netdev - Re: [Patch net] ipv4: fix a deadlock in ip_ra

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Date:   Mon, 17 Apr 2017 12:47:22 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     xiyou.wangcong@...il.com
Cc:     netdev@...r.kernel.org, dvyukov@...gle.com, andreyknvl@...gle.com
Subject: Re: [Patch net] ipv4: fix a deadlock in ip_ra_control

From: Cong Wang <xiyou.wangcong@...il.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@...gle.com>
> Tested-by: Andrey Konovalov <andreyknvl@...gle.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

Applied.