netdev - Re: [PATCH net 2/2] ip_tunnel: Add fallback tunnels to the hash lists

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Date:	Thu, 26 Sep 2013 11:24:07 -0700
From:	Pravin Shelar <pshelar@...ira.com>
To:	Steffen Klassert <steffen.klassert@...unet.com>
Cc:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net 2/2] ip_tunnel: Add fallback tunnels to the hash lists

On Thu, Sep 26, 2013 at 1:13 AM, Steffen Klassert
<steffen.klassert@...unet.com> wrote:
> On Wed, Sep 25, 2013 at 09:03:11AM -0700, Pravin Shelar wrote:
>> On Tue, Sep 24, 2013 at 10:55 PM, Steffen Klassert
>> <steffen.klassert@...unet.com> wrote:
>> > Currently we can not update the tunnel parameters of
>> > the fallback tunnels because we don't find them in the
>> > hash lists. Fix this by adding them on initialization.
>> >
>> > Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
>> > ---
>> >  net/ipv4/ip_tunnel.c |    4 +++-
>> >  1 file changed, 3 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
>> > index b8ce640..f2348f2 100644
>> > --- a/net/ipv4/ip_tunnel.c
>> > +++ b/net/ipv4/ip_tunnel.c
>> > @@ -853,8 +853,10 @@ int ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
>> >         /* FB netdevice is special: we have one, and only one per netns.
>> >          * Allowing to move it to another netns is clearly unsafe.
>> >          */
>> > -       if (!IS_ERR(itn->fb_tunnel_dev))
>> > +       if (!IS_ERR(itn->fb_tunnel_dev)) {
>> >                 itn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;
>> > +               ip_tunnel_add(itn, netdev_priv(itn->fb_tunnel_dev));
>> > +       }
>> >         rtnl_unlock();
>> >
>> fallback tunnel s not required to be in hash table, Its is returned if
>> none of hashed tunnels are matched, ref ip_tunnel_lookup().
>> Can you post command to reproduce this issue?
>>
>
> Something like
>
> ip tunnel change tunl0 mode ipip remote 0.0.0.0 local 0.0.0.0 ttl 0 tos 1
>
> worked until v3.9 and stopped working with v3.10.

OK, I see the bug, tunnel exact match lookup does not check fb tunnel.
There are two options.
1. Fix ip_tunnel_find() to check for fb tunnel.
2. Add fb tunnel to hash table, which is what ur patch does.
I think your patch is better solution as it get rid of special case.
But patch is not complete. It needs to remove fb tunnel checks on
netdev unregister.
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