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

[Andrew Rybchenko <arybchenko@solarflare.com>]

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>