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[2a02:8388:e103:2700:a09a:f854:4544:3d0d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45626cde7aasm13247185e9.1.2025.07.15.07.24.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Jul 2025 07:24:24 -0700 (PDT) Message-ID: Date: Tue, 15 Jul 2025 16:24:22 +0200 Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] can: gs_usb: fix kernel oops during restart To: Marc Kleine-Budde Cc: mailhol.vincent@wanadoo.fr, linux-kernel@vger.kernel.org, linux-can@vger.kernel.org References: <20250714175520.307467-1-andrey.lalaev@gmail.com> <20250715-almond-zebra-of-perception-9d2e6c-mkl@pengutronix.de> Content-Language: en-GB From: Andrei Lalaev In-Reply-To: <20250715-almond-zebra-of-perception-9d2e6c-mkl@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 15.07.2025 11:37, Marc Kleine-Budde wrote: > 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. Hi Mark, 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; > > regards, > Marc > Thanks for the patch. As expected, it fixes the kernel OOPS, but the interface never leaves the BUS_OFF state. -- Best regards, Andrei Lalaev