linux-kernel - Re: 2.6.35 -> 2.6.36 panic when vlan and promisc with tg3

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Message-ID: <AANLkTik8Wn5B9Ovn5yp5fR+Y=CyfXkqta7JpaN6EqsvE@mail.gmail.com>
Date:	Tue, 30 Nov 2010 14:27:22 -0800
From:	Jesse Gross <jesse@...ira.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Michael Leun <lkml20101129@...ton.leun.net>,
	Ben Greear <greearb@...delatech.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: 2.6.35 -> 2.6.36 panic when vlan and promisc with tg3

On Tue, Nov 30, 2010 at 1:20 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le mardi 30 novembre 2010 à 09:59 +0100, Michael Leun a écrit :
>> On Mon, 29 Nov 2010 16:19:06 -0800
>> Ben Greear <greearb@...delatech.com> wrote:
>>
>> > On 11/29/2010 11:17 AM, Michael Leun wrote:
>> > > UG: unable to handle kernel paging request at 01cc921c
>> > > IP: [<c034bfce>] vlan_hwaccel_do_receive+0x59/0xd0
>> > > *pdpt = 0000000036a2a001 *pde = 0000000000000000
>> > > Oops: 0002 [#1] SMP
>> > > last sysfs
>> > >
>> > > Then machine dead.
>> > >
>> > > In 2.6.35.x this did not happen (but vlans broken - cannot see vlan
>> > > tags with tcpdump),
>> >
>> > Try this patch:
>> >
>> > http://permalink.gmane.org/gmane.linux.network/176566
>> >
>> > It looks like this hasn't made it into stable yet?
>>
>> > > To reproduce:
>> > >
>> > > ip link set eth0 up
>> > > vconfig add eth0 2
>> > > ip link set eth0 promisc on
>>
>> It makes it better - it does not crash anymore on this commands - but
>> if you add an "tcpdump -i eth0 -n" at the end it does. So,
>> unfortunately no real solution.
>>
>> I guess, "dropping packet no one is interested in" (as noted in the
>> patch) does not work very well if tcpdump is actually interested?
>>
>
> Could you try with following patch instead, for net/core/dev.c
>
> (and keep the net/8021q/vlan_core.c part)
>
> --- net/core/dev.c.orig
> +++ net/core/dev.c
> @@ -2891,6 +2891,9 @@
>  ncls:
>  #endif
>
> +       if (unlikely(vlan_tx_tag_present(skb)))
> +               goto bypass;
> +
>        /* Handle special case of bridge or macvlan */
>        rx_handler = rcu_dereference(skb->dev->rx_handler);
>        if (rx_handler) {
> @@ -2927,6 +2930,7 @@
>                }
>        }
>
> +bypass:
>        if (pt_prev) {
>                ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
>        } else {

Hmm, it looks like I forgot an else between pt_prev->func() and
kfree_skb() in my patch.  Yours is cleaner, so I like it better
anyways (assuming it fixes the problem).

Thanks.
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