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Date: Tue, 7 Jul 2015 11:34:34 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: Julien Grall <julien.grall@...rix.com>
Cc: <xen-devel@...ts.xenproject.org>, <pablo@...filter.org>,
<kaber@...sh.net>, <kadlec@...ckhole.kfki.hu>,
<davem@...emloft.net>, <netfilter-devel@...r.kernel.org>,
<coreteam@...filter.org>, <bridge@...ts.linux-foundation.org>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Bernhard Thaler <bernhard.thaler@...et.at>, <fw@...len.de>,
<ian.campbell@...rix.com>, <wei.liu2@...rix.com>,
Bob Liu <bob.liu@...cle.com>
Subject: Re: [PATCH v2] net/bridge: Use __in6_dev_get rather than
in6_dev_get in br_validate_ipv6
On Tue, 7 Jul 2015 15:55:21 +0100
Julien Grall <julien.grall@...rix.com> wrote:
> The commit efb6de9b4ba0092b2c55f6a52d16294a8a698edd "netfilter: bridge:
> forward IPv6 fragmented packets" introduced a new function
> br_validate_ipv6 which take a reference on the inet6 device. Although,
> the reference is not released at the end.
>
> This will result to the impossibility to destroy any netdevice using
> ipv6 and bridge.
>
> It's possible to directly retrieve the inet6 device without taking a
> reference as all netfilter hooks are protected by rcu_read_lock via
> nf_hook_slow.
>
> Spotted while trying to destroy a Xen guest on the upstream Linux:
> "unregister_netdevice: waiting for vif1.0 to become free. Usage count = 1"
>
> Signed-off-by: Julien Grall <julien.grall@...rix.com>
> Cc: Bernhard Thaler <bernhard.thaler@...et.at>
> Cc: Pablo Neira Ayuso <pablo@...filter.org>
> Cc: fw@...len.de
> Cc: ian.campbell@...rix.com
> Cc: wei.liu2@...rix.com
> Cc: Bob Liu <bob.liu@...cle.com>
>
> ---
> Note that it's impossible to create new guest after this message.
> I'm not sure if it's normal.
>
> Changes in v2:
> - Don't take a reference to inet6.
> - This was "net/bridge: Add missing in6_dev_put in
> br_validate_ipv6" [0]
>
> [0] https://lkml.org/lkml/2015/7/3/443
> ---
> net/bridge/br_netfilter_ipv6.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
I like this simple solution
Acked-by: Stephen Hemminger <stephen@...workplumber.org>
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