[ 3.5.y.z extended stable ] Patch "Bluetooth: Add missing lock nesting notation" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    Bluetooth: Add missing lock nesting notation

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 8f1873b8eac1ff67ab26fd944002fdbdaaa2e8cf Mon Sep 17 00:00:00 2001
From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
Date: Tue, 20 Nov 2012 23:25:54 -0200
Subject: [PATCH] Bluetooth: Add missing lock nesting notation

commit dc2a0e20fbc85a71c63aa4330b496fda33f6bf80 upstream.

This patch fixes the following report, it happens when accepting rfcomm
connections:

[  228.165378] =============================================
[  228.165378] [ INFO: possible recursive locking detected ]
[  228.165378] 3.7.0-rc1-00536-gc1d5dc4 #120 Tainted: G        W
[  228.165378] ---------------------------------------------
[  228.165378] bluetoothd/1341 is trying to acquire lock:
[  228.165378]  (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+...}, at:
[<ffffffffa0000aa0>] bt_accept_dequeue+0xa0/0x180 [bluetooth]
[  228.165378]
[  228.165378] but task is already holding lock:
[  228.165378]  (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+...}, at:
[<ffffffffa0205118>] rfcomm_sock_accept+0x58/0x2d0 [rfcomm]
[  228.165378]
[  228.165378] other info that might help us debug this:
[  228.165378]  Possible unsafe locking scenario:
[  228.165378]
[  228.165378]        CPU0
[  228.165378]        ----
[  228.165378]   lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
[  228.165378]   lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
[  228.165378]
[  228.165378]  *** DEADLOCK ***
[  228.165378]
[  228.165378]  May be due to missing lock nesting notation

Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/bluetooth/rfcomm/sock.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 2df6956..20bd148 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -486,7 +486,7 @@ static int rfcomm_sock_accept(struct socket *sock, struct socket *newsock, int f
 	long timeo;
 	int err = 0;

-	lock_sock(sk);
+	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);

 	if (sk->sk_type != SOCK_STREAM) {
 		err = -EINVAL;
@@ -523,7 +523,7 @@ static int rfcomm_sock_accept(struct socket *sock, struct socket *newsock, int f

 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
-		lock_sock(sk);
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 	}
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(sk_sleep(sk), &wait);
--
1.7.9.5