netdev - Re: [PATCH net] bnxt: don't handle XDP in netpoll

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Date: Thu, 27 Jul 2023 12:29:24 -0700
From: Michael Chan <michael.chan@...adcom.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com, 
	pabeni@...hat.com, gospo@...adcom.com
Subject: Re: [PATCH net] bnxt: don't handle XDP in netpoll

On Thu, Jul 27, 2023 at 12:05 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 27 Jul 2023 11:52:10 -0700 Michael Chan wrote:
> > These TX packet completions have already been counted in
> > __bnxt_poll_work().  If we do nothing here, I think the TX ring will
> > forever be out-of-sync with the completion ring.
>
> I see...
>
> Do you prefer adding a return value to tx_int() to tell
> __bnxt_poll_work_done() whether the work has been done;
> or to clear tx_pkts in the handler itself rather than
> the caller?
>

It's a bigger problem.  When we transmit packets, we store these
packet buffers and advance the producer index.  The completion ring
tells us how many TX packets have completed.  We then walk the TX ring
for the number of TX packets completed and free the buffers.  If we
cannot free the buffers now, we have to save this information (the
consumer index).  We won't get this information again in the
completion ring.

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