linux/include/linux/rwlock.h

#ifndef __LINUX_RWLOCK_H
#define __LINUX_RWLOCK_H

#ifndef __LINUX_INSIDE_SPINLOCK_H
# error "please don't include this file directly"
#endif

/*
 * rwlock related methods
 *
 * split out from spinlock.h
 *
 * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
 * Released under the General Public License (GPL).
 */

#ifdef CONFIG_DEBUG_SPINLOCK
  extern void __rwlock_init(rwlock_t *lock, const char *name,
			    struct lock_class_key *key);
#define rwlock_init(lock) …
#else
#define rwlock_init …
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 extern void do_raw_read_lock(rwlock_t *lock) __acquires(…);
 extern int do_raw_read_trylock(rwlock_t *lock);
 extern void do_raw_read_unlock(rwlock_t *lock) __releases(…);
 extern void do_raw_write_lock(rwlock_t *lock) __acquires(…);
 extern int do_raw_write_trylock(rwlock_t *lock);
 extern void do_raw_write_unlock(rwlock_t *lock) __releases(…);
#else
#define do_raw_read_lock …
#define do_raw_read_trylock …
#define do_raw_read_unlock …
#define do_raw_write_lock …
#define do_raw_write_trylock …
#define do_raw_write_unlock …
#endif

/*
 * Define the various rw_lock methods.  Note we define these
 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 * methods are defined as nops in the case they are not required.
 */
#define read_trylock(lock) …
#define write_trylock(lock) …

#define write_lock(lock) …
#define read_lock(lock) …

#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define write_lock_nested(lock, subclass) …
#else
#define write_lock_nested …
#endif

#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)

#define read_lock_irqsave(lock, flags) …
#define write_lock_irqsave(lock, flags) …

#else

#define read_lock_irqsave …
#define write_lock_irqsave …

#endif

#define read_lock_irq(lock) …
#define read_lock_bh(lock) …
#define write_lock_irq(lock) …
#define write_lock_bh(lock) …
#define read_unlock(lock) …
#define write_unlock(lock) …
#define read_unlock_irq(lock) …
#define write_unlock_irq(lock) …

#define read_unlock_irqrestore(lock, flags) …
#define read_unlock_bh(lock) …

#define write_unlock_irqrestore(lock, flags) …
#define write_unlock_bh(lock) …

#define write_trylock_irqsave(lock, flags) …

#ifdef arch_rwlock_is_contended
#define rwlock_is_contended(lock) …
#else
#define rwlock_is_contended …
#endif /* arch_rwlock_is_contended */

#endif /* __LINUX_RWLOCK_H */