Commit 7c3f1875 authored by Roman Kapl's avatar Roman Kapl Committed by David S. Miller

net: move somaxconn init from sysctl code

The default value for somaxconn is set in sysctl_core_net_init(), but this
function is not called when kernel is configured without CONFIG_SYSCTL.

This results in the kernel not being able to accept TCP connections,
because the backlog has zero size. Usually, the user ends up with:
"TCP: request_sock_TCP: Possible SYN flooding on port 7. Dropping request.  Check SNMP counters."
If SYN cookies are not enabled the connection is rejected.

Before ef547f2a (tcp: remove max_qlen_log), the effects were less
severe, because the backlog was always at least eight slots long.
Signed-off-by: default avatarRoman Kapl <>
Signed-off-by: default avatarDavid S. Miller <>
parent 65d786c2
......@@ -315,6 +315,25 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
goto out;
static int __net_init net_defaults_init_net(struct net *net)
net->core.sysctl_somaxconn = SOMAXCONN;
return 0;
static struct pernet_operations net_defaults_ops = {
.init = net_defaults_init_net,
static __init int net_defaults_init(void)
if (register_pernet_subsys(&net_defaults_ops))
panic("Cannot initialize net default settings");
return 0;
static struct ucounts *inc_net_namespaces(struct user_namespace *ns)
......@@ -479,8 +479,6 @@ static __net_init int sysctl_core_net_init(struct net *net)
struct ctl_table *tbl;
net->core.sysctl_somaxconn = SOMAXCONN;
tbl = netns_core_table;
if (!net_eq(net, &init_net)) {
tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
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