linux/arch/alpha/include/asm/barrier.h
Will Deacon d646285885 alpha: Override READ_ONCE() with barriered implementation
Rather then relying on the core code to use smp_read_barrier_depends()
as part of the READ_ONCE() definition, instead override __READ_ONCE()
in the Alpha code so that it generates the required mb() and then
implement smp_load_acquire() using the new macro to avoid redundant
back-to-back barriers from the generic implementation.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
2020-07-21 10:50:35 +01:00

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C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __BARRIER_H
#define __BARRIER_H
#define mb() __asm__ __volatile__("mb": : :"memory")
#define rmb() __asm__ __volatile__("mb": : :"memory")
#define wmb() __asm__ __volatile__("wmb": : :"memory")
#define __smp_load_acquire(p) \
({ \
compiletime_assert_atomic_type(*p); \
__READ_ONCE(*p); \
})
#ifdef CONFIG_SMP
#define __ASM_SMP_MB "\tmb\n"
#else
#define __ASM_SMP_MB
#endif
#include <asm-generic/barrier.h>
#endif /* __BARRIER_H */