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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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3
include/asm-sparc/atomic.h
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@@ -20,6 +20,7 @@ typedef struct { volatile int counter; } atomic_t;
extern int __atomic_add_return(int, atomic_t *);
extern int atomic_cmpxchg(atomic_t *, int, int);
extern int atomic_add_unless(atomic_t *, int, int);
extern void atomic_set(atomic_t *, int);
#define atomic_read(v) ((v)->counter)
@@ -49,6 +50,8 @@ extern void atomic_set(atomic_t *, int);
#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
/* This is the old 24-bit implementation. It's still used internally
* by some sparc-specific code, notably the semaphore implementation.
*/