From abe84903a8efc6b83fa92161429e0e3a28bde15c Mon Sep 17 00:00:00 2001 From: Johan Hedberg Date: Wed, 12 Nov 2014 22:22:21 +0200 Subject: Bluetooth: Use proper nesting annotation for l2cap_chan lock By default lockdep considers all L2CAP channels equal. This would mean that we get warnings if a channel is locked when another one's lock is tried to be acquired in the same thread. This kind of inter-channel locking dependencies exist in the form of parent-child channels as well as any channel wishing to elevate the security by requesting procedures on the SMP channel. To eliminate the chance for these lockdep warnings we introduce a nesting level for each channel and use that when acquiring the channel lock. For now there exists the earlier mentioned three identified categories: SMP, "normal" channels and parent channels (i.e. those in BT_LISTEN state). The nesting level is defined as atomic_t since we need access to it before the lock is actually acquired. Signed-off-by: Johan Hedberg Signed-off-by: Marcel Holtmann --- net/bluetooth/l2cap_sock.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'net/bluetooth/l2cap_sock.c') diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index ad1cf82fee02..f1a51564b8fd 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -285,6 +285,12 @@ static int l2cap_sock_listen(struct socket *sock, int backlog) sk->sk_max_ack_backlog = backlog; sk->sk_ack_backlog = 0; + /* Listening channels need to use nested locking in order not to + * cause lockdep warnings when the created child channels end up + * being locked in the same thread as the parent channel. + */ + atomic_set(&chan->nesting, L2CAP_NESTING_PARENT); + chan->state = BT_LISTEN; sk->sk_state = BT_LISTEN; @@ -1497,6 +1503,9 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent) l2cap_chan_set_defaults(chan); } + /* Set default lock nesting level */ + atomic_set(&chan->nesting, L2CAP_NESTING_NORMAL); + /* Default config options */ chan->flush_to = L2CAP_DEFAULT_FLUSH_TO; -- cgit v1.2.3