cregit-Linux how code gets into the kernel

Release 4.7 include/asm-generic/barrier.h

/*
 * Generic barrier definitions, originally based on MN10300 definitions.
 *
 * It should be possible to use these on really simple architectures,
 * but it serves more as a starting point for new ports.
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#ifndef __ASM_GENERIC_BARRIER_H

#define __ASM_GENERIC_BARRIER_H

#ifndef __ASSEMBLY__

#include <linux/compiler.h>

#ifndef nop

#define nop()	asm volatile ("nop")
#endif

/*
 * Force strict CPU ordering. And yes, this is required on UP too when we're
 * talking to devices.
 *
 * Fall back to compiler barriers if nothing better is provided.
 */

#ifndef mb

#define mb()	barrier()
#endif

#ifndef rmb

#define rmb()	mb()
#endif

#ifndef wmb

#define wmb()	mb()
#endif

#ifndef dma_rmb

#define dma_rmb()	rmb()
#endif

#ifndef dma_wmb

#define dma_wmb()	wmb()
#endif

#ifndef read_barrier_depends

#define read_barrier_depends()		do { } while (0)
#endif

#ifndef __smp_mb

#define __smp_mb()	mb()
#endif

#ifndef __smp_rmb

#define __smp_rmb()	rmb()
#endif

#ifndef __smp_wmb

#define __smp_wmb()	wmb()
#endif

#ifndef __smp_read_barrier_depends

#define __smp_read_barrier_depends()	read_barrier_depends()
#endif

#ifdef CONFIG_SMP

#ifndef smp_mb

#define smp_mb()	__smp_mb()
#endif

#ifndef smp_rmb

#define smp_rmb()	__smp_rmb()
#endif

#ifndef smp_wmb

#define smp_wmb()	__smp_wmb()
#endif

#ifndef smp_read_barrier_depends

#define smp_read_barrier_depends()	__smp_read_barrier_depends()
#endif

#else	/* !CONFIG_SMP */

#ifndef smp_mb

#define smp_mb()	barrier()
#endif

#ifndef smp_rmb

#define smp_rmb()	barrier()
#endif

#ifndef smp_wmb

#define smp_wmb()	barrier()
#endif

#ifndef smp_read_barrier_depends

#define smp_read_barrier_depends()	do { } while (0)
#endif

#endif	/* CONFIG_SMP */

#ifndef __smp_store_mb

#define __smp_store_mb(var, value)  do { WRITE_ONCE(var, value); __smp_mb(); } while (0)
#endif

#ifndef __smp_mb__before_atomic

#define __smp_mb__before_atomic()	__smp_mb()
#endif

#ifndef __smp_mb__after_atomic

#define __smp_mb__after_atomic()	__smp_mb()
#endif

#ifndef __smp_store_release

#define __smp_store_release(p, v)					\
do {                                                                    \
        compiletime_assert_atomic_type(*p);                             \
        __smp_mb();                                                     \
        WRITE_ONCE(*p, v);                                              \
} while (0)
#endif

#ifndef __smp_load_acquire

#define __smp_load_acquire(p)						\
({                                                                      \
        typeof(*p) ___p1 = READ_ONCE(*p);                               \
        compiletime_assert_atomic_type(*p);                             \
        __smp_mb();                                                     \
        ___p1;                                                          \
})
#endif

#ifdef CONFIG_SMP

#ifndef smp_store_mb

#define smp_store_mb(var, value)  __smp_store_mb(var, value)
#endif

#ifndef smp_mb__before_atomic

#define smp_mb__before_atomic()	__smp_mb__before_atomic()
#endif

#ifndef smp_mb__after_atomic

#define smp_mb__after_atomic()	__smp_mb__after_atomic()
#endif

#ifndef smp_store_release

#define smp_store_release(p, v) __smp_store_release(p, v)
#endif

#ifndef smp_load_acquire

#define smp_load_acquire(p) __smp_load_acquire(p)
#endif

#else	/* !CONFIG_SMP */

#ifndef smp_store_mb

#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); barrier(); } while (0)
#endif

#ifndef smp_mb__before_atomic

#define smp_mb__before_atomic()	barrier()
#endif

#ifndef smp_mb__after_atomic

#define smp_mb__after_atomic()	barrier()
#endif

#ifndef smp_store_release

#define smp_store_release(p, v)						\
do {                                                                    \
        compiletime_assert_atomic_type(*p);                             \
        barrier();                                                      \
        WRITE_ONCE(*p, v);                                              \
} while (0)
#endif

#ifndef smp_load_acquire

#define smp_load_acquire(p)						\
({                                                                      \
        typeof(*p) ___p1 = READ_ONCE(*p);                               \
        compiletime_assert_atomic_type(*p);                             \
        barrier();                                                      \
        ___p1;                                                          \
})
#endif

#endif

/* Barriers for virtual machine guests when talking to an SMP host */

#define virt_mb() __smp_mb()

#define virt_rmb() __smp_rmb()

#define virt_wmb() __smp_wmb()

#define virt_read_barrier_depends() __smp_read_barrier_depends()

#define virt_store_mb(var, value) __smp_store_mb(var, value)

#define virt_mb__before_atomic() __smp_mb__before_atomic()

#define virt_mb__after_atomic()	__smp_mb__after_atomic()

#define virt_store_release(p, v) __smp_store_release(p, v)

#define virt_load_acquire(p) __smp_load_acquire(p)

#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_BARRIER_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
michael s. tsirkinmichael s. tsirkin24552.46%327.27%
peter zijlstrapeter zijlstra8618.42%436.36%
david howellsdavid howells7415.85%19.09%
vineet guptavineet gupta408.57%19.09%
alexander duyckalexander duyck204.28%19.09%
linus torvaldslinus torvalds20.43%19.09%
Total467100.00%11100.00%
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