blob: bb55675f0685e1a52accb47c734d1b2f8eb6368d [file] [log] [blame]
* NET Generic infrastructure for Network protocols.
* Authors: Arnaldo Carvalho de Melo <>
* From code originally in include/net/tcp.h
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
#include <linux/module.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <net/request_sock.h>
* Maximum number of SYN_RECV sockets in queue per LISTEN socket.
* One SYN_RECV socket costs about 80bytes on a 32bit machine.
* It would be better to replace it with a global counter for all sockets
* but then some measure against one socket starving all other sockets
* would be needed.
* It was 128 by default. Experiments with real servers show, that
* it is absolutely not enough even at 100conn/sec. 256 cures most
* of problems. This value is adjusted to 128 for very small machines
* (<=32Mb of memory) and to 1024 on normal or better ones (>=256Mb).
* Further increasing requires to change hash table size.
int sysctl_max_syn_backlog = 256;
int reqsk_queue_alloc(struct request_sock_queue *queue,
const int nr_table_entries)
const int lopt_size = sizeof(struct listen_sock) +
nr_table_entries * sizeof(struct request_sock *);
struct listen_sock *lopt = kmalloc(lopt_size, GFP_KERNEL);
if (lopt == NULL)
return -ENOMEM;
memset(lopt, 0, lopt_size);
for (lopt->max_qlen_log = 6;
(1 << lopt->max_qlen_log) < sysctl_max_syn_backlog;
get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
queue->rskq_accept_head = queue->rskq_accept_head = NULL;
queue->listen_opt = lopt;
return 0;