/*
   * 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/slab.h>
  #include <linux/in.h>
  #include <linux/module.h>
  #include <net/tcp.h>
  
  #include "rds.h"
  #include "tcp.h"
  
  /* only for info exporting */
  static DEFINE_SPINLOCK(rds_tcp_tc_list_lock);
  static LIST_HEAD(rds_tcp_tc_list);
  static unsigned int rds_tcp_tc_count;
  
  /* Track rds_tcp_connection structs so they can be cleaned up */
  static DEFINE_SPINLOCK(rds_tcp_conn_lock);
  static LIST_HEAD(rds_tcp_conn_list);
  
  static struct kmem_cache *rds_tcp_conn_slab;
  
  #define RDS_TCP_DEFAULT_BUFSIZE (128 * 1024)
  
  /* doing it this way avoids calling tcp_sk() */
  void rds_tcp_nonagle(struct socket *sock)
  {
  	mm_segment_t oldfs = get_fs();
  	int val = 1;
  
  	set_fs(KERNEL_DS);
  	sock->ops->setsockopt(sock, SOL_TCP, TCP_NODELAY, (char __user *)&val,
  			      sizeof(val));
  	set_fs(oldfs);
  }
  
  void rds_tcp_tune(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	rds_tcp_nonagle(sock);
  
  	/*
  	 * We're trying to saturate gigabit with the default,
  	 * see svc_sock_setbufsize().
  	 */
  	lock_sock(sk);
  	sk->sk_sndbuf = RDS_TCP_DEFAULT_BUFSIZE;
  	sk->sk_rcvbuf = RDS_TCP_DEFAULT_BUFSIZE;
  	sk->sk_userlocks |= SOCK_SNDBUF_LOCK|SOCK_RCVBUF_LOCK;
  	release_sock(sk);
  }
  
  u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc)
  {
  	return tcp_sk(tc->t_sock->sk)->snd_nxt;
  }
  
  u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)
  {
  	return tcp_sk(tc->t_sock->sk)->snd_una;
  }
  
  void rds_tcp_restore_callbacks(struct socket *sock,
  			       struct rds_tcp_connection *tc)
  {
  	rdsdebug("restoring sock %p callbacks from tc %p
  ", sock, tc);
  	write_lock_bh(&sock->sk->sk_callback_lock);
  
  	/* done under the callback_lock to serialize with write_space */
  	spin_lock(&rds_tcp_tc_list_lock);
  	list_del_init(&tc->t_list_item);
  	rds_tcp_tc_count--;
  	spin_unlock(&rds_tcp_tc_list_lock);
  
  	tc->t_sock = NULL;
  
  	sock->sk->sk_write_space = tc->t_orig_write_space;
  	sock->sk->sk_data_ready = tc->t_orig_data_ready;
  	sock->sk->sk_state_change = tc->t_orig_state_change;
  	sock->sk->sk_user_data = NULL;
  
  	write_unlock_bh(&sock->sk->sk_callback_lock);
  }
  
  /*
   * This is the only path that sets tc->t_sock.  Send and receive trust that
   * it is set.  The RDS_CONN_CONNECTED bit protects those paths from being
   * called while it isn't set.
   */
  void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
  {
  	struct rds_tcp_connection *tc = conn->c_transport_data;
  
  	rdsdebug("setting sock %p callbacks to tc %p
  ", sock, tc);
  	write_lock_bh(&sock->sk->sk_callback_lock);
  
  	/* done under the callback_lock to serialize with write_space */
  	spin_lock(&rds_tcp_tc_list_lock);
  	list_add_tail(&tc->t_list_item, &rds_tcp_tc_list);
  	rds_tcp_tc_count++;
  	spin_unlock(&rds_tcp_tc_list_lock);
  
  	/* accepted sockets need our listen data ready undone */
  	if (sock->sk->sk_data_ready == rds_tcp_listen_data_ready)
  		sock->sk->sk_data_ready = sock->sk->sk_user_data;
  
  	tc->t_sock = sock;
  	tc->conn = conn;
  	tc->t_orig_data_ready = sock->sk->sk_data_ready;
  	tc->t_orig_write_space = sock->sk->sk_write_space;
  	tc->t_orig_state_change = sock->sk->sk_state_change;
  
  	sock->sk->sk_user_data = conn;
  	sock->sk->sk_data_ready = rds_tcp_data_ready;
  	sock->sk->sk_write_space = rds_tcp_write_space;
  	sock->sk->sk_state_change = rds_tcp_state_change;
  
  	write_unlock_bh(&sock->sk->sk_callback_lock);
  }
  
  static void rds_tcp_tc_info(struct socket *sock, unsigned int len,
  			    struct rds_info_iterator *iter,
  			    struct rds_info_lengths *lens)
  {
  	struct rds_info_tcp_socket tsinfo;
  	struct rds_tcp_connection *tc;
  	unsigned long flags;
  	struct sockaddr_in sin;
  	int sinlen;
  
  	spin_lock_irqsave(&rds_tcp_tc_list_lock, flags);
  
  	if (len / sizeof(tsinfo) < rds_tcp_tc_count)
  		goto out;
  
  	list_for_each_entry(tc, &rds_tcp_tc_list, t_list_item) {
  
  		sock->ops->getname(sock, (struct sockaddr *)&sin, &sinlen, 0);
  		tsinfo.local_addr = sin.sin_addr.s_addr;
  		tsinfo.local_port = sin.sin_port;
  		sock->ops->getname(sock, (struct sockaddr *)&sin, &sinlen, 1);
  		tsinfo.peer_addr = sin.sin_addr.s_addr;
  		tsinfo.peer_port = sin.sin_port;
  
  		tsinfo.hdr_rem = tc->t_tinc_hdr_rem;
  		tsinfo.data_rem = tc->t_tinc_data_rem;
  		tsinfo.last_sent_nxt = tc->t_last_sent_nxt;
  		tsinfo.last_expected_una = tc->t_last_expected_una;
  		tsinfo.last_seen_una = tc->t_last_seen_una;
  
  		rds_info_copy(iter, &tsinfo, sizeof(tsinfo));
  	}
  
  out:
  	lens->nr = rds_tcp_tc_count;
  	lens->each = sizeof(tsinfo);
  
  	spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
  }
  
  static int rds_tcp_laddr_check(__be32 addr)
  {
  	if (inet_addr_type(&init_net, addr) == RTN_LOCAL)
  		return 0;
  	return -EADDRNOTAVAIL;
  }
  
  static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
  {
  	struct rds_tcp_connection *tc;
  
  	tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
  	if (!tc)
  		return -ENOMEM;
  
  	tc->t_sock = NULL;
  	tc->t_tinc = NULL;
  	tc->t_tinc_hdr_rem = sizeof(struct rds_header);
  	tc->t_tinc_data_rem = 0;
  
  	conn->c_transport_data = tc;
  
  	spin_lock_irq(&rds_tcp_conn_lock);
  	list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
  	spin_unlock_irq(&rds_tcp_conn_lock);
  
  	rdsdebug("alloced tc %p
  ", conn->c_transport_data);
  	return 0;
  }
  
  static void rds_tcp_conn_free(void *arg)
  {
  	struct rds_tcp_connection *tc = arg;
  	unsigned long flags;
  	rdsdebug("freeing tc %p
  ", tc);
  
  	spin_lock_irqsave(&rds_tcp_conn_lock, flags);
  	list_del(&tc->t_tcp_node);
  	spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
  
  	kmem_cache_free(rds_tcp_conn_slab, tc);
  }
  
  static void rds_tcp_destroy_conns(void)
  {
  	struct rds_tcp_connection *tc, *_tc;
  	LIST_HEAD(tmp_list);
  
  	/* avoid calling conn_destroy with irqs off */
  	spin_lock_irq(&rds_tcp_conn_lock);
  	list_splice(&rds_tcp_conn_list, &tmp_list);
  	INIT_LIST_HEAD(&rds_tcp_conn_list);
  	spin_unlock_irq(&rds_tcp_conn_lock);
  
  	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {
  		if (tc->conn->c_passive)
  			rds_conn_destroy(tc->conn->c_passive);
  		rds_conn_destroy(tc->conn);
  	}
  }
  
  static void rds_tcp_exit(void)
  {
  	rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
  	rds_tcp_listen_stop();
  	rds_tcp_destroy_conns();
  	rds_trans_unregister(&rds_tcp_transport);
  	rds_tcp_recv_exit();
  	kmem_cache_destroy(rds_tcp_conn_slab);
  }
  module_exit(rds_tcp_exit);
  
  struct rds_transport rds_tcp_transport = {
  	.laddr_check		= rds_tcp_laddr_check,
  	.xmit_prepare		= rds_tcp_xmit_prepare,
  	.xmit_complete		= rds_tcp_xmit_complete,
  	.xmit			= rds_tcp_xmit,
  	.recv			= rds_tcp_recv,
  	.conn_alloc		= rds_tcp_conn_alloc,
  	.conn_free		= rds_tcp_conn_free,
  	.conn_connect		= rds_tcp_conn_connect,
  	.conn_shutdown		= rds_tcp_conn_shutdown,
  	.inc_copy_to_user	= rds_tcp_inc_copy_to_user,
  	.inc_free		= rds_tcp_inc_free,
  	.stats_info_copy	= rds_tcp_stats_info_copy,
  	.exit			= rds_tcp_exit,
  	.t_owner		= THIS_MODULE,
  	.t_name			= "tcp",
  	.t_type			= RDS_TRANS_TCP,
  	.t_prefer_loopback	= 1,
  };
  
  static int rds_tcp_init(void)
  {
  	int ret;
  
  	rds_tcp_conn_slab = kmem_cache_create("rds_tcp_connection",
  					      sizeof(struct rds_tcp_connection),
  					      0, 0, NULL);
  	if (!rds_tcp_conn_slab) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	ret = rds_tcp_recv_init();
  	if (ret)
  		goto out_slab;
  
  	ret = rds_trans_register(&rds_tcp_transport);
  	if (ret)
  		goto out_recv;
  
  	ret = rds_tcp_listen_init();
  	if (ret)
  		goto out_register;
  
  	rds_info_register_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
  
  	goto out;
  
  out_register:
  	rds_trans_unregister(&rds_tcp_transport);
  out_recv:
  	rds_tcp_recv_exit();
  out_slab:
  	kmem_cache_destroy(rds_tcp_conn_slab);
  out:
  	return ret;
  }
  module_init(rds_tcp_init);
  
  MODULE_AUTHOR("Oracle Corporation <rds-devel@oss.oracle.com>");
  MODULE_DESCRIPTION("RDS: TCP transport");
  MODULE_LICENSE("Dual BSD/GPL");