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[PATCH] atomic: inc_not_zero

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Introduce an atomic_inc_not_zero operation.  Make this a special case of
atomic_add_unless because lockless pagecache actually wants
atomic_inc_not_negativeone due to its offset refcount.

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 16:07:25 -08:00
committed by Linus Torvalds
parent 4a6dae6d38
commit 8426e1f6af
23 changed files with 321 additions and 1 deletions
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15
arch/sparc/lib/atomic32.c
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@@ -53,6 +53,21 @@ int atomic_cmpxchg(atomic_t *v, int old, int new)
return ret;
}
int atomic_add_unless(atomic_t *v, int a, int u)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
ret = v->counter;
if (ret != u)
v->counter += a;
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
return ret != u;
}
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
/* Atomic operations are already serializing */
void atomic_set(atomic_t *v, int i)
{
unsigned long flags;