Commit 4acb4190 authored by Glauber Costa's avatar Glauber Costa Committed by David S. Miller
Browse files

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



sysctl_tcp_mem() initialization was moved to sysctl_tcp_ipv4.c
in commit 3dc43e3e, 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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarGlauber 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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8a8ee9af

include/net/tcp.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

net/ipv4/sysctl_net_ipv4.c

+1 −0
Original line number Diff line number Diff line
@@ -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;

net/ipv4/tcp.c

+13 −3
Original line number Diff line number Diff line
@@ -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;

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