitpid() should be
1671 : * implemented by calling sys_wait4() from libc.a.
1672 : */
1673 0 : SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1674 : {
1675 0 : return kernel_wait4(pid, stat_addr, options, NULL);
1676 : }
1677 :
1678 : #endif
1679 :
1680 : #ifdef CONFIG_COMPAT
1681 0 : COMPAT_SYSCALL_DEFINE4(wait4,
1682 : compat_pid_t, pid,
1683 : compat_uint_t __user *, stat_addr,
1684 : int, options,
1685 : struct compat_rusage __user *, ru)
1686 : {
1687 0 : struct rusage r;
1688 0 : long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1689 0 : if (err > 0) {
1690 0 : if (ru && put_compat_rusage(&r, ru))
1691 0 : return -EFAULT;
1692 : }
1693 : return err;
1694 : }
1695 :
1696 0 : COMPAT_SYSCALL_DEFINE5(waitid,
1697 : int, which, compat_pid_t, pid,
1698 : struct compat_siginfo __user *, infop, int, options,
1699 : struct compat_rusage __user *, uru)
1700 : {
1701 0 : struct rusage ru;
1702 0 : struct waitid_info info = {.status = 0};
1703 0 : long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1704 0 : int signo = 0;
1705 0 : if (err > 0) {
1706 0 : signo = SIGCHLD;
1707 0 : err = 0;
1708 0 : if (uru) {
1709 : /* kernel_waitid() overwrites everything in ru */
1710 0 : if (COMPAT_USE_64BIT_TIME)
1711 : err = copy_to_user(uru, &ru, sizeof(ru));
1712 : else
1713 0 : err = put_compat_rusage(&ru, uru);
1714 0 : if (err)
1715 : return -EFAULT;
1716 : }
1717 : }
1718 :
1719 0 : if (!infop)
1720 : return err;
1721 :
1722 0 : if (!user_write_access_begin(infop, sizeof(*infop)))
1723 : return -EFAULT;
1724 :
1725 0 : unsafe_put_user(signo, &infop->si_signo, Efault);
1726 0 : unsafe_put_user(0, &infop->si_errno, Efault);
1727 0 : unsafe_put_user(info.cause, &infop->si_code, Efault);
1728 0 : unsafe_put_user(info.pid, &infop->si_pid, Efault);
1729 0 : unsafe_put_user(info.uid, &infop->si_uid, Efault);
1730 0 : unsafe_put_user(info.status, &infop->si_status, Efault);
1731 0 : user_write_access_end();
1732 0 : return err;
1733 0 : Efault:
1734 : user_write_access_end();
1735 : return -EFAULT;
1736 : }
1737 : #endif
1738 :
1739 : /**
1740 : * thread_group_exited - check that a thread group has exited
1741 : * @pid: tgid of thread group to be checked.
1742 : *
1743 : * Test if the thread group represented by tgid has exited (all
1744 : * threads are zombies, dead or completely gone).
1745 : *
1746 : * Return: true if the thread group has exited. false otherwise.
1747 : */
1748 0 : bool thread_group_exited(struct pid *pid)
1749 : {
1750 0 : struct task_struct *task;
1751 0 : bool exited;
1752 :
1753 0 : rcu_read_lock();
1754 0 : task = pid_task(pid, PIDTYPE_PID);
1755 0 : exited = !task ||
1756 0 : (READ_ONCE(task->exit_state) && thread_group_empty(task));
1757 0 : rcu_read_unlock();
1758 :
1759 0 : return exited;
1760 : }
1761 : EXPORT_SYMBOL(thread_group_exited);
1762 :
1763 0 : __weak void abort(void)
1764 : {
1765 0 : BUG();
1766 :
1767 : /* if that doesn't kill us, halt */
1768 : panic("Oops failed to kill thread");
1769 : }
1770 : EXPORT_SYMBOL(abort);
|
