netdev - Re: [PATCH net-next v1] page_pool: avoid infinite loop to schedule delayed worker

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Message-ID: <CAL+tcoATHuHxpZ+4ofEkg7cba=OZxnHJSbqNHxMC5s+ZMQNR9A@mail.gmail.com>
Date: Wed, 12 Feb 2025 12:38:28 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Mina Almasry <almasrymina@...gle.com>, davem@...emloft.net, edumazet@...gle.com, 
	pabeni@...hat.com, hawk@...nel.org, ilias.apalodimas@...aro.org, 
	horms@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v1] page_pool: avoid infinite loop to schedule
 delayed worker

On Wed, Feb 12, 2025 at 11:43 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Wed, 12 Feb 2025 11:20:16 +0800 Jason Xing wrote:
> > On Wed, Feb 12, 2025 at 10:46 AM Jakub Kicinski <kuba@...nel.org> wrote:
> > >
> > > On Tue, 11 Feb 2025 18:37:22 -0800 Mina Almasry wrote:
> > > > Isn't it the condition in page_pool_release_retry() that you want. to
> > > > modify? That is the one that handles whether the worker keeps spinning
> > > > no?
> > >
> > > +1
> > >
> > > A code comment may be useful BTW.
> >
> > I will add it in the next version. Yes, my intention is to avoid
> > initializing the delayed work since we don't expect the worker in
> > page_pool_release_retry() to try over and over again.
>
> Initializing a work isn't much cost, is it?

Not that much, but it's pointless to start a kworker under this
circumstance, right? And it will flood the dmesg.

>
> Just to state the obvious the current patch will not catch the
> situation when there is traffic outstanding (inflight is positive)
> at the time of detach from the driver. But then the inflight goes
> negative before the work / time kicks in.

Right, only mitigating the side effect. I will add this statement as
well while keeping the code itself as-is.

Thanks,
Jason