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- /* 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.
- */
- #define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
- #define atomic_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
- #define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
- #define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
- /*
- * 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; \
- })
- #ifdef ARCH_ATOMIC
- #include <linux/atomic-arch-fallback.h>
- #include <asm-generic/atomic-instrumented.h>
- #else
- #include <linux/atomic-fallback.h>
- #endif
- #include <asm-generic/atomic-long.h>
- #endif /* _LINUX_ATOMIC_H */
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