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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>
This commit is contained in:
Eric Dumazet 2018-11-27 15:03:21 -08:00 committed by David S. Miller
parent 2f69555315
commit 6015c71e65
4 changed files with 30 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
include/net/tcp.h
View File

@ -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,

5
net/ipv4/tcp.c
View File

@ -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);
}

11
net/ipv4/tcp_ipv4.c
View File

@ -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,

6
net/ipv4/tcp_output.c
View File

@ -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;