[PATCH 2/2] ipv4: Namespaceify tcp_max_syn_backlog knob

From: Haishuang Yan
Date: Wed Dec 28 2016 - 04:53:19 EST


Different namespace application might require different maximal
number of remembered connection requests.

Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
---
include/net/netns/ipv4.h | 1 +
include/net/request_sock.h | 4 +---
net/core/request_sock.c | 2 --
net/ipv4/sysctl_net_ipv4.c | 14 +++++++-------
net/ipv4/tcp.c | 2 --
net/ipv4/tcp_input.c | 4 ++--
net/ipv4/tcp_ipv4.c | 7 +++++--
7 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 99becaf..96b15a2 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -122,6 +122,7 @@ struct netns_ipv4 {
unsigned int sysctl_tcp_notsent_lowat;
int sysctl_tcp_tw_reuse;
struct inet_timewait_death_row tcp_death_row;
+ int sysctl_max_syn_backlog;

int sysctl_igmp_max_memberships;
int sysctl_igmp_max_msf;
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 6ebe13e..a12a5d2 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -1,7 +1,7 @@
/*
* NET Generic infrastructure for Network protocols.
*
- * Definitions for request_sock
+ * Definitions for request_sock
*
* Authors: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxx>
*
@@ -123,8 +123,6 @@ static inline void reqsk_put(struct request_sock *req)
reqsk_free(req);
}

-extern int sysctl_max_syn_backlog;
-
/*
* For a TCP Fast Open listener -
* lock - protects the access to all the reqsk, which is co-owned by
diff --git a/net/core/request_sock.c b/net/core/request_sock.c
index 5d26056..9b8727c 100644
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ -34,8 +34,6 @@
* and it will increase in proportion to the memory of machine.
* Note : Dont forget somaxconn that may limit backlog too.
*/
-int sysctl_max_syn_backlog = 256;
-EXPORT_SYMBOL(sysctl_max_syn_backlog);

void reqsk_queue_alloc(struct request_sock_queue *queue)
{
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 66f8f1b..134d8e1 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -324,13 +324,6 @@ static struct ctl_table ipv4_table[] = {
.proc_handler = proc_dointvec
},
{
- .procname = "tcp_max_syn_backlog",
- .data = &sysctl_max_syn_backlog,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec
- },
- {
.procname = "inet_peer_threshold",
.data = &inet_peer_threshold,
.maxlen = sizeof(int),
@@ -960,6 +953,13 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
+ {
+ .procname = "tcp_max_syn_backlog",
+ .data = &init_net.ipv4.sysctl_max_syn_backlog,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
#ifdef CONFIG_IP_ROUTE_MULTIPATH
{
.procname = "fib_multipath_use_neigh",
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 91938c9..f0637a9 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3378,9 +3378,7 @@ void __init tcp_init(void)


cnt = tcp_hashinfo.ehash_mask + 1;
-
sysctl_tcp_max_orphans = cnt / 2;
- sysctl_max_syn_backlog = max(128, cnt / 256);

tcp_init_mem();
/* Set per-socket limits to no more than 1/128 the pressure threshold */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c614802..ec6d843 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6377,8 +6377,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
}
/* Kill the following clause, if you dislike this way. */
else if (!net->ipv4.sysctl_tcp_syncookies &&
- (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
- (sysctl_max_syn_backlog >> 2)) &&
+ (net->ipv4.sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+ (net->ipv4.sysctl_max_syn_backlog >> 2)) &&
!tcp_peer_is_proven(req, dst, false,
tmp_opt.saw_tstamp)) {
/* Without syncookies last quarter of
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 56b5f49..7e4be4f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2419,7 +2419,7 @@ static void __net_exit tcp_sk_exit(struct net *net)

static int __net_init tcp_sk_init(struct net *net)
{
- int res, cpu;
+ int res, cpu, cnt;

net->ipv4.tcp_sk = alloc_percpu(struct sock *);
if (!net->ipv4.tcp_sk)
@@ -2458,10 +2458,13 @@ static int __net_init tcp_sk_init(struct net *net)
net->ipv4.sysctl_tcp_notsent_lowat = UINT_MAX;
net->ipv4.sysctl_tcp_tw_reuse = 0;

+ cnt = tcp_hashinfo.ehash_mask + 1;
net->ipv4.tcp_death_row.sysctl_tw_recycle = 0;
- net->ipv4.tcp_death_row.sysctl_max_tw_buckets = (tcp_hashinfo.ehash_mask + 1) / 2;
+ net->ipv4.tcp_death_row.sysctl_max_tw_buckets = (cnt + 1) / 2;
net->ipv4.tcp_death_row.hashinfo = &tcp_hashinfo;

+ net->ipv4.sysctl_max_syn_backlog = max(128, cnt / 256);
+
return 0;
fail:
tcp_sk_exit(net);
--
2.5.0