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[S390] percpu: implement arch specific irqsafe_cpu_ops

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Implement arch specific irqsafe_cpu ops. The arch specific ops do not
disable/enable interrupts since that is an expensive operation. Instead
we disable preemption and perform a compare and swap loop.
Since on server distros (the ones we care about) preemption is disabled
the preempt_disable()/preempt_enable() pair is a nop.
In the end this code should be faster than the generic one.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens
2011-05-23 10:24:32 +02:00
committed by Martin Schwidefsky
parent add7490c27
commit 4c2241fd42
2 changed files with 68 additions and 1 deletions
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arch/s390/include/asm/cmpxchg.h
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@@ -167,7 +167,6 @@ static inline unsigned long __cmpxchg(void *ptr, unsigned long old,
#ifdef CONFIG_64BIT
#define cmpxchg64(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
cmpxchg((ptr), (o), (n)); \
})
#else /* CONFIG_64BIT */