mtd: fix race in cfi_cmdset_0001 driver

[mv-sheeva.git] / lib / kref.c

diff --git a/lib/kref.c b/lib/kref.c
index e7a6e106712231ba43b0aa426bcfd003ce8409a7..3efb882b11db0ce3255b3163029989a96bf90713 100644 (file)
--- a/lib/kref.c
+++ b/lib/kref.c
@@ -37,37 +37,54 @@ void kref_get(struct kref *kref)
 }
 
 /**
- * kref_test_and_get - increment refcount for object only if refcount is not
- * zero.
+ * 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.
  *
- * Return non-zero if the refcount was incremented, 0 otherwise
+ * 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.
  */
-int kref_test_and_get(struct kref *kref)
+int kref_put(struct kref *kref, void (*release)(struct kref *kref))
 {
-       return atomic_inc_not_zero(&kref->refcount);
+       WARN_ON(release == NULL);
+       WARN_ON(release == (void (*)(struct kref *))kfree);
+
+       if (atomic_dec_and_test(&kref->refcount)) {
+               release(kref);
+               return 1;
+       }
+       return 0;
 }
 
+
 /**
- * kref_put - decrement refcount for object.
+ * 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.
  *
- * Decrement the refcount, and if 0, call release().
+ * 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_put(struct kref *kref, void (*release)(struct kref *kref))
+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_dec_and_test(&kref->refcount)) {
+       if (atomic_sub_and_test((int) count, &kref->refcount)) {
                release(kref);
                return 1;
        }
@@ -77,3 +94,4 @@ int kref_put(struct kref *kref, void (*release)(struct kref *kref))
 EXPORT_SYMBOL(kref_init);
 EXPORT_SYMBOL(kref_get);
 EXPORT_SYMBOL(kref_put);
+EXPORT_SYMBOL(kref_sub);