[Devel] [PATCH][VLAN] Merge tree equal tails in vlan_skb_recv

[Pavel Emelyanov]

There are tree paths in it, that set the skb->proto and then
perform common receive manipulations (basically call netif_rx()).

I think, that we can make this code flow easier to understand
by introducing the vlan_set_encap_proto() function (I hope the 
name is good) to setup the skb proto and merge the paths calling 
netif_rx() together.

Surprisingly, but gcc detects this thing and merges these paths
by itself, so this patch doesn't make the vlan module smaller.

Fits both net-2.6 and net-2.6.25.

Signed-off-by: Pavel Emelyanov <xemul at openvz.org>

---

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 4f99bb8..11198c1 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -90,6 +90,40 @@ static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
 	return skb;
 }
 
+static inline void vlan_set_encap_proto(struct sk_buff *skb,
+		struct vlan_hdr *vhdr)
+{
+	__be16 proto;
+	unsigned char *rawp;
+
+	/*
+	 * Was a VLAN packet, grab the encapsulated protocol, which the layer
+	 * three protocols care about.
+	 */
+
+	proto = vhdr->h_vlan_encapsulated_proto;
+	if (ntohs(proto) >= 1536) {
+		skb->protocol = proto;
+		return;
+	}
+
+	rawp = skb->data;
+	if (*(unsigned short *)rawp == 0xFFFF)
+		/*
+		 * This is a magic hack to spot IPX packets. Older Novell
+		 * breaks the protocol design and runs IPX over 802.3 without
+		 * an 802.2 LLC layer. We look for FFFF which isn't a used
+		 * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
+		 * but does for the rest.
+		 */
+		skb->protocol = htons(ETH_P_802_3);
+	else
+		/*
+		 * Real 802.2 LLC
+		 */
+		skb->protocol = htons(ETH_P_802_2);
+}
+
 /*
  *	Determine the packet's protocol ID. The rule here is that we
  *	assume 802.3 if the type field is short enough to be a length.
@@ -115,12 +149,10 @@ static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
 int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
 		  struct packet_type* ptype, struct net_device *orig_dev)
 {
-	unsigned char *rawp = NULL;
 	struct vlan_hdr *vhdr;
 	unsigned short vid;
 	struct net_device_stats *stats;
 	unsigned short vlan_TCI;
-	__be16 proto;
 
 	if (dev->nd_net != &init_net) {
 		kfree_skb(skb);
@@ -236,70 +268,11 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
 		break;
 	}
 
-	/*  Was a VLAN packet, grab the encapsulated protocol, which the layer
-	 * three protocols care about.
-	 */
-	/* proto = get_unaligned(&vhdr->h_vlan_encapsulated_proto); */
-	proto = vhdr->h_vlan_encapsulated_proto;
-
-	skb->protocol = proto;
-	if (ntohs(proto) >= 1536) {
-		/* place it back on the queue to be handled by
-		 * true layer 3 protocols.
-		 */
-
-		/* See if we are configured to re-write the VLAN header
-		 * to make it look like ethernet...
-		 */
-		skb = vlan_check_reorder_header(skb);
-
-		/* Can be null if skb-clone fails when re-ordering */
-		if (skb) {
-			netif_rx(skb);
-		} else {
-			/* TODO:  Add a more specific counter here. */
-			stats->rx_errors++;
-		}
-		rcu_read_unlock();
-		return 0;
-	}
-
-	rawp = skb->data;
-
-	/*
-	 * This is a magic hack to spot IPX packets. Older Novell breaks
-	 * the protocol design and runs IPX over 802.3 without an 802.2 LLC
-	 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
-	 * won't work for fault tolerant netware but does for the rest.
-	 */
-	if (*(unsigned short *)rawp == 0xFFFF) {
-		skb->protocol = htons(ETH_P_802_3);
-		/* place it back on the queue to be handled by true layer 3 protocols.
-		 */
-
-		/* See if we are configured to re-write the VLAN header
-		 * to make it look like ethernet...
-		 */
-		skb = vlan_check_reorder_header(skb);
-
-		/* Can be null if skb-clone fails when re-ordering */
-		if (skb) {
-			netif_rx(skb);
-		} else {
-			/* TODO:  Add a more specific counter here. */
-			stats->rx_errors++;
-		}
-		rcu_read_unlock();
-		return 0;
-	}
-
-	/*
-	 *	Real 802.2 LLC
-	 */
-	skb->protocol = htons(ETH_P_802_2);
 	/* place it back on the queue to be handled by upper layer protocols.
 	 */
 
+	vlan_set_encap_proto(skb, vhdr);
+
 	/* See if we are configured to re-write the VLAN header
 	 * to make it look like ethernet...
 	 */
-- 
1.5.3.4