[v3.3-rc2+ PATCH] tcp: properly initialize tcp memory limits

From: Jason Wang
Date: Thu Feb 02 2012 - 05:11:03 EST


Commit 4acb4190 tries to fix the using uninitialized value
introduced by commit 3dc43e3, but it would make the
per-socket memory limits too small.

This patch fixes this and also remove the redundant codes
introduced in 4acb4190.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
net/ipv4/sysctl_net_ipv4.c | 5 -----
net/ipv4/tcp.c | 4 ++--
2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 4cb9cd2..1eb8caa 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -815,11 +815,6 @@ 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.sysctl_tcp_mem[1] = limit;
- net->ipv4.sysctl_tcp_mem[2] = net->ipv4.sysctl_tcp_mem[0] * 2;

net->ipv4.ipv4_hdr = register_net_sysctl_table(net,
net_ipv4_ctl_path, table);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 06373b4..3a7514b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3218,7 +3218,6 @@ __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;
@@ -3287,7 +3286,8 @@ void __init tcp_init(void)
sysctl_max_syn_backlog = max(128, cnt / 256);

tcp_init_mem(&init_net);
- limit = nr_free_buffer_pages() / 8;
+ /* Set per-socket limits to no more than 1/128 the pressure threshold */
+ limit = nr_free_buffer_pages() << (PAGE_SHIFT - 10);
limit = max(limit, 128UL);
max_share = min(4UL*1024*1024, limit);


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