From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Date: Wed, 21 Nov 2012 01:25:54 +0000 (-0200)
Subject: Bluetooth: Add missing lock nesting notation
X-Git-Tag: v3.2.36~71
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=37021f68aa5cfe2b838bea7dfdeae99d7c9bdc6e;p=karo-tx-linux.git

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@collabora.co.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 7ee4eaded5d6..14c48647958b 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);