rcu.h

  1/* SPDX-License-Identifier: GPL-2.0+ */
  2/*
  3 * Read-Copy Update definitions shared among RCU implementations.
  4 *
  5 * Copyright IBM Corporation, 2011
  6 *
  7 * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  8 */
  9
 10#ifndef __LINUX_RCU_H
 11#define __LINUX_RCU_H
 12
 13#include <linux/slab.h>
 14#include <trace/events/rcu.h>
 15
 16/*
 17 * Grace-period counter management.
 18 *
 19 * The two least significant bits contain the control flags.
 20 * The most significant bits contain the grace-period sequence counter.
 21 *
 22 * When both control flags are zero, no grace period is in progress.
 23 * When either bit is non-zero, a grace period has started and is in
 24 * progress. When the grace period completes, the control flags are reset
 25 * to 0 and the grace-period sequence counter is incremented.
 26 *
 27 * However some specific RCU usages make use of custom values.
 28 *
 29 * SRCU special control values:
 30 *
 31 *	SRCU_SNP_INIT_SEQ	:	Invalid/init value set when SRCU node
 32 *					is initialized.
 33 *
 34 *	SRCU_STATE_IDLE		:	No SRCU gp is in progress
 35 *
 36 *	SRCU_STATE_SCAN1	:	State set by rcu_seq_start(). Indicates
 37 *					we are scanning the readers on the slot
 38 *					defined as inactive (there might well
 39 *					be pending readers that will use that
 40 *					index, but their number is bounded).
 41 *
 42 *	SRCU_STATE_SCAN2	:	State set manually via rcu_seq_set_state()
 43 *					Indicates we are flipping the readers
 44 *					index and then scanning the readers on the
 45 *					slot newly designated as inactive (again,
 46 *					the number of pending readers that will use
 47 *					this inactive index is bounded).
 48 *
 49 * RCU polled GP special control value:
 50 *
 51 *	RCU_GET_STATE_COMPLETED :	State value indicating an already-completed
 52 *					polled GP has completed.  This value covers
 53 *					both the state and the counter of the
 54 *					grace-period sequence number.
 55 */
 56
 57/* Low-order bit definition for polled grace-period APIs. */
 58#define RCU_GET_STATE_COMPLETED	0x1
 59
 60/* A complete grace period count */
 61#define RCU_SEQ_GP (RCU_SEQ_STATE_MASK + 1)
 62
 63extern int sysctl_sched_rt_runtime;
 64
 65/*
 66 * Return the counter portion of a sequence number previously returned
 67 * by rcu_seq_snap() or rcu_seq_current().
 68 */
 69static inline unsigned long rcu_seq_ctr(unsigned long s)
 70{
 71	return s >> RCU_SEQ_CTR_SHIFT;
 72}
 73
 74/*
 75 * Return the state portion of a sequence number previously returned
 76 * by rcu_seq_snap() or rcu_seq_current().
 77 */
 78static inline int rcu_seq_state(unsigned long s)
 79{
 80	return s & RCU_SEQ_STATE_MASK;
 81}
 82
 83/*
 84 * Set the state portion of the pointed-to sequence number.
 85 * The caller is responsible for preventing conflicting updates.
 86 */
 87static inline void rcu_seq_set_state(unsigned long *sp, int newstate)
 88{
 89	WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK);
 90	WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate);
 91}
 92
 93/* Adjust sequence number for start of update-side operation. */
 94static inline void rcu_seq_start(unsigned long *sp)
 95{
 96	WRITE_ONCE(*sp, *sp + 1);
 97	smp_mb(); /* Ensure update-side operation after counter increment. */
 98	WARN_ON_ONCE(rcu_seq_state(*sp) != 1);
 99}
100
101/* Compute the end-of-grace-period value for the specified sequence number. */
102static inline unsigned long rcu_seq_endval(unsigned long *sp)
103{
104	return (*sp | RCU_SEQ_STATE_MASK) + 1;
105}
106
107/* Adjust sequence number for end of update-side operation. */
108static inline void rcu_seq_end(unsigned long *sp)
109{
110	smp_mb(); /* Ensure update-side operation before counter increment. */
111	WARN_ON_ONCE(!rcu_seq_state(*sp));
112	WRITE_ONCE(*sp, rcu_seq_endval(sp));
113}
114
115/*
116 * rcu_seq_snap - Take a snapshot of the update side's sequence number.
117 *
118 * This function returns the earliest value of the grace-period sequence number
119 * that will indicate that a full grace period has elapsed since the current
120 * time.  Once the grace-period sequence number has reached this value, it will
121 * be safe to invoke all callbacks that have been registered prior to the
122 * current time. This value is the current grace-period number plus two to the
123 * power of the number of low-order bits reserved for state, then rounded up to
124 * the next value in which the state bits are all zero.
125 */
126static inline unsigned long rcu_seq_snap(unsigned long *sp)
127{
128	unsigned long s;
129
130	s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK;
131	smp_mb(); /* Above access must not bleed into critical section. */
132	return s;
133}
134
135/* Return the current value the update side's sequence number, no ordering. */
136static inline unsigned long rcu_seq_current(unsigned long *sp)
137{
138	return READ_ONCE(*sp);
139}
140
141/*
142 * Given a snapshot from rcu_seq_snap(), determine whether or not the
143 * corresponding update-side operation has started.
144 */
145static inline bool rcu_seq_started(unsigned long *sp, unsigned long s)
146{
147	return ULONG_CMP_LT((s - 1) & ~RCU_SEQ_STATE_MASK, READ_ONCE(*sp));
148}
149
150/*
151 * Given a snapshot from rcu_seq_snap(), determine whether or not a
152 * full update-side operation has occurred.
153 */
154static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
155{
156	return ULONG_CMP_GE(READ_ONCE(*sp), s);
157}
158
159/*
160 * Given a snapshot from rcu_seq_snap(), determine whether or not a
161 * full update-side operation has occurred, but do not allow the
162 * (ULONG_MAX / 2) safety-factor/guard-band.
163 *
164 * The token returned by get_state_synchronize_rcu_full() is based on
165 * rcu_state.gp_seq but it is tested in poll_state_synchronize_rcu_full()
166 * against the root rnp->gp_seq. Since rcu_seq_start() is first called
167 * on rcu_state.gp_seq and only later reflected on the root rnp->gp_seq,
168 * it is possible that rcu_seq_snap(rcu_state.gp_seq) returns 2 full grace
169 * periods ahead of the root rnp->gp_seq. To prevent false-positives with the
170 * full polling API that a wrap around instantly completed the GP, when nothing
171 * like that happened, adjust for the 2 GPs in the ULONG_CMP_LT().
172 */
173static inline bool rcu_seq_done_exact(unsigned long *sp, unsigned long s)
174{
175	unsigned long cur_s = READ_ONCE(*sp);
176
177	return ULONG_CMP_GE(cur_s, s) || ULONG_CMP_LT(cur_s, s - (2 * RCU_SEQ_GP));
178}
179
180/*
181 * Has a grace period completed since the time the old gp_seq was collected?
182 */
183static inline bool rcu_seq_completed_gp(unsigned long old, unsigned long new)
184{
185	return ULONG_CMP_LT(old, new & ~RCU_SEQ_STATE_MASK);
186}
187
188/*
189 * Has a grace period started since the time the old gp_seq was collected?
190 */
191static inline bool rcu_seq_new_gp(unsigned long old, unsigned long new)
192{
193	return ULONG_CMP_LT((old + RCU_SEQ_STATE_MASK) & ~RCU_SEQ_STATE_MASK,
194			    new);
195}
196
197/*
198 * Roughly how many full grace periods have elapsed between the collection
199 * of the two specified grace periods?
200 */
201static inline unsigned long rcu_seq_diff(unsigned long new, unsigned long old)
202{
203	unsigned long rnd_diff;
204
205	if (old == new)
206		return 0;
207	/*
208	 * Compute the number of grace periods (still shifted up), plus
209	 * one if either of new and old is not an exact grace period.
210	 */
211	rnd_diff = (new & ~RCU_SEQ_STATE_MASK) -
212		   ((old + RCU_SEQ_STATE_MASK) & ~RCU_SEQ_STATE_MASK) +
213		   ((new & RCU_SEQ_STATE_MASK) || (old & RCU_SEQ_STATE_MASK));
214	if (ULONG_CMP_GE(RCU_SEQ_STATE_MASK, rnd_diff))
215		return 1; /* Definitely no grace period has elapsed. */
216	return ((rnd_diff - RCU_SEQ_STATE_MASK - 1) >> RCU_SEQ_CTR_SHIFT) + 2;
217}
218
219/*
220 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
221 * by call_rcu() and rcu callback execution, and are therefore not part
222 * of the RCU API. These are in rcupdate.h because they are used by all
223 * RCU implementations.
224 */
225
226#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
227# define STATE_RCU_HEAD_READY	0
228# define STATE_RCU_HEAD_QUEUED	1
229
230extern const struct debug_obj_descr rcuhead_debug_descr;
231
232static inline int debug_rcu_head_queue(struct rcu_head *head)
233{
234	int r1;
235
236	r1 = debug_object_activate(head, &rcuhead_debug_descr);
237	debug_object_active_state(head, &rcuhead_debug_descr,
238				  STATE_RCU_HEAD_READY,
239				  STATE_RCU_HEAD_QUEUED);
240	return r1;
241}
242
243static inline void debug_rcu_head_unqueue(struct rcu_head *head)
244{
245	debug_object_active_state(head, &rcuhead_debug_descr,
246				  STATE_RCU_HEAD_QUEUED,
247				  STATE_RCU_HEAD_READY);
248	debug_object_deactivate(head, &rcuhead_debug_descr);
249}
250#else	/* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
251static inline int debug_rcu_head_queue(struct rcu_head *head)
252{
253	return 0;
254}
255
256static inline void debug_rcu_head_unqueue(struct rcu_head *head)
257{
258}
259#endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
260
261static inline void debug_rcu_head_callback(struct rcu_head *rhp)
262{
263	if (unlikely(!rhp->func))
264		kmem_dump_obj(rhp);
265}
266
267static inline bool rcu_barrier_cb_is_done(struct rcu_head *rhp)
268{
269	return rhp->next == rhp;
270}
271
272extern int rcu_cpu_stall_suppress_at_boot;
273
274static inline bool rcu_stall_is_suppressed_at_boot(void)
275{
276	return rcu_cpu_stall_suppress_at_boot && !rcu_inkernel_boot_has_ended();
277}
278
279extern int rcu_cpu_stall_notifiers;
280
281#ifdef CONFIG_RCU_STALL_COMMON
282
283extern int rcu_cpu_stall_ftrace_dump;
284extern int rcu_cpu_stall_suppress;
285extern int rcu_cpu_stall_timeout;
286extern int rcu_exp_cpu_stall_timeout;
287extern int rcu_cpu_stall_cputime;
288extern bool rcu_exp_stall_task_details __read_mostly;
289int rcu_jiffies_till_stall_check(void);
290int rcu_exp_jiffies_till_stall_check(void);
291
292static inline bool rcu_stall_is_suppressed(void)
293{
294	return rcu_stall_is_suppressed_at_boot() || rcu_cpu_stall_suppress;
295}
296
297#define rcu_ftrace_dump_stall_suppress() \
298do { \
299	if (!rcu_cpu_stall_suppress) \
300		rcu_cpu_stall_suppress = 3; \
301} while (0)
302
303#define rcu_ftrace_dump_stall_unsuppress() \
304do { \
305	if (rcu_cpu_stall_suppress == 3) \
306		rcu_cpu_stall_suppress = 0; \
307} while (0)
308
309#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
310
311static inline bool rcu_stall_is_suppressed(void)
312{
313	return rcu_stall_is_suppressed_at_boot();
314}
315#define rcu_ftrace_dump_stall_suppress()
316#define rcu_ftrace_dump_stall_unsuppress()
317#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
318
319/*
320 * Strings used in tracepoints need to be exported via the
321 * tracing system such that tools like perf and trace-cmd can
322 * translate the string address pointers to actual text.
323 */
324#define TPS(x)  tracepoint_string(x)
325
326/*
327 * Dump the ftrace buffer, but only one time per callsite per boot.
328 */
329#define rcu_ftrace_dump(oops_dump_mode) \
330do { \
331	static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
332	\
333	if (!atomic_read(&___rfd_beenhere) && \
334	    !atomic_xchg(&___rfd_beenhere, 1)) { \
335		tracing_off(); \
336		rcu_ftrace_dump_stall_suppress(); \
337		ftrace_dump(oops_dump_mode); \
338		rcu_ftrace_dump_stall_unsuppress(); \
339	} \
340} while (0)
341
342void rcu_early_boot_tests(void);
343void rcu_test_sync_prims(void);
344
345/*
346 * This function really isn't for public consumption, but RCU is special in
347 * that context switches can allow the state machine to make progress.
348 */
349extern void resched_cpu(int cpu);
350
351#if !defined(CONFIG_TINY_RCU)
352
353#include <linux/rcu_node_tree.h>
354
355extern int rcu_num_lvls;
356extern int num_rcu_lvl[];
357extern int rcu_num_nodes;
358static bool rcu_fanout_exact;
359static int rcu_fanout_leaf;
360
361/*
362 * Compute the per-level fanout, either using the exact fanout specified
363 * or balancing the tree, depending on the rcu_fanout_exact boot parameter.
364 */
365static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
366{
367	int i;
368
369	for (i = 0; i < RCU_NUM_LVLS; i++)
370		levelspread[i] = INT_MIN;
371	if (rcu_fanout_exact) {
372		levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
373		for (i = rcu_num_lvls - 2; i >= 0; i--)
374			levelspread[i] = RCU_FANOUT;
375	} else {
376		int ccur;
377		int cprv;
378
379		cprv = nr_cpu_ids;
380		for (i = rcu_num_lvls - 1; i >= 0; i--) {
381			ccur = levelcnt[i];
382			levelspread[i] = (cprv + ccur - 1) / ccur;
383			cprv = ccur;
384		}
385	}
386}
387
388extern void rcu_init_geometry(void);
389
390/* Returns a pointer to the first leaf rcu_node structure. */
391#define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1])
392
393/* Is this rcu_node a leaf? */
394#define rcu_is_leaf_node(rnp) ((rnp)->level == rcu_num_lvls - 1)
395
396/* Is this rcu_node the last leaf? */
397#define rcu_is_last_leaf_node(rnp) ((rnp) == &rcu_state.node[rcu_num_nodes - 1])
398
399/*
400 * Do a full breadth-first scan of the {s,}rcu_node structures for the
401 * specified state structure (for SRCU) or the only rcu_state structure
402 * (for RCU).
403 */
404#define _rcu_for_each_node_breadth_first(sp, rnp) \
405	for ((rnp) = &(sp)->node[0]; \
406	     (rnp) < &(sp)->node[rcu_num_nodes]; (rnp)++)
407#define rcu_for_each_node_breadth_first(rnp) \
408	_rcu_for_each_node_breadth_first(&rcu_state, rnp)
409#define srcu_for_each_node_breadth_first(ssp, rnp) \
410	_rcu_for_each_node_breadth_first(ssp->srcu_sup, rnp)
411
412/*
413 * Scan the leaves of the rcu_node hierarchy for the rcu_state structure.
414 * Note that if there is a singleton rcu_node tree with but one rcu_node
415 * structure, this loop -will- visit the rcu_node structure.  It is still
416 * a leaf node, even if it is also the root node.
417 */
418#define rcu_for_each_leaf_node(rnp) \
419	for ((rnp) = rcu_first_leaf_node(); \
420	     (rnp) < &rcu_state.node[rcu_num_nodes]; (rnp)++)
421
422/*
423 * Iterate over all possible CPUs in a leaf RCU node.
424 */
425#define for_each_leaf_node_possible_cpu(rnp, cpu) \
426	for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \
427	     (cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \
428	     (cpu) <= rnp->grphi; \
429	     (cpu) = cpumask_next((cpu), cpu_possible_mask))
430
431/*
432 * Iterate over all CPUs in a leaf RCU node's specified mask.
433 */
434#define rcu_find_next_bit(rnp, cpu, mask) \
435	((rnp)->grplo + find_next_bit(&(mask), BITS_PER_LONG, (cpu)))
436#define for_each_leaf_node_cpu_mask(rnp, cpu, mask) \
437	for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \
438	     (cpu) = rcu_find_next_bit((rnp), 0, (mask)); \
439	     (cpu) <= rnp->grphi; \
440	     (cpu) = rcu_find_next_bit((rnp), (cpu) + 1 - (rnp->grplo), (mask)))
441
442#endif /* !defined(CONFIG_TINY_RCU) */
443
444#if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC)
445
446/*
447 * Wrappers for the rcu_node::lock acquire and release.
448 *
449 * Because the rcu_nodes form a tree, the tree traversal locking will observe
450 * different lock values, this in turn means that an UNLOCK of one level
451 * followed by a LOCK of another level does not imply a full memory barrier;
452 * and most importantly transitivity is lost.
453 *
454 * In order to restore full ordering between tree levels, augment the regular
455 * lock acquire functions with smp_mb__after_unlock_lock().
456 *
457 * As ->lock of struct rcu_node is a __private field, therefore one should use
458 * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
459 */
460#define raw_spin_lock_rcu_node(p)					\
461do {									\
462	raw_spin_lock(&ACCESS_PRIVATE(p, lock));			\
463	smp_mb__after_unlock_lock();					\
464} while (0)
465
466#define raw_spin_unlock_rcu_node(p)					\
467do {									\
468	lockdep_assert_irqs_disabled();					\
469	raw_spin_unlock(&ACCESS_PRIVATE(p, lock));			\
470} while (0)
471
472#define raw_spin_lock_irq_rcu_node(p)					\
473do {									\
474	raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock));			\
475	smp_mb__after_unlock_lock();					\
476} while (0)
477
478#define raw_spin_unlock_irq_rcu_node(p)					\
479do {									\
480	lockdep_assert_irqs_disabled();					\
481	raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock));			\
482} while (0)
483
484#define raw_spin_lock_irqsave_rcu_node(p, flags)			\
485do {									\
486	raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags);	\
487	smp_mb__after_unlock_lock();					\
488} while (0)
489
490#define raw_spin_unlock_irqrestore_rcu_node(p, flags)			\
491do {									\
492	lockdep_assert_irqs_disabled();					\
493	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags);	\
494} while (0)
495
496#define raw_spin_trylock_rcu_node(p)					\
497({									\
498	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock));	\
499									\
500	if (___locked)							\
501		smp_mb__after_unlock_lock();				\
502	___locked;							\
503})
504
505#define raw_lockdep_assert_held_rcu_node(p)				\
506	lockdep_assert_held(&ACCESS_PRIVATE(p, lock))
507
508#endif // #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC)
509
510#ifdef CONFIG_TINY_RCU
511/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
512static inline bool rcu_gp_is_normal(void) { return true; }
513static inline bool rcu_gp_is_expedited(void) { return false; }
514static inline bool rcu_async_should_hurry(void) { return false; }
515static inline void rcu_expedite_gp(void) { }
516static inline void rcu_unexpedite_gp(void) { }
517static inline void rcu_async_hurry(void) { }
518static inline void rcu_async_relax(void) { }
519static inline bool rcu_cpu_online(int cpu) { return true; }
520#else /* #ifdef CONFIG_TINY_RCU */
521bool rcu_gp_is_normal(void);     /* Internal RCU use. */
522bool rcu_gp_is_expedited(void);  /* Internal RCU use. */
523bool rcu_async_should_hurry(void);  /* Internal RCU use. */
524void rcu_expedite_gp(void);
525void rcu_unexpedite_gp(void);
526void rcu_async_hurry(void);
527void rcu_async_relax(void);
528void rcupdate_announce_bootup_oddness(void);
529bool rcu_cpu_online(int cpu);
530#ifdef CONFIG_TASKS_RCU_GENERIC
531void show_rcu_tasks_gp_kthreads(void);
532#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
533static inline void show_rcu_tasks_gp_kthreads(void) {}
534#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
535#endif /* #else #ifdef CONFIG_TINY_RCU */
536
537#ifdef CONFIG_TASKS_RCU
538struct task_struct *get_rcu_tasks_gp_kthread(void);
539void rcu_tasks_get_gp_data(int *flags, unsigned long *gp_seq);
540#endif // # ifdef CONFIG_TASKS_RCU
541
542#ifdef CONFIG_TASKS_RUDE_RCU
543struct task_struct *get_rcu_tasks_rude_gp_kthread(void);
544void rcu_tasks_rude_get_gp_data(int *flags, unsigned long *gp_seq);
545#endif // # ifdef CONFIG_TASKS_RUDE_RCU
546
547#ifdef CONFIG_TASKS_TRACE_RCU
548void rcu_tasks_trace_get_gp_data(int *flags, unsigned long *gp_seq);
549#endif
550
551#ifdef CONFIG_TASKS_RCU_GENERIC
552void tasks_cblist_init_generic(void);
553#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
554static inline void tasks_cblist_init_generic(void) { }
555#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
556
557#define RCU_SCHEDULER_INACTIVE	0
558#define RCU_SCHEDULER_INIT	1
559#define RCU_SCHEDULER_RUNNING	2
560
561enum rcutorture_type {
562	RCU_FLAVOR,
563	RCU_TASKS_FLAVOR,
564	RCU_TASKS_RUDE_FLAVOR,
565	RCU_TASKS_TRACING_FLAVOR,
566	RCU_TRIVIAL_FLAVOR,
567	SRCU_FLAVOR,
568	INVALID_RCU_FLAVOR
569};
570
571#if defined(CONFIG_RCU_LAZY)
572unsigned long rcu_get_jiffies_lazy_flush(void);
573void rcu_set_jiffies_lazy_flush(unsigned long j);
574#else
575static inline unsigned long rcu_get_jiffies_lazy_flush(void) { return 0; }
576static inline void rcu_set_jiffies_lazy_flush(unsigned long j) { }
577#endif
578
579#if defined(CONFIG_TREE_RCU)
580void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq);
581void do_trace_rcu_torture_read(const char *rcutorturename,
582			       struct rcu_head *rhp,
583			       unsigned long secs,
584			       unsigned long c_old,
585			       unsigned long c);
586void rcu_gp_set_torture_wait(int duration);
587void rcu_set_gpwrap_lag(unsigned long lag);
588int rcu_get_gpwrap_count(int cpu);
589#else
590static inline void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq)
591{
592	*flags = 0;
593	*gp_seq = 0;
594}
595#ifdef CONFIG_RCU_TRACE
596void do_trace_rcu_torture_read(const char *rcutorturename,
597			       struct rcu_head *rhp,
598			       unsigned long secs,
599			       unsigned long c_old,
600			       unsigned long c);
601#else
602#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
603	do { } while (0)
604#endif
605static inline void rcu_gp_set_torture_wait(int duration) { }
606static inline void rcu_set_gpwrap_lag(unsigned long lag) { }
607static inline int rcu_get_gpwrap_count(int cpu) { return 0; }
608#endif
609unsigned long long rcutorture_gather_gp_seqs(void);
610void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp, size_t len);
611
612#ifdef CONFIG_TINY_SRCU
613
614static inline void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
615					   unsigned long *gp_seq)
616{
617	*flags = 0;
618	*gp_seq = sp->srcu_idx;
619}
620
621#elif defined(CONFIG_TREE_SRCU)
622
623void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
624			     unsigned long *gp_seq);
625
626#endif
627
628#ifdef CONFIG_TINY_RCU
629static inline bool rcu_watching_zero_in_eqs(int cpu, int *vp) { return false; }
630static inline unsigned long rcu_get_gp_seq(void) { return 0; }
631static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
632static inline void rcu_force_quiescent_state(void) { }
633static inline bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { return true; }
634static inline void show_rcu_gp_kthreads(void) { }
635static inline int rcu_get_gp_kthreads_prio(void) { return 0; }
636static inline void rcu_fwd_progress_check(unsigned long j) { }
637static inline void rcu_gp_slow_register(atomic_t *rgssp) { }
638static inline void rcu_gp_slow_unregister(atomic_t *rgssp) { }
639#else /* #ifdef CONFIG_TINY_RCU */
640bool rcu_watching_zero_in_eqs(int cpu, int *vp);
641unsigned long rcu_get_gp_seq(void);
642unsigned long rcu_exp_batches_completed(void);
643bool rcu_check_boost_fail(unsigned long gp_state, int *cpup);
644void show_rcu_gp_kthreads(void);
645int rcu_get_gp_kthreads_prio(void);
646void rcu_fwd_progress_check(unsigned long j);
647void rcu_force_quiescent_state(void);
648extern struct workqueue_struct *rcu_gp_wq;
649extern struct kthread_worker *rcu_exp_gp_kworker;
650void rcu_gp_slow_register(atomic_t *rgssp);
651void rcu_gp_slow_unregister(atomic_t *rgssp);
652#endif /* #else #ifdef CONFIG_TINY_RCU */
653
654#ifdef CONFIG_TINY_SRCU
655static inline unsigned long srcu_batches_completed(struct srcu_struct *sp) { return 0; }
656#else // #ifdef CONFIG_TINY_SRCU
657unsigned long srcu_batches_completed(struct srcu_struct *sp);
658#endif // #else // #ifdef CONFIG_TINY_SRCU
659
660#ifdef CONFIG_RCU_NOCB_CPU
661void rcu_bind_current_to_nocb(void);
662#else
663static inline void rcu_bind_current_to_nocb(void) { }
664#endif
665
666#if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RCU)
667void show_rcu_tasks_classic_gp_kthread(void);
668#else
669static inline void show_rcu_tasks_classic_gp_kthread(void) {}
670#endif
671#if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RUDE_RCU)
672void show_rcu_tasks_rude_gp_kthread(void);
673#else
674static inline void show_rcu_tasks_rude_gp_kthread(void) {}
675#endif
676#if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_TRACE_RCU)
677void show_rcu_tasks_trace_gp_kthread(void);
678#else
679static inline void show_rcu_tasks_trace_gp_kthread(void) {}
680#endif
681
682#ifdef CONFIG_TINY_RCU
683static inline bool rcu_cpu_beenfullyonline(int cpu) { return true; }
684#else
685bool rcu_cpu_beenfullyonline(int cpu);
686#endif
687
688#if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
689int rcu_stall_notifier_call_chain(unsigned long val, void *v);
690#else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
691static inline int rcu_stall_notifier_call_chain(unsigned long val, void *v) { return NOTIFY_DONE; }
692#endif // #else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
693
694#endif /* __LINUX_RCU_H */