/*
* Pull in the generic implementation for the mutex fastpath.
*
* TODO: implement optimized primitives instead, or leave the generic
* implementation in place, or pick the atomic_xchg() based generic
* implementation. (see asm-generic/mutex-xchg.h for details)
* Copyright 2006-2009 Analog Devices Inc.
* Licensed under the GPL-2 or later.
*/
#ifndef _ASM_MUTEX_H
#define _ASM_MUTEX_H
#ifndef CONFIG_SMP
#include <asm-generic/mutex.h>
#else
static inline void
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
if (unlikely(atomic_dec_return(count) < 0))
fail_fn(count);
else
smp_mb();
}
static inline int
__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
return fail_fn(count);
else {
return 0;
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
if (unlikely(atomic_inc_return(count) <= 0))
#define __mutex_slowpath_needs_to_unlock() 1
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
* We have two variants here. The cmpxchg based one is the best one
* because it never induce a false contention state. It is included
* here because architectures using the inc/dec algorithms over the
* xchg ones are much more likely to support cmpxchg natively.
* If not we fall back to the spinlock based variant - that is
* just as efficient (and simpler) as a 'destructive' probing of
* the mutex state would be.
#ifdef __HAVE_ARCH_CMPXCHG
if (likely(atomic_cmpxchg(count, 1, 0) == 1)) {
return 1;
#endif