From 171087646e56809025219199e6c58de2180f5bb1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 17 Aug 2012 20:10:46 -0400
Subject: [PATCH] --- yaml --- r: 322091 b: refs/heads/master c:
 8ad5db8a8ddbe3bd33078863a027011e28f1f4ee h: refs/heads/master i:   322089:
 498043f8657cc6fbf4f5c4ab145341c26aa2b212   322087:
 9bda5f5aaece65344385b567220a72982b30840e v: v3

---
 [refs]                     |  2 +-
 trunk/include/linux/kref.h | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index fc35240fa8fe..23a5672451d1 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 934ad4c235f87dcb9206abdfa22922358999afab
+refs/heads/master: 8ad5db8a8ddbe3bd33078863a027011e28f1f4ee
diff --git a/trunk/include/linux/kref.h b/trunk/include/linux/kref.h
index 9c07dcebded7..65af6887872f 100644
--- a/trunk/include/linux/kref.h
+++ b/trunk/include/linux/kref.h
@@ -18,6 +18,7 @@
 #include <linux/bug.h>
 #include <linux/atomic.h>
 #include <linux/kernel.h>
+#include <linux/mutex.h>
 
 struct kref {
 	atomic_t refcount;
@@ -93,4 +94,21 @@ static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)
 {
 	return kref_sub(kref, 1, release);
 }
+
+static inline int kref_put_mutex(struct kref *kref,
+				 void (*release)(struct kref *kref),
+				 struct mutex *lock)
+{
+	WARN_ON(release == NULL);
+        if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
+		mutex_lock(lock);
+		if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
+			mutex_unlock(lock);
+			return 0;
+		}
+		release(kref);
+		return 1;
+	}
+	return 0;
+}
 #endif /* _KREF_H_ */