/*
* Sleepable Read-Copy Update mechanism for mutual exclusion
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
* Copyright (C) IBM Corporation, 2006
* Author: Paul McKenney <paulmck@us.ibm.com>
* For detailed explanation of Read-Copy Update mechanism see -
* Documentation/RCU/ *.txt
*/
#ifndef _LINUX_SRCU_H
#define _LINUX_SRCU_H
#include <linux/mutex.h>
struct srcu_struct_array {
int c[2];
};
struct srcu_struct {
int completed;
struct srcu_struct_array __percpu *per_cpu_ref;
struct mutex mutex;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
#ifndef CONFIG_PREEMPT
#define srcu_barrier() barrier()
#else /* #ifndef CONFIG_PREEMPT */
#define srcu_barrier()
#endif /* #else #ifndef CONFIG_PREEMPT */
int __init_srcu_struct(struct srcu_struct *sp, const char *name,
struct lock_class_key *key);
#define init_srcu_struct(sp) \
({ \
static struct lock_class_key __srcu_key; \
\
__init_srcu_struct((sp), #sp, &__srcu_key); \
})
# define srcu_read_acquire(sp) \
lock_acquire(&(sp)->dep_map, 0, 0, 2, 1, NULL, _THIS_IP_)
# define srcu_read_release(sp) \
lock_release(&(sp)->dep_map, 1, _THIS_IP_)
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
int init_srcu_struct(struct srcu_struct *sp);
# define srcu_read_acquire(sp) do { } while (0)
# define srcu_read_release(sp) do { } while (0)
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
void cleanup_srcu_struct(struct srcu_struct *sp);
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu_expedited(struct srcu_struct *sp);
long srcu_batches_completed(struct srcu_struct *sp);
/**
* srcu_read_lock_held - might we be in SRCU read-side critical section?
* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
* this assumes we are in an SRCU read-side critical section unless it can
* prove otherwise.
static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
if (debug_locks)
return lock_is_held(&sp->dep_map);
return 1;
}
* srcu_dereference - fetch SRCU-protected pointer with checking
* Makes rcu_dereference_check() do the dirty work.
#define srcu_dereference(p, sp) \
rcu_dereference_check(p, srcu_read_lock_held(sp))
* srcu_read_lock - register a new reader for an SRCU-protected structure.
* @sp: srcu_struct in which to register the new reader.
* Enter an SRCU read-side critical section. Note that SRCU read-side
* critical sections may be nested.
static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
int retval = __srcu_read_lock(sp);
srcu_read_acquire(sp);
return retval;
* srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
* @sp: srcu_struct in which to unregister the old reader.
* @idx: return value from corresponding srcu_read_lock().
* Exit an SRCU read-side critical section.
static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
__releases(sp)
srcu_read_release(sp);
__srcu_read_unlock(sp, idx);
#endif