Re: 1e918876 breaks r8169 (linux-3.18+)

Florian Westphal
2015-02-21T18:32:18Z

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.