netdev - Re: [PATCH v3] net: af_packet: don't call tpacket_destruct

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Message-ID: <AANLkTik4d76GBa9Jwn9BOnC07_0CnMsy-XoKM_MhF_sc@mail.gmail.com>
Date:	Thu, 23 Sep 2010 22:17:53 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	"Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v3] net: af_packet: don't call tpacket_destruct_skb()
 until the skb is sent out

On Thu, Sep 23, 2010 at 8:29 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le jeudi 23 septembre 2010 à 18:15 +0800, Changli Gao a écrit :
>> Since skb->destructor() is used to account socket memory, and maybe called
>> before the skb is sent out, a corrupt skb maybe sent out finally.
>>
>> A new destructor is added into structure skb_shared_info(), and it won't
>> be called until the last reference to the data of an skb is put. af_packet
>> uses this destructor instead.
>>
>> Signed-off-by: Changli Gao <xiaosuo@...il.com>
>> ---
>> v3: rename destructor to data_destructor, destructor_arg to data_destructor_arg,
>>     fix splice the skbs generated by AF_PACKET socket to the pipe.
>
> I dont understand this.
>
> Could you describe how splice(from af_packet to pipe) is possible with
> af_packet send path ?

af_packet sends packets to lo(127.0.0.1), and a local socket is
receiving packets via splice.

>
> Also, on such risky patch, could you please avoid inserting cleanups ?
> I am referring to these bits :
>

OK. Thanks.

-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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