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locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations

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By defining our SMP atomics in terms of relaxed operations, we gain
a small reduction in code size and have acquire/release/fence variants
generated automatically by the core code.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman.Long@hp.com
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1438880084-18856-9-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Will Deacon
2015-08-06 17:54:44 +01:00
committed by Ingo Molnar
parent cd074aea92
commit 0ca326de7a
2 changed files with 24 additions and 60 deletions
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47
arch/arm/include/asm/cmpxchg.h
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@@ -35,7 +35,6 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
unsigned int tmp;
#endif
smp_mb();
prefetchw((const void *)ptr);
switch (size) {
@@ -98,12 +97,11 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
__bad_xchg(ptr, size), ret = 0;
break;
}
smp_mb();
return ret;
}
#define xchg(ptr, x) ({ \
#define xchg_relaxed(ptr, x) ({ \
(__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), \
sizeof(*(ptr))); \
})
@@ -117,6 +115,8 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
#error "SMP is not supported on this platform"
#endif
#define xchg xchg_relaxed
/*
* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
* them available.
@@ -194,23 +194,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
return oldval;
}
static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
unsigned long ret;
smp_mb();
ret = __cmpxchg(ptr, old, new, size);
smp_mb();
return ret;
}
#define cmpxchg(ptr,o,n) ({ \
(__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
(unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))); \
#define cmpxchg_relaxed(ptr,o,n) ({ \
(__typeof__(*(ptr)))__cmpxchg((ptr), \
(unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))); \
})
static inline unsigned long __cmpxchg_local(volatile void *ptr,
@@ -273,25 +261,6 @@ static inline unsigned long long __cmpxchg64(unsigned long long *ptr,
#define cmpxchg64_local(ptr, o, n) cmpxchg64_relaxed((ptr), (o), (n))
static inline unsigned long long __cmpxchg64_mb(unsigned long long *ptr,
unsigned long long old,
unsigned long long new)
{
unsigned long long ret;
smp_mb();
ret = __cmpxchg64(ptr, old, new);
smp_mb();
return ret;
}
#define cmpxchg64(ptr, o, n) ({ \
(__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \
(unsigned long long)(o), \
(unsigned long long)(n)); \
})
#endif /* __LINUX_ARM_ARCH__ >= 6 */
#endif /* __ASM_ARM_CMPXCHG_H */