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author | Jiri Kosina <jkosina@suse.cz> | 2010-12-10 15:19:18 +0100 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2010-12-10 15:19:18 +0100 |
commit | 2ade0c1d9d93b7642212657ef76f4a1e30233711 (patch) | |
tree | 63bc720c0ffe5f4760cac4ed617b9870b050175e /include/linux/atomic.h | |
parent | 504499f22c08a03e2e19dc88d31aa0ecd2ac815e (diff) | |
parent | 6313e3c21743cc88bb5bd8aa72948ee1e83937b6 (diff) | |
download | op-kernel-dev-2ade0c1d9d93b7642212657ef76f4a1e30233711.zip op-kernel-dev-2ade0c1d9d93b7642212657ef76f4a1e30233711.tar.gz |
Merge branch 'master' into upstream
Diffstat (limited to 'include/linux/atomic.h')
-rw-r--r-- | include/linux/atomic.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h new file mode 100644 index 0000000..96c038e --- /dev/null +++ b/include/linux/atomic.h @@ -0,0 +1,37 @@ +#ifndef _LINUX_ATOMIC_H +#define _LINUX_ATOMIC_H +#include <asm/atomic.h> + +/** + * atomic_inc_not_zero_hint - increment if not null + * @v: pointer of type atomic_t + * @hint: probable value of the atomic before the increment + * + * This version of atomic_inc_not_zero() gives a hint of probable + * value of the atomic. This helps processor to not read the memory + * before doing the atomic read/modify/write cycle, lowering + * number of bus transactions on some arches. + * + * Returns: 0 if increment was not done, 1 otherwise. + */ +#ifndef atomic_inc_not_zero_hint +static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint) +{ + int val, c = hint; + + /* sanity test, should be removed by compiler if hint is a constant */ + if (!hint) + return atomic_inc_not_zero(v); + + do { + val = atomic_cmpxchg(v, c, c + 1); + if (val == c) + return 1; + c = val; + } while (c); + + return 0; +} +#endif + +#endif /* _LINUX_ATOMIC_H */ |