rwlock.h

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#ifndef __LINUX_RWLOCK_H
#define __LINUX_RWLOCK_H

#ifndef __LINUX_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)                  \
do {                                \
    static struct lock_class_key __key;         \
                                \
    __rwlock_init((lock), #lock, &__key);           \
} while (0)
#else
# define rwlock_init(lock)                  \
    do { *(lock) = __RW_LOCK_UNLOCKED(lock); } while (0)
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 extern void do_raw_read_lock(rwlock_t *lock) __acquires(lock);
#define do_raw_read_lock_flags(lock, flags) do_raw_read_lock(lock)
 extern int do_raw_read_trylock(rwlock_t *lock);
 extern void do_raw_read_unlock(rwlock_t *lock) __releases(lock);
 extern void do_raw_write_lock(rwlock_t *lock) __acquires(lock);
#define do_raw_write_lock_flags(lock, flags) do_raw_write_lock(lock)
 extern int do_raw_write_trylock(rwlock_t *lock);
 extern void do_raw_write_unlock(rwlock_t *lock) __releases(lock);
#else
# define do_raw_read_lock(rwlock)   do {__acquire(lock); arch_read_lock(&(rwlock)->raw_lock); } while (0)
# define do_raw_read_lock_flags(lock, flags) \
        do {__acquire(lock); arch_read_lock_flags(&(lock)->raw_lock, *(flags)); } while (0)
# define do_raw_read_trylock(rwlock)    arch_read_trylock(&(rwlock)->raw_lock)
# define do_raw_read_unlock(rwlock) do {arch_read_unlock(&(rwlock)->raw_lock); __release(lock); } while (0)
# define do_raw_write_lock(rwlock)  do {__acquire(lock); arch_write_lock(&(rwlock)->raw_lock); } while (0)
# define do_raw_write_lock_flags(lock, flags) \
        do {__acquire(lock); arch_write_lock_flags(&(lock)->raw_lock, *(flags)); } while (0)
# define do_raw_write_trylock(rwlock)   arch_write_trylock(&(rwlock)->raw_lock)
# define do_raw_write_unlock(rwlock)    do {arch_write_unlock(&(rwlock)->raw_lock); __release(lock); } while (0)
#endif

#define read_can_lock(rwlock)       arch_read_can_lock(&(rwlock)->raw_lock)
#define write_can_lock(rwlock)      arch_write_can_lock(&(rwlock)->raw_lock)

/*
 * 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)  __cond_lock(lock, _raw_read_trylock(lock))
#define write_trylock(lock) __cond_lock(lock, _raw_write_trylock(lock))

#define write_lock(lock)    _raw_write_lock(lock)
#define read_lock(lock)     _raw_read_lock(lock)

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

#define read_lock_irqsave(lock, flags)          \
    do {                        \
        typecheck(unsigned long, flags);    \
        flags = _raw_read_lock_irqsave(lock);   \
    } while (0)
#define write_lock_irqsave(lock, flags)         \
    do {                        \
        typecheck(unsigned long, flags);    \
        flags = _raw_write_lock_irqsave(lock);  \
    } while (0)

#else

#define read_lock_irqsave(lock, flags)          \
    do {                        \
        typecheck(unsigned long, flags);    \
        _raw_read_lock_irqsave(lock, flags);    \
    } while (0)
#define write_lock_irqsave(lock, flags)         \
    do {                        \
        typecheck(unsigned long, flags);    \
        _raw_write_lock_irqsave(lock, flags);   \
    } while (0)

#endif

#define read_lock_irq(lock)     _raw_read_lock_irq(lock)
#define read_lock_bh(lock)      _raw_read_lock_bh(lock)
#define write_lock_irq(lock)        _raw_write_lock_irq(lock)
#define write_lock_bh(lock)     _raw_write_lock_bh(lock)
#define read_unlock(lock)       _raw_read_unlock(lock)
#define write_unlock(lock)      _raw_write_unlock(lock)
#define read_unlock_irq(lock)       _raw_read_unlock_irq(lock)
#define write_unlock_irq(lock)      _raw_write_unlock_irq(lock)

#define read_unlock_irqrestore(lock, flags)         \
    do {                            \
        typecheck(unsigned long, flags);        \
        _raw_read_unlock_irqrestore(lock, flags);   \
    } while (0)
#define read_unlock_bh(lock)        _raw_read_unlock_bh(lock)

#define write_unlock_irqrestore(lock, flags)        \
    do {                        \
        typecheck(unsigned long, flags);    \
        _raw_write_unlock_irqrestore(lock, flags);  \
    } while (0)
#define write_unlock_bh(lock)       _raw_write_unlock_bh(lock)

#define write_trylock_irqsave(lock, flags) \
({ \
    local_irq_save(flags); \
    write_trylock(lock) ? \
    1 : ({ local_irq_restore(flags); 0; }); \
})

#endif /* __LINUX_RWLOCK_H */