From: Johan Hedberg Date: Wed, 12 Nov 2014 07:15:50 +0000 (+0200) Subject: Bluetooth: Fix l2cap_sock_teardown_cb lockdep warning X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f03567040cbf874834c9e3e52b72fdcb672b9bbb;p=linux-beck.git Bluetooth: Fix l2cap_sock_teardown_cb lockdep warning Any code calling bt_accept_dequeue() to get a new child socket from a server socket should use lock_sock_nested to avoid lockdep warnings due to the parent and child sockets being locked at the same time. The l2cap_sock_accept() function is already doing this correctly but a second place calling bt_accept_dequeue() is the code path from l2cap_sock_teardown_cb() that calls l2cap_sock_cleanup_listen(). This patch fixes the proper nested locking annotation and thereby avoids the following style of lockdep warning. [ +0.000224] [ INFO: possible recursive locking detected ] [ +0.000222] 3.17.0+ #1153 Not tainted [ +0.000130] --------------------------------------------- [ +0.000227] l2cap-tester/562 is trying to acquire lock: [ +0.000210] (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+...}, at: [] bt_accept_dequeue+0x68/0x11b [ +0.000467] but task is already holding lock: [ +0.000186] (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+...}, at: [] lock_sock+0xa/0xc [ +0.000421] other info that might help us debug this: [ +0.000199] Possible unsafe locking scenario: [ +0.000117] CPU0 [ +0.000000] ---- [ +0.000000] lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP); [ +0.000000] lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP); [ +0.000000] *** DEADLOCK *** Signed-off-by: Johan Hedberg Signed-off-by: Marcel Holtmann --- diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 31f106e61ca2..ad1cf82fee02 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1246,7 +1246,7 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err) struct sock *sk = chan->data; struct sock *parent; - lock_sock(sk); + lock_sock_nested(sk, SINGLE_DEPTH_NESTING); parent = bt_sk(sk)->parent;