can: isotp: remove re-binding of bound socket

JIRA: https://issues.redhat.com/browse/RHEL-80832

commit 72ed3ee
Author: Oliver Hartkopp <socketcan@hartkopp.net>
Date:   Fri Apr 22 10:23:37 2022 +0200

    can: isotp: remove re-binding of bound socket

    As a carry over from the CAN_RAW socket (which allows to change the CAN
    interface while mantaining the filter setup) the re-binding of the
    CAN_ISOTP socket needs to take care about CAN ID address information and
    subscriptions. It turned out that this feature is so limited (e.g. the
    sockopts remain fix) that it finally has never been needed/used.

    In opposite to the stateless CAN_RAW socket the switching of the CAN ID
    subscriptions might additionally lead to an interrupted ongoing PDU
    reception. So better remove this unneeded complexity.

    Fixes: e057dd3 ("can: add ISO 15765-2:2016 transport protocol")
    Link: https://lore.kernel.org/all/20220422082337.1676-1-socketcan@hartkopp.net
    Cc: stable@vger.kernel.org
    Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
    Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Signed-off-by: Radu Rendec <rrendec@redhat.com>

Author: rrendec

net/can/isotp.c

@@ -1182,6 +1182,11 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 
 	lock_sock(sk);
 
+	if (so->bound) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	/* do not register frame reception for functional addressing */
 	if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
 		do_rx_reg = 0;
@@ -1192,10 +1197,6 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 		goto out;
 	}
 
-	if (so->bound && addr->can_ifindex == so->ifindex &&
-	    rx_id == so->rxid && tx_id == so->txid)
-		goto out;
-
 	dev = dev_get_by_index(net, addr->can_ifindex);
 	if (!dev) {
 		err = -ENODEV;
@@ -1230,22 +1231,6 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 
 	dev_put(dev);
 
-	if (so->bound && do_rx_reg) {
-		/* unregister old filter */
-		if (so->ifindex) {
-			dev = dev_get_by_index(net, so->ifindex);
-			if (dev) {
-				can_rx_unregister(net, dev, so->rxid,
-						  SINGLE_MASK(so->rxid),
-						  isotp_rcv, sk);
-				can_rx_unregister(net, dev, so->txid,
-						  SINGLE_MASK(so->txid),
-						  isotp_rcv_echo, sk);
-				dev_put(dev);
-			}
-		}
-	}
-
 	/* switch to new settings */
 	so->ifindex = ifindex;
 	so->rxid = rx_id;