[PATCH net] can: rockchip_canfd: stop bus-off restart before closing the device

[Cunhao Lu]

Hi Marc,

> AFAICS this is a systematic problem and should IMHO not worked around in
> one driver only.

Agreed. I initially only noticed the problem in the Rockchip CAN-FD
driver and did not consider the common CAN code.

> netif_running() tests __LINK_STATE_START, which is removed in
> __dev_close_many() prior to calling the driver's ndo_stop().
>
> Can we make use of netif_running() prior to calling do_set_mode(dev,
> CAN_MODE_START)? from can_restart()?

If you have no objections, I think it would be better to put the
netif_running() check after the existing !priv->do_set_mode check and
before netif_carrier_ok():

        if (!priv->do_set_mode)
                return -EOPNOTSUPP;

        if (!netif_running(dev))
                return -ENETDOWN;

This would preserve the existing error precedence for devices that do
not support restart.

> can_bus_off() should not schedule_delayed_work() if !netif_running().

Agreed. Although this would change the behavior of some drivers, I think
it should help improve stability.

> We still have to call cancel_delayed_work_sync(&priv->can.restart_work)
> from each driver, though.

I can make changes to the other drivers. However, I do not have the
corresponding hardware and would not be able to test the changes on
real devices, so I am concerned about the risk. I would like to confirm:
do I need to audit and fix the restart behavior of every CAN device
driver?

> What do you think?

I will address these comments in v2. Thanks for your review.

Regards,
Cunhao Lu