aboutsummaryrefslogtreecommitdiff
path: root/lib/kref.c
diff options
context:
space:
mode:
authorThomas Hellstrom <thellstrom@vmware.com>2010-11-16 15:21:07 +0100
committerDave Airlie <airlied@redhat.com>2010-11-22 13:25:13 +1000
commitecf7ace9a8450303a987aa8364e53860cd50e554 (patch)
treebbad2c5982c3b76462cbee9e15458072bc80055d /lib/kref.c
parentd6ea88865d3e5b0c62040531310c1f2c6a994f46 (diff)
downloadlinux-linaro-precise-ecf7ace9a8450303a987aa8364e53860cd50e554.tar.gz
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>
Diffstat (limited to 'lib/kref.c')
-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);