1 // SPDX-License-Identifier: GPL-2.0+
3 * Read-Copy Update mechanism for mutual exclusion
5 * Copyright IBM Corporation, 2001
7 * Authors: Dipankar Sarma <dipankar@in.ibm.com>
8 * Manfred Spraul <manfred@colorfullife.com>
10 * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
11 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
13 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
14 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
16 * For detailed explanation of Read-Copy Update mechanism see -
17 * http://lse.sourceforge.net/locking/rcupdate.html
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>
48 #define CREATE_TRACE_POINTS
52 #ifdef MODULE_PARAM_PREFIX
53 #undef MODULE_PARAM_PREFIX
55 #define MODULE_PARAM_PREFIX "rcupdate."
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);
64 #endif /* #ifndef CONFIG_TINY_RCU */
66 #ifdef CONFIG_DEBUG_LOCK_ALLOC
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
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
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
85 * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
86 * and while lockdep is disabled.
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.
100 * Similarly, we avoid claiming an RCU read lock held if the current
103 static bool rcu_read_lock_held_common(bool *ret
)
105 if (!debug_lockdep_rcu_enabled()) {
109 if (!rcu_is_watching()) {
113 if (!rcu_lockdep_current_cpu_online()) {
120 int rcu_read_lock_sched_held(void)
124 if (rcu_read_lock_held_common(&ret
))
126 return lock_is_held(&rcu_sched_lock_map
) || !preemptible();
128 EXPORT_SYMBOL(rcu_read_lock_sched_held
);
131 #ifndef CONFIG_TINY_RCU
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.)
141 bool rcu_gp_is_normal(void)
143 return READ_ONCE(rcu_normal
) &&
144 rcu_scheduler_active
!= RCU_SCHEDULER_INIT
;
146 EXPORT_SYMBOL_GPL(rcu_gp_is_normal
);
148 static atomic_t rcu_async_hurry_nesting
= ATOMIC_INIT(1);
150 * Should call_rcu() callbacks be processed with urgency or are
151 * they OK being executed with arbitrary delays?
153 bool rcu_async_should_hurry(void)
155 return !IS_ENABLED(CONFIG_RCU_LAZY
) ||
156 atomic_read(&rcu_async_hurry_nesting
);
158 EXPORT_SYMBOL_GPL(rcu_async_should_hurry
);
161 * rcu_async_hurry - Make future async RCU callbacks not lazy.
163 * After a call to this function, future calls to call_rcu()
164 * will be processed in a timely fashion.
166 void rcu_async_hurry(void)
168 if (IS_ENABLED(CONFIG_RCU_LAZY
))
169 atomic_inc(&rcu_async_hurry_nesting
);
171 EXPORT_SYMBOL_GPL(rcu_async_hurry
);
174 * rcu_async_relax - Make future async RCU callbacks lazy.
176 * After a call to this function, future calls to call_rcu()
177 * will be processed in a lazy fashion.
179 void rcu_async_relax(void)
181 if (IS_ENABLED(CONFIG_RCU_LAZY
))
182 atomic_dec(&rcu_async_hurry_nesting
);
184 EXPORT_SYMBOL_GPL(rcu_async_relax
);
186 static atomic_t rcu_expedited_nesting
= ATOMIC_INIT(1);
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.
194 bool rcu_gp_is_expedited(void)
196 return rcu_expedited
|| atomic_read(&rcu_expedited_nesting
);
198 EXPORT_SYMBOL_GPL(rcu_gp_is_expedited
);
201 * rcu_expedite_gp - Expedite future RCU grace periods
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.
207 void rcu_expedite_gp(void)
209 atomic_inc(&rcu_expedited_nesting
);
211 EXPORT_SYMBOL_GPL(rcu_expedite_gp
);
214 * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation
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.
222 void rcu_unexpedite_gp(void)
224 atomic_dec(&rcu_expedited_nesting
);
226 EXPORT_SYMBOL_GPL(rcu_unexpedite_gp
);
228 static bool rcu_boot_ended __read_mostly
;
231 * Inform RCU of the end of the in-kernel boot sequence.
233 void rcu_end_inkernel_boot(void)
237 if (rcu_normal_after_boot
)
238 WRITE_ONCE(rcu_normal
, 1);
239 rcu_boot_ended
= true;
243 * Let rcutorture know when it is OK to turn it up to eleven.
245 bool rcu_inkernel_boot_has_ended(void)
247 return rcu_boot_ended
;
249 EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended
);
251 #endif /* #ifndef CONFIG_TINY_RCU */
254 * Test each non-SRCU synchronous grace-period wait API. This is
255 * useful just after a change in mode for these primitives, and
258 void rcu_test_sync_prims(void)
260 if (!IS_ENABLED(CONFIG_PROVE_RCU
))
262 pr_info("Running RCU synchronous self tests\n");
264 synchronize_rcu_expedited();
267 #if !defined(CONFIG_TINY_RCU)
270 * Switch to run-time mode once RCU has fully initialized.
272 static int __init
rcu_set_runtime_mode(void)
274 rcu_test_sync_prims();
275 rcu_scheduler_active
= RCU_SCHEDULER_RUNNING
;
276 kfree_rcu_scheduler_running();
277 rcu_test_sync_prims();
280 core_initcall(rcu_set_runtime_mode
);
282 #endif /* #if !defined(CONFIG_TINY_RCU) */
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 */
292 EXPORT_SYMBOL_GPL(rcu_lock_map
);
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. */
301 EXPORT_SYMBOL_GPL(rcu_bh_lock_map
);
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
,
310 EXPORT_SYMBOL_GPL(rcu_sched_lock_map
);
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
);
318 noinstr
int notrace
debug_lockdep_rcu_enabled(void)
320 return rcu_scheduler_active
!= RCU_SCHEDULER_INACTIVE
&& READ_ONCE(debug_locks
) &&
321 current
->lockdep_recursion
== 0;
323 EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled
);
326 * rcu_read_lock_held() - might we be in RCU read-side critical section?
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.
334 * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
335 * and while lockdep is disabled.
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.
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.
345 int rcu_read_lock_held(void)
349 if (rcu_read_lock_held_common(&ret
))
351 return lock_is_held(&rcu_lock_map
);
353 EXPORT_SYMBOL_GPL(rcu_read_lock_held
);
356 * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
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
365 * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
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.
370 int rcu_read_lock_bh_held(void)
374 if (rcu_read_lock_held_common(&ret
))
376 return in_softirq() || irqs_disabled();
378 EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held
);
380 int rcu_read_lock_any_held(void)
384 if (rcu_read_lock_held_common(&ret
))
386 if (lock_is_held(&rcu_lock_map
) ||
387 lock_is_held(&rcu_bh_lock_map
) ||
388 lock_is_held(&rcu_sched_lock_map
))
390 return !preemptible();
392 EXPORT_SYMBOL_GPL(rcu_read_lock_any_held
);
394 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
397 * wakeme_after_rcu() - Callback function to awaken a task after grace period
398 * @head: Pointer to rcu_head member within rcu_synchronize structure
400 * Awaken the corresponding task now that a grace period has elapsed.
402 void wakeme_after_rcu(struct rcu_head
*head
)
404 struct rcu_synchronize
*rcu
;
406 rcu
= container_of(head
, struct rcu_synchronize
, head
);
407 complete(&rcu
->completion
);
409 EXPORT_SYMBOL_GPL(wakeme_after_rcu
);
411 void __wait_rcu_gp(bool checktiny
, unsigned int state
, int n
, call_rcu_func_t
*crcu_array
,
412 struct rcu_synchronize
*rs_array
)
417 /* Initialize and register callbacks for each crcu_array element. */
418 for (i
= 0; i
< n
; i
++) {
420 (crcu_array
[i
] == call_rcu
)) {
424 for (j
= 0; j
< i
; j
++)
425 if (crcu_array
[j
] == crcu_array
[i
])
428 init_rcu_head_on_stack(&rs_array
[i
].head
);
429 init_completion(&rs_array
[i
].completion
);
430 (crcu_array
[i
])(&rs_array
[i
].head
, wakeme_after_rcu
);
434 /* Wait for all callbacks to be invoked. */
435 for (i
= 0; i
< n
; i
++) {
437 (crcu_array
[i
] == call_rcu
))
439 for (j
= 0; j
< i
; j
++)
440 if (crcu_array
[j
] == crcu_array
[i
])
443 wait_for_completion_state(&rs_array
[i
].completion
, state
);
444 destroy_rcu_head_on_stack(&rs_array
[i
].head
);
448 EXPORT_SYMBOL_GPL(__wait_rcu_gp
);
450 void finish_rcuwait(struct rcuwait
*w
)
452 rcu_assign_pointer(w
->task
, NULL
);
453 __set_current_state(TASK_RUNNING
);
455 EXPORT_SYMBOL_GPL(finish_rcuwait
);
457 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
458 void init_rcu_head(struct rcu_head
*head
)
460 debug_object_init(head
, &rcuhead_debug_descr
);
462 EXPORT_SYMBOL_GPL(init_rcu_head
);
464 void destroy_rcu_head(struct rcu_head
*head
)
466 debug_object_free(head
, &rcuhead_debug_descr
);
468 EXPORT_SYMBOL_GPL(destroy_rcu_head
);
470 static bool rcuhead_is_static_object(void *addr
)
476 * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects
477 * @head: pointer to rcu_head structure to be initialized
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.
485 void init_rcu_head_on_stack(struct rcu_head
*head
)
487 debug_object_init_on_stack(head
, &rcuhead_debug_descr
);
489 EXPORT_SYMBOL_GPL(init_rcu_head_on_stack
);
492 * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects
493 * @head: pointer to rcu_head structure to be initialized
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.
502 void destroy_rcu_head_on_stack(struct rcu_head
*head
)
504 debug_object_free(head
, &rcuhead_debug_descr
);
506 EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack
);
508 const struct debug_obj_descr rcuhead_debug_descr
= {
510 .is_static_object
= rcuhead_is_static_object
,
512 EXPORT_SYMBOL_GPL(rcuhead_debug_descr
);
513 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
515 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE)
516 void do_trace_rcu_torture_read(const char *rcutorturename
, struct rcu_head
*rhp
,
518 unsigned long c_old
, unsigned long c
)
520 trace_rcu_torture_read(rcutorturename
, rhp
, secs
, c_old
, c
);
522 EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read
);
524 #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
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
)
534 ret
= sched_setaffinity(pid
, in_mask
);
535 WARN_ONCE(ret
, "%s: sched_setaffinity(%d) returned %d\n", __func__
, pid
, ret
);
538 EXPORT_SYMBOL_GPL(torture_sched_setaffinity
);
541 int rcu_cpu_stall_notifiers __read_mostly
; // !0 = provide stall notifiers (rarely useful)
542 EXPORT_SYMBOL_GPL(rcu_cpu_stall_notifiers
);
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 */
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);
570 * get_completed_synchronize_rcu - Return a pre-completed polled state cookie
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
576 unsigned long get_completed_synchronize_rcu(void)
578 return RCU_GET_STATE_COMPLETED
;
580 EXPORT_SYMBOL_GPL(get_completed_synchronize_rcu
);
582 #ifdef CONFIG_PROVE_RCU
585 * Early boot self test parameters.
587 static bool rcu_self_test
;
588 module_param(rcu_self_test
, bool, 0444);
590 static int rcu_self_test_counter
;
592 static void test_callback(struct rcu_head
*r
)
594 rcu_self_test_counter
++;
595 pr_info("RCU test callback executed %d\n", rcu_self_test_counter
);
598 DEFINE_STATIC_SRCU(early_srcu
);
599 static unsigned long early_srcu_cookie
;
601 struct early_boot_kfree_rcu
{
605 static void early_boot_test_call_rcu(void)
607 static struct rcu_head head
;
609 static struct rcu_head shead
;
610 struct early_boot_kfree_rcu
*rhp
;
612 idx
= srcu_down_read(&early_srcu
);
613 srcu_up_read(&early_srcu
, idx
);
614 call_rcu(&head
, test_callback
);
615 early_srcu_cookie
= start_poll_synchronize_srcu(&early_srcu
);
616 call_srcu(&early_srcu
, &shead
, test_callback
);
617 rhp
= kmalloc(sizeof(*rhp
), GFP_KERNEL
);
618 if (!WARN_ON_ONCE(!rhp
))
622 void rcu_early_boot_tests(void)
624 pr_info("Running RCU self tests\n");
627 early_boot_test_call_rcu();
628 rcu_test_sync_prims();
631 static int rcu_verify_early_boot_tests(void)
634 int early_boot_test_counter
= 0;
637 early_boot_test_counter
++;
639 early_boot_test_counter
++;
640 srcu_barrier(&early_srcu
);
641 WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu
, early_srcu_cookie
));
642 cleanup_srcu_struct(&early_srcu
);
644 if (rcu_self_test_counter
!= early_boot_test_counter
) {
651 late_initcall(rcu_verify_early_boot_tests
);
653 void rcu_early_boot_tests(void) {}
654 #endif /* CONFIG_PROVE_RCU */
658 #ifndef CONFIG_TINY_RCU
661 * Print any significant non-default boot-time settings.
663 void __init
rcupdate_announce_bootup_oddness(void)
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();
678 #endif /* #ifndef CONFIG_TINY_RCU */