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1/* SPDX-License-Identifier: GPL-2.0 */2/* Atomic operations usable in machine independent code */3#ifndef _LINUX_ATOMIC_H4#define _LINUX_ATOMIC_H5#include <linux/types.h>6 7#include <asm/atomic.h>8#include <asm/barrier.h>9 10/*11 * Relaxed variants of xchg, cmpxchg and some atomic operations.12 *13 * We support four variants:14 *15 * - Fully ordered: The default implementation, no suffix required.16 * - Acquire: Provides ACQUIRE semantics, _acquire suffix.17 * - Release: Provides RELEASE semantics, _release suffix.18 * - Relaxed: No ordering guarantees, _relaxed suffix.19 *20 * For compound atomics performing both a load and a store, ACQUIRE21 * semantics apply only to the load and RELEASE semantics only to the22 * store portion of the operation. Note that a failed cmpxchg_acquire23 * does -not- imply any memory ordering constraints.24 *25 * See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions.26 */27 28#define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))29#define atomic_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))30 31#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))32#define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))33 34/*35 * The idea here is to build acquire/release variants by adding explicit36 * barriers on top of the relaxed variant. In the case where the relaxed37 * variant is already fully ordered, no additional barriers are needed.38 *39 * If an architecture overrides __atomic_acquire_fence() it will probably40 * want to define smp_mb__after_spinlock().41 */42#ifndef __atomic_acquire_fence43#define __atomic_acquire_fence smp_mb__after_atomic44#endif45 46#ifndef __atomic_release_fence47#define __atomic_release_fence smp_mb__before_atomic48#endif49 50#ifndef __atomic_pre_full_fence51#define __atomic_pre_full_fence smp_mb__before_atomic52#endif53 54#ifndef __atomic_post_full_fence55#define __atomic_post_full_fence smp_mb__after_atomic56#endif57 58#define __atomic_op_acquire(op, args...) \59({ \60 typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \61 __atomic_acquire_fence(); \62 __ret; \63})64 65#define __atomic_op_release(op, args...) \66({ \67 __atomic_release_fence(); \68 op##_relaxed(args); \69})70 71#define __atomic_op_fence(op, args...) \72({ \73 typeof(op##_relaxed(args)) __ret; \74 __atomic_pre_full_fence(); \75 __ret = op##_relaxed(args); \76 __atomic_post_full_fence(); \77 __ret; \78})79 80#include <linux/atomic/atomic-arch-fallback.h>81#include <linux/atomic/atomic-long.h>82#include <linux/atomic/atomic-instrumented.h>83 84#endif /* _LINUX_ATOMIC_H */85