[PATCH] atomic: inc_not_zero

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 <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Nick Piggin 2005-11-13 16:07:25 -08:00 • committed by Linus Torvalds
commit 8426e1f6af
23 changed files with 321 additions and 1 deletions

View file

@ -113,6 +113,21 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
return ret;
}
static inline int atomic_add_unless(atomic_t *v, int a, int u)
{
int ret;
unsigned long flags;
local_irq_save(flags);
ret = v->counter;
if (ret != u)
v->counter += a;
local_irq_restore(flags);
return ret != u;
}
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
static __inline__ void atomic_clear_mask(unsigned int mask, atomic_t *v)
{
unsigned long flags;