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Subject: Re: [Regression?] fib_rules: Added NLM_F_EXCL support to
 fib_nl_newrule breaks Android userspace
To: John Stultz <john.stultz@linaro.org>
References: <CALAqxLUrJ86pJ20ppTycG3e2wv=zegC6UfQdXtnjeQYxQw2iMg@mail.gmail.com>
 <20160728.212031.549387302791502368.davem@davemloft.net>
 <5ff19cc3-e607-282d-853a-410b985f8756@cumulusnetworks.com>
 <CALAqxLWBFyS8VF02tBmAR-Zu1j6Nh7ETZFoWx1fzVgx81rUk1Q@mail.gmail.com>
Cc: David Miller <davem@davemloft.net>,
        Mateusz Bajorski <mateusz.bajorski@nokia.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Guodong Xu <guodong.xu@linaro.org>,
        Dmitry Shmidt <dimitrysh@google.com>, Chih-Hung Hsieh <chh@google.com>,
        Eric Caruso <ejcaruso@google.com>,
        Lorenzo Colitti <lorenzo@google.com>
From: David Ahern <dsa@cumulusnetworks.com>
Message-ID: <54c59314-8f0e-542d-93e6-7953cbcd430e@cumulusnetworks.com>
Date: Fri, 29 Jul 2016 13:10:10 -0600
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On 7/29/16 10:57 AM, John Stultz wrote:
>> I take Android userspace inserts the same rule multiple times? (ip rule ls)
>
> With the patch reverted, and the system working,  I see:
>
> # ip rule ls
> 0:      from all lookup local
> 10000:  from all fwmark 0xc0000/0xd0000 lookup legacy_system
> 13000:  from all fwmark 0x10063/0x1ffff lookup local_network
> 13000:  from all fwmark 0x10065/0x1ffff lookup wlan0
> 14000:  from all oif wlan0 lookup wlan0
> 14000:  from all oif wlan0 lookup wlan0

duplicate rules.

> 15000:  from all fwmark 0x0/0x10000 lookup legacy_system
> 16000:  from all fwmark 0x0/0x10000 lookup legacy_network
> 17000:  from all fwmark 0x0/0x10000 lookup local_network
> 19000:  from all fwmark 0x64/0x1ffff lookup wlan0
> 19000:  from all fwmark 0x65/0x1ffff lookup wlan0
> 22000:  from all fwmark 0x0/0xffff lookup wlan0
> 32000:  from all unreachable
>
> With the patch applied, and after toggling wifi, when I see the problem:
>
> # ip rule ls
> 0:      from all lookup local
> 10000:  from all fwmark 0xc0000/0xd0000 lookup legacy_system
> 13000:  from all fwmark 0x10063/0x1ffff lookup local_network
> 13000:  from all fwmark 0x10065/0x1ffff lookup wlan0
> 14000:  from all oif wlan0 lookup wlan0

The failure would be happening on the insertion of the second wlan0 rule.

> 15000:  from all fwmark 0x0/0x10000 lookup legacy_system
> 16000:  from all fwmark 0x0/0x10000 lookup legacy_network
> 17000:  from all fwmark 0x0/0x10000 lookup local_network
> 19000:  from all fwmark 0x64/0x1ffff lookup wlan0
> 32000:  from all unreachable
>
>
>> If so and multiple components expect to manage their own 'copy' of the rule
>> they will need to remove the NLM_F_EXCL flag.
>
> Adding more networky Android folks to the CC.
>
> thanks
> -john
>