tcp: md5: add tcp_md5_needed jump label

Most linux hosts never setup TCP MD5 keys. We can avoid a
cache line miss (accessing tp->md5ig_info) on RX and TX
using a jump label.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 3 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3b522259da7d..0681afc62354 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1555,9 +1555,21 @@ struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
 					 const struct sock *addr_sk);
 
 #ifdef CONFIG_TCP_MD5SIG
-struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
-					 const union tcp_md5_addr *addr,
-					 int family);
+#include <linux/jump_label.h>
+extern struct static_key tcp_md5_needed;
+struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
+					   const union tcp_md5_addr *addr,
+					   int family);
+static inline struct tcp_md5sig_key *
+tcp_md5_do_lookup(const struct sock *sk,
+		  const union tcp_md5_addr *addr,
+		  int family)
+{
+	if (!static_key_false(&tcp_md5_needed))
+		return NULL;
+	return __tcp_md5_do_lookup(sk, addr, family);
+}
+
 #define tcp_twsk_md5_key(twsk)	((twsk)->tw_md5_key)
 #else
 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,