Re: [dpdk-dev] [PATCH] net/af_xdp: submit valid count to Tx queue

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 04/11, David Marchand wrote:
>Hello Xiaolong,
>
>On Thu, Apr 11, 2019 at 4:30 AM Ye Xiaolong <xiaolong.ye@intel.com> wrote:
>
>> On 04/10, David Marchand wrote:
>> >If we reserve N slots, but only submit n slots, we end up with an
>> incorrect
>> >opinion of the number of available slots later.
>> >Either xsk_ring_prod__submit should also update cached_prod (but I am not
>> >sure it was the intent of this api), or we must ensure that both reserve
>> >and submit are consistent.
>>
>> I think you are right, current design does have the flaw, I haven't
>> thought of
>> it before :( So in order to make sure both reserve and submit are
>> consistent, what
>> about we check the valid count of mbuf at the beginning, then reserve the
>> valid
>> count slots?
>>
>>
>Ok, I can see other places to inspect in the driver: reserve_fill_queue()
>for the same issue, and eth_af_xdp_rx() for a similar issue but with
>xsk_ring_cons__peek()/xsk_ring_cons__release() ?
>Validating the needed slots count before reserving/peeking in the prod/cons
>rings seems the most simple fix.

Ok, then I'll handle them in a following patch.

Thanks,
Xiaolong
>
>
>-- 
>David Marchand