Re: [PATCH net 1/2] sit: allow to use rtnl ops on fb tunnel

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Le 22/10/2013 01:30, Willem de Bruijn a écrit :
On Wed, Oct 2, 2013 at 3:15 AM, Nicolas Dichtel
<nicolas.dichtel@xxxxxxxxx> wrote:
Le 01/10/2013 18:59, David Miller a écrit :

From: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
Date: Tue,  1 Oct 2013 18:04:59 +0200

rtnl ops where introduced by ba3e3f50a0e5 ("sit: advertise tunnel param
via
rtnl"), but I forget to assign rtnl ops to fb tunnels.

Now that it is done, we must remove the explicit call to
unregister_netdevice_queue(), because  the fallback tunnel is added to
the queue
in sit_destroy_tunnels() when checking rtnl_link_ops of all netdevices
(this
is valid since commit 5e6700b3bf98 ("sit: add support of x-netns")).

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>


Applied and queued up for -stable.

But I imagine since the x-netns changes aren't in various -stable
branches this will need to be adjusted a bit?

Yes, it's what I've tried to say in the commit log ;-)

In fact, before the x-netns changes, we must keep the
unregister_netdevice_queue() line.

In 3.11 linux-stable, this patch was merged between 3.11.4 and 3.11.5
in commit 3783100, after the x-netns changes in commit 5e6700b3bf, but
the unregister_netdevice_queue was kept.

I think that caused the following bug. In 3.11.6, a simple `modprobe
sit && rmmod sit` hits the BUG at net/core/dev.c:5039:

   BUG_ON(dev->reg_state != NETREG_REGISTERED);

The device is actually NETREG_RELEASED at one point because the device
is now unregistered twice. The issue goes away by porting the
remainder of the original commit: the one liner that removes the call
to unregister_netdevice_queue.

+++ b/net/ipv6/sit.c
@@ -1708,7 +1708,6 @@ static void __net_exit sit_exit_net(struct net *net)

         sit_destroy_tunnels(sitn, &list);
-       unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
         unregister_netdevice_many(&list);

If correct, let me know if I should send a proper one-line patch
against 3.11.y. Since I haven't looked at this code before, I found it
safer to report the issue first.
Yes, this line should be removed, like it was done in the original patch
(x-netns for sit is part of 3.11).


5e6700b3bf was not applied to 3.10 stable, so that branch is not affected.
Right.
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