[NET]: Avoid unnecessary cloning for ingress filtering

As it is we always invoke pt_prev before ing_filter, even if there are no
ingress filters attached.  This can cause unnecessary cloning in pt_prev.

This patch changes it so that we only invoke pt_prev if there are ingress
filters attached.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 40 insertions, 28 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 99b7bda37d10..39aba4862f21 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1949,27 +1949,51 @@ static int ing_filter(struct sk_buff *skb)
         struct Qdisc *q;
         struct net_device *dev = skb->dev;
         int result = TC_ACT_OK;
+        u32 ttl = G_TC_RTTL(skb->tc_verd);
 
-        if (dev->qdisc_ingress) {
-                __u32 ttl = (__u32) G_TC_RTTL(skb->tc_verd);
-                if (MAX_RED_LOOP < ttl++) {
-                        printk(KERN_WARNING "Redir loop detected Dropping packet (%d->%d)\n",
-                                skb->iif, skb->dev->ifindex);
-                        return TC_ACT_SHOT;
-                }
+        if (MAX_RED_LOOP < ttl++) {
+                printk(KERN_WARNING
+                       "Redir loop detected Dropping packet (%d->%d)\n",
+                       skb->iif, dev->ifindex);
+                return TC_ACT_SHOT;
+        }
 
-                skb->tc_verd = SET_TC_RTTL(skb->tc_verd,ttl);
+        skb->tc_verd = SET_TC_RTTL(skb->tc_verd, ttl);
+        skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_INGRESS);
 
-                skb->tc_verd = SET_TC_AT(skb->tc_verd,AT_INGRESS);
+        spin_lock(&dev->ingress_lock);
+        if ((q = dev->qdisc_ingress) != NULL)
+                result = q->enqueue(skb, q);
+        spin_unlock(&dev->ingress_lock);
+
+        return result;
+}
 
-                spin_lock(&dev->ingress_lock);
-                if ((q = dev->qdisc_ingress) != NULL)
-                        result = q->enqueue(skb, q);
-                spin_unlock(&dev->ingress_lock);
+static inline struct sk_buff *handle_ing(struct sk_buff *skb,
+                                         struct packet_type **pt_prev,
+                                         int *ret, struct net_device *orig_dev)
+{
+        if (!skb->dev->qdisc_ingress)
+                goto out;
 
+        if (*pt_prev) {
+                *ret = deliver_skb(skb, *pt_prev, orig_dev);
+                *pt_prev = NULL;
+        } else {
+                /* Huh? Why does turning on AF_PACKET affect this? */
+                skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
         }
 
-        return result;
+        switch (ing_filter(skb)) {
+        case TC_ACT_SHOT:
+        case TC_ACT_STOLEN:
+                kfree_skb(skb);
+                return NULL;
+        }
+
+out:
+        skb->tc_verd = 0;
+        return skb;
 }
 #endif
 
@@ -2021,21 +2045,9 @@ int netif_receive_skb(struct sk_buff *skb)
         }
 
 #ifdef CONFIG_NET_CLS_ACT
-        if (pt_prev) {
-                ret = deliver_skb(skb, pt_prev, orig_dev);
-                pt_prev = NULL; /* noone else should process this after*/
-        } else {
-                skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
-        }
-
-        ret = ing_filter(skb);
-
-        if (ret == TC_ACT_SHOT || (ret == TC_ACT_STOLEN)) {
-                kfree_skb(skb);
+        skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
+        if (!skb)
                 goto out;
-        }
-
-        skb->tc_verd = 0;
 ncls:
 #endif