/*
   * Copyright (c) 2006 Oracle.  All rights reserved.
   *
   * This software is available to you under a choice of one of two
   * licenses.  You may choose to be licensed under the terms of the GNU
   * General Public License (GPL) Version 2, available from the file
   * COPYING in the main directory of this source tree, or the
   * OpenIB.org BSD license below:
   *
   *     Redistribution and use in source and binary forms, with or
   *     without modification, are permitted provided that the following
   *     conditions are met:
   *
   *      - Redistributions of source code must retain the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer.
   *
   *      - Redistributions in binary form must reproduce the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer in the documentation and/or other materials
   *        provided with the distribution.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   */
  #include <linux/kernel.h>

  #include <linux/gfp.h>

  #include <linux/in.h>
  #include <net/tcp.h>
  
  #include "rds.h"
  #include "tcp.h"
  
  /*
   * cheesy, but simple..
   */
  static void rds_tcp_accept_worker(struct work_struct *work);
  static DECLARE_WORK(rds_tcp_listen_work, rds_tcp_accept_worker);
  static struct socket *rds_tcp_listen_sock;
  
  static int rds_tcp_accept_one(struct socket *sock)
  {
  	struct socket *new_sock = NULL;
  	struct rds_connection *conn;
  	int ret;
  	struct inet_sock *inet;
  
  	ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
  			       sock->sk->sk_protocol, &new_sock);
  	if (ret)
  		goto out;
  
  	new_sock->type = sock->type;
  	new_sock->ops = sock->ops;
  	ret = sock->ops->accept(sock, new_sock, O_NONBLOCK);
  	if (ret < 0)
  		goto out;
  
  	rds_tcp_tune(new_sock);
  
  	inet = inet_sk(new_sock->sk);

  	rdsdebug("accepted tcp %pI4:%u -> %pI4:%u
  ",
  		 &inet->inet_saddr, ntohs(inet->inet_sport),
  		 &inet->inet_daddr, ntohs(inet->inet_dport));

  	conn = rds_conn_create(inet->inet_saddr, inet->inet_daddr,
  			       &rds_tcp_transport, GFP_KERNEL);

  	if (IS_ERR(conn)) {
  		ret = PTR_ERR(conn);
  		goto out;
  	}
  
  	/*
  	 * see the comment above rds_queue_delayed_reconnect()
  	 */
  	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
  		if (rds_conn_state(conn) == RDS_CONN_UP)
  			rds_tcp_stats_inc(s_tcp_listen_closed_stale);
  		else
  			rds_tcp_stats_inc(s_tcp_connect_raced);
  		rds_conn_drop(conn);
  		ret = 0;
  		goto out;
  	}
  
  	rds_tcp_set_callbacks(new_sock, conn);
  	rds_connect_complete(conn);
  	new_sock = NULL;
  	ret = 0;
  
  out:
  	if (new_sock)
  		sock_release(new_sock);
  	return ret;
  }
  
  static void rds_tcp_accept_worker(struct work_struct *work)
  {
  	while (rds_tcp_accept_one(rds_tcp_listen_sock) == 0)
  		cond_resched();
  }
  
  void rds_tcp_listen_data_ready(struct sock *sk, int bytes)
  {
  	void (*ready)(struct sock *sk, int bytes);
  
  	rdsdebug("listen data ready sk %p
  ", sk);

  	read_lock(&sk->sk_callback_lock);

  	ready = sk->sk_user_data;

  	if (!ready) { /* check for teardown race */

  		ready = sk->sk_data_ready;
  		goto out;
  	}
  
  	/*
  	 * ->sk_data_ready is also called for a newly established child socket
  	 * before it has been accepted and the accepter has set up their
  	 * data_ready.. we only want to queue listen work for our listening
  	 * socket
  	 */
  	if (sk->sk_state == TCP_LISTEN)
  		queue_work(rds_wq, &rds_tcp_listen_work);
  
  out:

  	read_unlock(&sk->sk_callback_lock);

  	ready(sk, bytes);
  }

  int rds_tcp_listen_init(void)

  {
  	struct sockaddr_in sin;
  	struct socket *sock = NULL;
  	int ret;
  
  	ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
  	if (ret < 0)
  		goto out;

  	sock->sk->sk_reuse = SK_CAN_REUSE;

  	rds_tcp_nonagle(sock);
  
  	write_lock_bh(&sock->sk->sk_callback_lock);
  	sock->sk->sk_user_data = sock->sk->sk_data_ready;
  	sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
  	write_unlock_bh(&sock->sk->sk_callback_lock);
  
  	sin.sin_family = PF_INET,
  	sin.sin_addr.s_addr = (__force u32)htonl(INADDR_ANY);
  	sin.sin_port = (__force u16)htons(RDS_TCP_PORT);
  
  	ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
  	if (ret < 0)
  		goto out;
  
  	ret = sock->ops->listen(sock, 64);
  	if (ret < 0)
  		goto out;
  
  	rds_tcp_listen_sock = sock;
  	sock = NULL;
  out:
  	if (sock)
  		sock_release(sock);
  	return ret;
  }
  
  void rds_tcp_listen_stop(void)
  {
  	struct socket *sock = rds_tcp_listen_sock;
  	struct sock *sk;

  	if (!sock)

  		return;
  
  	sk = sock->sk;
  
  	/* serialize with and prevent further callbacks */
  	lock_sock(sk);
  	write_lock_bh(&sk->sk_callback_lock);
  	if (sk->sk_user_data) {
  		sk->sk_data_ready = sk->sk_user_data;
  		sk->sk_user_data = NULL;
  	}
  	write_unlock_bh(&sk->sk_callback_lock);
  	release_sock(sk);
  
  	/* wait for accepts to stop and close the socket */
  	flush_workqueue(rds_wq);
  	sock_release(sock);
  	rds_tcp_listen_sock = NULL;
  }