[deliverable/linux.git] / net / core / request_sock.c

/*
 * NET		Generic infrastructure for Network protocols.
 *
 * Authors:	Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 * 		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 = kzalloc(lopt_size, GFP_KERNEL);

	if (lopt == NULL)
		return -ENOMEM;

	for (lopt->max_qlen_log = 6;
	     (1 << lopt->max_qlen_log) < sysctl_max_syn_backlog;
	     lopt->max_qlen_log++);

	get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
	rwlock_init(&queue->syn_wait_lock);
	queue->rskq_accept_head = NULL;
	lopt->nr_table_entries = nr_table_entries;

	write_lock_bh(&queue->syn_wait_lock);
	queue->listen_opt = lopt;
	write_unlock_bh(&queue->syn_wait_lock);

	return 0;
}

EXPORT_SYMBOL(reqsk_queue_alloc);

void reqsk_queue_destroy(struct request_sock_queue *queue)
{
	/* make all the listen_opt local to us */
	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);

	if (lopt->qlen != 0) {
		int i;

		for (i = 0; i < lopt->nr_table_entries; i++) {
			struct request_sock *req;

			while ((req = lopt->syn_table[i]) != NULL) {
				lopt->syn_table[i] = req->dl_next;
				lopt->qlen--;
				reqsk_free(req);
			}
		}
	}

	BUG_TRAP(lopt->qlen == 0);
	kfree(lopt);
}

EXPORT_SYMBOL(reqsk_queue_destroy);
Commit	Line	Data
0e87506f ACM	1	/*
	2	* NET Generic infrastructure for Network protocols.
	3	*
	4	* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
	5	*
	6	* From code originally in include/net/tcp.h
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License
	10	* as published by the Free Software Foundation; either version
	11	* 2 of the License, or (at your option) any later version.
	12	*/
	13
	14	#include <linux/module.h>
	15	#include <linux/random.h>
	16	#include <linux/slab.h>
	17	#include <linux/string.h>
	18
	19	#include <net/request_sock.h>
	20
e52c1f17 DM	21	/*
	22	* Maximum number of SYN_RECV sockets in queue per LISTEN socket.
	23	* One SYN_RECV socket costs about 80bytes on a 32bit machine.
	24	* It would be better to replace it with a global counter for all sockets
	25	* but then some measure against one socket starving all other sockets
	26	* would be needed.
	27	*
	28	* It was 128 by default. Experiments with real servers show, that
	29	* it is absolutely not enough even at 100conn/sec. 256 cures most
	30	* of problems. This value is adjusted to 128 for very small machines
	31	* (<=32Mb of memory) and to 1024 on normal or better ones (>=256Mb).
	32	* Further increasing requires to change hash table size.
	33	*/
	34	int sysctl_max_syn_backlog = 256;
e52c1f17	35
0e87506f ACM	36	int reqsk_queue_alloc(struct request_sock_queue *queue,
	37	const int nr_table_entries)
	38	{
2ad69c55	39	const int lopt_size = sizeof(struct listen_sock) +
0e87506f	40	nr_table_entries * sizeof(struct request_sock *);
77d04bd9	41	struct listen_sock *lopt = kzalloc(lopt_size, GFP_KERNEL);
0e87506f ACM	42
	43	if (lopt == NULL)
	44	return -ENOMEM;
	45
0e87506f ACM	46	for (lopt->max_qlen_log = 6;
	47	(1 << lopt->max_qlen_log) < sysctl_max_syn_backlog;
	48	lopt->max_qlen_log++);
	49
	50	get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
	51	rwlock_init(&queue->syn_wait_lock);
3eb4801d	52	queue->rskq_accept_head = NULL;
83e3609e	53	lopt->nr_table_entries = nr_table_entries;
0e87506f ACM	54
	55	write_lock_bh(&queue->syn_wait_lock);
	56	queue->listen_opt = lopt;
	57	write_unlock_bh(&queue->syn_wait_lock);
	58
	59	return 0;
	60	}
	61
	62	EXPORT_SYMBOL(reqsk_queue_alloc);
83e3609e ACM	63
	64	void reqsk_queue_destroy(struct request_sock_queue *queue)
	65	{
	66	/* make all the listen_opt local to us */
	67	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);
	68
	69	if (lopt->qlen != 0) {
	70	int i;
	71
	72	for (i = 0; i < lopt->nr_table_entries; i++) {
	73	struct request_sock *req;
	74
	75	while ((req = lopt->syn_table[i]) != NULL) {
	76	lopt->syn_table[i] = req->dl_next;
	77	lopt->qlen--;
	78	reqsk_free(req);
	79	}
	80	}
	81	}
	82
	83	BUG_TRAP(lopt->qlen == 0);
	84	kfree(lopt);
	85	}
	86
	87	EXPORT_SYMBOL(reqsk_queue_destroy);