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From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Florian Westphal <fw@strlen.de>,
	Tomas Szepe <szepe@pinerecords.com>,
	Francois Romieu <romieu@fr.zoreil.com>,
	Hayes Wang <hayeswang@realtek.com>,
	Eric Dumazet <edumazet@google.com>,
	Tom Herbert <therbert@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Marco Berizzi <pupilla@hotmail.com>,
	linux-kernel@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: 1e918876 breaks r8169 (linux-3.18+)
Date: Sat, 21 Feb 2015 19:32:09 +0100	[thread overview]
Message-ID: <20150221183209.GA30167@breakpoint.cc> (raw)
In-Reply-To: <1424542141.5565.46.camel@edumazet-glaptop2.roam.corp.google.com>

Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Sat, 2015-02-21 at 18:46 +0100, Florian Westphal wrote:
> > Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > > Hold on.
> > > 
> > > I believe there is one race in the way you access skb->xmit_more _after_
> > > 
> > > txd->opts1 = cpu_to_le32(status);
> > > 
> > > After this point, TX might have completed and TX completion already have
> > > freed skb
> > 
> > Hmm, I _thought_ HW would not start xmit of this descriptor/skb until after
> > 
> > RTL_W8(TxPoll, NPQ);
> 
> Note this 'kick' does not provide tail ptr.
> 
> NIC basically looks at TX descriptors to find ones with the DescOwn bit
> set. It stops when if find one TX descriptor _without_ DescOwn.

Makes sense, thanks for explaining this.

  reply	other threads:[~2015-02-21 18:32 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-03 10:08 Tomas Szepe
2015-02-03 10:42 ` Florian Westphal
2015-02-05 16:56   ` Tomáš Szépe
2015-02-06 14:04     ` Tomas Szepe
2015-02-08 12:18       ` Holger Hoffstätte
2015-02-10 15:45   ` Florian Westphal
2015-02-11  9:46     ` Tomáš Szépe
2015-02-21 10:15     ` Tomas Szepe
2015-02-21 10:31       ` Florian Westphal
2015-02-21 10:57         ` Holger Hoffstätte
2015-02-21 16:22         ` Eric Dumazet
2015-02-21 17:46           ` Florian Westphal
2015-02-21 18:09             ` Eric Dumazet
2015-02-21 18:32               ` Florian Westphal [this message]
2015-02-21 19:26             ` Tomas Szepe
2015-02-21 19:05           ` Tomas Szepe
2015-02-21 19:54             ` Eric Dumazet
2015-02-22  0:41               ` Tomas Szepe
2015-02-22 20:57                 ` David Miller
     [not found] <E1YqR6a-0007T7-Dz@feisty.vs19.net>
2015-05-07 19:22 ` Daniel Exner

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