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.
next prev parent reply other threads:[~2015-02-21 18:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20150203100816.GA5807@louise.pinerecords.com>
[not found] ` <20150203104214.GG24751@breakpoint.cc>
[not found] ` <20150210154536.GB16264@breakpoint.cc>
[not found] ` <20150221101512.GB17223@louise.pinerecords.com>
[not found] ` <20150221103104.GA26574@breakpoint.cc>
2015-02-21 16:22 ` 1e918876 breaks r8169 (linux-3.18+) 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
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