[dpdk-dev] [dpdk-stable] [PATCH] net/mlx5: fix calculating TSO inline size

Ferruh Yigit ferruh.yigit at intel.com
Fri Sep 15 10:39:04 CEST 2017


On 9/13/2017 8:26 AM, Nélio Laranjeiro wrote:
> On Wed, Sep 13, 2017 at 05:05:14AM +0000, Shahaf Shuler wrote:
>> Tuesday, September 12, 2017 9:34 PM, Nélio Laranjeiro:
>>>> On Sep 12, 2017, at 12:24 AM, Nélio Laranjeiro
>>>>>> Is not it dangerous to assume inl will always be 4 bytes long?  Why
>>>>>> not writing the real value instead?
>>>>> That was for readability of the code and uint32_t will be always
>>>>> 4bytes. But for better readability, it should be 'inline_header'
>>>>> instead of 'inl' though. I'm also okay with using "4" as well. Which way do
>>> you prefer?
>>>>
>>>> I agree on both, I was not clear enough to explain my thought, if for
>>>> some reason the inl moves from uint32_t to uint16_t without touching
>>>> the sizeof later, it will cause an issue.
>>>
>>> I tried to change the sizeof but I found that there are more "sizeof(inl)" in the
>>> following lines. Changing all the sizeof would be beyond the scope of this
>>> patch. So, how about leaving it as is for consistency?
>>
>> The inline segment format is not expected to change so easily. It is parsed
>> by the HW and HW maintains backward compatibility for all of the WQE
>> structures. 
> 
> We are not talking here about the hardware behavior but about wrong ways to
> define hardware values which should be used trough define and not by size of
> variable which can be wrongly modified.
> If the hardware inline_header size of 4, it should be defined as is.
> 
> I won't block this patch as it is not the single place where this sizeof is
> used, but it should be replaced as soon as possible by a define to avoid wrong
> behaviors in the future.
> 
> Acked-by: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>

Applied to dpdk-next-net/master, thanks.


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