Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0+
2 : /*
3 : * Read-Copy Update mechanism for mutual exclusion
4 : *
5 : * Copyright IBM Corporation, 2001
6 : *
7 : * Authors: Dipankar Sarma <dipankar@in.ibm.com>
8 : * Manfred Spraul <manfred@colorfullife.com>
9 : *
10 : * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
11 : * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
12 : * Papers:
13 : * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
14 : * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
15 : *
16 : * For detailed explanation of Read-Copy Update mechanism see -
17 : * http://lse.sourceforge.net/locking/rcupdate.html
18 : *
19 : */
20 : #include <linux/types.h>
21 : #include <linux/kernel.h>
22 : #include <linux/init.h>
23 : #include <linux/spinlock.h>
24 : #include <linux/smp.h>
25 : #include <linux/interrupt.h>
26 : #include <linux/sched/signal.h>
27 : #include <linux/sched/debug.h>
28 : #include <linux/atomic.h>
29 : #include <linux/bitops.h>
30 : #include <linux/percpu.h>
31 : #include <linux/notifier.h>
32 : #include <linux/cpu.h>
33 : #include <linux/mutex.h>
34 : #include <linux/export.h>
35 : #include <linux/hardirq.h>
36 : #include <linux/delay.h>
37 : #include <linux/moduleparam.h>
38 : #include <linux/kthread.h>
39 : #include <linux/tick.h>
40 : #include <linux/rcupdate_wait.h>
41 : #include <linux/sched/isolation.h>
42 : #include <linux/kprobes.h>
43 : #include <linux/slab.h>
44 : #include <linux/irq_work.h>
45 : #include <linux/rcupdate_trace.h>
46 :
47 : #define CREATE_TRACE_POINTS
48 :
49 : #include "rcu.h"
50 :
51 : #ifdef MODULE_PARAM_PREFIX
52 : #undef MODULE_PARAM_PREFIX
53 : #endif
54 : #define MODULE_PARAM_PREFIX "rcupdate."
55 :
56 : #ifndef CONFIG_TINY_RCU
57 : module_param(rcu_expedited, int, 0);
58 : module_param(rcu_normal, int, 0);
59 : static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT);
60 : #ifndef CONFIG_PREEMPT_RT
61 : module_param(rcu_normal_after_boot, int, 0);
62 : #endif
63 : #endif /* #ifndef CONFIG_TINY_RCU */
64 :
65 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
66 : /**
67 : * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
68 : * @ret: Best guess answer if lockdep cannot be relied on
69 : *
70 : * Returns true if lockdep must be ignored, in which case ``*ret`` contains
71 : * the best guess described below. Otherwise returns false, in which
72 : * case ``*ret`` tells the caller nothing and the caller should instead
73 : * consult lockdep.
74 : *
75 : * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an
76 : * RCU-sched read-side critical section. In absence of
77 : * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
78 : * critical section unless it can prove otherwise. Note that disabling
79 : * of preemption (including disabling irqs) counts as an RCU-sched
80 : * read-side critical section. This is useful for debug checks in functions
81 : * that required that they be called within an RCU-sched read-side
82 : * critical section.
83 : *
84 : * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
85 : * and while lockdep is disabled.
86 : *
87 : * Note that if the CPU is in the idle loop from an RCU point of view (ie:
88 : * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
89 : * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an
90 : * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are
91 : * in such a section, considering these as in extended quiescent state,
92 : * so such a CPU is effectively never in an RCU read-side critical section
93 : * regardless of what RCU primitives it invokes. This state of affairs is
94 : * required --- we need to keep an RCU-free window in idle where the CPU may
95 : * possibly enter into low power mode. This way we can notice an extended
96 : * quiescent state to other CPUs that started a grace period. Otherwise
97 : * we would delay any grace period as long as we run in the idle task.
98 : *
99 : * Similarly, we avoid claiming an RCU read lock held if the current
100 : * CPU is offline.
101 : */
102 34794043 : static bool rcu_read_lock_held_common(bool *ret)
103 : {
104 34794043 : if (!debug_lockdep_rcu_enabled()) {
105 0 : *ret = true;
106 0 : return true;
107 : }
108 34794043 : if (!rcu_is_watching()) {
109 0 : *ret = false;
110 0 : return true;
111 : }
112 34864193 : if (!rcu_lockdep_current_cpu_online()) {
113 0 : *ret = false;
114 0 : return true;
115 : }
116 : return false;
117 : }
118 :
119 32188025 : int rcu_read_lock_sched_held(void)
120 : {
121 32188025 : bool ret;
122 :
123 32188025 : if (rcu_read_lock_held_common(&ret))
124 0 : return ret;
125 32296065 : return lock_is_held(&rcu_sched_lock_map) || !preemptible();
126 : }
127 : EXPORT_SYMBOL(rcu_read_lock_sched_held);
128 : #endif
129 :
130 : #ifndef CONFIG_TINY_RCU
131 :
132 : /*
133 : * Should expedited grace-period primitives always fall back to their
134 : * non-expedited counterparts? Intended for use within RCU. Note
135 : * that if the user specifies both rcu_expedited and rcu_normal, then
136 : * rcu_normal wins. (Except during the time period during boot from
137 : * when the first task is spawned until the rcu_set_runtime_mode()
138 : * core_initcall() is invoked, at which point everything is expedited.)
139 : */
140 220 : bool rcu_gp_is_normal(void)
141 : {
142 220 : return READ_ONCE(rcu_normal) &&
143 0 : rcu_scheduler_active != RCU_SCHEDULER_INIT;
144 : }
145 : EXPORT_SYMBOL_GPL(rcu_gp_is_normal);
146 :
147 : static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);
148 :
149 : /*
150 : * Should normal grace-period primitives be expedited? Intended for
151 : * use within RCU. Note that this function takes the rcu_expedited
152 : * sysfs/boot variable and rcu_scheduler_active into account as well
153 : * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp()
154 : * until rcu_gp_is_expedited() returns false is a -really- bad idea.
155 : */
156 6 : bool rcu_gp_is_expedited(void)
157 : {
158 12 : return rcu_expedited || atomic_read(&rcu_expedited_nesting);
159 : }
160 : EXPORT_SYMBOL_GPL(rcu_gp_is_expedited);
161 :
162 : /**
163 : * rcu_expedite_gp - Expedite future RCU grace periods
164 : *
165 : * After a call to this function, future calls to synchronize_rcu() and
166 : * friends act as the corresponding synchronize_rcu_expedited() function
167 : * had instead been called.
168 : */
169 0 : void rcu_expedite_gp(void)
170 : {
171 0 : atomic_inc(&rcu_expedited_nesting);
172 0 : }
173 : EXPORT_SYMBOL_GPL(rcu_expedite_gp);
174 :
175 : /**
176 : * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation
177 : *
178 : * Undo a prior call to rcu_expedite_gp(). If all prior calls to
179 : * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(),
180 : * and if the rcu_expedited sysfs/boot parameter is not set, then all
181 : * subsequent calls to synchronize_rcu() and friends will return to
182 : * their normal non-expedited behavior.
183 : */
184 1 : void rcu_unexpedite_gp(void)
185 : {
186 1 : atomic_dec(&rcu_expedited_nesting);
187 1 : }
188 : EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
189 :
190 : static bool rcu_boot_ended __read_mostly;
191 :
192 : /*
193 : * Inform RCU of the end of the in-kernel boot sequence.
194 : */
195 1 : void rcu_end_inkernel_boot(void)
196 : {
197 1 : rcu_unexpedite_gp();
198 1 : if (rcu_normal_after_boot)
199 0 : WRITE_ONCE(rcu_normal, 1);
200 1 : rcu_boot_ended = true;
201 1 : }
202 :
203 : /*
204 : * Let rcutorture know when it is OK to turn it up to eleven.
205 : */
206 0 : bool rcu_inkernel_boot_has_ended(void)
207 : {
208 0 : return rcu_boot_ended;
209 : }
210 : EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended);
211 :
212 : #endif /* #ifndef CONFIG_TINY_RCU */
213 :
214 : /*
215 : * Test each non-SRCU synchronous grace-period wait API. This is
216 : * useful just after a change in mode for these primitives, and
217 : * during early boot.
218 : */
219 5 : void rcu_test_sync_prims(void)
220 : {
221 5 : if (!IS_ENABLED(CONFIG_PROVE_RCU))
222 : return;
223 2 : synchronize_rcu();
224 5 : synchronize_rcu_expedited();
225 : }
226 :
227 : #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU)
228 :
229 : /*
230 : * Switch to run-time mode once RCU has fully initialized.
231 : */
232 1 : static int __init rcu_set_runtime_mode(void)
233 : {
234 1 : rcu_test_sync_prims();
235 1 : rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
236 1 : kfree_rcu_scheduler_running();
237 1 : rcu_test_sync_prims();
238 1 : return 0;
239 : }
240 : core_initcall(rcu_set_runtime_mode);
241 :
242 : #endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */
243 :
244 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
245 : static struct lock_class_key rcu_lock_key;
246 : struct lockdep_map rcu_lock_map = {
247 : .name = "rcu_read_lock",
248 : .key = &rcu_lock_key,
249 : .wait_type_outer = LD_WAIT_FREE,
250 : .wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
251 : };
252 : EXPORT_SYMBOL_GPL(rcu_lock_map);
253 :
254 : static struct lock_class_key rcu_bh_lock_key;
255 : struct lockdep_map rcu_bh_lock_map = {
256 : .name = "rcu_read_lock_bh",
257 : .key = &rcu_bh_lock_key,
258 : .wait_type_outer = LD_WAIT_FREE,
259 : .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
260 : };
261 : EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
262 :
263 : static struct lock_class_key rcu_sched_lock_key;
264 : struct lockdep_map rcu_sched_lock_map = {
265 : .name = "rcu_read_lock_sched",
266 : .key = &rcu_sched_lock_key,
267 : .wait_type_outer = LD_WAIT_FREE,
268 : .wait_type_inner = LD_WAIT_SPIN,
269 : };
270 : EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
271 :
272 : // Tell lockdep when RCU callbacks are being invoked.
273 : static struct lock_class_key rcu_callback_key;
274 : struct lockdep_map rcu_callback_map =
275 : STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);
276 : EXPORT_SYMBOL_GPL(rcu_callback_map);
277 :
278 80630585 : noinstr int notrace debug_lockdep_rcu_enabled(void)
279 : {
280 80630585 : return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks &&
281 80474868 : current->lockdep_recursion == 0;
282 : }
283 : EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
284 :
285 : /**
286 : * rcu_read_lock_held() - might we be in RCU read-side critical section?
287 : *
288 : * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
289 : * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
290 : * this assumes we are in an RCU read-side critical section unless it can
291 : * prove otherwise. This is useful for debug checks in functions that
292 : * require that they be called within an RCU read-side critical section.
293 : *
294 : * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
295 : * and while lockdep is disabled.
296 : *
297 : * Note that rcu_read_lock() and the matching rcu_read_unlock() must
298 : * occur in the same context, for example, it is illegal to invoke
299 : * rcu_read_unlock() in process context if the matching rcu_read_lock()
300 : * was invoked from within an irq handler.
301 : *
302 : * Note that rcu_read_lock() is disallowed if the CPU is either idle or
303 : * offline from an RCU perspective, so check for those as well.
304 : */
305 2606905 : int rcu_read_lock_held(void)
306 : {
307 2606905 : bool ret;
308 :
309 2606905 : if (rcu_read_lock_held_common(&ret))
310 0 : return ret;
311 2607041 : return lock_is_held(&rcu_lock_map);
312 : }
313 : EXPORT_SYMBOL_GPL(rcu_read_lock_held);
314 :
315 : /**
316 : * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
317 : *
318 : * Check for bottom half being disabled, which covers both the
319 : * CONFIG_PROVE_RCU and not cases. Note that if someone uses
320 : * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
321 : * will show the situation. This is useful for debug checks in functions
322 : * that require that they be called within an RCU read-side critical
323 : * section.
324 : *
325 : * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
326 : *
327 : * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
328 : * offline from an RCU perspective, so check for those as well.
329 : */
330 1317 : int rcu_read_lock_bh_held(void)
331 : {
332 1317 : bool ret;
333 :
334 1317 : if (rcu_read_lock_held_common(&ret))
335 0 : return ret;
336 1317 : return in_softirq() || irqs_disabled();
337 : }
338 : EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
339 :
340 50324 : int rcu_read_lock_any_held(void)
341 : {
342 50324 : bool ret;
343 :
344 50324 : if (rcu_read_lock_held_common(&ret))
345 0 : return ret;
346 50323 : if (lock_is_held(&rcu_lock_map) ||
347 50323 : lock_is_held(&rcu_bh_lock_map) ||
348 50323 : lock_is_held(&rcu_sched_lock_map))
349 0 : return 1;
350 50323 : return !preemptible();
351 : }
352 : EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
353 :
354 : #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
355 :
356 : /**
357 : * wakeme_after_rcu() - Callback function to awaken a task after grace period
358 : * @head: Pointer to rcu_head member within rcu_synchronize structure
359 : *
360 : * Awaken the corresponding task now that a grace period has elapsed.
361 : */
362 61 : void wakeme_after_rcu(struct rcu_head *head)
363 : {
364 61 : struct rcu_synchronize *rcu;
365 :
366 61 : rcu = container_of(head, struct rcu_synchronize, head);
367 61 : complete(&rcu->completion);
368 61 : }
369 : EXPORT_SYMBOL_GPL(wakeme_after_rcu);
370 :
371 1 : void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
372 : struct rcu_synchronize *rs_array)
373 : {
374 1 : int i;
375 1 : int j;
376 :
377 : /* Initialize and register callbacks for each crcu_array element. */
378 2 : for (i = 0; i < n; i++) {
379 1 : if (checktiny &&
380 0 : (crcu_array[i] == call_rcu)) {
381 0 : might_sleep();
382 0 : continue;
383 : }
384 1 : for (j = 0; j < i; j++)
385 0 : if (crcu_array[j] == crcu_array[i])
386 : break;
387 1 : if (j == i) {
388 2 : init_rcu_head_on_stack(&rs_array[i].head);
389 1 : init_completion(&rs_array[i].completion);
390 1 : (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
391 : }
392 : }
393 :
394 : /* Wait for all callbacks to be invoked. */
395 2 : for (i = 0; i < n; i++) {
396 1 : if (checktiny &&
397 0 : (crcu_array[i] == call_rcu))
398 0 : continue;
399 1 : for (j = 0; j < i; j++)
400 0 : if (crcu_array[j] == crcu_array[i])
401 : break;
402 1 : if (j == i) {
403 1 : wait_for_completion(&rs_array[i].completion);
404 1 : destroy_rcu_head_on_stack(&rs_array[i].head);
405 : }
406 : }
407 1 : }
408 : EXPORT_SYMBOL_GPL(__wait_rcu_gp);
409 :
410 : #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
411 17 : void init_rcu_head(struct rcu_head *head)
412 : {
413 17 : debug_object_init(head, &rcuhead_debug_descr);
414 17 : }
415 : EXPORT_SYMBOL_GPL(init_rcu_head);
416 :
417 0 : void destroy_rcu_head(struct rcu_head *head)
418 : {
419 0 : debug_object_free(head, &rcuhead_debug_descr);
420 0 : }
421 : EXPORT_SYMBOL_GPL(destroy_rcu_head);
422 :
423 625156 : static bool rcuhead_is_static_object(void *addr)
424 : {
425 625156 : return true;
426 : }
427 :
428 : /**
429 : * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects
430 : * @head: pointer to rcu_head structure to be initialized
431 : *
432 : * This function informs debugobjects of a new rcu_head structure that
433 : * has been allocated as an auto variable on the stack. This function
434 : * is not required for rcu_head structures that are statically defined or
435 : * that are dynamically allocated on the heap. This function has no
436 : * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
437 : */
438 61 : void init_rcu_head_on_stack(struct rcu_head *head)
439 : {
440 61 : debug_object_init_on_stack(head, &rcuhead_debug_descr);
441 60 : }
442 : EXPORT_SYMBOL_GPL(init_rcu_head_on_stack);
443 :
444 : /**
445 : * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects
446 : * @head: pointer to rcu_head structure to be initialized
447 : *
448 : * This function informs debugobjects that an on-stack rcu_head structure
449 : * is about to go out of scope. As with init_rcu_head_on_stack(), this
450 : * function is not required for rcu_head structures that are statically
451 : * defined or that are dynamically allocated on the heap. Also as with
452 : * init_rcu_head_on_stack(), this function has no effect for
453 : * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
454 : */
455 61 : void destroy_rcu_head_on_stack(struct rcu_head *head)
456 : {
457 61 : debug_object_free(head, &rcuhead_debug_descr);
458 1 : }
459 : EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
460 :
461 : const struct debug_obj_descr rcuhead_debug_descr = {
462 : .name = "rcu_head",
463 : .is_static_object = rcuhead_is_static_object,
464 : };
465 : EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
466 : #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
467 :
468 : #if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE)
469 0 : void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp,
470 : unsigned long secs,
471 : unsigned long c_old, unsigned long c)
472 : {
473 0 : trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c);
474 0 : }
475 : EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
476 : #else
477 : #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
478 : do { } while (0)
479 : #endif
480 :
481 : #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST)
482 : /* Get rcutorture access to sched_setaffinity(). */
483 : long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
484 : {
485 : int ret;
486 :
487 : ret = sched_setaffinity(pid, in_mask);
488 : WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
489 : return ret;
490 : }
491 : EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
492 : #endif
493 :
494 : #ifdef CONFIG_RCU_STALL_COMMON
495 : int rcu_cpu_stall_ftrace_dump __read_mostly;
496 : module_param(rcu_cpu_stall_ftrace_dump, int, 0644);
497 : int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings.
498 : EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
499 : module_param(rcu_cpu_stall_suppress, int, 0644);
500 : int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
501 : module_param(rcu_cpu_stall_timeout, int, 0644);
502 : #endif /* #ifdef CONFIG_RCU_STALL_COMMON */
503 :
504 : // Suppress boot-time RCU CPU stall warnings and rcutorture writer stall
505 : // warnings. Also used by rcutorture even if stall warnings are excluded.
506 : int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls.
507 : EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot);
508 : module_param(rcu_cpu_stall_suppress_at_boot, int, 0444);
509 :
510 : #ifdef CONFIG_PROVE_RCU
511 :
512 : /*
513 : * Early boot self test parameters.
514 : */
515 : static bool rcu_self_test;
516 : module_param(rcu_self_test, bool, 0444);
517 :
518 : static int rcu_self_test_counter;
519 :
520 0 : static void test_callback(struct rcu_head *r)
521 : {
522 0 : rcu_self_test_counter++;
523 0 : pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
524 0 : }
525 :
526 : DEFINE_STATIC_SRCU(early_srcu);
527 :
528 : struct early_boot_kfree_rcu {
529 : struct rcu_head rh;
530 : };
531 :
532 0 : static void early_boot_test_call_rcu(void)
533 : {
534 0 : static struct rcu_head head;
535 0 : static struct rcu_head shead;
536 0 : struct early_boot_kfree_rcu *rhp;
537 :
538 0 : call_rcu(&head, test_callback);
539 0 : if (IS_ENABLED(CONFIG_SRCU))
540 0 : call_srcu(&early_srcu, &shead, test_callback);
541 0 : rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
542 0 : if (!WARN_ON_ONCE(!rhp))
543 0 : kfree_rcu(rhp, rh);
544 0 : }
545 :
546 1 : void rcu_early_boot_tests(void)
547 : {
548 1 : pr_info("Running RCU self tests\n");
549 :
550 1 : if (rcu_self_test)
551 0 : early_boot_test_call_rcu();
552 1 : rcu_test_sync_prims();
553 1 : }
554 :
555 1 : static int rcu_verify_early_boot_tests(void)
556 : {
557 1 : int ret = 0;
558 1 : int early_boot_test_counter = 0;
559 :
560 1 : if (rcu_self_test) {
561 0 : early_boot_test_counter++;
562 0 : rcu_barrier();
563 0 : if (IS_ENABLED(CONFIG_SRCU)) {
564 0 : early_boot_test_counter++;
565 0 : srcu_barrier(&early_srcu);
566 : }
567 : }
568 1 : if (rcu_self_test_counter != early_boot_test_counter) {
569 0 : WARN_ON(1);
570 0 : ret = -1;
571 : }
572 :
573 1 : return ret;
574 : }
575 : late_initcall(rcu_verify_early_boot_tests);
576 : #else
577 : void rcu_early_boot_tests(void) {}
578 : #endif /* CONFIG_PROVE_RCU */
579 :
580 : #include "tasks.h"
581 :
582 : #ifndef CONFIG_TINY_RCU
583 :
584 : /*
585 : * Print any significant non-default boot-time settings.
586 : */
587 1 : void __init rcupdate_announce_bootup_oddness(void)
588 : {
589 1 : if (rcu_normal)
590 0 : pr_info("\tNo expedited grace period (rcu_normal).\n");
591 1 : else if (rcu_normal_after_boot)
592 0 : pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n");
593 1 : else if (rcu_expedited)
594 0 : pr_info("\tAll grace periods are expedited (rcu_expedited).\n");
595 1 : if (rcu_cpu_stall_suppress)
596 0 : pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n");
597 1 : if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT)
598 0 : pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout);
599 1 : rcu_tasks_bootup_oddness();
600 1 : }
601 :
602 : #endif /* #ifndef CONFIG_TINY_RCU */
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