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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-13 19:07:25 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-13 21:14:16 -0500
commit8426e1f6af0fd7f44d040af7263750c5a52f3cc3 (patch)
tree827bd2588c2b73d11cea6869de8ff42dba134375 /include/asm-powerpc
parent4a6dae6d382e9edf3ff440b819e554ed706359bc (diff)
[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 <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-powerpc')
-rw-r--r--include/asm-powerpc/atomic.h25
1 files changed, 25 insertions, 0 deletions
diff --git a/include/asm-powerpc/atomic.h b/include/asm-powerpc/atomic.h
index 37205faa9d7c..ec4b14468959 100644
--- a/include/asm-powerpc/atomic.h
+++ b/include/asm-powerpc/atomic.h
@@ -166,6 +166,31 @@ static __inline__ int atomic_dec_return(atomic_t *v)
166 166
167#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) 167#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
168 168
169/**
170 * atomic_add_unless - add unless the number is a given value
171 * @v: pointer of type atomic_t
172 * @a: the amount to add to v...
173 * @u: ...unless v is equal to u.
174 *
175 * Atomically adds @a to @v, so long as it was not @u.
176 * Returns non-zero if @v was not @u, and zero otherwise.
177 */
178#define atomic_add_unless(v, a, u) \
179({ \
180 int c, old; \
181 c = atomic_read(v); \
182 for (;;) { \
183 if (unlikely(c == (u))) \
184 break; \
185 old = atomic_cmpxchg((v), c, c + (a)); \
186 if (likely(old == c)) \
187 break; \
188 c = old; \
189 } \
190 c != (u); \
191})
192#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
193
169#define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0) 194#define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0)
170#define atomic_dec_and_test(v) (atomic_dec_return((v)) == 0) 195#define atomic_dec_and_test(v) (atomic_dec_return((v)) == 0)
171 196