author: Miklos Szeredi <miklos@szeredi.hu> 2009-04-14 19:48:41 +0200
committer: Jens Axboe <jens.axboe@oracle.com> 2009-04-15 12:10:12 +0200
commit: 61e0d47c33cc371f725bcda4a47ae0efe652dba8
parent: f8cc774ce4844811a55e2352f1443055e3994e28
Commit Summary:
Diffstat:
1 file changed, 34 insertions, 4 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 4af7aa521813..13414ec45b8d 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -37,6 +37,42 @@
* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
*/
+static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
+{
+ if (pipe->inode)
+ mutex_lock_nested(&pipe->inode->i_mutex, subclass);
+}
+
+void pipe_lock(struct pipe_inode_info *pipe)
+{
+ /*
+ * pipe_lock() nests non-pipe inode locks (for writing to a file)
+ */
+ pipe_lock_nested(pipe, I_MUTEX_PARENT);
+}
+EXPORT_SYMBOL(pipe_lock);
+
+void pipe_unlock(struct pipe_inode_info *pipe)
+{
+ if (pipe->inode)
+ mutex_unlock(&pipe->inode->i_mutex);
+}
+EXPORT_SYMBOL(pipe_unlock);
+
+void pipe_double_lock(struct pipe_inode_info *pipe1,
+ struct pipe_inode_info *pipe2)
+{
+ BUG_ON(pipe1 == pipe2);
+
+ if (pipe1 < pipe2) {
+ 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);
+ }
+}
+
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct pipe_inode_info *pipe)
{
@@ -47,12 +83,10 @@ void pipe_wait(struct pipe_inode_info *pipe)
* is considered a noninteractive wait:
*/
prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
- if (pipe->inode)
- mutex_unlock(&pipe->inode->i_mutex);
+ pipe_unlock(pipe);
schedule();
finish_wait(&pipe->wait, &wait);
- if (pipe->inode)
- mutex_lock(&pipe->inode->i_mutex);
+ pipe_lock(pipe);
}
static int