ipv6: helper function to get tclass

Implement helper inline function to get traffic class from IPv6 header.

Signed-off-by: Jiri Benc <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/ipv6.h

···
 	return (struct ipv6hdr *)skb_transport_header(skb);
 }
 
+static inline __u8 ipv6_tclass(const struct ipv6hdr *iph)
+{
+	return (ntohl(*(__be32 *)iph) >> 20) & 0xff;
+}
+
 /* 
    This structure contains results of exthdrs parsing
    as offsets from skb->nh.

net/ipv6/datagram.c

···
 	}
 
 	if (np->rxopt.bits.rxtclass) {
-		int tclass = (ntohl(*(__be32 *)ipv6_hdr(skb)) >> 20) & 0xff;
+		int tclass = ipv6_tclass(ipv6_hdr(skb));
 		put_cmsg(msg, SOL_IPV6, IPV6_TCLASS, sizeof(tclass), &tclass);
 	}