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From: David Ahern <dsa@cumulusnetworks.com>
Newsgroups: linux.kernel
Subject: Re: [Regression?] fib_rules: Added NLM_F_EXCL support to  fib_nl_newrule breaks Android userspace
Date: Fri, 29 Jul 2016 21:20:02 +0200
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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
>