[net-next-2.6] net: Introduce skb_orphan_try()

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 22 Apr 2010 09:10:33 +0200

> Le mercredi 21 avril 2010 à 22:56 -0700, David Miller a écrit :
> 
>> Right, I've applied this, thanks.
>> 
>> What we should probably do instead is call and NULL out the
>> DEV_GSO_CB() destructor.  Right?
> 
> Yes, probably, I'll take a look at this if you want.

It might look something like this:

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Le jeudi 22 avril 2010 à 00:16 -0700, David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Thu, 22 Apr 2010 09:10:33 +0200
> 
> > Le mercredi 21 avril 2010 à 22:56 -0700, David Miller a écrit :
> > 
> >> Right, I've applied this, thanks.
> >> 
> >> What we should probably do instead is call and NULL out the
> >> DEV_GSO_CB() destructor.  Right?
> > 
> > Yes, probably, I'll take a look at this if you want.
> 
> It might look something like this:
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 9bf1ccc..13241da 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1892,6 +1892,20 @@ static inline void skb_orphan_try(struct sk_buff *skb)
>  		skb_orphan(skb);
>  }
>  
> +/*
> + * GSO packets need to be handled specially because such packets
> + * hold the normal SKB destructor in a backup pointer.
> + */
> +static inline void skb_orphan_try_gso(struct sk_buff *skb)
> +{
> +	if (!skb_tx(skb)->flags) {
> +		if (DEV_GSO_CB(skb)->destructor)
> +			DEV_GSO_CB(skb)->destructor(skb);
> +		DEV_GSO_CB(skb)->destructor = NULL;
> +		skb->sk = NULL;
> +	}
> +}
> +
>  int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
>  			struct netdev_queue *txq)
>  {
> @@ -1937,6 +1951,7 @@ gso:
>  		if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
>  			skb_dst_drop(nskb);
>  
> +		skb_orphan_try_gso(skb);
>  		rc = ops->ndo_start_xmit(nskb, dev);
>  		if (unlikely(rc != NETDEV_TX_OK)) {
>  			if (rc & ~NETDEV_TX_MASK)

Hmm... are you sure we want to call destructor for each skb ?

Should'nt we do it before initial skb is split ?



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