linux-kernel - Re: [RFC PATCH] can: gs_usb: fix kernel oops during restart

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Message-ID: <20250715-almond-zebra-of-perception-9d2e6c-mkl@pengutronix.de>
Date: Tue, 15 Jul 2025 11:37:15 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Andrei Lalaev <andrey.lalaev@...il.com>
Cc: mailhol.vincent@...adoo.fr, linux-kernel@...r.kernel.org, 
	linux-can@...r.kernel.org
Subject: Re: [RFC PATCH] can: gs_usb: fix kernel oops during restart

On 14.07.2025 19:55:02, Andrei Lalaev wrote:
> When CAN adapter in BUS_OFF state and "can_restart" is called,
> it causes the following kernel oops:

Doh!

I wonder why no one stumbled over this before. That's a systematic
problem for all CAN drivers that don't implement this callback.

What about this fix?

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 13826e8a707b..94603c9eb4aa 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -285,6 +285,12 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
         }
 
         if (data[IFLA_CAN_RESTART_MS]) {
+                if (!priv->do_set_mode) {
+                        NL_SET_ERR_MSG(extack,
+                                       "device doesn't support restart from Bus Off");
+                        return -EOPNOTSUPP;
+                }
+
                 /* Do not allow changing restart delay while running */
                 if (dev->flags & IFF_UP)
                         return -EBUSY;
@@ -292,6 +298,12 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
         }
 
         if (data[IFLA_CAN_RESTART]) {
+                if (!priv->do_set_mode) {
+                        NL_SET_ERR_MSG(extack,
+                                       "device doesn't support restart from Bus Off");
+                        return -EOPNOTSUPP;
+                }
+
                 /* Do not allow a restart while not running */
                 if (!(dev->flags & IFF_UP))
                         return -EINVAL;

regards,
Marc

-- 
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