Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff

[linux-2.6.git] / lib / kref.c

diff --git a/lib/kref.c b/lib/kref.c
index 2218b7a..4a467fa 100644 (file)
--- a/lib/kref.c
+++ b/lib/kref.c
@@ -42,14 +42,26 @@ void kref_get(struct kref *kref)
  *          in as this function.
  *
  * Decrement 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.
  */
-void kref_put(struct kref *kref, void (*release) (struct kref *kref))
+int kref_put(struct kref *kref, void (*release)(struct kref *kref))
 {
        WARN_ON(release == NULL);
        WARN_ON(release == (void (*)(struct kref *))kfree);
 
-       if (atomic_dec_and_test(&kref->refcount))
+       /*
+        * if current count is one, we are the last user and can release object
+        * right now, avoiding an atomic operation on 'refcount'
+        */
+       if ((atomic_read(&kref->refcount) == 1) ||
+           (atomic_dec_and_test(&kref->refcount))) {
                release(kref);
+               return 1;
+       }
+       return 0;
 }
 
 EXPORT_SYMBOL(kref_init);