aboutsummaryrefslogtreecommitdiffstats
path: root/net/core/request_sock.c
blob: b8203de5ff073c4e3bda5166ef1542b793141a0c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
/*
 * 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 = 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;
	     lopt->max_qlen_log++);

	get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
	rwlock_init(&queue->syn_wait_lock);
	queue->rskq_accept_head = queue->rskq_accept_head = NULL;
	queue->rskq_defer_accept = 0;
	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);