On Sat, 2015-02-21 at 18:46 +0100, Florian Westphal wrote: > Eric Dumazet <eric.duma...@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. So what can happen here is the NIC was kicked earlier (prior transmit), but found your TX descriptor, before you got a chance to read skb->xmit_more This is why we have these wmb() everywhere. We want to do txd->opts1 = XXX Only when we are really ready. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
