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arch,x86: Convert smp_mb__*()

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x86 is strongly ordered and all its atomic ops imply a full barrier.

Implement the two new primitives as the old ones were.

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-knswsr5mldkr0w1lrdxvc81w@git.kernel.org
Cc: Dave Jones <davej@redhat.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2014-03-13 19:00:35 +01:00 committed by Ingo Molnar
parent ce3609f934
commit d00a569284
5 changed files with 9 additions and 12 deletions
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7
arch/x86/include/asm/atomic.h
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@ -7,6 +7,7 @@
#include <asm/alternative.h> #include <asm/alternative.h>
#include <asm/cmpxchg.h> #include <asm/cmpxchg.h>
#include <asm/rmwcc.h> #include <asm/rmwcc.h>
#include <asm/barrier.h>
/* /*
* Atomic operations that C can't guarantee us. Useful for * Atomic operations that C can't guarantee us. Useful for
@ -243,12 +244,6 @@ static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
: : "r" ((unsigned)(mask)), "m" (*(addr)) \ : : "r" ((unsigned)(mask)), "m" (*(addr)) \
: "memory") : "memory")
/* Atomic operations are already serializing on x86 */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()
#define smp_mb__before_atomic_inc() barrier()
#define smp_mb__after_atomic_inc() barrier()
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
# include <asm/atomic64_32.h> # include <asm/atomic64_32.h>
#else #else

4
arch/x86/include/asm/barrier.h
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@ -137,6 +137,10 @@ do { \
#endif #endif
/* Atomic operations are already serializing on x86 */
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
/* /*
* Stop RDTSC speculation. This is needed when you need to use RDTSC * Stop RDTSC speculation. This is needed when you need to use RDTSC
* (or get_cycles or vread that possibly accesses the TSC) in a defined * (or get_cycles or vread that possibly accesses the TSC) in a defined

6
arch/x86/include/asm/bitops.h
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@ -15,6 +15,7 @@
#include <linux/compiler.h> #include <linux/compiler.h>
#include <asm/alternative.h> #include <asm/alternative.h>
#include <asm/rmwcc.h> #include <asm/rmwcc.h>
#include <asm/barrier.h>
#if BITS_PER_LONG == 32 #if BITS_PER_LONG == 32
# define _BITOPS_LONG_SHIFT 5 # define _BITOPS_LONG_SHIFT 5
@ -102,7 +103,7 @@ static inline void __set_bit(long nr, volatile unsigned long *addr)
* *
* clear_bit() is atomic and may not be reordered. However, it does * clear_bit() is atomic and may not be reordered. However, it does
* not contain a memory barrier, so if it is used for locking purposes, * not contain a memory barrier, so if it is used for locking purposes,
* you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit() * you should call smp_mb__before_atomic() and/or smp_mb__after_atomic()
* in order to ensure changes are visible on other processors. * in order to ensure changes are visible on other processors.
*/ */
static __always_inline void static __always_inline void
@ -156,9 +157,6 @@ static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
__clear_bit(nr, addr); __clear_bit(nr, addr);
} }
#define smp_mb__before_clear_bit() barrier()
#define smp_mb__after_clear_bit() barrier()
/** /**
* __change_bit - Toggle a bit in memory * __change_bit - Toggle a bit in memory
* @nr: the bit to change * @nr: the bit to change

2
arch/x86/include/asm/sync_bitops.h
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@ -41,7 +41,7 @@ static inline void sync_set_bit(long nr, volatile unsigned long *addr)
* *
* sync_clear_bit() is atomic and may not be reordered. However, it does * sync_clear_bit() is atomic and may not be reordered. However, it does
* not contain a memory barrier, so if it is used for locking purposes, * not contain a memory barrier, so if it is used for locking purposes,
* you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit() * you should call smp_mb__before_atomic() and/or smp_mb__after_atomic()
* in order to ensure changes are visible on other processors. * in order to ensure changes are visible on other processors.
*/ */
static inline void sync_clear_bit(long nr, volatile unsigned long *addr) static inline void sync_clear_bit(long nr, volatile unsigned long *addr)

2
arch/x86/kernel/apic/hw_nmi.c
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@ -57,7 +57,7 @@ void arch_trigger_all_cpu_backtrace(void)
} }
clear_bit(0, &backtrace_flag); clear_bit(0, &backtrace_flag);
smp_mb__after_clear_bit(); smp_mb__after_atomic();
} }
static int __kprobes static int __kprobes