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89 lines
2.6 KiB
89 lines
2.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* Atomic operations usable in machine independent code */ |
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#ifndef _LINUX_ATOMIC_H |
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#define _LINUX_ATOMIC_H |
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#include <linux/types.h> |
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#include <asm/atomic.h> |
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#include <asm/barrier.h> |
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/* |
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* Relaxed variants of xchg, cmpxchg and some atomic operations. |
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* |
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* We support four variants: |
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* |
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* - Fully ordered: The default implementation, no suffix required. |
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* - Acquire: Provides ACQUIRE semantics, _acquire suffix. |
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* - Release: Provides RELEASE semantics, _release suffix. |
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* - Relaxed: No ordering guarantees, _relaxed suffix. |
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* |
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* For compound atomics performing both a load and a store, ACQUIRE |
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* semantics apply only to the load and RELEASE semantics only to the |
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* store portion of the operation. Note that a failed cmpxchg_acquire |
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* does -not- imply any memory ordering constraints. |
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* |
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* See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions. |
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*/ |
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#define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c)) |
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#define atomic_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c)) |
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#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c)) |
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#define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c)) |
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/* |
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* The idea here is to build acquire/release variants by adding explicit |
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* barriers on top of the relaxed variant. In the case where the relaxed |
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* variant is already fully ordered, no additional barriers are needed. |
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* |
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* If an architecture overrides __atomic_acquire_fence() it will probably |
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* want to define smp_mb__after_spinlock(). |
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*/ |
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#ifndef __atomic_acquire_fence |
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#define __atomic_acquire_fence smp_mb__after_atomic |
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#endif |
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#ifndef __atomic_release_fence |
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#define __atomic_release_fence smp_mb__before_atomic |
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#endif |
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#ifndef __atomic_pre_full_fence |
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#define __atomic_pre_full_fence smp_mb__before_atomic |
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#endif |
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#ifndef __atomic_post_full_fence |
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#define __atomic_post_full_fence smp_mb__after_atomic |
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#endif |
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#define __atomic_op_acquire(op, args...) \ |
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({ \ |
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typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \ |
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__atomic_acquire_fence(); \ |
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__ret; \ |
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}) |
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#define __atomic_op_release(op, args...) \ |
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({ \ |
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__atomic_release_fence(); \ |
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op##_relaxed(args); \ |
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}) |
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#define __atomic_op_fence(op, args...) \ |
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({ \ |
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typeof(op##_relaxed(args)) __ret; \ |
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__atomic_pre_full_fence(); \ |
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__ret = op##_relaxed(args); \ |
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__atomic_post_full_fence(); \ |
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__ret; \ |
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}) |
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#ifdef ARCH_ATOMIC |
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#include <linux/atomic-arch-fallback.h> |
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#include <asm-generic/atomic-instrumented.h> |
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#else |
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#include <linux/atomic-fallback.h> |
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#endif |
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#include <asm-generic/atomic-long.h> |
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#endif /* _LINUX_ATOMIC_H */
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