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/*
* 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 = 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);
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