linux-kernel - Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page Pool

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Message-ID: <20190704170920.1e81ed6e@carbon>
Date:   Thu, 4 Jul 2019 17:09:20 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, brouer@...hat.com
Subject: Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page
 Pool

On Thu, 4 Jul 2019 14:45:59 +0000
Jose Abreu <Jose.Abreu@...opsys.com> wrote:

> From: Jesper Dangaard Brouer <brouer@...hat.com>
> 
> > The page_pool_request_shutdown() API return indication if there are any
> > in-flight frames/pages, to know when it is safe to call
> > page_pool_free(), which you are also missing a call to.
> > 
> > This page_pool_request_shutdown() is only intended to be called from
> > xdp_rxq_info_unreg() code, that handles and schedule a work queue if it
> > need to wait for in-flight frames/pages.  
> 
> So you mean I can't call it or I should implement the same deferred work 
> ?
> 
> Notice that in stmmac case there will be no in-flight frames/pages 
> because we free them all before calling this ...

You can just use page_pool_free() (p.s I'm working on reintroducing
page_pool_destroy wrapper).  As you say, you will not have in-flight
frames/pages in this driver use-case.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer