ipv6: move tcp_ipv6_hash_secret and udp_ipv6_hash_secret to net_hotdata

Use a 32bit hole in "struct net_offload" to store
the remaining 32bit secrets used by TCPv6 and UDPv6.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240306160031.874438-17-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/hotdata.h

@@ -39,7 +39,9 @@ struct net_hotdata {
 #define inet_ehash_secret	net_hotdata.tcp_protocol.secret
 #define udp_ehash_secret	net_hotdata.udp_protocol.secret
 #define inet6_ehash_secret	net_hotdata.tcpv6_protocol.secret
+#define tcp_ipv6_hash_secret	net_hotdata.tcpv6_offload.secret
 #define udp6_ehash_secret	net_hotdata.udpv6_protocol.secret
+#define udp_ipv6_hash_secret	net_hotdata.udpv6_offload.secret
 
 extern struct net_hotdata net_hotdata;
 

include/net/protocol.h

@@ -70,6 +70,7 @@ struct inet6_protocol {
 struct net_offload {
 	struct offload_callbacks callbacks;
 	unsigned int		 flags;	/* Flags used by IPv6 for now */
+	u32			 secret;
 };
 /* This should be set for any extension header which is compatible with GSO. */
 #define INET6_PROTO_GSO_EXTHDR	0x1

net/ipv6/inet6_hashtables.c

@@ -26,15 +26,13 @@ u32 inet6_ehashfn(const struct net *net,
 		  const struct in6_addr *laddr, const u16 lport,
 		  const struct in6_addr *faddr, const __be16 fport)
 {
-	static u32 ipv6_hash_secret __read_mostly;
-
 	u32 lhash, fhash;
 
 	net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
-	net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
+	net_get_random_once(&tcp_ipv6_hash_secret, sizeof(tcp_ipv6_hash_secret));
 
 	lhash = (__force u32)laddr->s6_addr32[3];
-	fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
+	fhash = __ipv6_addr_jhash(faddr, tcp_ipv6_hash_secret);
 
 	return __inet6_ehashfn(lhash, lport, fhash, fport,
 			       inet6_ehash_secret + net_hash_mix(net));

net/ipv6/udp.c

@@ -79,8 +79,6 @@ u32 udp6_ehashfn(const struct net *net,
 		 const struct in6_addr *faddr,
 		 const __be16 fport)
 {
-	static u32 udp_ipv6_hash_secret __read_mostly;
-
 	u32 lhash, fhash;
 
 	net_get_random_once(&udp6_ehash_secret,