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Date: Thu, 28 Jul 2016 21:20:31 -0700 (PDT)
Message-Id: <20160728.212031.549387302791502368.davem@davemloft.net>
To: john.stultz@linaro.org
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        linux-kernel@vger.kernel.org, guodong.xu@linaro.org,
        dimitrysh@google.com
Subject: Re: [Regression?] fib_rules: Added NLM_F_EXCL support to
 fib_nl_newrule breaks Android userspace
From: David Miller <davem@davemloft.net>
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From: John Stultz <john.stultz@linaro.org>
Date: Thu, 28 Jul 2016 21:18:16 -0700

> After moving my HiKey tree to pre-v4.8-rc, I noticed when using
> Android that I was getting routing errors after toggling networking on
> and off (or entering suspend). Wifi associated, but I got some
> rounting errors in the logcat the connection manager wouldn't detect a
> valid network.
> 
> Not being able to figure out exactly what was going wrong from the
> userspace side, I bisected (manually rebasing a 70 patch stack each
> step :P) it down and it seems that the commit: 153380ec4b9b
> ("fib_rules: Added NLM_F_EXCL support to fib_nl_newrule") is causing
> the problem.
> 
> Reverting that patch seems to make things work again.
> 
> I'm no networking guru, but I'm happy to help debug this further if
> folks can walk me through it a bit.

It simply sounds like Android's userspace is specifying NLM_F_EXCL when
it shouldn't be during FIB rule netlink operations.