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Subject: Re: [PATCH] net: mellanox: mlx5: fix error return code of
 mlx5e_stats_flower()
To:     Roi Dayan <roid@nvidia.com>, saeedm@nvidia.com, leon@kernel.org,
        davem@davemloft.net, kuba@kernel.org
Cc:     netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20210306134718.17566-1-baijiaju1990@gmail.com>
 <99807217-c2a3-928f-4c8c-2195f3500594@nvidia.com>
 <1fdf71d7-7a54-0b69-3339-e792dd03b2c8@nvidia.com>
From:   Jia-Ju Bai <baijiaju1990@gmail.com>
Message-ID: <3a1a2089-a7fa-2a7c-7040-c0aa62b08960@gmail.com>
Date:   Tue, 9 Mar 2021 16:32:59 +0800
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On 2021/3/9 16:24, Roi Dayan wrote:
>
>
> On 2021-03-09 10:20 AM, Roi Dayan wrote:
>>
>>
>> On 2021-03-06 3:47 PM, Jia-Ju Bai wrote:
>>> When mlx5e_tc_get_counter() returns NULL to counter or
>>> mlx5_devcom_get_peer_data() returns NULL to peer_esw, no error return
>>> code of mlx5e_stats_flower() is assigned.
>>> To fix this bug, err is assigned with -EINVAL in these cases.
>>>
>>> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
>>> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
>>> ---
>>>   drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 12 +++++++++---
>>>   1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c 
>>> b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
>>> index 0da69b98f38f..1f2c9da7bd35 100644
>>> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
>>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
>>> @@ -4380,8 +4380,10 @@ int mlx5e_stats_flower(struct net_device 
>>> *dev, struct mlx5e_priv *priv,
>>>       if (mlx5e_is_offloaded_flow(flow) || flow_flag_test(flow, CT)) {
>>>           counter = mlx5e_tc_get_counter(flow);
>>> -        if (!counter)
>>> +        if (!counter) {
>>> +            err = -EINVAL;
>>>               goto errout;
>>> +        }
>>>           mlx5_fc_query_cached(counter, &bytes, &packets, &lastuse);
>>>       }
>>> @@ -4390,8 +4392,10 @@ int mlx5e_stats_flower(struct net_device 
>>> *dev, struct mlx5e_priv *priv,
>>>        * un-offloaded while the other rule is offloaded.
>>>        */
>>>       peer_esw = mlx5_devcom_get_peer_data(devcom, 
>>> MLX5_DEVCOM_ESW_OFFLOADS);
>>> -    if (!peer_esw)
>>> +    if (!peer_esw) {
>>> +        err = -EINVAL;
>>
>> note here it's not an error. it could be there is no peer esw
>> so just continue with the stats update.
>>
>>>           goto out;
>>> +    }
>>>       if (flow_flag_test(flow, DUP) &&
>>>           flow_flag_test(flow->peer_flow, OFFLOADED)) {
>>> @@ -4400,8 +4404,10 @@ int mlx5e_stats_flower(struct net_device 
>>> *dev, struct mlx5e_priv *priv,
>>>           u64 lastuse2;
>>>           counter = mlx5e_tc_get_counter(flow->peer_flow);
>>> -        if (!counter)
>>> +        if (!counter) {
>>> +            err = -EINVAL;
>
> this change is problematic. the current goto is to do stats update with
> the first counter stats we got but if you now want to return an error
> then you probably should not do any update at all.

Thanks for your reply :)
I am not sure whether an error code should be returned here?
If so, flow_stats_update(...) should not be called here?


Best wishes,
Jia-Ju Bai

>
>>>               goto no_peer_counter;
>>> +        }
>>>           mlx5_fc_query_cached(counter, &bytes2, &packets2, &lastuse2);
>>>           bytes += bytes2;
>>>
>>
>>