ipv6: lockless IPV6_AUTOFLOWLABEL implementation

Move np->autoflowlabel and np->autoflowlabel_set in inet->inet_flags,
to fix data-races.

Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/ipv6.h

···
 						 * 100: prefer care-of address
 						 */
 				dontfrag:1,
-				autoflowlabel:1,
-				autoflowlabel_set:1,
 				rtalert_isolate:1;
 	__u8			min_hopcount;
 	__u8			tclass;

include/net/inet_sock.h

···
 	INET_FLAGS_MC6_LOOP	= 20,
 	INET_FLAGS_RECVERR6_RFC4884 = 21,
 	INET_FLAGS_MC6_ALL	= 22,
+	INET_FLAGS_AUTOFLOWLABEL_SET = 23,
+	INET_FLAGS_AUTOFLOWLABEL = 24,
 };
 
 /* cmsg flags for inet */

include/net/ipv6.h

···
 			   int flags);
 int ip6_flowlabel_init(void);
 void ip6_flowlabel_cleanup(void);
-bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np);
+bool ip6_autoflowlabel(struct net *net, const struct sock *sk);
 
 static inline void fl6_sock_release(struct ip6_flowlabel *fl)
 {

net/ipv6/ip6_output.c

···
 }
 EXPORT_SYMBOL(ip6_output);
 
-bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np)
+bool ip6_autoflowlabel(struct net *net, const struct sock *sk)
 {
-	if (!np->autoflowlabel_set)
+	if (!inet6_test_bit(AUTOFLOWLABEL_SET, sk))
 		return ip6_default_np_autolabel(net);
-	else
-		return np->autoflowlabel;
+	return inet6_test_bit(AUTOFLOWLABEL, sk);
 }
 
 /*
···
 		hlimit = ip6_dst_hoplimit(dst);
 
 	ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
-				ip6_autoflowlabel(net, np), fl6));
+				ip6_autoflowlabel(net, sk), fl6));
 
 	hdr->payload_len = htons(seg_len);
 	hdr->nexthdr = proto;
···
 	struct sk_buff *skb, *tmp_skb;
 	struct sk_buff **tail_skb;
 	struct in6_addr *final_dst;
-	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net *net = sock_net(sk);
 	struct ipv6hdr *hdr;
 	struct ipv6_txoptions *opt = v6_cork->opt;
···
 
 	ip6_flow_hdr(hdr, v6_cork->tclass,
 		     ip6_make_flowlabel(net, skb, fl6->flowlabel,
-					ip6_autoflowlabel(net, np), fl6));
+					ip6_autoflowlabel(net, sk), fl6));
 	hdr->hop_limit = v6_cork->hop_limit;
 	hdr->nexthdr = proto;
 	hdr->saddr = fl6->saddr;

net/ipv6/ipv6_sockglue.c

···
 			return -EINVAL;
 		inet6_assign_bit(MC6_ALL, sk, valbool);
 		return 0;
+	case IPV6_AUTOFLOWLABEL:
+		inet6_assign_bit(AUTOFLOWLABEL, sk, valbool);
+		inet6_set_bit(AUTOFLOWLABEL_SET, sk);
+		return 0;
 	}
 	if (needs_rtnl)
 		rtnl_lock();
···
 		np->dontfrag = valbool;
 		retv = 0;
 		break;
-	case IPV6_AUTOFLOWLABEL:
-		np->autoflowlabel = valbool;
-		np->autoflowlabel_set = 1;
-		retv = 0;
-		break;
 	case IPV6_RECVFRAGSIZE:
 		np->rxopt.bits.recvfragsize = valbool;
 		retv = 0;
···
 		break;
 
 	case IPV6_AUTOFLOWLABEL:
-		val = ip6_autoflowlabel(sock_net(sk), np);
+		val = ip6_autoflowlabel(sock_net(sk), sk);
 		break;
 
 	case IPV6_RECVFRAGSIZE: