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

Pavel Skripkin
2021-11-15T07:40:50Z

On 11/15/21 08:27, Vincent MAILHOL wrote:
> Hi Pavel,
>
> Thanks for the patch!
>
> On Mon. 15 Nov 2021 at 05:58, 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: 004653f0abf2 ("can: etas_es58x: add es58x_free_netdevs() to factorize code")
>

Hi, Vincent!

> Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X
> CAN USB interfaces")
>
> The bug existed from the initial commit. Prior to the
> introduction of es58x_free_netdevs(), unregister_candev() was
> called in the error handling of es58x_probe():
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/can/usb/etas_es58x/es58x_core.c?id=8537257874e949a59c834cecfd5a063e11b64b0b#n2234
>

I see, will fix in v2

>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
>> ---
>> 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;
>
> A nitpick, but if you don’t mind, I would prefer to set
> es58x_dev->netdev[channel_idx] after register_candev() succeeds
> so that we do not have to reset it to NULL in the error handling.
>
> diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c
> b/drivers/net/can/usb/etas_es58x/es58x_core.c
> index ce2b9e1ce3af..fb0daad9b9c8 100644
> --- a/drivers/net/can/usb/etas_es58x/es58x_core.c
> +++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
> @@ -2091,18 +2091,20 @@ static int es58x_init_netdev(struct
> es58x_device *es58x_dev, int channel_idx)
> return -ENOMEM;
> }
> SET_NETDEV_DEV(netdev, dev);
> - es58x_dev->netdev[channel_idx] = netdev;
> es58x_init_priv(es58x_dev, es58x_priv(netdev), channel_idx);
>
> netdev->netdev_ops = &es58x_netdev_ops;
> netdev->flags |= IFF_ECHO; /* We support local echo */
>
> ret = register_candev(netdev);
> - if (ret)
> + if (ret) {
> + free_candev(netdev);
> return ret;
> + }
>
> netdev_queue_set_dql_min_limit(netdev_get_tx_queue(netdev, 0),
> es58x_dev->param->dql_min_limit);
> + es58x_dev->netdev[channel_idx] = netdev;
>
> return ret;
> }
>

Also will do in v2. Thank you for your review :)

With regards,
Pavel Skripkin