[mirror_ubuntu-bionic-kernel.git] / kernel / rcu / rcu.h

/*
 * Read-Copy Update definitions shared among RCU implementations.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you can access it online at
 * http://www.gnu.org/licenses/gpl-2.0.html.
 *
 * Copyright IBM Corporation, 2011
 *
 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 */

#ifndef __LINUX_RCU_H
#define __LINUX_RCU_H

#include <trace/events/rcu.h>
#ifdef CONFIG_RCU_TRACE
#define RCU_TRACE(stmt) stmt
#else /* #ifdef CONFIG_RCU_TRACE */
#define RCU_TRACE(stmt)
#endif /* #else #ifdef CONFIG_RCU_TRACE */

/*
 * Process-level increment to ->dynticks_nesting field.  This allows for
 * architectures that use half-interrupts and half-exceptions from
 * process context.
 *
 * DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
 * that counts the number of process-based reasons why RCU cannot
 * consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
 * is the value used to increment or decrement this field.
 *
 * The rest of the bits could in principle be used to count interrupts,
 * but this would mean that a negative-one value in the interrupt
 * field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
 * We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
 * that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
 * The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
 * initial exit from idle.
 */
#define DYNTICK_TASK_NEST_WIDTH 7
#define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
#define DYNTICK_TASK_NEST_MASK  (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
#define DYNTICK_TASK_FLAG	   ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
#define DYNTICK_TASK_MASK	   ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
#define DYNTICK_TASK_EXIT_IDLE	   (DYNTICK_TASK_NEST_VALUE + \
				    DYNTICK_TASK_FLAG)


/*
 * Grace-period counter management.
 */

#define RCU_SEQ_CTR_SHIFT	2
#define RCU_SEQ_STATE_MASK	((1 << RCU_SEQ_CTR_SHIFT) - 1)

/*
 * Return the counter portion of a sequence number previously returned
 * by rcu_seq_snap() or rcu_seq_current().
 */
static inline unsigned long rcu_seq_ctr(unsigned long s)
{
	return s >> RCU_SEQ_CTR_SHIFT;
}

/*
 * Return the state portion of a sequence number previously returned
 * by rcu_seq_snap() or rcu_seq_current().
 */
static inline int rcu_seq_state(unsigned long s)
{
	return s & RCU_SEQ_STATE_MASK;
}

/*
 * Set the state portion of the pointed-to sequence number.
 * The caller is responsible for preventing conflicting updates.
 */
static inline void rcu_seq_set_state(unsigned long *sp, int newstate)
{
	WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK);
	WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate);
}

/* Adjust sequence number for start of update-side operation. */
static inline void rcu_seq_start(unsigned long *sp)
{
	WRITE_ONCE(*sp, *sp + 1);
	smp_mb(); /* Ensure update-side operation after counter increment. */
	WARN_ON_ONCE(rcu_seq_state(*sp) != 1);
}

/* Adjust sequence number for end of update-side operation. */
static inline void rcu_seq_end(unsigned long *sp)
{
	smp_mb(); /* Ensure update-side operation before counter increment. */
	WARN_ON_ONCE(!rcu_seq_state(*sp));
	WRITE_ONCE(*sp, (*sp | RCU_SEQ_STATE_MASK) + 1);
}

/* Take a snapshot of the update side's sequence number. */
static inline unsigned long rcu_seq_snap(unsigned long *sp)
{
	unsigned long s;

	s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK;
	smp_mb(); /* Above access must not bleed into critical section. */
	return s;
}

/* Return the current value the update side's sequence number, no ordering. */
static inline unsigned long rcu_seq_current(unsigned long *sp)
{
	return READ_ONCE(*sp);
}

/*
 * Given a snapshot from rcu_seq_snap(), determine whether or not a
 * full update-side operation has occurred.
 */
static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
{
	return ULONG_CMP_GE(READ_ONCE(*sp), s);
}

/*
 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
 * by call_rcu() and rcu callback execution, and are therefore not part of the
 * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
 */

#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
# define STATE_RCU_HEAD_READY	0
# define STATE_RCU_HEAD_QUEUED	1

extern struct debug_obj_descr rcuhead_debug_descr;

static inline int debug_rcu_head_queue(struct rcu_head *head)
{
	int r1;

	r1 = debug_object_activate(head, &rcuhead_debug_descr);
	debug_object_active_state(head, &rcuhead_debug_descr,
				  STATE_RCU_HEAD_READY,
				  STATE_RCU_HEAD_QUEUED);
	return r1;
}

static inline void debug_rcu_head_unqueue(struct rcu_head *head)
{
	debug_object_active_state(head, &rcuhead_debug_descr,
				  STATE_RCU_HEAD_QUEUED,
				  STATE_RCU_HEAD_READY);
	debug_object_deactivate(head, &rcuhead_debug_descr);
}
#else	/* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
static inline int debug_rcu_head_queue(struct rcu_head *head)
{
	return 0;
}

static inline void debug_rcu_head_unqueue(struct rcu_head *head)
{
}
#endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */

void kfree(const void *);

/*
 * Reclaim the specified callback, either by invoking it (non-lazy case)
 * or freeing it directly (lazy case).  Return true if lazy, false otherwise.
 */
static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
{
	unsigned long offset = (unsigned long)head->func;

	rcu_lock_acquire(&rcu_callback_map);
	if (__is_kfree_rcu_offset(offset)) {
		RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);)
		kfree((void *)head - offset);
		rcu_lock_release(&rcu_callback_map);
		return true;
	} else {
		RCU_TRACE(trace_rcu_invoke_callback(rn, head);)
		head->func(head);
		rcu_lock_release(&rcu_callback_map);
		return false;
	}
}

#ifdef CONFIG_RCU_STALL_COMMON

extern int rcu_cpu_stall_suppress;
int rcu_jiffies_till_stall_check(void);

#define rcu_ftrace_dump_stall_suppress() \
do { \
	if (!rcu_cpu_stall_suppress) \
		rcu_cpu_stall_suppress = 3; \
} while (0)

#define rcu_ftrace_dump_stall_unsuppress() \
do { \
	if (rcu_cpu_stall_suppress == 3) \
		rcu_cpu_stall_suppress = 0; \
} while (0)

#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
#define rcu_ftrace_dump_stall_suppress()
#define rcu_ftrace_dump_stall_unsuppress()
#endif /* #ifdef CONFIG_RCU_STALL_COMMON */

/*
 * Strings used in tracepoints need to be exported via the
 * tracing system such that tools like perf and trace-cmd can
 * translate the string address pointers to actual text.
 */
#define TPS(x)  tracepoint_string(x)

/*
 * Dump the ftrace buffer, but only one time per callsite per boot.
 */
#define rcu_ftrace_dump(oops_dump_mode) \
do { \
	static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
	\
	if (!atomic_read(&___rfd_beenhere) && \
	    !atomic_xchg(&___rfd_beenhere, 1)) { \
		tracing_off(); \
		rcu_ftrace_dump_stall_suppress(); \
		ftrace_dump(oops_dump_mode); \
		rcu_ftrace_dump_stall_unsuppress(); \
	} \
} while (0)

void rcu_early_boot_tests(void);
void rcu_test_sync_prims(void);

/*
 * This function really isn't for public consumption, but RCU is special in
 * that context switches can allow the state machine to make progress.
 */
extern void resched_cpu(int cpu);

#if defined(SRCU) || !defined(TINY_RCU)

#include <linux/rcu_node_tree.h>

extern int rcu_num_lvls;
extern int num_rcu_lvl[];
extern int rcu_num_nodes;
static bool rcu_fanout_exact;
static int rcu_fanout_leaf;

/*
 * Compute the per-level fanout, either using the exact fanout specified
 * or balancing the tree, depending on the rcu_fanout_exact boot parameter.
 */
static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
{
	int i;

	if (rcu_fanout_exact) {
		levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
		for (i = rcu_num_lvls - 2; i >= 0; i--)
			levelspread[i] = RCU_FANOUT;
	} else {
		int ccur;
		int cprv;

		cprv = nr_cpu_ids;
		for (i = rcu_num_lvls - 1; i >= 0; i--) {
			ccur = levelcnt[i];
			levelspread[i] = (cprv + ccur - 1) / ccur;
			cprv = ccur;
		}
	}
}

/*
 * Do a full breadth-first scan of the rcu_node structures for the
 * specified rcu_state structure.
 */
#define rcu_for_each_node_breadth_first(rsp, rnp) \
	for ((rnp) = &(rsp)->node[0]; \
	     (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)

/*
 * Do a breadth-first scan of the non-leaf rcu_node structures for the
 * specified rcu_state structure.  Note that if there is a singleton
 * rcu_node tree with but one rcu_node structure, this loop is a no-op.
 */
#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
	for ((rnp) = &(rsp)->node[0]; \
	     (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)

/*
 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
 * structure.  Note that if there is a singleton rcu_node tree with but
 * one rcu_node structure, this loop -will- visit the rcu_node structure.
 * It is still a leaf node, even if it is also the root node.
 */
#define rcu_for_each_leaf_node(rsp, rnp) \
	for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
	     (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)

/*
 * Iterate over all possible CPUs in a leaf RCU node.
 */
#define for_each_leaf_node_possible_cpu(rnp, cpu) \
	for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
	     cpu <= rnp->grphi; \
	     cpu = cpumask_next((cpu), cpu_possible_mask))

/*
 * Wrappers for the rcu_node::lock acquire and release.
 *
 * Because the rcu_nodes form a tree, the tree traversal locking will observe
 * different lock values, this in turn means that an UNLOCK of one level
 * followed by a LOCK of another level does not imply a full memory barrier;
 * and most importantly transitivity is lost.
 *
 * In order to restore full ordering between tree levels, augment the regular
 * lock acquire functions with smp_mb__after_unlock_lock().
 *
 * As ->lock of struct rcu_node is a __private field, therefore one should use
 * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
 */
#define raw_spin_lock_rcu_node(p)					\
do {									\
	raw_spin_lock(&ACCESS_PRIVATE(p, lock));			\
	smp_mb__after_unlock_lock();					\
} while (0)

#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irq_rcu_node(p)					\
do {									\
	raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock));			\
	smp_mb__after_unlock_lock();					\
} while (0)

#define raw_spin_unlock_irq_rcu_node(p)					\
	raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))

#define raw_spin_lock_irqsave_rcu_node(p, flags)			\
do {									\
	raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags);	\
	smp_mb__after_unlock_lock();					\
} while (0)

#define raw_spin_unlock_irqrestore_rcu_node(p, flags)			\
	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags)	\

#define raw_spin_trylock_rcu_node(p)					\
({									\
	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock));	\
									\
	if (___locked)							\
		smp_mb__after_unlock_lock();				\
	___locked;							\
})

#endif /* #if defined(SRCU) || !defined(TINY_RCU) */

#ifdef CONFIG_TINY_RCU
/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
static inline bool rcu_gp_is_normal(void) { return true; }
static inline bool rcu_gp_is_expedited(void) { return false; }
static inline void rcu_expedite_gp(void) { }
static inline void rcu_unexpedite_gp(void) { }
#else /* #ifdef CONFIG_TINY_RCU */
bool rcu_gp_is_normal(void);     /* Internal RCU use. */
bool rcu_gp_is_expedited(void);  /* Internal RCU use. */
void rcu_expedite_gp(void);
void rcu_unexpedite_gp(void);
void rcupdate_announce_bootup_oddness(void);
#endif /* #else #ifdef CONFIG_TINY_RCU */

#define RCU_SCHEDULER_INACTIVE	0
#define RCU_SCHEDULER_INIT	1
#define RCU_SCHEDULER_RUNNING	2

#ifdef CONFIG_TINY_RCU
static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
#else /* #ifdef CONFIG_TINY_RCU */
void rcu_request_urgent_qs_task(struct task_struct *t);
#endif /* #else #ifdef CONFIG_TINY_RCU */

enum rcutorture_type {
	RCU_FLAVOR,
	RCU_BH_FLAVOR,
	RCU_SCHED_FLAVOR,
	RCU_TASKS_FLAVOR,
	SRCU_FLAVOR,
	INVALID_RCU_FLAVOR
};

#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
			    unsigned long *gpnum, unsigned long *completed);
void rcutorture_record_test_transition(void);
void rcutorture_record_progress(unsigned long vernum);
void do_trace_rcu_torture_read(const char *rcutorturename,
			       struct rcu_head *rhp,
			       unsigned long secs,
			       unsigned long c_old,
			       unsigned long c);
#else
static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
					  int *flags,
					  unsigned long *gpnum,
					  unsigned long *completed)
{
	*flags = 0;
	*gpnum = 0;
	*completed = 0;
}
static inline void rcutorture_record_test_transition(void) { }
static inline void rcutorture_record_progress(unsigned long vernum) { }
#ifdef CONFIG_RCU_TRACE
void do_trace_rcu_torture_read(const char *rcutorturename,
			       struct rcu_head *rhp,
			       unsigned long secs,
			       unsigned long c_old,
			       unsigned long c);
#else
#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
	do { } while (0)
#endif
#endif

#ifdef CONFIG_TINY_SRCU

static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
					   struct srcu_struct *sp, int *flags,
					   unsigned long *gpnum,
					   unsigned long *completed)
{
	if (test_type != SRCU_FLAVOR)
		return;
	*flags = 0;
	*completed = sp->srcu_idx;
	*gpnum = *completed;
}

#elif defined(CONFIG_TREE_SRCU)

void srcutorture_get_gp_data(enum rcutorture_type test_type,
			     struct srcu_struct *sp, int *flags,
			     unsigned long *gpnum, unsigned long *completed);

#endif

#ifdef CONFIG_TINY_RCU
static inline unsigned long rcu_batches_started(void) { return 0; }
static inline unsigned long rcu_batches_started_bh(void) { return 0; }
static inline unsigned long rcu_batches_started_sched(void) { return 0; }
static inline unsigned long rcu_batches_completed(void) { return 0; }
static inline unsigned long rcu_batches_completed_bh(void) { return 0; }
static inline unsigned long rcu_batches_completed_sched(void) { return 0; }
static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; }
static inline unsigned long
srcu_batches_completed(struct srcu_struct *sp) { return 0; }
static inline void rcu_force_quiescent_state(void) { }
static inline void rcu_bh_force_quiescent_state(void) { }
static inline void rcu_sched_force_quiescent_state(void) { }
static inline void show_rcu_gp_kthreads(void) { }
#else /* #ifdef CONFIG_TINY_RCU */
extern unsigned long rcutorture_testseq;
extern unsigned long rcutorture_vernum;
unsigned long rcu_batches_started(void);
unsigned long rcu_batches_started_bh(void);
unsigned long rcu_batches_started_sched(void);
unsigned long rcu_batches_completed(void);
unsigned long rcu_batches_completed_bh(void);
unsigned long rcu_batches_completed_sched(void);
unsigned long rcu_exp_batches_completed(void);
unsigned long rcu_exp_batches_completed_sched(void);
unsigned long srcu_batches_completed(struct srcu_struct *sp);
void show_rcu_gp_kthreads(void);
void rcu_force_quiescent_state(void);
void rcu_bh_force_quiescent_state(void);
void rcu_sched_force_quiescent_state(void);
#endif /* #else #ifdef CONFIG_TINY_RCU */

#ifdef CONFIG_RCU_NOCB_CPU
bool rcu_is_nocb_cpu(int cpu);
#else
static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
#endif

#endif /* __LINUX_RCU_H */
Commit	Line	Data
29c00b4a PM	1	/*
	2	* Read-Copy Update definitions shared among RCU implementations.
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
87de1cfd PM	15	* along with this program; if not, you can access it online at
87de1cfd PM	16	* http://www.gnu.org/licenses/gpl-2.0.html.
29c00b4a PM	17	*
	18	* Copyright IBM Corporation, 2011
	19	*
	20	* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
	21	*/
	22
	23	#ifndef __LINUX_RCU_H
	24	#define __LINUX_RCU_H
	25
5cb5c6e1	26	#include <trace/events/rcu.h>
e99033c5 PM	27	#ifdef CONFIG_RCU_TRACE
	28	#define RCU_TRACE(stmt) stmt
	29	#else /* #ifdef CONFIG_RCU_TRACE */
	30	#define RCU_TRACE(stmt)
	31	#endif /* #else #ifdef CONFIG_RCU_TRACE */
	32
4145fa7f PM	33	/*
	34	* Process-level increment to ->dynticks_nesting field. This allows for
	35	* architectures that use half-interrupts and half-exceptions from
	36	* process context.
29e37d81 PM	37	*
	38	* DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
	39	* that counts the number of process-based reasons why RCU cannot
	40	* consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
	41	* is the value used to increment or decrement this field.
	42	*
	43	* The rest of the bits could in principle be used to count interrupts,
	44	* but this would mean that a negative-one value in the interrupt
	45	* field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
	46	* We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
	47	* that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
	48	* The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
	49	* initial exit from idle.
4145fa7f	50	*/
29e37d81 PM	51	#define DYNTICK_TASK_NEST_WIDTH 7
	52	#define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
	53	#define DYNTICK_TASK_NEST_MASK (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
	54	#define DYNTICK_TASK_FLAG ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
	55	#define DYNTICK_TASK_MASK ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
	56	#define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \
	57	DYNTICK_TASK_FLAG)
4145fa7f	58
2e8c28c2 PM	59
	60	/*
	61	* Grace-period counter management.
	62	*/
	63
f1ec57a4	64	#define RCU_SEQ_CTR_SHIFT 2
031aeee0 PM	65	#define RCU_SEQ_STATE_MASK ((1 << RCU_SEQ_CTR_SHIFT) - 1)
	66
	67	/*
	68	* Return the counter portion of a sequence number previously returned
	69	* by rcu_seq_snap() or rcu_seq_current().
	70	*/
	71	static inline unsigned long rcu_seq_ctr(unsigned long s)
	72	{
	73	return s >> RCU_SEQ_CTR_SHIFT;
	74	}
	75
	76	/*
	77	* Return the state portion of a sequence number previously returned
	78	* by rcu_seq_snap() or rcu_seq_current().
	79	*/
	80	static inline int rcu_seq_state(unsigned long s)
	81	{
	82	return s & RCU_SEQ_STATE_MASK;
	83	}
	84
80a7956f PM	85	/*
	86	* Set the state portion of the pointed-to sequence number.
	87	* The caller is responsible for preventing conflicting updates.
	88	*/
	89	static inline void rcu_seq_set_state(unsigned long *sp, int newstate)
	90	{
	91	WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK);
	92	WRITE_ONCE(sp, (sp & ~RCU_SEQ_STATE_MASK) + newstate);
	93	}
	94
2e8c28c2 PM	95	/* Adjust sequence number for start of update-side operation. */
	96	static inline void rcu_seq_start(unsigned long *sp)
	97	{
	98	WRITE_ONCE(sp, sp + 1);
	99	smp_mb(); /* Ensure update-side operation after counter increment. */
031aeee0	100	WARN_ON_ONCE(rcu_seq_state(*sp) != 1);
2e8c28c2 PM	101	}
	102
	103	/* Adjust sequence number for end of update-side operation. */
	104	static inline void rcu_seq_end(unsigned long *sp)
	105	{
	106	smp_mb(); /* Ensure update-side operation before counter increment. */
031aeee0 PM	107	WARN_ON_ONCE(!rcu_seq_state(*sp));
031aeee0 PM	108	WRITE_ONCE(sp, (sp \| RCU_SEQ_STATE_MASK) + 1);
2e8c28c2 PM	109	}
	110
	111	/* Take a snapshot of the update side's sequence number. */
	112	static inline unsigned long rcu_seq_snap(unsigned long *sp)
	113	{
	114	unsigned long s;
	115
031aeee0	116	s = (READ_ONCE(sp) + 2 RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK;
2e8c28c2 PM	117	smp_mb(); /* Above access must not bleed into critical section. */
	118	return s;
	119	}
	120
8660b7d8 PM	121	/* Return the current value the update side's sequence number, no ordering. */
	122	static inline unsigned long rcu_seq_current(unsigned long *sp)
	123	{
	124	return READ_ONCE(*sp);
	125	}
	126
2e8c28c2 PM	127	/*
	128	* Given a snapshot from rcu_seq_snap(), determine whether or not a
	129	* full update-side operation has occurred.
	130	*/
	131	static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
	132	{
	133	return ULONG_CMP_GE(READ_ONCE(*sp), s);
	134	}
	135
29c00b4a PM	136	/*
	137	* debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
	138	* by call_rcu() and rcu callback execution, and are therefore not part of the
	139	* RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
	140	*/
	141
	142	#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
	143	# define STATE_RCU_HEAD_READY 0
	144	# define STATE_RCU_HEAD_QUEUED 1
	145
	146	extern struct debug_obj_descr rcuhead_debug_descr;
	147
ae150184	148	static inline int debug_rcu_head_queue(struct rcu_head *head)
29c00b4a	149	{
ae150184 PM	150	int r1;
	151
	152	r1 = debug_object_activate(head, &rcuhead_debug_descr);
29c00b4a PM	153	debug_object_active_state(head, &rcuhead_debug_descr,
	154	STATE_RCU_HEAD_READY,
	155	STATE_RCU_HEAD_QUEUED);
ae150184	156	return r1;
29c00b4a PM	157	}
	158
	159	static inline void debug_rcu_head_unqueue(struct rcu_head *head)
	160	{
	161	debug_object_active_state(head, &rcuhead_debug_descr,
	162	STATE_RCU_HEAD_QUEUED,
	163	STATE_RCU_HEAD_READY);
	164	debug_object_deactivate(head, &rcuhead_debug_descr);
	165	}
	166	#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
ae150184	167	static inline int debug_rcu_head_queue(struct rcu_head *head)
29c00b4a	168	{
ae150184	169	return 0;
29c00b4a PM	170	}
	171
	172	static inline void debug_rcu_head_unqueue(struct rcu_head *head)
	173	{
	174	}
	175	#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
	176
bd73a7f5	177	void kfree(const void *);
29c00b4a	178
406e3e53 PM	179	/*
	180	* Reclaim the specified callback, either by invoking it (non-lazy case)
	181	* or freeing it directly (lazy case). Return true if lazy, false otherwise.
	182	*/
e66c33d5	183	static inline bool __rcu_reclaim(const char rn, struct rcu_head head)
29c00b4a PM	184	{
	185	unsigned long offset = (unsigned long)head->func;
	186
24ef659a	187	rcu_lock_acquire(&rcu_callback_map);
29c00b4a	188	if (__is_kfree_rcu_offset(offset)) {
dffd06a7	189	RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);)
29c00b4a	190	kfree((void *)head - offset);
24ef659a	191	rcu_lock_release(&rcu_callback_map);
406e3e53	192	return true;
29c00b4a	193	} else {
dffd06a7	194	RCU_TRACE(trace_rcu_invoke_callback(rn, head);)
29c00b4a	195	head->func(head);
24ef659a	196	rcu_lock_release(&rcu_callback_map);
406e3e53	197	return false;
29c00b4a PM	198	}
	199	}
	200
6bfc09e2 PM	201	#ifdef CONFIG_RCU_STALL_COMMON
	202
	203	extern int rcu_cpu_stall_suppress;
	204	int rcu_jiffies_till_stall_check(void);
	205
f22ce091 PM	206	#define rcu_ftrace_dump_stall_suppress() \
	207	do { \
	208	if (!rcu_cpu_stall_suppress) \
	209	rcu_cpu_stall_suppress = 3; \
	210	} while (0)
	211
	212	#define rcu_ftrace_dump_stall_unsuppress() \
	213	do { \
	214	if (rcu_cpu_stall_suppress == 3) \
	215	rcu_cpu_stall_suppress = 0; \
	216	} while (0)
	217
	218	#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
	219	#define rcu_ftrace_dump_stall_suppress()
	220	#define rcu_ftrace_dump_stall_unsuppress()
6bfc09e2 PM	221	#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
6bfc09e2 PM	222
0d752924 PM	223	/*
	224	* Strings used in tracepoints need to be exported via the
	225	* tracing system such that tools like perf and trace-cmd can
	226	* translate the string address pointers to actual text.
	227	*/
	228	#define TPS(x) tracepoint_string(x)
	229
b8989b76 PM	230	/*
	231	* Dump the ftrace buffer, but only one time per callsite per boot.
	232	*/
	233	#define rcu_ftrace_dump(oops_dump_mode) \
	234	do { \
	235	static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
	236	\
	237	if (!atomic_read(&___rfd_beenhere) && \
83b6ca1f PM	238	!atomic_xchg(&___rfd_beenhere, 1)) { \
83b6ca1f PM	239	tracing_off(); \
f22ce091	240	rcu_ftrace_dump_stall_suppress(); \
b8989b76	241	ftrace_dump(oops_dump_mode); \
f22ce091	242	rcu_ftrace_dump_stall_unsuppress(); \
83b6ca1f	243	} \
b8989b76 PM	244	} while (0)
b8989b76 PM	245
aa23c6fb	246	void rcu_early_boot_tests(void);
52d7e48b	247	void rcu_test_sync_prims(void);
aa23c6fb	248
5f6130fa LJ	249	/*
	250	* This function really isn't for public consumption, but RCU is special in
	251	* that context switches can allow the state machine to make progress.
	252	*/
	253	extern void resched_cpu(int cpu);
	254
2b34c43c PM	255	#if defined(SRCU) \|\| !defined(TINY_RCU)
	256
	257	#include <linux/rcu_node_tree.h>
	258
	259	extern int rcu_num_lvls;
e95d68d2	260	extern int num_rcu_lvl[];
2b34c43c PM	261	extern int rcu_num_nodes;
	262	static bool rcu_fanout_exact;
	263	static int rcu_fanout_leaf;
	264
	265	/*
	266	* Compute the per-level fanout, either using the exact fanout specified
	267	* or balancing the tree, depending on the rcu_fanout_exact boot parameter.
	268	*/
	269	static inline void rcu_init_levelspread(int levelspread, const int levelcnt)
	270	{
	271	int i;
	272
	273	if (rcu_fanout_exact) {
	274	levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
	275	for (i = rcu_num_lvls - 2; i >= 0; i--)
	276	levelspread[i] = RCU_FANOUT;
	277	} else {
	278	int ccur;
	279	int cprv;
	280
	281	cprv = nr_cpu_ids;
	282	for (i = rcu_num_lvls - 1; i >= 0; i--) {
	283	ccur = levelcnt[i];
	284	levelspread[i] = (cprv + ccur - 1) / ccur;
	285	cprv = ccur;
	286	}
	287	}
	288	}
	289
efbe451d PM	290	/*
	291	* Do a full breadth-first scan of the rcu_node structures for the
	292	* specified rcu_state structure.
	293	*/
	294	#define rcu_for_each_node_breadth_first(rsp, rnp) \
	295	for ((rnp) = &(rsp)->node[0]; \
	296	(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
	297
	298	/*
	299	* Do a breadth-first scan of the non-leaf rcu_node structures for the
	300	* specified rcu_state structure. Note that if there is a singleton
	301	* rcu_node tree with but one rcu_node structure, this loop is a no-op.
	302	*/
	303	#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
	304	for ((rnp) = &(rsp)->node[0]; \
	305	(rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
	306
	307	/*
	308	* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
	309	* structure. Note that if there is a singleton rcu_node tree with but
	310	* one rcu_node structure, this loop -will- visit the rcu_node structure.
	311	* It is still a leaf node, even if it is also the root node.
	312	*/
	313	#define rcu_for_each_leaf_node(rsp, rnp) \
	314	for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
	315	(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
	316
	317	/*
	318	* Iterate over all possible CPUs in a leaf RCU node.
	319	*/
	320	#define for_each_leaf_node_possible_cpu(rnp, cpu) \
	321	for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
	322	cpu <= rnp->grphi; \
	323	cpu = cpumask_next((cpu), cpu_possible_mask))
	324
83d40bd3 PM	325	/*
	326	* Wrappers for the rcu_node::lock acquire and release.
	327	*
	328	* Because the rcu_nodes form a tree, the tree traversal locking will observe
	329	* different lock values, this in turn means that an UNLOCK of one level
	330	* followed by a LOCK of another level does not imply a full memory barrier;
	331	* and most importantly transitivity is lost.
	332	*
	333	* In order to restore full ordering between tree levels, augment the regular
	334	* lock acquire functions with smp_mb__after_unlock_lock().
	335	*
	336	* As ->lock of struct rcu_node is a __private field, therefore one should use
	337	* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
	338	*/
	339	#define raw_spin_lock_rcu_node(p) \
	340	do { \
	341	raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \
	342	smp_mb__after_unlock_lock(); \
	343	} while (0)
	344
	345	#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))
	346
	347	#define raw_spin_lock_irq_rcu_node(p) \
	348	do { \
	349	raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
	350	smp_mb__after_unlock_lock(); \
	351	} while (0)
	352
	353	#define raw_spin_unlock_irq_rcu_node(p) \
	354	raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))
	355
4e4bea74	356	#define raw_spin_lock_irqsave_rcu_node(p, flags) \
83d40bd3	357	do { \
4e4bea74	358	raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
83d40bd3 PM	359	smp_mb__after_unlock_lock(); \
	360	} while (0)
	361
4e4bea74 PM	362	#define raw_spin_unlock_irqrestore_rcu_node(p, flags) \
4e4bea74 PM	363	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) \
83d40bd3 PM	364
	365	#define raw_spin_trylock_rcu_node(p) \
	366	({ \
	367	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \
	368	\
	369	if (___locked) \
	370	smp_mb__after_unlock_lock(); \
	371	___locked; \
	372	})
	373
2b34c43c PM	374	#endif /* #if defined(SRCU) \|\| !defined(TINY_RCU) */
2b34c43c PM	375
25c36329 PM	376	#ifdef CONFIG_TINY_RCU
25c36329 PM	377	/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
7414fac0 PM	378	static inline bool rcu_gp_is_normal(void) { return true; }
	379	static inline bool rcu_gp_is_expedited(void) { return false; }
	380	static inline void rcu_expedite_gp(void) { }
	381	static inline void rcu_unexpedite_gp(void) { }
25c36329 PM	382	#else /* #ifdef CONFIG_TINY_RCU */
	383	bool rcu_gp_is_normal(void); /* Internal RCU use. */
	384	bool rcu_gp_is_expedited(void); /* Internal RCU use. */
	385	void rcu_expedite_gp(void);
	386	void rcu_unexpedite_gp(void);
	387	void rcupdate_announce_bootup_oddness(void);
	388	#endif /* #else #ifdef CONFIG_TINY_RCU */
	389
82118249 PM	390	#define RCU_SCHEDULER_INACTIVE 0
	391	#define RCU_SCHEDULER_INIT 1
	392	#define RCU_SCHEDULER_RUNNING 2
	393
fe21a27e PM	394	#ifdef CONFIG_TINY_RCU
	395	static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
	396	#else /* #ifdef CONFIG_TINY_RCU */
	397	void rcu_request_urgent_qs_task(struct task_struct *t);
	398	#endif /* #else #ifdef CONFIG_TINY_RCU */
	399
cad7b389 PM	400	enum rcutorture_type {
	401	RCU_FLAVOR,
	402	RCU_BH_FLAVOR,
	403	RCU_SCHED_FLAVOR,
	404	RCU_TASKS_FLAVOR,
	405	SRCU_FLAVOR,
	406	INVALID_RCU_FLAVOR
	407	};
	408
	409	#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_PREEMPT_RCU)
	410	void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
	411	unsigned long gpnum, unsigned long completed);
	412	void rcutorture_record_test_transition(void);
	413	void rcutorture_record_progress(unsigned long vernum);
	414	void do_trace_rcu_torture_read(const char *rcutorturename,
	415	struct rcu_head *rhp,
	416	unsigned long secs,
	417	unsigned long c_old,
	418	unsigned long c);
	419	#else
	420	static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
	421	int *flags,
	422	unsigned long *gpnum,
	423	unsigned long *completed)
	424	{
	425	*flags = 0;
	426	*gpnum = 0;
	427	*completed = 0;
	428	}
7414fac0 PM	429	static inline void rcutorture_record_test_transition(void) { }
7414fac0 PM	430	static inline void rcutorture_record_progress(unsigned long vernum) { }
cad7b389 PM	431	#ifdef CONFIG_RCU_TRACE
	432	void do_trace_rcu_torture_read(const char *rcutorturename,
	433	struct rcu_head *rhp,
	434	unsigned long secs,
	435	unsigned long c_old,
	436	unsigned long c);
	437	#else
	438	#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
	439	do { } while (0)
	440	#endif
	441	#endif
	442
	443	#ifdef CONFIG_TINY_SRCU
	444
	445	static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
	446	struct srcu_struct sp, int flags,
	447	unsigned long *gpnum,
	448	unsigned long *completed)
	449	{
	450	if (test_type != SRCU_FLAVOR)
	451	return;
	452	*flags = 0;
2464dd94	453	*completed = sp->srcu_idx;
cad7b389 PM	454	gpnum = completed;
	455	}
	456
	457	#elif defined(CONFIG_TREE_SRCU)
	458
	459	void srcutorture_get_gp_data(enum rcutorture_type test_type,
	460	struct srcu_struct sp, int flags,
	461	unsigned long gpnum, unsigned long completed);
	462
cad7b389 PM	463	#endif
cad7b389 PM	464
e3c8d51e	465	#ifdef CONFIG_TINY_RCU
7414fac0 PM	466	static inline unsigned long rcu_batches_started(void) { return 0; }
	467	static inline unsigned long rcu_batches_started_bh(void) { return 0; }
	468	static inline unsigned long rcu_batches_started_sched(void) { return 0; }
	469	static inline unsigned long rcu_batches_completed(void) { return 0; }
	470	static inline unsigned long rcu_batches_completed_bh(void) { return 0; }
	471	static inline unsigned long rcu_batches_completed_sched(void) { return 0; }
	472	static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
	473	static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; }
	474	static inline unsigned long
	475	srcu_batches_completed(struct srcu_struct *sp) { return 0; }
	476	static inline void rcu_force_quiescent_state(void) { }
	477	static inline void rcu_bh_force_quiescent_state(void) { }
	478	static inline void rcu_sched_force_quiescent_state(void) { }
	479	static inline void show_rcu_gp_kthreads(void) { }
e3c8d51e PM	480	#else /* #ifdef CONFIG_TINY_RCU */
	481	extern unsigned long rcutorture_testseq;
	482	extern unsigned long rcutorture_vernum;
	483	unsigned long rcu_batches_started(void);
	484	unsigned long rcu_batches_started_bh(void);
	485	unsigned long rcu_batches_started_sched(void);
	486	unsigned long rcu_batches_completed(void);
	487	unsigned long rcu_batches_completed_bh(void);
	488	unsigned long rcu_batches_completed_sched(void);
	489	unsigned long rcu_exp_batches_completed(void);
	490	unsigned long rcu_exp_batches_completed_sched(void);
5a0465e1	491	unsigned long srcu_batches_completed(struct srcu_struct *sp);
e3c8d51e PM	492	void show_rcu_gp_kthreads(void);
	493	void rcu_force_quiescent_state(void);
	494	void rcu_bh_force_quiescent_state(void);
	495	void rcu_sched_force_quiescent_state(void);
	496	#endif /* #else #ifdef CONFIG_TINY_RCU */
	497
44c65ff2	498	#ifdef CONFIG_RCU_NOCB_CPU
3d54f798 PM	499	bool rcu_is_nocb_cpu(int cpu);
	500	#else
	501	static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
	502	#endif
	503
29c00b4a	504	#endif /* __LINUX_RCU_H */