https://github.com/torvalds/linux
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Tip revision: 2c85ebc57b3e1817b6ce1a6b703928e113a90442 authored by Linus Torvalds on 13 December 2020, 22:41:30 UTC
Linux 5.10
Tip revision: 2c85ebc
barrier.h
/* SPDX-License-Identifier: GPL-2.0 */
#include <stdlib.h>
#if defined(__i386__) || defined(__x86_64__)
#define barrier() asm volatile("" ::: "memory")
#define virt_mb() __sync_synchronize()
#define virt_rmb() barrier()
#define virt_wmb() barrier()
/* Atomic store should be enough, but gcc generates worse code in that case. */
#define virt_store_mb(var, value)  do { \
	typeof(var) virt_store_mb_value = (value); \
	__atomic_exchange(&(var), &virt_store_mb_value, &virt_store_mb_value, \
			  __ATOMIC_SEQ_CST); \
	barrier(); \
} while (0);
/* Weak barriers should be used. If not - it's a bug */
# define mb() abort()
# define dma_rmb() abort()
# define dma_wmb() abort()
#else
#error Please fill in barrier macros
#endif

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