vlan: Move vlan_set_encap_proto() to vlan header file

Open vSwitch needs this function for vlan handling.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 12d5543..070ac50 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -310,6 +310,40 @@
 
 	return protocol;
 }
+
+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);
+}
 #endif /* __KERNEL__ */
 
 /* VLAN IOCTLs are found in sockios.h */