Re: [dpdk-dev] [PATCH v2] ethdev: fix updating device data when ops pointer is NULL

["Wei Hu (Xavier)" <xavier_huwei@163.com>]

Hi,Andrew Rybchenko

On 2020/1/17 15:57, Andrew Rybchenko wrote:
> On 1/17/20 9:23 AM, Wei Hu (Xavier) wrote:
>> From: "Wei Hu (Xavier)" <xavier.huwei@huawei.com>
> 
> I think summary is misleading. It is too generic and does not
> mention VLAN offloads. Consider something like:
> ethdev: fix VLAN offloads set if no driver callback
> 
>> Currently, there is a potential problem that changing the content of
>> dev->data->dev_conf.rxmode.offloads even when the pointer named
>> dev->dev_ops->vlan_offload_set is NULL in the API function named
>> rte_eth_dev_set_vlan_offload.
> 
> Consider to change
> "when the pointer named dev->dev_ops->vlan_offload_set is NULL in the
> API function named rte_eth_dev_set_vlan_offload."  to "when there is no
> vlan_offload_set driver callback."
> 
>> It is a good idea that prevent the side effect and make the API return
>> success if no change requested. This patch fixes the problem, the detail
>> information as below:
>> - Update a local 'dev_offloads' variable, instead of directly updating the
>> device config data
>> - if no change requested, "mask == 0", return success
>> - if change requested, check the 'vlan_offload_set' dev_ops in this stage
>> - assign the local 'dev_offloads' to 'dev->data->dev_conf.rxmode.offloads'
>> and call the dev_ops
>> - On error recover the 'dev->data->dev_conf.rxmode.offloads' to
>> 'orig_offloads'
> 
> I see no point to repeat in description what the code does.
> IMHO it is sufficient to mention main ideas:
>   - keep possibility to do dummy set even if there is no driver
>     callback
>   - do not touch Rx mode offloads in device data before
>     checking the driver callback availability
>   - ensure that Rx mode offloads are rolled back correctly if
>     driver callback returns error
> 
>> Fixes: 01eb53eefeb4 ("ethdev: rename folder to library name")
> 
> I think it is wrong Fixes. Rename just moves the code, it is
> not the changeset which introduces the bug.
> 
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
>> Signed-off-by: Chunsong Feng <fengchunsong@huawei.com>
>> Signed-off-by: Min Wang (Jushui) <wangmin3@huawei.com>
>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> 
> with above notes processed
> 
> Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
> 

Thanks for your comments, I will update it and send V3.

Regards
Xavier