Subject: Re: [PATCH v3] net-tcp: TCP/IP stack bypass for loopback connections

From: Stephen Clark <[email-masked]>
Date: Thu, 20 Sep 2012 07:28:41 -0400

On 09/19/2012 05:19 PM, Bruce Curtis wrote:
> On Wed, Sep 19, 2012 at 2:03 PM, Eric Dumazet<[email-masked]>  wrote:
>    
>> On Wed, 2012-09-19 at 16:34 -0400, David Miller wrote:
>>
>>      
>>> I have an idea on how to handle this.
>>>
>>> In drivers/net/loopback.c:loopback_tx(), skip the SKB orphan operation
>>> if there is a friend socket at skb->friend.
>>>
>>> When sending such friend SKBs out at connection startup, arrange it
>>> such that the skb->destructor will zap the skb->friend pointer to
>>> NULL.
>>>
>>> Also, in skb_orphan*(), if necessary, set skb->friend to NULL.
>>>
>>> skb->sk will hold a reference to the socket, and since skb->friend
>>> will be equal, this will make sure a pointer to an unreferenced
>>> socket does not escape.
>>>        
>> I now am wondering if we still need skb->friend field.
>>
>> If skb->sk is not zeroed by a premature skb_orphan(), then
>>
>> skb->sk->sk_friend gives the friend ?
>>
>>
>>      
Does this mean traffic on the loopback interface will not traverse 
netfilter?

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