ipv6: move IPV6_TCLASS_SHIFT into ipv6.h and define a helper

Two places defined IPV6_TCLASS_SHIFT, so we should move it into ipv6.h,
and use this macro as possible. And define ip6_tclass helper to return
tclass

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ipv6.h

@@ -239,6 +239,7 @@ struct ip6_flowlabel {
 #define IPV6_FLOWINFO_MASK	cpu_to_be32(0x0FFFFFFF)
 #define IPV6_FLOWLABEL_MASK	cpu_to_be32(0x000FFFFF)
 #define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK)
+#define IPV6_TCLASS_SHIFT	20
 
 struct ipv6_fl_socklist {
 	struct ipv6_fl_socklist	__rcu	*next;
@@ -681,6 +682,10 @@ static inline __be32 ip6_flowlabel(const struct ipv6hdr *hdr)
 	return *(__be32 *)hdr & IPV6_FLOWLABEL_MASK;
 }
 
+static inline u8 ip6_tclass(__be32 flowinfo)
+{
+	return ntohl(flowinfo & IPV6_TCLASS_MASK) >> IPV6_TCLASS_SHIFT;
+}
 /*
  *	Prototypes exported by ipv6
  */

net/ipv6/fib6_rules.c

@@ -169,7 +169,7 @@ static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 			return 0;
 	}
 
-	if (r->tclass && r->tclass != ((ntohl(fl6->flowlabel) >> 20) & 0xff))
+	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
 		return 0;
 
 	return 1;

net/ipv6/ip6_gre.c

@@ -61,8 +61,6 @@ static bool log_ecn_error = true;
 module_param(log_ecn_error, bool, 0644);
 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
 
-#define IPV6_TCLASS_SHIFT 20
-
 #define HASH_SIZE_SHIFT  5
 #define HASH_SIZE (1 << HASH_SIZE_SHIFT)
 

net/ipv6/ip6_tunnel.c

@@ -69,8 +69,6 @@ MODULE_ALIAS_NETDEV("ip6tnl0");
 #define IP6_TNL_TRACE(x...) do {;} while(0)
 #endif
 
-#define IPV6_TCLASS_SHIFT 20
-
 #define HASH_SIZE_SHIFT  5
 #define HASH_SIZE (1 << HASH_SIZE_SHIFT)
 

net/ipv6/ipv6_sockglue.c

@@ -1019,7 +1019,8 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 				put_cmsg(&msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
 			}
 			if (np->rxopt.bits.rxtclass) {
-				int tclass = ntohl(np->rcv_flowinfo & IPV6_TCLASS_MASK) >> 20;
+				int tclass = (int)ip6_tclass(np->rcv_flowinfo);
+
 				put_cmsg(&msg, SOL_IPV6, IPV6_TCLASS, sizeof(tclass), &tclass);
 			}
 			if (np->rxopt.bits.rxoinfo) {