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net/tcp: Fix tcp memory limits initialization when !CONFIG_SYSCTL 

sysctl_tcp_mem() initialization was moved to sysctl_tcp_ipv4.c
in commit 3dc43e3e4d, since it
became a per-ns value.

That code, however, will never run when CONFIG_SYSCTL is
disabled, leading to bogus values on those fields - causing hung
TCP sockets.

This patch fixes it by keeping an initialization code in
tcp_init(). It will be overwritten by the first net namespace
init if CONFIG_SYSCTL is compiled in, and do the right thing if
it is compiled out.

It is also named properly as tcp_init_mem(), to properly signal
its non-sysctl side effect on TCP limits.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: David S. Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/4F22D05A.8030604@parallels.com
[ renamed the function, tidied up the changelog a bit ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Glauber Costa 2012-01-30 01:20:17 +00:00 committed by David S. Miller
parent 8a8ee9aff6
commit 4acb41903b
3 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/tcp.h
View File

@ -311,6 +311,8 @@ extern struct proto tcp_prot;
#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
extern void tcp_init_mem(struct net *net);
extern void tcp_v4_err(struct sk_buff *skb, u32);
extern void tcp_shutdown (struct sock *sk, int how);

1
net/ipv4/sysctl_net_ipv4.c
View File

@ -814,6 +814,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
net->ipv4.sysctl_rt_cache_rebuild_count = 4;
tcp_init_mem(net);
limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
net->ipv4.sysctl_tcp_mem[0] = limit / 4 * 3;

16
net/ipv4/tcp.c
View File

@ -3216,6 +3216,16 @@ static int __init set_thash_entries(char *str)
}
__setup("thash_entries=", set_thash_entries);
void tcp_init_mem(struct net *net)
{
/* Set per-socket limits to no more than 1/128 the pressure threshold */
unsigned long limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
net->ipv4.sysctl_tcp_mem[0] = limit / 4 * 3;
net->ipv4.sysctl_tcp_mem[1] = limit;
net->ipv4.sysctl_tcp_mem[2] = net->ipv4.sysctl_tcp_mem[0] * 2;
}
void __init tcp_init(void)
{
struct sk_buff *skb = NULL;
@ -3276,9 +3286,9 @@ void __init tcp_init(void)
sysctl_tcp_max_orphans = cnt / 2;
sysctl_max_syn_backlog = max(128, cnt / 256);
/* Set per-socket limits to no more than 1/128 the pressure threshold */
limit = ((unsigned long)init_net.ipv4.sysctl_tcp_mem[1])
<< (PAGE_SHIFT - 7);
tcp_init_mem(&init_net);
limit = nr_free_buffer_pages() / 8;
limit = max(limit, 128UL);
max_share = min(4UL*1024*1024, limit);
sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;