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Message-ID: <1271922423.7895.4819.camel@edumazet-laptop>
Date: Thu, 22 Apr 2010 09:47:03 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH net-next-2.6] net: Introduce skb_orphan_try()
Le jeudi 22 avril 2010 à 00:41 -0700, David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Thu, 22 Apr 2010 09:33:57 +0200
>
> > Le jeudi 22 avril 2010 à 00:26 -0700, David Miller a écrit :
> >> @@ -1865,6 +1865,7 @@ static int dev_gso_segment(struct sk_buff *skb)
> >> int features = dev->features & ~(illegal_highdma(dev, skb) ?
> >> NETIF_F_SG : 0);
> >>
> >> + skb_orphan_try(skb);
> >> segs = skb_gso_segment(skb, features);
> >>
> >> /* Verifying header integrity only. */
> >
> > Yes, it seems better.
> >
> > What about the
> >
> > if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
> > skb_dst_drop(skb);
> >
> > This thing might also be moved before the split, since split probably
> > clone all dst ?
>
> Good catch, agreed.
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 3ba774b..4f897e2 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1851,6 +1851,17 @@ static void dev_gso_skb_destructor(struct sk_buff *skb)
> cb->destructor(skb);
> }
>
> +/*
> + * Try to orphan skb early, right before transmission by the device.
> + * We cannot orphan skb if tx timestamp is requested, since
> + * drivers need to call skb_tstamp_tx() to send the timestamp.
> + */
> +static inline void skb_orphan_try(struct sk_buff *skb)
> +{
> + if (!skb_tx(skb)->flags)
> + skb_orphan(skb);
> +}
> +
> /**
> * dev_gso_segment - Perform emulated hardware segmentation on skb.
> * @skb: buffer to segment
> @@ -1865,6 +1876,7 @@ static int dev_gso_segment(struct sk_buff *skb)
> int features = dev->features & ~(illegal_highdma(dev, skb) ?
> NETIF_F_SG : 0);
>
> + skb_orphan_try(skb);
> segs = skb_gso_segment(skb, features);
>
> /* Verifying header integrity only. */
> @@ -1881,17 +1893,6 @@ static int dev_gso_segment(struct sk_buff *skb)
> return 0;
> }
>
> -/*
> - * Try to orphan skb early, right before transmission by the device.
> - * We cannot orphan skb if tx timestamp is requested, since
> - * drivers need to call skb_tstamp_tx() to send the timestamp.
> - */
> -static inline void skb_orphan_try(struct sk_buff *skb)
> -{
> - if (!skb_tx(skb)->flags)
> - skb_orphan(skb);
> -}
> -
> int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
> struct netdev_queue *txq)
> {
> @@ -1902,13 +1903,6 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
> if (!list_empty(&ptype_all))
> dev_queue_xmit_nit(skb, dev);
>
> - if (netif_needs_gso(dev, skb)) {
> - if (unlikely(dev_gso_segment(skb)))
> - goto out_kfree_skb;
> - if (skb->next)
> - goto gso;
> - }
> -
> /*
> * If device doesnt need skb->dst, release it right now while
> * its hot in this cpu cache
> @@ -1916,6 +1910,13 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
> if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
> skb_dst_drop(skb);
>
> + if (netif_needs_gso(dev, skb)) {
> + if (unlikely(dev_gso_segment(skb)))
> + goto out_kfree_skb;
> + if (skb->next)
> + goto gso;
> + }
> +
> skb_orphan_try(skb);
> rc = ops->ndo_start_xmit(skb, dev);
> if (rc == NETDEV_TX_OK)
You could have one skb_orphan_try() call before the
if (netif_needs_gso(dev, skb)) {
and remove it from dev_gso_segment() ?
--
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