Date:   Thu, 2 Feb 2023 16:16:22 +0100
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc:     linux-can@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] can: etas_es58x: do not send disable channel command if
 device is unplugged
Message-ID: <20230202151622.sotqfwmgwwtgv4dl@pengutronix.de>
References: <20230128133815.1796221-1-mailhol.vincent@wanadoo.fr>
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On 28.01.2023 22:38:15, Vincent Mailhol wrote:
> When turning the network interface down, es58x_stop() is called and
> will send a command to the ES58x device to disable the channel
> c.f. es58x_ops::disable_channel().
>=20
> However, if the device gets unplugged while the network interface is
> still up, es58x_ops::disable_channel() will obviously fail to send the
> URB command and the driver emits below error message:
>=20
>   es58x_submit_urb: USB send urb failure: -ENODEV
>=20
> Check the usb device state before sending the disable channel command
> in order to silence above error message.
>=20
> Update the documentation of es58x_stop() accordingly.
>=20
> The check being added in es58x_stop() is:
>=20
>   	if (es58x_dev->udev->state >=3D USB_STATE_UNAUTHENTICATED)
>=20
> This is just the negation of the check done in usb_submit_urb()[1].
>=20
> [1] usb_submit_urb(), verify usb device's state.
> Link: https://elixir.bootlin.com/linux/v6.1/source/drivers/usb/core/urb.c=
#L384
>=20
> Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CA=
N USB interfaces")
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
> As far as I know, there doesn't seem to be an helper function to check
> udev->state values. If anyone is aware of such helper function, let me
> know..

The constant USB_STATE_UNAUTHENTICATED is not used very often in the
kernel. Maybe Greg can point out what is best to do here.

regards,
Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
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