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author | Thomas Hellstrom <thellstrom@vmware.com> | 2010-11-16 15:21:07 +0100 |
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committer | Dave Airlie <airlied@redhat.com> | 2010-11-22 13:25:13 +1000 |
commit | ecf7ace9a8450303a987aa8364e53860cd50e554 (patch) | |
tree | bbad2c5982c3b76462cbee9e15458072bc80055d | |
parent | d6ea88865d3e5b0c62040531310c1f2c6a994f46 (diff) | |
download | linux-3.10-ecf7ace9a8450303a987aa8364e53860cd50e554.tar.gz linux-3.10-ecf7ace9a8450303a987aa8364e53860cd50e554.tar.bz2 linux-3.10-ecf7ace9a8450303a987aa8364e53860cd50e554.zip |
kref: Add a kref_sub function
Makes it possible to optimize batched multiple unrefs.
Initial user will be drivers/gpu/ttm which accumulates unrefs to be
processed outside of atomic code.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r-- | include/linux/kref.h | 2 | ||||
-rw-r--r-- | lib/kref.c | 30 |
2 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h index 6cc38fc07ab..d4a62ab2ee5 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -24,5 +24,7 @@ struct kref { void kref_init(struct kref *kref); void kref_get(struct kref *kref); int kref_put(struct kref *kref, void (*release) (struct kref *kref)); +int kref_sub(struct kref *kref, unsigned int count, + void (*release) (struct kref *kref)); #endif /* _KREF_H_ */ diff --git a/lib/kref.c b/lib/kref.c index d3d227a08a4..3efb882b11d 100644 --- a/lib/kref.c +++ b/lib/kref.c @@ -62,6 +62,36 @@ int kref_put(struct kref *kref, void (*release)(struct kref *kref)) return 0; } + +/** + * kref_sub - subtract a number of refcounts for object. + * @kref: object. + * @count: Number of recounts to subtract. + * @release: pointer to the function that will clean up the object when the + * last reference to the object is released. + * This pointer is required, and it is not acceptable to pass kfree + * in as this function. + * + * Subtract @count from the refcount, and if 0, call release(). + * Return 1 if the object was removed, otherwise return 0. Beware, if this + * function returns 0, you still can not count on the kref from remaining in + * memory. Only use the return value if you want to see if the kref is now + * gone, not present. + */ +int kref_sub(struct kref *kref, unsigned int count, + void (*release)(struct kref *kref)) +{ + WARN_ON(release == NULL); + WARN_ON(release == (void (*)(struct kref *))kfree); + + if (atomic_sub_and_test((int) count, &kref->refcount)) { + release(kref); + return 1; + } + return 0; +} + EXPORT_SYMBOL(kref_init); EXPORT_SYMBOL(kref_get); EXPORT_SYMBOL(kref_put); +EXPORT_SYMBOL(kref_sub); |