Re: [Bridge] <kernel BUG> generated on bridge up/down & other issues

[Stephen Hemminger <shemminger@osdl.org>]

On Mon, 7 Nov 2005 18:07:37 +0000
James Blackburn <fjb31@cam.ac.uk> wrote:

> Hi,
> 
> I've been encountering some problems with bridging under linux  
> 2.6.12-9 (ubuntu Breezy Badger).  Apologies for the newbie-ish email:  
> problem is likely a config issues, but docs appear to be sparse and I  
> can't find much reference to the problem/solution on the 'net; trial  
> and error really isn't working...

Has this been logged in Ubuntu bug tracker. It would help.

> Am attempting to bridge an offsite network to the central network  
> over the internet with vtun (2.6-4).  The configuration I have works  
> intermittently.  vtun seems to work reliably - am using the -p  
> (persist) option to force reconnect on disconnect.  However I have  
> the following problems:
> 
> 1)    On system startup vtun connects to the server correctly, but  
> the bridge does not come up.  (my vtund.conf attached)
> brctl show - shows the "brookf" bridge, but 'Interfaces' declares:  
> "can't get port info: Function not implemented"
> Restarting vtun with /etc/init.d/vtun restart brings the bridge up  
> correctly. Why is this?  Currently I'm having to restart vtun on  
> system startup to have it function at all.

Never used vtun


> 2)    At the moment if I perform /etc/init.d/vtun restart as often as  
> not there will be a kernel bug dump to the console.  It begins:
> <kernel BUG at <bad filename>:21387!
> 	invalid operand: 0000[#1]
> ...  Process brctl
> (For some reason it's not being logged to kern.log, but I could  
> attempt to resolve that and get the whole dump if it would be useful...)

Yes, most likely brctl is sending request to vtun
and it is crashing.


>  From then on, ifconfig, hangs the console, as does sudo.  Also  
> restart/halt freezes on putting down the interfaces.  This means  
> that, with the persist option (as up/down are called on every connect/ 
> disconnect), the box quickly becomes unusable.

What has happened is that the kernel BUG() causes the process
to be exited but the big mutex that is used for network reconfiguration
is still being held. The bug needs to be fixed.

> I've read that there may be issues with IPv6 and kernel support.   
> Although I don't use it, it's enabled by default on this kernel -  
> should this be disabled?
> 
> I presume I'm doing something wrong in the vtund.conf.  Should I be  
> creating and removing the bridge here, or should I create the bridge  
> once when the system starts up?  How would vutn interact with the tap  
> interface - should I configure it (eg tap0)  with IP 0.0.0.0 on  
> startup, then specify the interface in vtun and change persist yes; - 
>  > persist keep;?
> 
> If anyone can give any suggestions, I would be most grateful!
> 
> Many thanks,
> 
> James
> 
> 
>    persist yes;
>    type  ether;          # Ethernet tunnel
>    up {
>          program /usr/sbin/brctl "addbr brookf";
>          ifconfig "%% 0.0.0.0";    #i.e. first available tap interface
>          ifconfig "eth1 down";
>          ifconfig "eth1 promisc";
>          program /usr/sbin/brctl "addif brookf %d";
>          program /usr/sbin/brctl "addif brookf eth1";
>          #Bring the bridge up
>          ifconfig "eth1 0.0.0.0";
>          ifconfig "brookf 172.28.22.223 netmask 255.255.255.0";
>    };
>    down {
>          ifconfig "brookf down";
>          ifconfig "%% down";
>          ifconfig "eth1 down";
> 
>          # Clear up bridge stuff
>          program /usr/sbin/brctl "delif brookf %%";
>          program /usr/sbin/brctl "delif brookf eth1";
>          program /usr/sbin/brctl "delbr brookf";
>    };
> 


-- 
Stephen Hemminger <shemminger@osdl.org>
OSDL http://developer.osdl.org/~shemminger