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

[Eric Dumazet <eric.dumazet@gmail.com>]

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@candelatech.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 {