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authorChris Wilson <chris@chris-wilson.co.uk>2010-12-16 21:02:15 +0000
committerChris Wilson <chris@chris-wilson.co.uk>2010-12-16 21:02:15 +0000
commitd8c58fabd75021cdd99abcd96513cb088d41092b (patch)
treef6554ecfb27c0d50f5ae6acae3a7077282813cab /lib
parent9c04f015ebc2cc2cca5a4a576deb82a311578edc (diff)
parentb08ebe7e776e5be0271ed1e1bbb384e1f29dd117 (diff)
downloadlinux-linaro-android-d8c58fabd75021cdd99abcd96513cb088d41092b.tar.gz
Merge remote branch 'airlied/drm-core-next' into drm-intel-next
Diffstat (limited to 'lib')
-rw-r--r--lib/kref.c30
1 files changed, 30 insertions, 0 deletions
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);