Bluetooth: Reorganize mutex lock in l2cap_sock_shutdown() (04ba72e6) · Commits · 戴 / test

This commit reorganizes the mutex lock and is now only protecting l2cap_chan_close(). This is now consistent with other places where l2cap_chan_close() is called. If a conn connection exists, call mutex_lock(&conn->chan_lock) before calling l2cap_chan_close() to ensure other L2CAP protocol operations do not interfere. Note that the conn structure has to be protected from being freed as it is possible for the connection to be disconnected whilst the locks are not held. This solution allows the mutex lock to be used even when the connection has just been disconnected. This commit also reduces the scope of chan locking. The only place where chan locking is needed is the call to l2cap_chan_close(chan, 0) which if necessary closes the channel. Therefore, move the l2cap_chan_lock(chan) and l2cap_chan_lock(chan) locking calls to around l2cap_chan_close(chan, 0). This allows __l2cap_wait_ack(sk, chan) to be called with no chan locks being held so L2CAP messaging over the ACL link can be done unimpaired. Signed-off-by:

Dean Jenkins <Dean_Jenkins@mentor.com> Signed-off-by:

Harish Jenny K N <harish_kandiga@mentor.com> Signed-off-by:

Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap_sock.c

+27 −17

Original line number	Diff line number	Diff line
		@@ -1111,6 +1111,8 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
		if (!sk)
		return 0;

		lock_sock(sk);

		if (sk->sk_shutdown)
		goto shutdown_already;

		@@ -1122,25 +1124,37 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
		chan = l2cap_pi(sk)->chan;
		/* prevent chan structure from being freed whilst unlocked */
		l2cap_chan_hold(chan);
		conn = chan->conn;

		BT_DBG("chan %p state %s", chan, state_to_string(chan->state));

		if (conn)
		mutex_lock(&conn->chan_lock);

		l2cap_chan_lock(chan);
		lock_sock(sk);

		if (chan->mode == L2CAP_MODE_ERTM &&
		chan->unacked_frames > 0 &&
		chan->state == BT_CONNECTED)
		err = __l2cap_wait_ack(sk, chan);

		sk->sk_shutdown = SHUTDOWN_MASK;

		release_sock(sk);

		l2cap_chan_lock(chan);
		conn = chan->conn;
		if (conn)
		/* prevent conn structure from being freed */
		l2cap_conn_get(conn);
		l2cap_chan_unlock(chan);

		if (conn)
		/* mutex lock must be taken before l2cap_chan_lock() */
		mutex_lock(&conn->chan_lock);

		l2cap_chan_lock(chan);
		l2cap_chan_close(chan, 0);
		l2cap_chan_unlock(chan);

		if (conn) {
		mutex_unlock(&conn->chan_lock);
		l2cap_conn_put(conn);
		}

		lock_sock(sk);

		if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
		@@ -1148,20 +1162,16 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
		err = bt_sock_wait_state(sk, BT_CLOSED,
		sk->sk_lingertime);

		l2cap_chan_put(chan);
		sock_put(sk);

		shutdown_already:
		if (!err && sk->sk_err)
		err = -sk->sk_err;

		release_sock(sk);
		l2cap_chan_unlock(chan);

		if (conn)
		mutex_unlock(&conn->chan_lock);

		l2cap_chan_put(chan);
		sock_put(sk);

		shutdown_already:
		BT_DBG("err: %d", err);
		BT_DBG("Sock shutdown complete err: %d", err);

		return err;
		}

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