netdev - Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+

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Message-ID: <1317933726.3457.33.camel@edumazet-laptop>
Date:	Thu, 06 Oct 2011 22:42:06 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ben Greear <greearb@...delatech.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+

Le mercredi 05 octobre 2011 à 23:36 +0200, Eric Dumazet a écrit :
> Le mercredi 05 octobre 2011 à 13:56 -0700, Ben Greear a écrit :
> 
> > Wouldn't you have the same problem with two real Ethernet interfaces on
> > the same LAN, or two 802.1Q devices for that matter?  The addrs will all
> > be the same in that case too?
> > 
> 
> Usually multicast is coupled with routing.
> 
> A JOIN message from your app wont be sent on all interfaces...
> 
> But yes, we might have a similar issue with regular vlans.
> 
> Probably nobody noticed yet. Just say no to fragments :)
> 
> > Also, if I have just a single mac-vlan active (the other 3 are 'ifconfig foo down'),
> > I still see the problem with mcast.
> > 
> 
> Thats another bug : macvlan doesnt test IFF_UP on broadcasts, only for
> unicast messages. Please test following patch.
> 
> >  From what you describe, I am thinking I may be hitting a different
> > issue.  Any ideas on how to figure out why exactly the NF_HOOK isn't
> > calling the ip_rcv_finish method?
> > 
> 
> Really I believe I tried to explain the thing already...
> 
> ip_local_deliver() -> ip_defrag() :
> 
> 
> [PATCH] macvlan: dont send frames on DOWN devices
> 
> Reported-by: Ben Greear <greearb@...delatech.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> ---
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index b100c90..94a0282 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -145,7 +145,8 @@ static void macvlan_broadcast(struct sk_buff *skb,
>  		hlist_for_each_entry_rcu(vlan, n, &port->vlan_hash[i], hlist) {
>  			if (vlan->dev == src || !(vlan->mode & mode))
>  				continue;
> -
> +			if (!(vlan->dev->flags & IFF_UP))
> +				continue;
>  			nskb = skb_clone(skb, GFP_ATOMIC);
>  			err = macvlan_broadcast_one(nskb, vlan, eth,
>  					 mode == MACVLAN_MODE_BRIDGE);
> 

This one is not needed.

When a port is down, its not in vlan_hash[] table anymore.

(Not sure why we perform the IFF_UP test for unicast frames.)



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