From 6015c71e656bb6895b416c31a8b7db457e45cecf Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 27 Nov 2018 15:03:21 -0800
Subject: [PATCH] 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>
---
include/net/tcp.h | 18 +++++++++++++++---
net/ipv4/tcp.c | 5 ++++-
net/ipv4/tcp_ipv4.c | 11 +++++++----
net/ipv4/tcp_output.c | 6 ++++--
4 files changed, 30 insertions(+), 10 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,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 252048776dbb..215e4d3b3616 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3656,8 +3656,11 @@ bool tcp_alloc_md5sig_pool(void)
if (unlikely(!tcp_md5sig_pool_populated)) {
mutex_lock(&tcp_md5sig_mutex);
- if (!tcp_md5sig_pool_populated)
+ if (!tcp_md5sig_pool_populated) {
__tcp_alloc_md5sig_pool();
+ if (tcp_md5sig_pool_populated)
+ static_key_slow_inc(&tcp_md5_needed);
+ }
mutex_unlock(&tcp_md5sig_mutex);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4904250a9aac..efc6fef692ff 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -970,10 +970,13 @@ static void tcp_v4_reqsk_destructor(struct request_sock *req)
* We need to maintain these in the sk structure.
*/
+struct static_key tcp_md5_needed __read_mostly;
+EXPORT_SYMBOL(tcp_md5_needed);
+
/* Find the Key structure for an address. */
-struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
- const union tcp_md5_addr *addr,
- int family)
+struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
+ const union tcp_md5_addr *addr,
+ int family)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct tcp_md5sig_key *key;
@@ -1011,7 +1014,7 @@ struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
}
return best_match;
}
-EXPORT_SYMBOL(tcp_md5_do_lookup);
+EXPORT_SYMBOL(__tcp_md5_do_lookup);
static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk,
const union tcp_md5_addr *addr,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e4c1e51b18c1..d3b691f3a9e8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -594,7 +594,8 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
*md5 = NULL;
#ifdef CONFIG_TCP_MD5SIG
- if (unlikely(rcu_access_pointer(tp->md5sig_info))) {
+ if (static_key_false(&tcp_md5_needed) &&
+ rcu_access_pointer(tp->md5sig_info)) {
*md5 = tp->af_specific->md5_lookup(sk, sk);
if (*md5) {
opts->options |= OPTION_MD5;
@@ -730,7 +731,8 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
*md5 = NULL;
#ifdef CONFIG_TCP_MD5SIG
- if (unlikely(rcu_access_pointer(tp->md5sig_info))) {
+ if (static_key_false(&tcp_md5_needed) &&
+ rcu_access_pointer(tp->md5sig_info)) {
*md5 = tp->af_specific->md5_lookup(sk, sk);
if (*md5) {
opts->options |= OPTION_MD5;
--
2.50.1