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Date: Tue, 2 Sep 2014 11:40:30 -0700
Message-ID: <CAHA+R7MMe+O9-sNHQvgOO78tBzDy+hO+GtJFsuJPKx0eG6eMaw@mail.gmail.com>
Subject: Re: RTNL: assertion failed at net/ipv6/addrconf.c (1699)
From: Cong Wang <cwang@twopensource.com>
To: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Sabrina Dubroca <sd@queasysnail.net>, Tommi Rantala <tt.rantala@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        James Morris <jmorris@namei.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Patrick McHardy <kaber@trash.net>, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, trinity@vger.kernel.org,
        Dave Jones <davej@redhat.com>
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On Tue, Sep 2, 2014 at 11:18 AM, Hannes Frederic Sowa
<hannes@stressinduktion.org> wrote:
> Those ASSERT_RTNLs were misplaced and only caught the callers mostly
> from addrconf.c. I don't mind getting reports from stable kernel users
> and fixing those, too (or help fixing those). ASSERT_RTNL is not
> dangerous.
>
> We had a long history in not correctly using rtnl lock in ipv6/multicast
> code and those wrongfully placed ASSERT_RTNLs were my bad when I fixed
> the duplicate address detection handling.
>
> If enough multicast addresses are subscribed to an interface we might
> again get those splats because enabling promisc mode on an interface
> will also check for rtnl lock.
>

Sure, I never doubt adding ASSERT_RTNL() is helpful, I just still think
this should be for net-next, or at least a separated patch. I don't want
my patch to be blamed in others' "Fixes:". :)