netdev - Re: [PATCH net] packet: Do not call fanout

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Date:   Wed, 15 Feb 2017 11:07:21 +0000
From:   Anoob Soman <anoob.soman@...rix.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
CC:     <netdev@...r.kernel.org>, <davem@...emloft.net>
Subject: Re: [PATCH net] packet: Do not call fanout_release from atomic
 contexts

On 13/02/17 14:50, Anoob Soman wrote:
> On 13/02/17 14:26, Eric Dumazet wrote:
>> On Mon, 2017-02-13 at 13:28 +0000, Anoob Soman wrote:
>>
>>> Wouldn't it be easier to call synchronize_net(), before calling
>>> fanout_release_data() and kfree(f).
>>> The behavior, wrt synchronize_net, would be same as before and
>>> fanout_release() will cleanup everything without leaving any residue.
>> So we would require two synchronize_net() calls instead of one ?
>>
>> synchronize_net() is very expensive on some hosts, it is a big hammer.
>>
>>
>>
>
> Yes, one before fanout_release_data() (will be called only if 
> fanout->sk_ref == 0) and one after fanout_release().
>
> I understand synchronize_net() is expensive, but adding another 
> synchronize_net(),  before fanout_release_data(), will be no different 
> from what we have in the existing code.
>
> I can also make sure second synchronize_net() doesn't get called 
> again, if fanout_release() calls synchronize_net(), by making 
> fanout_release() return something to indicate it has done 
> synchronize_net().

Hi Eric,

Did you get a chance to looks at my comments ?