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x86, perfcounters: add atomic64_xchg() 

Complete atomic64_t support on the 32-bit side by adding atomic64_xch().

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090406094518.445450972@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-04-07 11:30:17 +02:00
parent 6278af660f
commit 98c2aaf8be
1 changed files with 23 additions and 5 deletions
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28
arch/x86/include/asm/atomic_32.h
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@ -290,6 +290,28 @@ atomic64_cmpxchg(atomic64_t *ptr, unsigned long long old_val,
return cmpxchg8b(&ptr->counter, old_val, new_val);
}
/**
* atomic64_xchg - xchg atomic64 variable
* @ptr: pointer to type atomic64_t
* @new_val: value to assign
* @old_val: old value that was there
*
* Atomically xchgs the value of @ptr to @new_val and returns
* the old value.
*/
static inline unsigned long long
atomic64_xchg(atomic64_t *ptr, unsigned long long new_val)
{
unsigned long long old_val;
do {
old_val = atomic_read(ptr);
} while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
return old_val;
}
/**
* atomic64_set - set atomic64 variable
* @ptr: pointer to type atomic64_t
@ -299,11 +321,7 @@ atomic64_cmpxchg(atomic64_t *ptr, unsigned long long old_val,
*/
static inline void atomic64_set(atomic64_t *ptr, unsigned long long new_val)
{
unsigned long long old_val;
do {
old_val = atomic_read(ptr);
} while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
atomic64_xchg(ptr, new_val);
}
/**