Re: [dpdk-dev] [PATCH] net/mlx5: fix Tx doorbell

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 1/5/2017 4:52 PM, Adrien Mazarguil wrote:
> On Thu, Jan 05, 2017 at 05:32:26PM +0100, Adrien Mazarguil wrote:
>> Hi Ferruh,
>>
>> On Thu, Jan 05, 2017 at 03:19:35PM +0000, Ferruh Yigit wrote:
>>> On 12/9/2016 1:27 PM, Nelio Laranjeiro wrote:
>>>> Too much data is uselessly written to the Tx doorbell.
>>>>
>>>> Fixes: 1d88ba171942 ("net/mlx5: refactor Tx data path")
>>>>
>>>> Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
>>>> Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
>>>>
>>>
>>> Applied to dpdk-next-net/master, thanks.
>>>
>>> Is not CC'ing stable intentional, since this patch depends on a patch
>>> introduced in this release? If not intentional, please CC stable.
>>
>> I intended to update the commit message for this patch as in the meantime we
>> discovered it addresses a significant regression introduced in v16.11.
>>
>> CC'ing stable now.
>>
>> If possible, can you amend the commit log with:
>>
>> ---
>>
>> net/mlx5: fix Tx doorbell
>>
>> Too much data is uselessly written to the Tx doorbell, which since v16.11
>> may also cause Tx queues to behave erratically and crash applications.
>>
>> This regression was seen on VF devices when the BlueFlame buffer size is
>> zero (txq->cqe_n == 0) due to the following change:
>>
>>  -       cqe = &(*txq->cqes)[ci & (txq->cqe_n - 1)].cqe64;
>>  +       cqe = &(*txq->cqes)[ci & ((1 << txq->cqe_n) - 1)];
>>
>> Fixes: 1d88ba171942 ("net/mlx5: refactor Tx data path")
>> Fixes: e2f116ee3cac ("net/mlx5: reduce memory overhead for CQE handling")
>>
>> Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
>> Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
>> Cc: stable@dpdk.org
>>
>> ---
> 
> I mixed the commit that introduced the regression with a similar looking yet
> harmless one, here is the proper message to use, sorry for the noise:
> 
> ---
> 
> net/mlx5: fix Tx doorbell
> 
> Too much data is uselessly written to the Tx doorbell, which since v16.11
> may also cause Tx queues to behave erratically and crash applications.
> 
> This regression was seen on VF devices when the BlueFlame buffer size is
> zero (txq->bf_buf_size) due to the following change:
> 
>  -       txq->bf_offset ^= txq->bf_buf_size;
>  +       txq->bf_offset ^= (1 << txq->bf_buf_size);
> 
> Fixes: 1d88ba171942 ("net/mlx5: refactor Tx data path")
> Fixes: d5793daefec8 ("net/mlx5: reduce memory overhead for BF handling")
> 
> Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
> Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
> Cc: stable@dpdk.org
> 
> ---
> 

Can you please confirm commit in latest next-net?