mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
9fa45070a2
As a step to ensuring the atomic* APIs are consistent, switch to fallbacks generated by gen-atomic-fallback.sh. These are checked in rather than generated with Kbuild, since: * This allows inspection of the atomics with git grep and ctags on a pristine tree, which Linus strongly prefers being able to do. * The fallbacks are not affected by machine details or configuration options, so it is not necessary to regenerate them to take these into account. * These are included by files required *very* early in the build process (e.g. for generating bounds.h), and we'd rather not complicate the top-level Kbuild file with dependencies. The new fallback header should be equivalent to the old fallbacks in <linux/atomic.h>, but: * It is formatted a little differently due to scripting ensuring things are more regular than they used to be. * Fallbacks are now expanded in-place as static inline functions rather than macros. * The prototypes for fallbacks are arragned consistently with the return type on a separate line to try to keep to a sensible line length. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: catalin.marinas@arm.com Cc: linuxdrivers@attotech.com Cc: dvyukov@google.com Cc: Boqun Feng <boqun.feng@gmail.com> Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: glider@google.com Link: http://lkml.kernel.org/r/20180904104830.2975-3-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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 */
|