From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [Patch net] ipv4: fix a deadlock in ip_ra_control
Date: Mon, 17 Apr 2017 12:47:22 -0400 (EDT)
Message-ID: <20170417.124722.952972773056039579.davem@davemloft.net>
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Cc: netdev@vger.kernel.org, dvyukov@google.com, andreyknvl@google.com
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From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Wed, 12 Apr 2017 12:32:13 -0700

> Similar to commit 87e9f0315952
> ("ipv4: fix a potential deadlock in mcast getsockopt() path"),
> there is a deadlock scenario for IP_ROUTER_ALERT too:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(rtnl_mutex);
>                                lock(sk_lock-AF_INET);
>                                lock(rtnl_mutex);
>   lock(sk_lock-AF_INET);
> 
> Fix this by always locking RTNL first on all setsockopt() paths.
> 
> Note, after this patch ip_ra_lock is no longer needed either.
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Tested-by: Andrey Konovalov <andreyknvl@google.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Applied.