Merge to Fedora kernel-2.6.18-1.2224_FC5 patched with stable patch-2.6.18.1-vs2.0...

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

diff --git a/lib/kref.c b/lib/kref.c
index ee141ad..4a467fa 100644 (file)
--- a/lib/kref.c
+++ b/lib/kref.c
@@ -11,48 +11,57 @@
  *
  */
 
-/* #define DEBUG */
-
 #include <linux/kref.h>
 #include <linux/module.h>
 
 /**
  * kref_init - initialize object.
  * @kref: object in question.
- * @release: pointer to a function that will clean up the object
- *          when the last reference to the object is released.
- *          This pointer is required.
  */
-void kref_init(struct kref *kref, void (*release)(struct kref *kref))
+void kref_init(struct kref *kref)
 {
-       WARN_ON(release == NULL);
        atomic_set(&kref->refcount,1);
-       kref->release = release;
 }
 
 /**
  * kref_get - increment refcount for object.
  * @kref: object.
  */
-struct kref *kref_get(struct kref *kref)
+void kref_get(struct kref *kref)
 {
        WARN_ON(!atomic_read(&kref->refcount));
        atomic_inc(&kref->refcount);
-       return kref;
 }
 
 /**
  * kref_put - decrement refcount for object.
  * @kref: object.
+ * @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.
  *
- * Decrement the refcount, and if 0, call kref->release().
+ * 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)
+int kref_put(struct kref *kref, void (*release)(struct kref *kref))
 {
-       if (atomic_dec_and_test(&kref->refcount)) {
-               pr_debug("kref cleaning up\n");
-               kref->release(kref);
+       WARN_ON(release == NULL);
+       WARN_ON(release == (void (*)(struct kref *))kfree);
+
+       /*
+        * 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);