Re: 2.6.38-rc1: arp triggers RTNL assertion

From: David Miller
Date: Mon Jan 24 2011 - 16:13:31 EST


From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: Mon, 24 Jan 2011 22:11:38 +0100

> Le vendredi 21 janvier 2011 à 13:06 -0800, David Miller a écrit :
>> From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
>> Date: Fri, 21 Jan 2011 19:52:56 +0100
>>
>> > Here is how I fixed this, thanks again Jamie !
>> >
>> > [PATCH] net: neighbour: pneigh_lookup() doesnt need RTNL
>>
>> Eric, I don't think we can do this.
>>
>> Fundamentally, any time a user operation changes the configuration
>> of the networking, we must hold the RTNL.
>>
>> Eliding the RTNL for lookups is fine, but for things that change
>> state it is not.
>>
>> I therefore think you'll need to rework the arp_ioctl() portions
>> of the commit that introduced this regression.
>>
>
> Here is a second try of the fix, thanks !
>
> Note : Tested with CONFIG_PROVE_RCU=y
>
> [PATCH] net: arp_ioctl() must hold RTNL

Thanks Eric, this one looks a lot better. I'll apply this later
tonight.
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