Re: [PATCH v3] can: etas_es58x: fix error handling

Vincent MAILHOL
2021-11-15T09:15:46Z

On Mon. 15 Nov 2021 at 17:37, Pavel Skripkin <paskripkin@gmail.com> wrote:
> When register_candev() fails there are 2 possible device states:
> NETREG_UNINITIALIZED and NETREG_UNREGISTERED. None of them are suitable
> for calling unregister_candev(), because of following checks in
> unregister_netdevice_many():
>
> if (dev->reg_state == NETREG_UNINITIALIZED)
> WARN_ON(1);
> ...
> BUG_ON(dev->reg_state != NETREG_REGISTERED);
>
> To avoid possible BUG_ON or WARN_ON let's free current netdev before
> returning from es58x_init_netdev() and leave others (registered)
> net devices for es58x_free_netdevs().
>
> Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces")
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>

Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

> ---
>
> Changes in v3:
> - Moved back es58x_dev->netdev[channel_idx] initialization,
> since it's unsafe to intialize it _after_ register_candev()
> call. Thanks to Johan Hovold <johan@kernel.org> for spotting
> it

My bad on that. I missed the fact that the netdev_ops becomes
active once register_candev() returns.

> Changes in v2:
> - Fixed Fixes: tag
> - Moved es58x_dev->netdev[channel_idx] initialization at the end
> of the function
>
> ---
> drivers/net/can/usb/etas_es58x/es58x_core.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c
> index 96a13c770e4a..41c721f2fbbe 100644
> --- a/drivers/net/can/usb/etas_es58x/es58x_core.c
> +++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
> @@ -2098,8 +2098,11 @@ static int es58x_init_netdev(struct es58x_device *es58x_dev, int channel_idx)
> netdev->flags |= IFF_ECHO; /* We support local echo */
>
> ret = register_candev(netdev);
> - if (ret)
> + if (ret) {
> + free_candev(netdev);
> + es58x_dev->netdev[channel_idx] = NULL;
> return ret;
> + }
>
> netdev_queue_set_dql_min_limit(netdev_get_tx_queue(netdev, 0),
> es58x_dev->param->dql_min_limit);
> --
> 2.33.1
>