Commit b53be254 authored Sep 28, 2023 by Marc Kleine-Budde Committed by Greg Kroah-Hartman Nov 20, 2023

can: dev: can_restart(): don't crash kernel if carrier is OK

[ Upstream commit fe5c9940dfd8ba0c73672dddb30acd1b7a11d4c7 ]

During testing, I triggered a can_restart() with the netif carrier
being OK [1]. The BUG_ON, which checks if the carrier is OK, results
in a fatal kernel crash. This is neither helpful for debugging nor for
a production system.

[1] The root cause is a race condition in can_restart() which will be
fixed in the next patch.

Do not crash the kernel, issue an error message instead, and continue
restarting the CAN device anyway.

Fixes: 39549eef ("can: CAN Network device driver and Netlink interface")
Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-1-91b5c1fd922c@pengutronix.de


Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent a29f012a

drivers/net/can/dev/dev.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -552,7 +552,8 @@ static void can_restart(struct net_device *dev)
		struct can_frame *cf;
		int err;

		BUG_ON(netif_carrier_ok(dev));
		if (netif_carrier_ok(dev))
		netdev_err(dev, "Attempt to restart for bus-off recovery, but carrier is OK?\n");

		/* No synchronization needed because the device is bus-off and
		* no messages can come in or go out.