netdev - Re: [PATCH net-next] packet: respect devices with LLTX flag in direct xmit

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Message-ID: <1395936264.12610.300.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 27 Mar 2014 09:04:24 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: [PATCH net-next] packet: respect devices with LLTX flag in
 direct xmit

On Thu, 2014-03-27 at 09:01 -0700, Eric Dumazet wrote:

> > +	HARD_TX_LOCK(dev, txq, smp_processor_id());
> > +	if (!netif_xmit_frozen_or_stopped(txq)) {
> > +		ret = ops->ndo_start_xmit(skb, dev);
> > +		if (ret == NETDEV_TX_OK)
> > +			txq_trans_update(txq);


> I think this is problematic.
> 
> If you have concurrent traffic going through txq, and a flood
> going through packet_direct_xmit(), the timeout will trigger on txq
> because we do no longer update txq->trans_start
> 
> So I think you should force the update
> 
> 	txq->trans_start = jiffies;

Oh well, scratch that, I missed that you did the update.



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