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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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31
include/asm-arm/atomic.h
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@@ -80,6 +80,23 @@ static inline int atomic_sub_return(int i, atomic_t *v)
return result;
}
static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
{
u32 oldval, res;
do {
__asm__ __volatile__("@ atomic_cmpxchg\n"
"ldrex %1, [%2]\n"
"teq %1, %3\n"
"strexeq %0, %4, [%2]\n"
: "=&r" (res), "=&r" (oldval)
: "r" (&ptr->counter), "Ir" (old), "r" (new)
: "cc");
} while (res);
return oldval;
}
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long tmp, tmp2;
@@ -131,6 +148,20 @@ static inline int atomic_sub_return(int i, atomic_t *v)
return val;
}
static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
unsigned long flags;
local_irq_save(flags);
ret = v->counter;
if (likely(ret == old))
v->counter = new;
local_irq_restore(flags);
return ret;
}
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long flags;