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| author | Jerome Marchand <jmarchan@redhat.com> | 2011-01-05 16:57:37 +0100 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2011-01-05 16:57:37 +0100 |
| commit | e4a683c899cd5a49f8d684a054c95bd115a0c005 (patch) | |
| tree | c7e79e24199a5ed34a488b06cfd3fa890637db7d | |
| parent | a6e8dc46ff0b7defbfa4f29a71aee263377ec573 (diff) | |
| download | linux-e4a683c899cd5a49f8d684a054c95bd115a0c005.tar.bz2 | |
kref: add kref_test_and_get
Add kref_test_and_get() function, which atomically add a reference only if
refcount is not zero. This prevent to add a reference to an object that is
already being removed.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| -rw-r--r-- | include/linux/kref.h | 1 | ||||
| -rw-r--r-- | lib/kref.c | 12 |
2 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h index 6cc38fc07ab7..90b9e44abf54 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -23,6 +23,7 @@ struct kref { void kref_init(struct kref *kref); void kref_get(struct kref *kref); +int kref_test_and_get(struct kref *kref); int kref_put(struct kref *kref, void (*release) (struct kref *kref)); #endif /* _KREF_H_ */ diff --git a/lib/kref.c b/lib/kref.c index d3d227a08a4b..e7a6e1067122 100644 --- a/lib/kref.c +++ b/lib/kref.c @@ -37,6 +37,18 @@ void kref_get(struct kref *kref) } /** + * kref_test_and_get - increment refcount for object only if refcount is not + * zero. + * @kref: object. + * + * Return non-zero if the refcount was incremented, 0 otherwise + */ +int kref_test_and_get(struct kref *kref) +{ + return atomic_inc_not_zero(&kref->refcount); +} + +/** * kref_put - decrement refcount for object. * @kref: object. * @release: pointer to the function that will clean up the object when the |