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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-13 16:07:24 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-13 18:14:16 -0800
commit4a6dae6d382e9edf3ff440b819e554ed706359bc (patch)
tree2945a5095973e2ecf05b503d6deb859083045b8e /include/asm-sh/atomic.h
parent53e86b91b7ae66d4c2757195cbd42e00d9199cf2 (diff)
[PATCH] atomic: cmpxchg
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>
Diffstat (limited to 'include/asm-sh/atomic.h')
-rw-r--r--include/asm-sh/atomic.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/asm-sh/atomic.h b/include/asm-sh/atomic.h
index 3c4f805da1a..a148c762d36 100644
--- a/include/asm-sh/atomic.h
+++ b/include/asm-sh/atomic.h
@@ -87,6 +87,20 @@ static __inline__ int atomic_sub_return(int i, atomic_t * v)
#define atomic_inc(v) atomic_add(1,(v))
#define atomic_dec(v) atomic_sub(1,(v))
+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 int mask, atomic_t *v)
{
unsigned long flags;