netdev - Re: [PATCH net v3 2/4] flow_offload: fix incorrect cb_priv check for flow_block

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Message-ID: <c24444d5-8229-c835-ddf9-20d4ab322c54@ucloud.cn>
Date:   Wed, 17 Jun 2020 10:47:04 +0800
From:   wenxu <wenxu@...oud.cn>
To:     Simon Horman <simon.horman@...ronome.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, pablo@...filter.org,
        vladbu@...lanox.com
Subject: Re: [PATCH net v3 2/4] flow_offload: fix incorrect cb_priv check for
 flow_block_cb


On 6/16/2020 11:47 PM, Simon Horman wrote:
> On Tue, Jun 16, 2020 at 11:18:16PM +0800, wenxu wrote:
>> 在 2020/6/16 22:34, Simon Horman 写道:
>>> On Tue, Jun 16, 2020 at 10:20:46PM +0800, wenxu wrote:
>>>> 在 2020/6/16 18:51, Simon Horman 写道:
>>>>> On Tue, Jun 16, 2020 at 11:19:38AM +0800, wenxu@...oud.cn wrote:
>>>>>> From: wenxu <wenxu@...oud.cn>
>>>>>>
>>>>>> In the function __flow_block_indr_cleanup, The match stataments
>>>>>> this->cb_priv == cb_priv is always false, the flow_block_cb->cb_priv
>>>>>> is totally different data with the flow_indr_dev->cb_priv.
>>>>>>
>>>>>> Store the representor cb_priv to the flow_block_cb->indr.cb_priv in
>>>>>> the driver.
>>>>>>
>>>>>> Fixes: 1fac52da5942 ("net: flow_offload: consolidate indirect flow_block infrastructure")
>>>>>> Signed-off-by: wenxu <wenxu@...oud.cn>
>>>>> Hi Wenxu,
>>>>>
>>>>> I wonder if this can be resolved by using the cb_ident field of struct
>>>>> flow_block_cb.
>>>>>
>>>>> I observe that mlx5e_rep_indr_setup_block() seems to be the only call-site
>>>>> where the value of the cb_ident parameter of flow_block_cb_alloc() is
>>>>> per-block rather than per-device. So part of my proposal is to change
>>>>> that.
>>>> I check all the xxdriver_indr_setup_block. It seems all the cb_ident parameter of
>>>>
>>>> flow_block_cb_alloc is per-block. Both in the nfp_flower_setup_indr_tc_block
>>>>
>>>> and bnxt_tc_setup_indr_block.
>>>>
>>>>
>>>> nfp_flower_setup_indr_tc_block:
>>>>
>>>> struct nfp_flower_indr_block_cb_priv *cb_priv;
>>>>
>>>> block_cb = flow_block_cb_alloc(nfp_flower_setup_indr_block_cb,
>>>>                                                cb_priv, cb_priv,
>>>>                                                nfp_flower_setup_indr_tc_release);
>>>>
>>>>
>>>> bnxt_tc_setup_indr_block:
>>>>
>>>> struct bnxt_flower_indr_block_cb_priv *cb_priv;
>>>>
>>>> block_cb = flow_block_cb_alloc(bnxt_tc_setup_indr_block_cb,
>>>>                                                cb_priv, cb_priv,
>>>>                                                bnxt_tc_setup_indr_rel);
>>>>
>>>>
>>>> And the function flow_block_cb_is_busy called in most place. Pass the
>>>>
>>>> parameter as cb_priv but not cb_indent .
>>> Thanks, I see that now. But I still think it would be useful to understand
>>> the purpose of cb_ident. It feels like it would lead to a clean solution
>>> to the problem you have highlighted.
>> I think The cb_ident means identify.  It is used to identify the each flow block cb.
>>
>> In the both flow_block_cb_is_busy and flow_block_cb_lookup function check
>>
>> the block_cb->cb_ident == cb_ident.
> Thanks, I think that I now see what you mean about the different scope of
> cb_ident and your proposal to allow cleanup by flow_indr_dev_unregister().
>
> I do, however, still wonder if there is a nicer way than reaching into
> the structure and manually setting block_cb->indr.cb_priv
> at each call-site.
>
> Perhaps a variant of flow_block_cb_alloc() for indirect blocks
> would be nicer?
Yes, It seems a variant of flow_block_cb_alloc() for indirect blocks is better, Thanks.
>