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

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Message-ID: <20250715-smart-ultra-avocet-d7937a-mkl@pengutronix.de>
Date: Tue, 15 Jul 2025 16:29:14 +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 15.07.2025 16:24:22, Andrei Lalaev wrote:
> I was also surprised because this callback isn't marked as mandatory
> and that there are no additional checks.
> 
> > 
> > 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;
> 
> Thanks for the patch. As expected, it fixes the kernel OOPS,
> but the interface never leaves the BUS_OFF state.

Which device and which firmware are you using?

The gs_usb/candlelight interface is un(der)defined when it comes to
bus-off handling.

I think the original candlelight with the stm32f072 does auto bus-off
recovery. Not sure about the candlelight on stm32g0b1.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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