linux-kernel - Re: [PATCH 2.6.36] vlan: Avoid hwaccel vlan packets when vid not used

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Date:	Fri, 07 Jan 2011 00:34:47 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesse Gross <jesse@...ira.com>
Cc:	Matt Carlson <mcarlson@...adcom.com>,
	Michael Leun <lkml20101129@...ton.leun.net>,
	Michael Chan <mchan@...adcom.com>,
	David Miller <davem@...emloft.net>,
	Ben Greear <greearb@...delatech.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 2.6.36] vlan: Avoid hwaccel vlan packets when vid not
 used

Le jeudi 06 janvier 2011 à 16:01 -0500, Jesse Gross a écrit :

> Hmm, I thought that it might be some interaction with a corner case in
> the networking core but now it seems less likely.  There weren't too
> many vlan changes between the working and non-working states.  Plus,
> since the rx counter isn't increasing, the packets probably aren't
> making it anywhere.
> 
> I see that tg3 increases the drop counter in one place, which also
> happens to be checking for vlan errors (at tg3.c:4753).  That seems
> suspicious - maybe the NIC is only partially configured for vlan
> offloading.  If we can confirm that is where the drop counter is being
> incremented and what the error code is maybe it would shed some light.
> 

Hmm... I am pretty sure the drop counter is the dev rx_dropped (core
network handled, not tg3 one) incremented at the end of
__netif_receive_skb() : We found no suitable handler for packets.

atomic_long_inc(&skb->dev->rx_dropped);

But thats a guess, I'll have to check

> If it's a driver issue I don't have much insight - maybe Matt or
> bisect can help.
> 
> >> If it works on bnx2, it would seem to be a driver problem but it would
> >> be good to confirm that the tag in skb->vlan_tci is not being
> >> delievered to the networking core in this case.
> >
> > Hmm, where do you want me to check this ?
> 
> I was thinking right before vlan_gro_receive() at tg3.c:4837.  If my
> theory above is right then this obviously isn't relevant since it
> won't be hit at all.  Otherwise it would be good to know exactly what
> the driver is producing.


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