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d5a73cadf3
With commit b92b8b35a2 ("locking/arch: Rename set_mb() to smp_store_mb()")
it was made clear that the context of this call (and thus set_mb)
is strictly for CPU ordering, as opposed to IO. As such all archs
should use the smp variant of mb(), respecting the semantics and
saving a mandatory barrier on UP.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <linux-arch@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: dave@stgolabs.net
Link: http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
124 lines
2.4 KiB
C
124 lines
2.4 KiB
C
/*
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* Generic barrier definitions, originally based on MN10300 definitions.
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*
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* It should be possible to use these on really simple architectures,
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* but it serves more as a starting point for new ports.
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef __ASM_GENERIC_BARRIER_H
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#define __ASM_GENERIC_BARRIER_H
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#ifndef __ASSEMBLY__
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#include <linux/compiler.h>
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#ifndef nop
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#define nop() asm volatile ("nop")
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#endif
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/*
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* Force strict CPU ordering. And yes, this is required on UP too when we're
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* talking to devices.
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*
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* Fall back to compiler barriers if nothing better is provided.
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*/
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#ifndef mb
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#define mb() barrier()
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#endif
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#ifndef rmb
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#define rmb() mb()
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#endif
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#ifndef wmb
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#define wmb() mb()
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#endif
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#ifndef dma_rmb
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#define dma_rmb() rmb()
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#endif
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#ifndef dma_wmb
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#define dma_wmb() wmb()
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#endif
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#ifndef read_barrier_depends
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#define read_barrier_depends() do { } while (0)
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#endif
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#ifdef CONFIG_SMP
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#ifndef smp_mb
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#define smp_mb() mb()
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#endif
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#ifndef smp_rmb
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#define smp_rmb() rmb()
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#endif
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#ifndef smp_wmb
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#define smp_wmb() wmb()
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#endif
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#ifndef smp_read_barrier_depends
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#define smp_read_barrier_depends() read_barrier_depends()
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#endif
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#else /* !CONFIG_SMP */
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#ifndef smp_mb
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#define smp_mb() barrier()
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#endif
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#ifndef smp_rmb
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#define smp_rmb() barrier()
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#endif
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#ifndef smp_wmb
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#define smp_wmb() barrier()
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#endif
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#ifndef smp_read_barrier_depends
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#define smp_read_barrier_depends() do { } while (0)
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#endif
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#endif /* CONFIG_SMP */
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#ifndef smp_store_mb
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#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0)
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#endif
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#ifndef smp_mb__before_atomic
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#define smp_mb__before_atomic() smp_mb()
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#endif
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#ifndef smp_mb__after_atomic
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#define smp_mb__after_atomic() smp_mb()
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#endif
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#define smp_store_release(p, v) \
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do { \
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compiletime_assert_atomic_type(*p); \
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smp_mb(); \
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WRITE_ONCE(*p, v); \
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} while (0)
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#define smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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compiletime_assert_atomic_type(*p); \
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smp_mb(); \
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___p1; \
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})
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_GENERIC_BARRIER_H */
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