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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-11-13 16:07:24 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-13 18:14:16 -0800 |
| commit | 4a6dae6d382e9edf3ff440b819e554ed706359bc (patch) | |
| tree | 2945a5095973e2ecf05b503d6deb859083045b8e /arch/sparc/lib | |
| parent | 53e86b91b7ae66d4c2757195cbd42e00d9199cf2 (diff) | |
| download | linux-4a6dae6d382e9edf3ff440b819e554ed706359bc.tar.bz2 | |
[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 'arch/sparc/lib')
| -rw-r--r-- | arch/sparc/lib/atomic32.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c index 2e64e8c3e8e5..be46f6545184 100644 --- a/arch/sparc/lib/atomic32.c +++ b/arch/sparc/lib/atomic32.c @@ -37,17 +37,28 @@ int __atomic_add_return(int i, atomic_t *v) spin_unlock_irqrestore(ATOMIC_HASH(v), flags); return ret; } +EXPORT_SYMBOL(__atomic_add_return); -void atomic_set(atomic_t *v, int i) +int atomic_cmpxchg(atomic_t *v, int old, int new) { + int ret; unsigned long flags; - spin_lock_irqsave(ATOMIC_HASH(v), flags); - v->counter = i; + spin_lock_irqsave(ATOMIC_HASH(v), flags); + ret = v->counter; + if (likely(ret == old)) + v->counter = new; spin_unlock_irqrestore(ATOMIC_HASH(v), flags); + return ret; } -EXPORT_SYMBOL(__atomic_add_return); -EXPORT_SYMBOL(atomic_set); +void atomic_set(atomic_t *v, int i) +{ + unsigned long flags; + spin_lock_irqsave(ATOMIC_HASH(v), flags); + v->counter = i; + spin_unlock_irqrestore(ATOMIC_HASH(v), flags); +} +EXPORT_SYMBOL(atomic_set); |