[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);

#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)) \
		ftrace_dump(oops_dump_mode); \
} 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
	206	#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
	207
0d752924 PM	208	/*
	209	* Strings used in tracepoints need to be exported via the
	210	* tracing system such that tools like perf and trace-cmd can
	211	* translate the string address pointers to actual text.
	212	*/
	213	#define TPS(x) tracepoint_string(x)
	214
b8989b76 PM	215	/*
	216	* Dump the ftrace buffer, but only one time per callsite per boot.
	217	*/
	218	#define rcu_ftrace_dump(oops_dump_mode) \
	219	do { \
	220	static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
	221	\
	222	if (!atomic_read(&___rfd_beenhere) && \
	223	!atomic_xchg(&___rfd_beenhere, 1)) \
	224	ftrace_dump(oops_dump_mode); \
	225	} while (0)
	226
aa23c6fb	227	void rcu_early_boot_tests(void);
52d7e48b	228	void rcu_test_sync_prims(void);
aa23c6fb	229
5f6130fa LJ	230	/*
	231	* This function really isn't for public consumption, but RCU is special in
	232	* that context switches can allow the state machine to make progress.
	233	*/
	234	extern void resched_cpu(int cpu);
	235
2b34c43c PM	236	#if defined(SRCU) \|\| !defined(TINY_RCU)
	237
	238	#include <linux/rcu_node_tree.h>
	239
	240	extern int rcu_num_lvls;
e95d68d2	241	extern int num_rcu_lvl[];
2b34c43c PM	242	extern int rcu_num_nodes;
	243	static bool rcu_fanout_exact;
	244	static int rcu_fanout_leaf;
	245
	246	/*
	247	* Compute the per-level fanout, either using the exact fanout specified
	248	* or balancing the tree, depending on the rcu_fanout_exact boot parameter.
	249	*/
	250	static inline void rcu_init_levelspread(int levelspread, const int levelcnt)
	251	{
	252	int i;
	253
	254	if (rcu_fanout_exact) {
	255	levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
	256	for (i = rcu_num_lvls - 2; i >= 0; i--)
	257	levelspread[i] = RCU_FANOUT;
	258	} else {
	259	int ccur;
	260	int cprv;
	261
	262	cprv = nr_cpu_ids;
	263	for (i = rcu_num_lvls - 1; i >= 0; i--) {
	264	ccur = levelcnt[i];
	265	levelspread[i] = (cprv + ccur - 1) / ccur;
	266	cprv = ccur;
	267	}
	268	}
	269	}
	270
efbe451d PM	271	/*
	272	* Do a full breadth-first scan of the rcu_node structures for the
	273	* specified rcu_state structure.
	274	*/
	275	#define rcu_for_each_node_breadth_first(rsp, rnp) \
	276	for ((rnp) = &(rsp)->node[0]; \
	277	(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
	278
	279	/*
	280	* Do a breadth-first scan of the non-leaf rcu_node structures for the
	281	* specified rcu_state structure. Note that if there is a singleton
	282	* rcu_node tree with but one rcu_node structure, this loop is a no-op.
	283	*/
	284	#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
	285	for ((rnp) = &(rsp)->node[0]; \
	286	(rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
	287
	288	/*
	289	* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
	290	* structure. Note that if there is a singleton rcu_node tree with but
	291	* one rcu_node structure, this loop -will- visit the rcu_node structure.
	292	* It is still a leaf node, even if it is also the root node.
	293	*/
	294	#define rcu_for_each_leaf_node(rsp, rnp) \
	295	for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
	296	(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
	297
	298	/*
	299	* Iterate over all possible CPUs in a leaf RCU node.
	300	*/
	301	#define for_each_leaf_node_possible_cpu(rnp, cpu) \
	302	for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
	303	cpu <= rnp->grphi; \
	304	cpu = cpumask_next((cpu), cpu_possible_mask))
	305
83d40bd3 PM	306	/*
	307	* Wrappers for the rcu_node::lock acquire and release.
	308	*
	309	* Because the rcu_nodes form a tree, the tree traversal locking will observe
	310	* different lock values, this in turn means that an UNLOCK of one level
	311	* followed by a LOCK of another level does not imply a full memory barrier;
	312	* and most importantly transitivity is lost.
	313	*
	314	* In order to restore full ordering between tree levels, augment the regular
	315	* lock acquire functions with smp_mb__after_unlock_lock().
	316	*
	317	* As ->lock of struct rcu_node is a __private field, therefore one should use
	318	* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
	319	*/
	320	#define raw_spin_lock_rcu_node(p) \
	321	do { \
	322	raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \
	323	smp_mb__after_unlock_lock(); \
	324	} while (0)
	325
	326	#define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock))
	327
	328	#define raw_spin_lock_irq_rcu_node(p) \
	329	do { \
	330	raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
	331	smp_mb__after_unlock_lock(); \
	332	} while (0)
	333
	334	#define raw_spin_unlock_irq_rcu_node(p) \
	335	raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock))
	336
4e4bea74	337	#define raw_spin_lock_irqsave_rcu_node(p, flags) \
83d40bd3	338	do { \
4e4bea74	339	raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
83d40bd3 PM	340	smp_mb__after_unlock_lock(); \
	341	} while (0)
	342
4e4bea74 PM	343	#define raw_spin_unlock_irqrestore_rcu_node(p, flags) \
4e4bea74 PM	344	raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) \
83d40bd3 PM	345
	346	#define raw_spin_trylock_rcu_node(p) \
	347	({ \
	348	bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \
	349	\
	350	if (___locked) \
	351	smp_mb__after_unlock_lock(); \
	352	___locked; \
	353	})
	354
2b34c43c PM	355	#endif /* #if defined(SRCU) \|\| !defined(TINY_RCU) */
2b34c43c PM	356
25c36329 PM	357	#ifdef CONFIG_TINY_RCU
25c36329 PM	358	/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
7414fac0 PM	359	static inline bool rcu_gp_is_normal(void) { return true; }
	360	static inline bool rcu_gp_is_expedited(void) { return false; }
	361	static inline void rcu_expedite_gp(void) { }
	362	static inline void rcu_unexpedite_gp(void) { }
25c36329 PM	363	#else /* #ifdef CONFIG_TINY_RCU */
	364	bool rcu_gp_is_normal(void); /* Internal RCU use. */
	365	bool rcu_gp_is_expedited(void); /* Internal RCU use. */
	366	void rcu_expedite_gp(void);
	367	void rcu_unexpedite_gp(void);
	368	void rcupdate_announce_bootup_oddness(void);
	369	#endif /* #else #ifdef CONFIG_TINY_RCU */
	370
82118249 PM	371	#define RCU_SCHEDULER_INACTIVE 0
	372	#define RCU_SCHEDULER_INIT 1
	373	#define RCU_SCHEDULER_RUNNING 2
	374
fe21a27e PM	375	#ifdef CONFIG_TINY_RCU
	376	static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
	377	#else /* #ifdef CONFIG_TINY_RCU */
	378	void rcu_request_urgent_qs_task(struct task_struct *t);
	379	#endif /* #else #ifdef CONFIG_TINY_RCU */
	380
cad7b389 PM	381	enum rcutorture_type {
	382	RCU_FLAVOR,
	383	RCU_BH_FLAVOR,
	384	RCU_SCHED_FLAVOR,
	385	RCU_TASKS_FLAVOR,
	386	SRCU_FLAVOR,
	387	INVALID_RCU_FLAVOR
	388	};
	389
	390	#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_PREEMPT_RCU)
	391	void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
	392	unsigned long gpnum, unsigned long completed);
	393	void rcutorture_record_test_transition(void);
	394	void rcutorture_record_progress(unsigned long vernum);
	395	void do_trace_rcu_torture_read(const char *rcutorturename,
	396	struct rcu_head *rhp,
	397	unsigned long secs,
	398	unsigned long c_old,
	399	unsigned long c);
	400	#else
	401	static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
	402	int *flags,
	403	unsigned long *gpnum,
	404	unsigned long *completed)
	405	{
	406	*flags = 0;
	407	*gpnum = 0;
	408	*completed = 0;
	409	}
7414fac0 PM	410	static inline void rcutorture_record_test_transition(void) { }
7414fac0 PM	411	static inline void rcutorture_record_progress(unsigned long vernum) { }
cad7b389 PM	412	#ifdef CONFIG_RCU_TRACE
	413	void do_trace_rcu_torture_read(const char *rcutorturename,
	414	struct rcu_head *rhp,
	415	unsigned long secs,
	416	unsigned long c_old,
	417	unsigned long c);
	418	#else
	419	#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
	420	do { } while (0)
	421	#endif
	422	#endif
	423
	424	#ifdef CONFIG_TINY_SRCU
	425
	426	static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
	427	struct srcu_struct sp, int flags,
	428	unsigned long *gpnum,
	429	unsigned long *completed)
	430	{
	431	if (test_type != SRCU_FLAVOR)
	432	return;
	433	*flags = 0;
2464dd94	434	*completed = sp->srcu_idx;
cad7b389 PM	435	gpnum = completed;
	436	}
	437
	438	#elif defined(CONFIG_TREE_SRCU)
	439
	440	void srcutorture_get_gp_data(enum rcutorture_type test_type,
	441	struct srcu_struct sp, int flags,
	442	unsigned long gpnum, unsigned long completed);
	443
cad7b389 PM	444	#endif
cad7b389 PM	445
e3c8d51e	446	#ifdef CONFIG_TINY_RCU
7414fac0 PM	447	static inline unsigned long rcu_batches_started(void) { return 0; }
	448	static inline unsigned long rcu_batches_started_bh(void) { return 0; }
	449	static inline unsigned long rcu_batches_started_sched(void) { return 0; }
	450	static inline unsigned long rcu_batches_completed(void) { return 0; }
	451	static inline unsigned long rcu_batches_completed_bh(void) { return 0; }
	452	static inline unsigned long rcu_batches_completed_sched(void) { return 0; }
	453	static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
	454	static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; }
	455	static inline unsigned long
	456	srcu_batches_completed(struct srcu_struct *sp) { return 0; }
	457	static inline void rcu_force_quiescent_state(void) { }
	458	static inline void rcu_bh_force_quiescent_state(void) { }
	459	static inline void rcu_sched_force_quiescent_state(void) { }
	460	static inline void show_rcu_gp_kthreads(void) { }
e3c8d51e PM	461	#else /* #ifdef CONFIG_TINY_RCU */
	462	extern unsigned long rcutorture_testseq;
	463	extern unsigned long rcutorture_vernum;
	464	unsigned long rcu_batches_started(void);
	465	unsigned long rcu_batches_started_bh(void);
	466	unsigned long rcu_batches_started_sched(void);
	467	unsigned long rcu_batches_completed(void);
	468	unsigned long rcu_batches_completed_bh(void);
	469	unsigned long rcu_batches_completed_sched(void);
	470	unsigned long rcu_exp_batches_completed(void);
	471	unsigned long rcu_exp_batches_completed_sched(void);
5a0465e1	472	unsigned long srcu_batches_completed(struct srcu_struct *sp);
e3c8d51e PM	473	void show_rcu_gp_kthreads(void);
	474	void rcu_force_quiescent_state(void);
	475	void rcu_bh_force_quiescent_state(void);
	476	void rcu_sched_force_quiescent_state(void);
	477	#endif /* #else #ifdef CONFIG_TINY_RCU */
	478
44c65ff2	479	#ifdef CONFIG_RCU_NOCB_CPU
3d54f798 PM	480	bool rcu_is_nocb_cpu(int cpu);
	481	#else
	482	static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
	483	#endif
	484
29c00b4a	485	#endif /* __LINUX_RCU_H */