From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 21 Jul 2009 08:09:23 +0000 (+0200)
Subject: lockdep: Fix lockdep annotation for pipe_double_lock()
X-Git-Tag: v2.6.31-rc4~2^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=023d43c7b5a23a81fe8afa9f37296f8ed4be11fb;p=platform%2Fkernel%2Flinux-3.10.git

lockdep: Fix lockdep annotation for pipe_double_lock()

The presumed use of the pipe_double_lock() routine is to lock 2 locks in
a deadlock free way by ordering the locks by their address. However it
fails to keep the specified lock classes in order and explicitly
annotates a deadlock.

Rectify this.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
LKML-Reference: <1248163763.15751.11098.camel@twins>
---

diff --git a/fs/pipe.c b/fs/pipe.c
index f7dd21a..52c4151 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -68,8 +68,8 @@ void pipe_double_lock(struct pipe_inode_info *pipe1,
 		pipe_lock_nested(pipe1, I_MUTEX_PARENT);
 		pipe_lock_nested(pipe2, I_MUTEX_CHILD);
 	} else {
-		pipe_lock_nested(pipe2, I_MUTEX_CHILD);
-		pipe_lock_nested(pipe1, I_MUTEX_PARENT);
+		pipe_lock_nested(pipe2, I_MUTEX_PARENT);
+		pipe_lock_nested(pipe1, I_MUTEX_CHILD);
 	}
 }