[PATCH] net: increase skb->users instead of skb_clone()

Changli Gao
2010-12-16T05:57:50Z

In dev_queue_xmit_nit(), we have to clone skbs as we need to mangle skbs,
however, we don't need to clone skbs for all the packet_types.

Except for the first packet_type, we increase skb->users instead of
skb_clone().

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
---
net/core/dev.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index bf5ced5..888cb74 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1496,6 +1496,14 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(dev_forward_skb);

+static inline int deliver_skb(struct sk_buff *skb,
+ struct packet_type *pt_prev,
+ struct net_device *orig_dev)
+{
+ atomic_inc(&skb->users);
+ return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
+}
+
/*
* Support routine. Sends outgoing frames to any network
* taps currently in use.
@@ -1504,6 +1512,8 @@ EXPORT_SYMBOL_GPL(dev_forward_skb);
static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
{
struct packet_type *ptype;
+ struct sk_buff *skb2 = NULL;
+ struct packet_type *pt_prev = NULL;

#ifdef CONFIG_NET_CLS_ACT
if (!(skb->tstamp.tv64 && (G_TC_FROM(skb->tc_verd) & AT_INGRESS)))
@@ -1520,7 +1530,13 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
if ((ptype->dev == dev || !ptype->dev) &&
(ptype->af_packet_priv == NULL ||
(struct sock *)ptype->af_packet_priv != skb->sk)) {
- struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
+ if (pt_prev) {
+ deliver_skb(skb2, pt_prev, skb->dev);
+ pt_prev = ptype;
+ continue;
+ }
+
+ skb2 = skb_clone(skb, GFP_ATOMIC);
if (!skb2)
break;

@@ -1542,9 +1558,11 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)

skb2->transport_header = skb2->network_header;
skb2->pkt_type = PACKET_OUTGOING;
- ptype->func(skb2, skb->dev, ptype, skb->dev);
+ pt_prev = ptype;
}
}
+ if (pt_prev)
+ pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
rcu_read_unlock();
}

@@ -2788,14 +2806,6 @@ static void net_tx_action(struct softirq_action *h)
}
}

-static inline int deliver_skb(struct sk_buff *skb,
- struct packet_type *pt_prev,
- struct net_device *orig_dev)
-{
- atomic_inc(&skb->users);
- return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
-}
-
#if (defined(CONFIG_BRIDGE) || defined(CONFIG_BRIDGE_MODULE)) && \
(defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE))
/* This hook is defined here for ATM LANE */