ipv6: make ipv6_pinfo.saddr_cache a boolean

ipv6_pinfo.saddr_cache is either NULL or &np->saddr.

We do not need 8 bytes, a boolean is enough.

Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Reviewed-by: Kuniyuki Iwashima <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Reviewed-by: Jakub Kicinski <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>

include/linux/ipv6.h

···
 struct ipv6_pinfo {
 	struct in6_addr 	saddr;
 	struct in6_pktinfo	sticky_pktinfo;
-	const struct in6_addr		*daddr_cache;
 #ifdef CONFIG_IPV6_SUBTREES
-	const struct in6_addr		*saddr_cache;
+	bool			saddr_cache;
 #endif
+	const struct in6_addr		*daddr_cache;
 
 	__be32			flow_label;
 	__u32			frag_size;

include/net/ip6_route.h

···
  */
 static inline void ip6_dst_store(struct sock *sk, struct dst_entry *dst,
 				 const struct in6_addr *daddr,
-				 const struct in6_addr *saddr)
+				 bool saddr_set)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 
···
 	sk_setup_caps(sk, dst);
 	np->daddr_cache = daddr;
 #ifdef CONFIG_IPV6_SUBTREES
-	np->saddr_cache = saddr;
+	np->saddr_cache = saddr_set;
 #endif
 }
 

net/ipv6/af_inet6.c

···
 			return PTR_ERR(dst);
 		}
 
-		ip6_dst_store(sk, dst, NULL, NULL);
+		ip6_dst_store(sk, dst, NULL, false);
 	}
 
 	return 0;

net/ipv6/inet6_connection_sock.c

···
 		dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
 
 		if (!IS_ERR(dst))
-			ip6_dst_store(sk, dst, NULL, NULL);
+			ip6_dst_store(sk, dst, NULL, false);
 	}
 	return dst;
 }

net/ipv6/ip6_output.c

···
 	 */
 	if (ip6_rt_check(&rt->rt6i_dst, &fl6->daddr, np->daddr_cache) ||
 #ifdef CONFIG_IPV6_SUBTREES
-	    ip6_rt_check(&rt->rt6i_src, &fl6->saddr, np->saddr_cache) ||
+	    ip6_rt_check(&rt->rt6i_src, &fl6->saddr,
+			 np->saddr_cache ? &np->saddr : NULL) ||
 #endif
 	   (fl6->flowi6_oif && fl6->flowi6_oif != dst_dev(dst)->ifindex)) {
 		dst_release(dst);

net/ipv6/route.c

···
 		      &sk->sk_v6_daddr : NULL,
 #ifdef CONFIG_IPV6_SUBTREES
 		      ipv6_addr_equal(&fl6->saddr, &np->saddr) ?
-		      &np->saddr :
+		      true :
 #endif
-		      NULL);
+		      false);
 }
 
 static bool ip6_redirect_nh_match(const struct fib6_result *res,

net/ipv6/tcp_ipv6.c

···
 	inet->inet_rcv_saddr = LOOPBACK4_IPV6;
 
 	sk->sk_gso_type = SKB_GSO_TCPV6;
-	ip6_dst_store(sk, dst, NULL, NULL);
+	ip6_dst_store(sk, dst, NULL, false);
 
 	icsk->icsk_ext_hdr_len = 0;
 	if (opt)
···
 
 	memcpy(newnp, np, sizeof(struct ipv6_pinfo));
 
-	ip6_dst_store(newsk, dst, NULL, NULL);
+	ip6_dst_store(newsk, dst, NULL, false);
 
 	newnp->saddr = ireq->ir_v6_loc_addr;