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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-13 16:07:25 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-13 18:14:16 -0800
commit8426e1f6af0fd7f44d040af7263750c5a52f3cc3 (patch)
tree827bd2588c2b73d11cea6869de8ff42dba134375 /include/asm-s390
parent4a6dae6d382e9edf3ff440b819e554ed706359bc (diff)
downloadop-kernel-dev-8426e1f6af0fd7f44d040af7263750c5a52f3cc3.zip
op-kernel-dev-8426e1f6af0fd7f44d040af7263750c5a52f3cc3.tar.gz
[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-s390')
-rw-r--r--include/asm-s390/atomic.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/asm-s390/atomic.h b/include/asm-s390/atomic.h
index 631014d..b3bd4f6 100644
--- a/include/asm-s390/atomic.h
+++ b/include/asm-s390/atomic.h
@@ -200,6 +200,16 @@ atomic_compare_and_swap(int expected_oldval,int new_val,atomic_t *v)
#define atomic_cmpxchg(v, o, n) (atomic_compare_and_swap((o), (n), &((v)->counter)))
+#define atomic_add_unless(v, a, u) \
+({ \
+ int c, old; \
+ c = atomic_read(v); \
+ while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+ c = old; \
+ c != (u); \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
#define smp_mb__before_atomic_dec() smp_mb()
#define smp_mb__after_atomic_dec() smp_mb()
#define smp_mb__before_atomic_inc() smp_mb()
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