Comment # 1 on bug 1205597 from Jiri Slaby

Does this help? I don't understand why they think the CAN net device is UP at
tty close and so ndo_stop will be always called to flush the tx work. IMO it is
not called.

--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -870,6 +870,8 @@ static void slcan_close(struct tty_struct *tty)
         */
        unregister_candev(sl->dev);

+       flush_work(&sl->tx_work);
+
        /* Mark channel as dead */
        spin_lock_bh(&sl->lock);
        tty->disc_data = NULL;