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[PATCH] atomic: cmpxchg

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Introduce an atomic_cmpxchg operation.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin
2005-11-13 16:07:24 -08:00
committed by Linus Torvalds
parent 53e86b91b7
commit 4a6dae6d38
23 changed files with 169 additions and 5 deletions
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13
include/asm-cris/atomic.h
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@@ -123,6 +123,19 @@ static inline int atomic_inc_and_test(volatile atomic_t *v)
return retval;
}
static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
unsigned long flags;
cris_atomic_save(v, flags);
ret = v->counter;
if (likely(ret == old))
v->counter = new;
cris_atomic_restore(v, flags);
return ret;
}
/* Atomic operations are already serializing */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()