linux/arch/ia64/include/asm/barrier.h
Peter Zijlstra 0cd64efb61 arch,ia64: Convert smp_mb__*()
ia64 atomic ops are full barriers; implement the new
smp_mb__{before,after}_atomic().

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-hyp7yj68cmqz1nqbfpr541ca@git.kernel.org
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-04-18 14:20:35 +02:00

95 lines
2.8 KiB
C

/*
* Memory barrier definitions. This is based on information published
* in the Processor Abstraction Layer and the System Abstraction Layer
* manual.
*
* Copyright (C) 1998-2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
* Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
*/
#ifndef _ASM_IA64_BARRIER_H
#define _ASM_IA64_BARRIER_H
#include <linux/compiler.h>
/*
* Macros to force memory ordering. In these descriptions, "previous"
* and "subsequent" refer to program order; "visible" means that all
* architecturally visible effects of a memory access have occurred
* (at a minimum, this means the memory has been read or written).
*
* wmb(): Guarantees that all preceding stores to memory-
* like regions are visible before any subsequent
* stores and that all following stores will be
* visible only after all previous stores.
* rmb(): Like wmb(), but for reads.
* mb(): wmb()/rmb() combo, i.e., all previous memory
* accesses are visible before all subsequent
* accesses and vice versa. This is also known as
* a "fence."
*
* Note: "mb()" and its variants cannot be used as a fence to order
* accesses to memory mapped I/O registers. For that, mf.a needs to
* be used. However, we don't want to always use mf.a because (a)
* it's (presumably) much slower than mf and (b) mf.a is supported for
* sequential memory pages only.
*/
#define mb() ia64_mf()
#define rmb() mb()
#define wmb() mb()
#define read_barrier_depends() do { } while(0)
#ifdef CONFIG_SMP
# define smp_mb() mb()
# define smp_rmb() rmb()
# define smp_wmb() wmb()
# define smp_read_barrier_depends() read_barrier_depends()
#else
# define smp_mb() barrier()
# define smp_rmb() barrier()
# define smp_wmb() barrier()
# define smp_read_barrier_depends() do { } while(0)
#endif
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
/*
* IA64 GCC turns volatile stores into st.rel and volatile loads into ld.acq no
* need for asm trickery!
*/
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
ACCESS_ONCE(*p) = (v); \
} while (0)
#define smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = ACCESS_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
})
/*
* XXX check on this ---I suspect what Linus really wants here is
* acquire vs release semantics but we can't discuss this stuff with
* Linus just yet. Grrr...
*/
#define set_mb(var, value) do { (var) = (value); mb(); } while (0)
/*
* The group barrier in front of the rsm & ssm are necessary to ensure
* that none of the previous instructions in the same group are
* affected by the rsm/ssm.
*/
#endif /* _ASM_IA64_BARRIER_H */