79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/* Atomic operations usable in machine independent code */
|
|
#ifndef _LINUX_ATOMIC_H
|
|
#define _LINUX_ATOMIC_H
|
|
#include <linux/types.h>
|
|
|
|
#include <asm/atomic.h>
|
|
#include <asm/barrier.h>
|
|
|
|
/*
|
|
* Relaxed variants of xchg, cmpxchg and some atomic operations.
|
|
*
|
|
* We support four variants:
|
|
*
|
|
* - Fully ordered: The default implementation, no suffix required.
|
|
* - Acquire: Provides ACQUIRE semantics, _acquire suffix.
|
|
* - Release: Provides RELEASE semantics, _release suffix.
|
|
* - Relaxed: No ordering guarantees, _relaxed suffix.
|
|
*
|
|
* For compound atomics performing both a load and a store, ACQUIRE
|
|
* semantics apply only to the load and RELEASE semantics only to the
|
|
* store portion of the operation. Note that a failed cmpxchg_acquire
|
|
* does -not- imply any memory ordering constraints.
|
|
*
|
|
* See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions.
|
|
*/
|
|
|
|
/*
|
|
* The idea here is to build acquire/release variants by adding explicit
|
|
* barriers on top of the relaxed variant. In the case where the relaxed
|
|
* variant is already fully ordered, no additional barriers are needed.
|
|
*
|
|
* If an architecture overrides __atomic_acquire_fence() it will probably
|
|
* want to define smp_mb__after_spinlock().
|
|
*/
|
|
#ifndef __atomic_acquire_fence
|
|
#define __atomic_acquire_fence smp_mb__after_atomic
|
|
#endif
|
|
|
|
#ifndef __atomic_release_fence
|
|
#define __atomic_release_fence smp_mb__before_atomic
|
|
#endif
|
|
|
|
#ifndef __atomic_pre_full_fence
|
|
#define __atomic_pre_full_fence smp_mb__before_atomic
|
|
#endif
|
|
|
|
#ifndef __atomic_post_full_fence
|
|
#define __atomic_post_full_fence smp_mb__after_atomic
|
|
#endif
|
|
|
|
#define __atomic_op_acquire(op, args...) \
|
|
({ \
|
|
typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \
|
|
__atomic_acquire_fence(); \
|
|
__ret; \
|
|
})
|
|
|
|
#define __atomic_op_release(op, args...) \
|
|
({ \
|
|
__atomic_release_fence(); \
|
|
op##_relaxed(args); \
|
|
})
|
|
|
|
#define __atomic_op_fence(op, args...) \
|
|
({ \
|
|
typeof(op##_relaxed(args)) __ret; \
|
|
__atomic_pre_full_fence(); \
|
|
__ret = op##_relaxed(args); \
|
|
__atomic_post_full_fence(); \
|
|
__ret; \
|
|
})
|
|
|
|
#include <linux/atomic-fallback.h>
|
|
|
|
#include <asm-generic/atomic-long.h>
|
|
|
|
#endif /* _LINUX_ATOMIC_H */
|