linux-imx

/*

 * 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 <linux/tcp.h>

#include <linux/vmalloc.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.

 *

 * The minimum value of it is 128. 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 low memory machines,

 * and it will increase in proportion to the memory of machine.

 * Note : Dont forget somaxconn that may limit backlog too.

 */

​

void reqsk_queue_alloc(struct request_sock_queue *queue)

{

    spin_lock_init(&queue->rskq_lock);

​

    spin_lock_init(&queue->fastopenq.lock);

    queue->fastopenq.rskq_rst_head = NULL;

    queue->fastopenq.rskq_rst_tail = NULL;

    queue->fastopenq.qlen = 0;

​

    queue->rskq_accept_head = NULL;

}

​

/*

 * This function is called to set a Fast Open socket's "fastopen_rsk" field

 * to NULL when a TFO socket no longer needs to access the request_sock.

 * This happens only after 3WHS has been either completed or aborted (e.g.,

 * RST is received).

 *

 * Before TFO, a child socket is created only after 3WHS is completed,

 * hence it never needs to access the request_sock. things get a lot more

 * complex with TFO. A child socket, accepted or not, has to access its

 * request_sock for 3WHS processing, e.g., to retransmit SYN-ACK pkts,

 * until 3WHS is either completed or aborted. Afterwards the req will stay

 * until either the child socket is accepted, or in the rare case when the

 * listener is closed before the child is accepted.

 *