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/torture.h> |
29 | #include <linux/atomic.h> |
30 | #include <linux/bitops.h> |
31 | #include <linux/percpu.h> |
32 | #include <linux/notifier.h> |
33 | #include <linux/cpu.h> |
34 | #include <linux/mutex.h> |
35 | #include <linux/export.h> |
36 | #include <linux/hardirq.h> |
37 | #include <linux/delay.h> |
38 | #include <linux/moduleparam.h> |
39 | #include <linux/kthread.h> |
40 | #include <linux/tick.h> |
41 | #include <linux/rcupdate_wait.h> |
42 | #include <linux/sched/isolation.h> |
43 | #include <linux/kprobes.h> |
44 | #include <linux/slab.h> |
45 | #include <linux/irq_work.h> |
46 | #include <linux/rcupdate_trace.h> |
47 | |
48 | #define CREATE_TRACE_POINTS |
49 | |
50 | #include "rcu.h" |
51 | |
52 | #ifdef MODULE_PARAM_PREFIX |
53 | #undef MODULE_PARAM_PREFIX |
54 | #endif |
55 | #define MODULE_PARAM_PREFIX "rcupdate." |
56 | |
57 | #ifndef CONFIG_TINY_RCU |
58 | module_param(rcu_expedited, int, 0444); |
59 | module_param(rcu_normal, int, 0444); |
60 | static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT); |
61 | #if !defined(CONFIG_PREEMPT_RT) || defined(CONFIG_NO_HZ_FULL) |
62 | module_param(rcu_normal_after_boot, int, 0444); |
63 | #endif |
64 | #endif /* #ifndef CONFIG_TINY_RCU */ |
65 | |
66 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
67 | /** |
68 | * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? |
69 | * @ret: Best guess answer if lockdep cannot be relied on |
70 | * |
71 | * Returns true if lockdep must be ignored, in which case ``*ret`` contains |
72 | * the best guess described below. Otherwise returns false, in which |
73 | * case ``*ret`` tells the caller nothing and the caller should instead |
74 | * consult lockdep. |
75 | * |
76 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an |
77 | * RCU-sched read-side critical section. In absence of |
78 | * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side |
79 | * critical section unless it can prove otherwise. Note that disabling |
80 | * of preemption (including disabling irqs) counts as an RCU-sched |
81 | * read-side critical section. This is useful for debug checks in functions |
82 | * that required that they be called within an RCU-sched read-side |
83 | * critical section. |
84 | * |
85 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot |
86 | * and while lockdep is disabled. |
87 | * |
88 | * Note that if the CPU is in the idle loop from an RCU point of view (ie: |
89 | * that we are in the section between ct_idle_enter() and ct_idle_exit()) |
90 | * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an |
91 | * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are |
92 | * in such a section, considering these as in extended quiescent state, |
93 | * so such a CPU is effectively never in an RCU read-side critical section |
94 | * regardless of what RCU primitives it invokes. This state of affairs is |
95 | * required --- we need to keep an RCU-free window in idle where the CPU may |
96 | * possibly enter into low power mode. This way we can notice an extended |
97 | * quiescent state to other CPUs that started a grace period. Otherwise |
98 | * we would delay any grace period as long as we run in the idle task. |
99 | * |
100 | * Similarly, we avoid claiming an RCU read lock held if the current |
101 | * CPU is offline. |
102 | */ |
103 | static bool rcu_read_lock_held_common(bool *ret) |
104 | { |
105 | if (!debug_lockdep_rcu_enabled()) { |
106 | *ret = true; |
107 | return true; |
108 | } |
109 | if (!rcu_is_watching()) { |
110 | *ret = false; |
111 | return true; |
112 | } |
113 | if (!rcu_lockdep_current_cpu_online()) { |
114 | *ret = false; |
115 | return true; |
116 | } |
117 | return false; |
118 | } |
119 | |
120 | int rcu_read_lock_sched_held(void) |
121 | { |
122 | bool ret; |
123 | |
124 | if (rcu_read_lock_held_common(ret: &ret)) |
125 | return ret; |
126 | return lock_is_held(lock: &rcu_sched_lock_map) || !preemptible(); |
127 | } |
128 | EXPORT_SYMBOL(rcu_read_lock_sched_held); |
129 | #endif |
130 | |
131 | #ifndef CONFIG_TINY_RCU |
132 | |
133 | /* |
134 | * Should expedited grace-period primitives always fall back to their |
135 | * non-expedited counterparts? Intended for use within RCU. Note |
136 | * that if the user specifies both rcu_expedited and rcu_normal, then |
137 | * rcu_normal wins. (Except during the time period during boot from |
138 | * when the first task is spawned until the rcu_set_runtime_mode() |
139 | * core_initcall() is invoked, at which point everything is expedited.) |
140 | */ |
141 | bool rcu_gp_is_normal(void) |
142 | { |
143 | return READ_ONCE(rcu_normal) && |
144 | rcu_scheduler_active != RCU_SCHEDULER_INIT; |
145 | } |
146 | EXPORT_SYMBOL_GPL(rcu_gp_is_normal); |
147 | |
148 | static atomic_t rcu_async_hurry_nesting = ATOMIC_INIT(1); |
149 | /* |
150 | * Should call_rcu() callbacks be processed with urgency or are |
151 | * they OK being executed with arbitrary delays? |
152 | */ |
153 | bool rcu_async_should_hurry(void) |
154 | { |
155 | return !IS_ENABLED(CONFIG_RCU_LAZY) || |
156 | atomic_read(v: &rcu_async_hurry_nesting); |
157 | } |
158 | EXPORT_SYMBOL_GPL(rcu_async_should_hurry); |
159 | |
160 | /** |
161 | * rcu_async_hurry - Make future async RCU callbacks not lazy. |
162 | * |
163 | * After a call to this function, future calls to call_rcu() |
164 | * will be processed in a timely fashion. |
165 | */ |
166 | void rcu_async_hurry(void) |
167 | { |
168 | if (IS_ENABLED(CONFIG_RCU_LAZY)) |
169 | atomic_inc(v: &rcu_async_hurry_nesting); |
170 | } |
171 | EXPORT_SYMBOL_GPL(rcu_async_hurry); |
172 | |
173 | /** |
174 | * rcu_async_relax - Make future async RCU callbacks lazy. |
175 | * |
176 | * After a call to this function, future calls to call_rcu() |
177 | * will be processed in a lazy fashion. |
178 | */ |
179 | void rcu_async_relax(void) |
180 | { |
181 | if (IS_ENABLED(CONFIG_RCU_LAZY)) |
182 | atomic_dec(v: &rcu_async_hurry_nesting); |
183 | } |
184 | EXPORT_SYMBOL_GPL(rcu_async_relax); |
185 | |
186 | static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); |
187 | /* |
188 | * Should normal grace-period primitives be expedited? Intended for |
189 | * use within RCU. Note that this function takes the rcu_expedited |
190 | * sysfs/boot variable and rcu_scheduler_active into account as well |
191 | * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() |
192 | * until rcu_gp_is_expedited() returns false is a -really- bad idea. |
193 | */ |
194 | bool rcu_gp_is_expedited(void) |
195 | { |
196 | return rcu_expedited || atomic_read(v: &rcu_expedited_nesting); |
197 | } |
198 | EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); |
199 | |
200 | /** |
201 | * rcu_expedite_gp - Expedite future RCU grace periods |
202 | * |
203 | * After a call to this function, future calls to synchronize_rcu() and |
204 | * friends act as the corresponding synchronize_rcu_expedited() function |
205 | * had instead been called. |
206 | */ |
207 | void rcu_expedite_gp(void) |
208 | { |
209 | atomic_inc(v: &rcu_expedited_nesting); |
210 | } |
211 | EXPORT_SYMBOL_GPL(rcu_expedite_gp); |
212 | |
213 | /** |
214 | * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation |
215 | * |
216 | * Undo a prior call to rcu_expedite_gp(). If all prior calls to |
217 | * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), |
218 | * and if the rcu_expedited sysfs/boot parameter is not set, then all |
219 | * subsequent calls to synchronize_rcu() and friends will return to |
220 | * their normal non-expedited behavior. |
221 | */ |
222 | void rcu_unexpedite_gp(void) |
223 | { |
224 | atomic_dec(v: &rcu_expedited_nesting); |
225 | } |
226 | EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); |
227 | |
228 | static bool rcu_boot_ended __read_mostly; |
229 | |
230 | /* |
231 | * Inform RCU of the end of the in-kernel boot sequence. |
232 | */ |
233 | void rcu_end_inkernel_boot(void) |
234 | { |
235 | rcu_unexpedite_gp(); |
236 | rcu_async_relax(); |
237 | if (rcu_normal_after_boot) |
238 | WRITE_ONCE(rcu_normal, 1); |
239 | rcu_boot_ended = true; |
240 | } |
241 | |
242 | /* |
243 | * Let rcutorture know when it is OK to turn it up to eleven. |
244 | */ |
245 | bool rcu_inkernel_boot_has_ended(void) |
246 | { |
247 | return rcu_boot_ended; |
248 | } |
249 | EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended); |
250 | |
251 | #endif /* #ifndef CONFIG_TINY_RCU */ |
252 | |
253 | /* |
254 | * Test each non-SRCU synchronous grace-period wait API. This is |
255 | * useful just after a change in mode for these primitives, and |
256 | * during early boot. |
257 | */ |
258 | void rcu_test_sync_prims(void) |
259 | { |
260 | if (!IS_ENABLED(CONFIG_PROVE_RCU)) |
261 | return; |
262 | pr_info("Running RCU synchronous self tests\n" ); |
263 | synchronize_rcu(); |
264 | synchronize_rcu_expedited(); |
265 | } |
266 | |
267 | #if !defined(CONFIG_TINY_RCU) |
268 | |
269 | /* |
270 | * Switch to run-time mode once RCU has fully initialized. |
271 | */ |
272 | static int __init rcu_set_runtime_mode(void) |
273 | { |
274 | rcu_test_sync_prims(); |
275 | rcu_scheduler_active = RCU_SCHEDULER_RUNNING; |
276 | kfree_rcu_scheduler_running(); |
277 | rcu_test_sync_prims(); |
278 | return 0; |
279 | } |
280 | core_initcall(rcu_set_runtime_mode); |
281 | |
282 | #endif /* #if !defined(CONFIG_TINY_RCU) */ |
283 | |
284 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
285 | static struct lock_class_key rcu_lock_key; |
286 | struct lockdep_map rcu_lock_map = { |
287 | .name = "rcu_read_lock" , |
288 | .key = &rcu_lock_key, |
289 | .wait_type_outer = LD_WAIT_FREE, |
290 | .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT implies PREEMPT_RCU */ |
291 | }; |
292 | EXPORT_SYMBOL_GPL(rcu_lock_map); |
293 | |
294 | static struct lock_class_key rcu_bh_lock_key; |
295 | struct lockdep_map rcu_bh_lock_map = { |
296 | .name = "rcu_read_lock_bh" , |
297 | .key = &rcu_bh_lock_key, |
298 | .wait_type_outer = LD_WAIT_FREE, |
299 | .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */ |
300 | }; |
301 | EXPORT_SYMBOL_GPL(rcu_bh_lock_map); |
302 | |
303 | static struct lock_class_key rcu_sched_lock_key; |
304 | struct lockdep_map rcu_sched_lock_map = { |
305 | .name = "rcu_read_lock_sched" , |
306 | .key = &rcu_sched_lock_key, |
307 | .wait_type_outer = LD_WAIT_FREE, |
308 | .wait_type_inner = LD_WAIT_SPIN, |
309 | }; |
310 | EXPORT_SYMBOL_GPL(rcu_sched_lock_map); |
311 | |
312 | // Tell lockdep when RCU callbacks are being invoked. |
313 | static struct lock_class_key rcu_callback_key; |
314 | struct lockdep_map rcu_callback_map = |
315 | STATIC_LOCKDEP_MAP_INIT("rcu_callback" , &rcu_callback_key); |
316 | EXPORT_SYMBOL_GPL(rcu_callback_map); |
317 | |
318 | noinstr int notrace debug_lockdep_rcu_enabled(void) |
319 | { |
320 | return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) && |
321 | current->lockdep_recursion == 0; |
322 | } |
323 | EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); |
324 | |
325 | /** |
326 | * rcu_read_lock_held() - might we be in RCU read-side critical section? |
327 | * |
328 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU |
329 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, |
330 | * this assumes we are in an RCU read-side critical section unless it can |
331 | * prove otherwise. This is useful for debug checks in functions that |
332 | * require that they be called within an RCU read-side critical section. |
333 | * |
334 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot |
335 | * and while lockdep is disabled. |
336 | * |
337 | * Note that rcu_read_lock() and the matching rcu_read_unlock() must |
338 | * occur in the same context, for example, it is illegal to invoke |
339 | * rcu_read_unlock() in process context if the matching rcu_read_lock() |
340 | * was invoked from within an irq handler. |
341 | * |
342 | * Note that rcu_read_lock() is disallowed if the CPU is either idle or |
343 | * offline from an RCU perspective, so check for those as well. |
344 | */ |
345 | int rcu_read_lock_held(void) |
346 | { |
347 | bool ret; |
348 | |
349 | if (rcu_read_lock_held_common(ret: &ret)) |
350 | return ret; |
351 | return lock_is_held(lock: &rcu_lock_map); |
352 | } |
353 | EXPORT_SYMBOL_GPL(rcu_read_lock_held); |
354 | |
355 | /** |
356 | * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? |
357 | * |
358 | * Check for bottom half being disabled, which covers both the |
359 | * CONFIG_PROVE_RCU and not cases. Note that if someone uses |
360 | * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) |
361 | * will show the situation. This is useful for debug checks in functions |
362 | * that require that they be called within an RCU read-side critical |
363 | * section. |
364 | * |
365 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. |
366 | * |
367 | * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or |
368 | * offline from an RCU perspective, so check for those as well. |
369 | */ |
370 | int rcu_read_lock_bh_held(void) |
371 | { |
372 | bool ret; |
373 | |
374 | if (rcu_read_lock_held_common(ret: &ret)) |
375 | return ret; |
376 | return in_softirq() || irqs_disabled(); |
377 | } |
378 | EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); |
379 | |
380 | int rcu_read_lock_any_held(void) |
381 | { |
382 | bool ret; |
383 | |
384 | if (rcu_read_lock_held_common(ret: &ret)) |
385 | return ret; |
386 | if (lock_is_held(lock: &rcu_lock_map) || |
387 | lock_is_held(lock: &rcu_bh_lock_map) || |
388 | lock_is_held(lock: &rcu_sched_lock_map)) |
389 | return 1; |
390 | return !preemptible(); |
391 | } |
392 | EXPORT_SYMBOL_GPL(rcu_read_lock_any_held); |
393 | |
394 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
395 | |
396 | /** |
397 | * wakeme_after_rcu() - Callback function to awaken a task after grace period |
398 | * @head: Pointer to rcu_head member within rcu_synchronize structure |
399 | * |
400 | * Awaken the corresponding task now that a grace period has elapsed. |
401 | */ |
402 | void wakeme_after_rcu(struct rcu_head *head) |
403 | { |
404 | struct rcu_synchronize *rcu; |
405 | |
406 | rcu = container_of(head, struct rcu_synchronize, head); |
407 | complete(&rcu->completion); |
408 | } |
409 | EXPORT_SYMBOL_GPL(wakeme_after_rcu); |
410 | |
411 | void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, |
412 | struct rcu_synchronize *rs_array) |
413 | { |
414 | int i; |
415 | int j; |
416 | |
417 | /* Initialize and register callbacks for each crcu_array element. */ |
418 | for (i = 0; i < n; i++) { |
419 | if (checktiny && |
420 | (crcu_array[i] == call_rcu)) { |
421 | might_sleep(); |
422 | continue; |
423 | } |
424 | for (j = 0; j < i; j++) |
425 | if (crcu_array[j] == crcu_array[i]) |
426 | break; |
427 | if (j == i) { |
428 | init_rcu_head_on_stack(head: &rs_array[i].head); |
429 | init_completion(x: &rs_array[i].completion); |
430 | (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); |
431 | } |
432 | } |
433 | |
434 | /* Wait for all callbacks to be invoked. */ |
435 | for (i = 0; i < n; i++) { |
436 | if (checktiny && |
437 | (crcu_array[i] == call_rcu)) |
438 | continue; |
439 | for (j = 0; j < i; j++) |
440 | if (crcu_array[j] == crcu_array[i]) |
441 | break; |
442 | if (j == i) { |
443 | wait_for_completion(&rs_array[i].completion); |
444 | destroy_rcu_head_on_stack(head: &rs_array[i].head); |
445 | } |
446 | } |
447 | } |
448 | EXPORT_SYMBOL_GPL(__wait_rcu_gp); |
449 | |
450 | void finish_rcuwait(struct rcuwait *w) |
451 | { |
452 | rcu_assign_pointer(w->task, NULL); |
453 | __set_current_state(TASK_RUNNING); |
454 | } |
455 | EXPORT_SYMBOL_GPL(finish_rcuwait); |
456 | |
457 | #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD |
458 | void init_rcu_head(struct rcu_head *head) |
459 | { |
460 | debug_object_init(addr: head, descr: &rcuhead_debug_descr); |
461 | } |
462 | EXPORT_SYMBOL_GPL(init_rcu_head); |
463 | |
464 | void destroy_rcu_head(struct rcu_head *head) |
465 | { |
466 | debug_object_free(addr: head, descr: &rcuhead_debug_descr); |
467 | } |
468 | EXPORT_SYMBOL_GPL(destroy_rcu_head); |
469 | |
470 | static bool rcuhead_is_static_object(void *addr) |
471 | { |
472 | return true; |
473 | } |
474 | |
475 | /** |
476 | * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects |
477 | * @head: pointer to rcu_head structure to be initialized |
478 | * |
479 | * This function informs debugobjects of a new rcu_head structure that |
480 | * has been allocated as an auto variable on the stack. This function |
481 | * is not required for rcu_head structures that are statically defined or |
482 | * that are dynamically allocated on the heap. This function has no |
483 | * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. |
484 | */ |
485 | void init_rcu_head_on_stack(struct rcu_head *head) |
486 | { |
487 | debug_object_init_on_stack(addr: head, descr: &rcuhead_debug_descr); |
488 | } |
489 | EXPORT_SYMBOL_GPL(init_rcu_head_on_stack); |
490 | |
491 | /** |
492 | * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects |
493 | * @head: pointer to rcu_head structure to be initialized |
494 | * |
495 | * This function informs debugobjects that an on-stack rcu_head structure |
496 | * is about to go out of scope. As with init_rcu_head_on_stack(), this |
497 | * function is not required for rcu_head structures that are statically |
498 | * defined or that are dynamically allocated on the heap. Also as with |
499 | * init_rcu_head_on_stack(), this function has no effect for |
500 | * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. |
501 | */ |
502 | void destroy_rcu_head_on_stack(struct rcu_head *head) |
503 | { |
504 | debug_object_free(addr: head, descr: &rcuhead_debug_descr); |
505 | } |
506 | EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); |
507 | |
508 | const struct debug_obj_descr rcuhead_debug_descr = { |
509 | .name = "rcu_head" , |
510 | .is_static_object = rcuhead_is_static_object, |
511 | }; |
512 | EXPORT_SYMBOL_GPL(rcuhead_debug_descr); |
513 | #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ |
514 | |
515 | #if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE) |
516 | void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, |
517 | unsigned long secs, |
518 | unsigned long c_old, unsigned long c) |
519 | { |
520 | trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); |
521 | } |
522 | EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); |
523 | #else |
524 | #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ |
525 | do { } while (0) |
526 | #endif |
527 | |
528 | #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST) |
529 | /* Get rcutorture access to sched_setaffinity(). */ |
530 | long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask) |
531 | { |
532 | int ret; |
533 | |
534 | ret = sched_setaffinity(pid, new_mask: in_mask); |
535 | WARN_ONCE(ret, "%s: sched_setaffinity(%d) returned %d\n" , __func__, pid, ret); |
536 | return ret; |
537 | } |
538 | EXPORT_SYMBOL_GPL(torture_sched_setaffinity); |
539 | #endif |
540 | |
541 | int rcu_cpu_stall_notifiers __read_mostly; // !0 = provide stall notifiers (rarely useful) |
542 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_notifiers); |
543 | |
544 | #ifdef CONFIG_RCU_STALL_COMMON |
545 | int rcu_cpu_stall_ftrace_dump __read_mostly; |
546 | module_param(rcu_cpu_stall_ftrace_dump, int, 0644); |
547 | #ifdef CONFIG_RCU_CPU_STALL_NOTIFIER |
548 | module_param(rcu_cpu_stall_notifiers, int, 0444); |
549 | #endif // #ifdef CONFIG_RCU_CPU_STALL_NOTIFIER |
550 | int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings. |
551 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); |
552 | module_param(rcu_cpu_stall_suppress, int, 0644); |
553 | int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; |
554 | module_param(rcu_cpu_stall_timeout, int, 0644); |
555 | int rcu_exp_cpu_stall_timeout __read_mostly = CONFIG_RCU_EXP_CPU_STALL_TIMEOUT; |
556 | module_param(rcu_exp_cpu_stall_timeout, int, 0644); |
557 | int rcu_cpu_stall_cputime __read_mostly = IS_ENABLED(CONFIG_RCU_CPU_STALL_CPUTIME); |
558 | module_param(rcu_cpu_stall_cputime, int, 0644); |
559 | bool rcu_exp_stall_task_details __read_mostly; |
560 | module_param(rcu_exp_stall_task_details, bool, 0644); |
561 | #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ |
562 | |
563 | // Suppress boot-time RCU CPU stall warnings and rcutorture writer stall |
564 | // warnings. Also used by rcutorture even if stall warnings are excluded. |
565 | int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls. |
566 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot); |
567 | module_param(rcu_cpu_stall_suppress_at_boot, int, 0444); |
568 | |
569 | /** |
570 | * get_completed_synchronize_rcu - Return a pre-completed polled state cookie |
571 | * |
572 | * Returns a value that will always be treated by functions like |
573 | * poll_state_synchronize_rcu() as a cookie whose grace period has already |
574 | * completed. |
575 | */ |
576 | unsigned long get_completed_synchronize_rcu(void) |
577 | { |
578 | return RCU_GET_STATE_COMPLETED; |
579 | } |
580 | EXPORT_SYMBOL_GPL(get_completed_synchronize_rcu); |
581 | |
582 | #ifdef CONFIG_PROVE_RCU |
583 | |
584 | /* |
585 | * Early boot self test parameters. |
586 | */ |
587 | static bool rcu_self_test; |
588 | module_param(rcu_self_test, bool, 0444); |
589 | |
590 | static int rcu_self_test_counter; |
591 | |
592 | static void test_callback(struct rcu_head *r) |
593 | { |
594 | rcu_self_test_counter++; |
595 | pr_info("RCU test callback executed %d\n" , rcu_self_test_counter); |
596 | } |
597 | |
598 | DEFINE_STATIC_SRCU(early_srcu); |
599 | static unsigned long early_srcu_cookie; |
600 | |
601 | struct early_boot_kfree_rcu { |
602 | struct rcu_head rh; |
603 | }; |
604 | |
605 | static void early_boot_test_call_rcu(void) |
606 | { |
607 | static struct rcu_head head; |
608 | int idx; |
609 | static struct rcu_head shead; |
610 | struct early_boot_kfree_rcu *rhp; |
611 | |
612 | idx = srcu_down_read(ssp: &early_srcu); |
613 | srcu_up_read(ssp: &early_srcu, idx); |
614 | call_rcu(head: &head, func: test_callback); |
615 | early_srcu_cookie = start_poll_synchronize_srcu(ssp: &early_srcu); |
616 | call_srcu(ssp: &early_srcu, head: &shead, func: test_callback); |
617 | rhp = kmalloc(size: sizeof(*rhp), GFP_KERNEL); |
618 | if (!WARN_ON_ONCE(!rhp)) |
619 | kfree_rcu(rhp, rh); |
620 | } |
621 | |
622 | void rcu_early_boot_tests(void) |
623 | { |
624 | pr_info("Running RCU self tests\n" ); |
625 | |
626 | if (rcu_self_test) |
627 | early_boot_test_call_rcu(); |
628 | rcu_test_sync_prims(); |
629 | } |
630 | |
631 | static int rcu_verify_early_boot_tests(void) |
632 | { |
633 | int ret = 0; |
634 | int early_boot_test_counter = 0; |
635 | |
636 | if (rcu_self_test) { |
637 | early_boot_test_counter++; |
638 | rcu_barrier(); |
639 | early_boot_test_counter++; |
640 | srcu_barrier(ssp: &early_srcu); |
641 | WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie)); |
642 | cleanup_srcu_struct(ssp: &early_srcu); |
643 | } |
644 | if (rcu_self_test_counter != early_boot_test_counter) { |
645 | WARN_ON(1); |
646 | ret = -1; |
647 | } |
648 | |
649 | return ret; |
650 | } |
651 | late_initcall(rcu_verify_early_boot_tests); |
652 | #else |
653 | void rcu_early_boot_tests(void) {} |
654 | #endif /* CONFIG_PROVE_RCU */ |
655 | |
656 | #include "tasks.h" |
657 | |
658 | #ifndef CONFIG_TINY_RCU |
659 | |
660 | /* |
661 | * Print any significant non-default boot-time settings. |
662 | */ |
663 | void __init rcupdate_announce_bootup_oddness(void) |
664 | { |
665 | if (rcu_normal) |
666 | pr_info("\tNo expedited grace period (rcu_normal).\n" ); |
667 | else if (rcu_normal_after_boot) |
668 | pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n" ); |
669 | else if (rcu_expedited) |
670 | pr_info("\tAll grace periods are expedited (rcu_expedited).\n" ); |
671 | if (rcu_cpu_stall_suppress) |
672 | pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n" ); |
673 | if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT) |
674 | pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n" , rcu_cpu_stall_timeout); |
675 | rcu_tasks_bootup_oddness(); |
676 | } |
677 | |
678 | #endif /* #ifndef CONFIG_TINY_RCU */ |
679 | |