/*
   * 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/list.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  #include <net/inet_hashtables.h>
  
  #include "rds.h"
  #include "loop.h"

  
  #define RDS_CONNECTION_HASH_BITS 12
  #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
  #define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
  
  /* converting this to RCU is a chore for another day.. */
  static DEFINE_SPINLOCK(rds_conn_lock);
  static unsigned long rds_conn_count;
  static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
  static struct kmem_cache *rds_conn_slab;
  
  static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
  {

  	static u32 rds_hash_secret __read_mostly;
  
  	unsigned long hash;
  
  	net_get_random_once(&rds_hash_secret, sizeof(rds_hash_secret));

  	/* Pass NULL, don't need struct net for hash */

  	hash = __inet_ehashfn(be32_to_cpu(laddr), 0,
  			      be32_to_cpu(faddr), 0,
  			      rds_hash_secret);

  	return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
  }
  
  #define rds_conn_info_set(var, test, suffix) do {		\
  	if (test)						\
  		var |= RDS_INFO_CONNECTION_FLAG_##suffix;	\
  } while (0)

  /* rcu read lock must be held or the connection spinlock */

  static struct rds_connection *rds_conn_lookup(struct net *net,
  					      struct hlist_head *head,

  					      __be32 laddr, __be32 faddr,
  					      struct rds_transport *trans)
  {
  	struct rds_connection *conn, *ret = NULL;

  	hlist_for_each_entry_rcu(conn, head, c_hash_node) {

  		if (conn->c_faddr == faddr && conn->c_laddr == laddr &&

  		    conn->c_trans == trans && net == rds_conn_net(conn)) {

  			ret = conn;
  			break;
  		}
  	}
  	rdsdebug("returning conn %p for %pI4 -> %pI4
  ", ret,
  		 &laddr, &faddr);
  	return ret;
  }
  
  /*
   * This is called by transports as they're bringing down a connection.
   * It clears partial message state so that the transport can start sending
   * and receiving over this connection again in the future.  It is up to
   * the transport to have serialized this call with its send and recv.
   */

  static void rds_conn_path_reset(struct rds_conn_path *cp)

  {

  	struct rds_connection *conn = cp->cp_conn;

  	rdsdebug("connection %pI4 to %pI4 reset
  ",
  	  &conn->c_laddr, &conn->c_faddr);
  
  	rds_stats_inc(s_conn_reset);

  	rds_send_path_reset(cp);
  	cp->cp_flags = 0;

  
  	/* Do not clear next_rx_seq here, else we cannot distinguish
  	 * retransmitted packets from new packets, and will hand all
  	 * of them to the application. That is not consistent with the
  	 * reliability guarantees of RDS. */
  }

  static void __rds_conn_path_init(struct rds_connection *conn,
  				 struct rds_conn_path *cp, bool is_outgoing)
  {
  	spin_lock_init(&cp->cp_lock);
  	cp->cp_next_tx_seq = 1;
  	init_waitqueue_head(&cp->cp_waitq);
  	INIT_LIST_HEAD(&cp->cp_send_queue);
  	INIT_LIST_HEAD(&cp->cp_retrans);
  
  	cp->cp_conn = conn;
  	atomic_set(&cp->cp_state, RDS_CONN_DOWN);
  	cp->cp_send_gen = 0;

  	cp->cp_reconnect_jiffies = 0;
  	INIT_DELAYED_WORK(&cp->cp_send_w, rds_send_worker);
  	INIT_DELAYED_WORK(&cp->cp_recv_w, rds_recv_worker);
  	INIT_DELAYED_WORK(&cp->cp_conn_w, rds_connect_worker);
  	INIT_WORK(&cp->cp_down_w, rds_shutdown_worker);
  	mutex_init(&cp->cp_cm_lock);
  	cp->cp_flags = 0;
  }

  /*
   * There is only every one 'conn' for a given pair of addresses in the
   * system at a time.  They contain messages to be retransmitted and so
   * span the lifetime of the actual underlying transport connections.
   *
   * For now they are not garbage collected once they're created.  They
   * are torn down as the module is removed, if ever.
   */

  static struct rds_connection *__rds_conn_create(struct net *net,
  						__be32 laddr, __be32 faddr,

  				       struct rds_transport *trans, gfp_t gfp,
  				       int is_outgoing)
  {

  	struct rds_connection *conn, *parent = NULL;

  	struct hlist_head *head = rds_conn_bucket(laddr, faddr);

  	struct rds_transport *loop_trans;

  	unsigned long flags;

  	int ret, i;

  	int npaths = (trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);

  	rcu_read_lock();

  	conn = rds_conn_lookup(net, head, laddr, faddr, trans);

  	if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&

  	    laddr == faddr && !is_outgoing) {

  		/* This is a looped back IB connection, and we're
  		 * called by the code handling the incoming connect.
  		 * We need a second connection object into which we
  		 * can stick the other QP. */
  		parent = conn;
  		conn = parent->c_passive;
  	}

  	rcu_read_unlock();

  	if (conn)
  		goto out;

  	conn = kmem_cache_zalloc(rds_conn_slab, gfp);

  	if (!conn) {

  		conn = ERR_PTR(-ENOMEM);
  		goto out;
  	}

  	conn->c_path = kcalloc(npaths, sizeof(struct rds_conn_path), gfp);
  	if (!conn->c_path) {
  		kmem_cache_free(rds_conn_slab, conn);
  		conn = ERR_PTR(-ENOMEM);
  		goto out;
  	}

  	INIT_HLIST_NODE(&conn->c_hash_node);

  	conn->c_laddr = laddr;
  	conn->c_faddr = faddr;

  	rds_conn_net_set(conn, net);

  
  	ret = rds_cong_get_maps(conn);
  	if (ret) {

  		kfree(conn->c_path);

  		kmem_cache_free(rds_conn_slab, conn);
  		conn = ERR_PTR(ret);
  		goto out;
  	}
  
  	/*
  	 * This is where a connection becomes loopback.  If *any* RDS sockets
  	 * can bind to the destination address then we'd rather the messages
  	 * flow through loopback rather than either transport.
  	 */

  	loop_trans = rds_trans_get_preferred(net, faddr);

  	if (loop_trans) {
  		rds_trans_put(loop_trans);

  		conn->c_loopback = 1;
  		if (is_outgoing && trans->t_prefer_loopback) {
  			/* "outgoing" connection - and the transport
  			 * says it wants the connection handled by the
  			 * loopback transport. This is what TCP does.
  			 */
  			trans = &rds_loop_transport;
  		}
  	}
  
  	conn->c_trans = trans;

  	init_waitqueue_head(&conn->c_hs_waitq);

  	for (i = 0; i < npaths; i++) {

  		__rds_conn_path_init(conn, &conn->c_path[i],
  				     is_outgoing);
  		conn->c_path[i].cp_index = i;
  	}

  	ret = trans->conn_alloc(conn, gfp);
  	if (ret) {

  		kfree(conn->c_path);

  		kmem_cache_free(rds_conn_slab, conn);
  		conn = ERR_PTR(ret);
  		goto out;
  	}

  	rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s
  ",
  	  conn, &laddr, &faddr,
  	  trans->t_name ? trans->t_name : "[unknown]",
  	  is_outgoing ? "(outgoing)" : "");

  	/*
  	 * Since we ran without holding the conn lock, someone could
  	 * have created the same conn (either normal or passive) in the
  	 * interim. We check while holding the lock. If we won, we complete
  	 * init and return our conn. If we lost, we rollback and return the
  	 * other one.
  	 */

  	spin_lock_irqsave(&rds_conn_lock, flags);

  	if (parent) {
  		/* Creating passive conn */
  		if (parent->c_passive) {

  			trans->conn_free(conn->c_path[0].cp_transport_data);

  			kfree(conn->c_path);

  			kmem_cache_free(rds_conn_slab, conn);
  			conn = parent->c_passive;
  		} else {

  			parent->c_passive = conn;

  			rds_cong_add_conn(conn);
  			rds_conn_count++;
  		}

  	} else {

  		/* Creating normal conn */
  		struct rds_connection *found;

  		found = rds_conn_lookup(net, head, laddr, faddr, trans);

  		if (found) {

  			struct rds_conn_path *cp;
  			int i;

  			for (i = 0; i < npaths; i++) {

  				cp = &conn->c_path[i];

  				/* The ->conn_alloc invocation may have
  				 * allocated resource for all paths, so all
  				 * of them may have to be freed here.
  				 */
  				if (cp->cp_transport_data)
  					trans->conn_free(cp->cp_transport_data);

  			}

  			kfree(conn->c_path);

  			kmem_cache_free(rds_conn_slab, conn);
  			conn = found;
  		} else {

  			conn->c_my_gen_num = rds_gen_num;
  			conn->c_peer_gen_num = 0;

  			hlist_add_head_rcu(&conn->c_hash_node, head);

  			rds_cong_add_conn(conn);
  			rds_conn_count++;
  		}

  	}

  	spin_unlock_irqrestore(&rds_conn_lock, flags);
  
  out:
  	return conn;
  }

  struct rds_connection *rds_conn_create(struct net *net,
  				       __be32 laddr, __be32 faddr,

  				       struct rds_transport *trans, gfp_t gfp)
  {

  	return __rds_conn_create(net, laddr, faddr, trans, gfp, 0);

  }

  EXPORT_SYMBOL_GPL(rds_conn_create);

  struct rds_connection *rds_conn_create_outgoing(struct net *net,
  						__be32 laddr, __be32 faddr,

  				       struct rds_transport *trans, gfp_t gfp)
  {

  	return __rds_conn_create(net, laddr, faddr, trans, gfp, 1);

  }

  EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);

  void rds_conn_shutdown(struct rds_conn_path *cp)

  {

  	struct rds_connection *conn = cp->cp_conn;

  	/* shut it down unless it's down already */

  	if (!rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_DOWN)) {

  		/*
  		 * Quiesce the connection mgmt handlers before we start tearing
  		 * things down. We don't hold the mutex for the entire
  		 * duration of the shutdown operation, else we may be
  		 * deadlocking with the CM handler. Instead, the CM event
  		 * handler is supposed to check for state DISCONNECTING
  		 */

  		mutex_lock(&cp->cp_cm_lock);
  		if (!rds_conn_path_transition(cp, RDS_CONN_UP,
  					      RDS_CONN_DISCONNECTING) &&
  		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,
  					      RDS_CONN_DISCONNECTING)) {
  			rds_conn_path_error(cp,
  					    "shutdown called in state %d
  ",
  					    atomic_read(&cp->cp_state));
  			mutex_unlock(&cp->cp_cm_lock);

  			return;
  		}

  		mutex_unlock(&cp->cp_cm_lock);

  		wait_event(cp->cp_waitq,
  			   !test_bit(RDS_IN_XMIT, &cp->cp_flags));
  		wait_event(cp->cp_waitq,
  			   !test_bit(RDS_RECV_REFILL, &cp->cp_flags));

  		conn->c_trans->conn_path_shutdown(cp);

  		rds_conn_path_reset(cp);

  		if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,

  					      RDS_CONN_DOWN) &&
  		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,

  					      RDS_CONN_DOWN)) {

  			/* This can happen - eg when we're in the middle of tearing
  			 * down the connection, and someone unloads the rds module.

  			 * Quite reproducible with loopback connections.

  			 * Mostly harmless.

  			 *
  			 * Note that this also happens with rds-tcp because
  			 * we could have triggered rds_conn_path_drop in irq
  			 * mode from rds_tcp_state change on the receipt of
  			 * a FIN, thus we need to recheck for RDS_CONN_ERROR
  			 * here.

  			 */

  			rds_conn_path_error(cp, "%s: failed to transition "
  					    "to state DOWN, current state "
  					    "is %d
  ", __func__,
  					    atomic_read(&cp->cp_state));

  			return;
  		}
  	}
  
  	/* Then reconnect if it's still live.
  	 * The passive side of an IB loopback connection is never added
  	 * to the conn hash, so we never trigger a reconnect on this
  	 * conn - the reconnect is always triggered by the active peer. */

  	cancel_delayed_work_sync(&cp->cp_conn_w);

  	if (conn->c_destroy_in_prog)
  		return;

  	rcu_read_lock();
  	if (!hlist_unhashed(&conn->c_hash_node)) {
  		rcu_read_unlock();

  		rds_queue_reconnect(cp);

  	} else {
  		rcu_read_unlock();
  	}

  }

  /* destroy a single rds_conn_path. rds_conn_destroy() iterates over
   * all paths using rds_conn_path_destroy()
   */
  static void rds_conn_path_destroy(struct rds_conn_path *cp)
  {
  	struct rds_message *rm, *rtmp;

  	if (!cp->cp_transport_data)
  		return;

  	/* make sure lingering queued work won't try to ref the conn */
  	cancel_delayed_work_sync(&cp->cp_send_w);
  	cancel_delayed_work_sync(&cp->cp_recv_w);

  	rds_conn_path_drop(cp, true);
  	flush_work(&cp->cp_down_w);

  	/* tear down queued messages */
  	list_for_each_entry_safe(rm, rtmp,
  				 &cp->cp_send_queue,
  				 m_conn_item) {
  		list_del_init(&rm->m_conn_item);
  		BUG_ON(!list_empty(&rm->m_sock_item));
  		rds_message_put(rm);
  	}
  	if (cp->cp_xmit_rm)
  		rds_message_put(cp->cp_xmit_rm);
  
  	cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
  }

  /*
   * Stop and free a connection.

   *
   * This can only be used in very limited circumstances.  It assumes that once
   * the conn has been shutdown that no one else is referencing the connection.
   * We can only ensure this in the rmmod path in the current code.

   */

  void rds_conn_destroy(struct rds_connection *conn)
  {

  	unsigned long flags;

  	int i;
  	struct rds_conn_path *cp;

  	int npaths = (conn->c_trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);

  
  	rdsdebug("freeing conn %p for %pI4 -> "
  		 "%pI4
  ", conn, &conn->c_laddr,
  		 &conn->c_faddr);

  	conn->c_destroy_in_prog = 1;

  	/* Ensure conn will not be scheduled for reconnect */
  	spin_lock_irq(&rds_conn_lock);

  	hlist_del_init_rcu(&conn->c_hash_node);

  	spin_unlock_irq(&rds_conn_lock);

  	synchronize_rcu();

  	/* shut the connection down */

  	for (i = 0; i < npaths; i++) {

  		cp = &conn->c_path[i];
  		rds_conn_path_destroy(cp);
  		BUG_ON(!list_empty(&cp->cp_retrans));

  	}

  
  	/*
  	 * The congestion maps aren't freed up here.  They're
  	 * freed by rds_cong_exit() after all the connections
  	 * have been freed.
  	 */
  	rds_cong_remove_conn(conn);

  	kfree(conn->c_path);

  	kmem_cache_free(rds_conn_slab, conn);

  	spin_lock_irqsave(&rds_conn_lock, flags);

  	rds_conn_count--;

  	spin_unlock_irqrestore(&rds_conn_lock, flags);

  }

  EXPORT_SYMBOL_GPL(rds_conn_destroy);

  
  static void rds_conn_message_info(struct socket *sock, unsigned int len,
  				  struct rds_info_iterator *iter,
  				  struct rds_info_lengths *lens,
  				  int want_send)
  {
  	struct hlist_head *head;

  	struct list_head *list;
  	struct rds_connection *conn;
  	struct rds_message *rm;

  	unsigned int total = 0;

  	unsigned long flags;

  	size_t i;

  	int j;

  
  	len /= sizeof(struct rds_info_message);

  	rcu_read_lock();

  
  	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
  	     i++, head++) {

  		hlist_for_each_entry_rcu(conn, head, c_hash_node) {

  			struct rds_conn_path *cp;

  			int npaths;
  
  			npaths = (conn->c_trans->t_mp_capable ?
  				 RDS_MPATH_WORKERS : 1);

  			for (j = 0; j < npaths; j++) {

  				cp = &conn->c_path[j];
  				if (want_send)
  					list = &cp->cp_send_queue;
  				else
  					list = &cp->cp_retrans;
  
  				spin_lock_irqsave(&cp->cp_lock, flags);
  
  				/* XXX too lazy to maintain counts.. */
  				list_for_each_entry(rm, list, m_conn_item) {
  					total++;
  					if (total <= len)
  						rds_inc_info_copy(&rm->m_inc,
  								  iter,
  								  conn->c_laddr,
  								  conn->c_faddr,
  								  0);
  				}
  
  				spin_unlock_irqrestore(&cp->cp_lock, flags);

  			}

  		}
  	}

  	rcu_read_unlock();

  
  	lens->nr = total;
  	lens->each = sizeof(struct rds_info_message);
  }
  
  static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
  				       struct rds_info_iterator *iter,
  				       struct rds_info_lengths *lens)
  {
  	rds_conn_message_info(sock, len, iter, lens, 1);
  }
  
  static void rds_conn_message_info_retrans(struct socket *sock,
  					  unsigned int len,
  					  struct rds_info_iterator *iter,
  					  struct rds_info_lengths *lens)
  {
  	rds_conn_message_info(sock, len, iter, lens, 0);
  }
  
  void rds_for_each_conn_info(struct socket *sock, unsigned int len,
  			  struct rds_info_iterator *iter,
  			  struct rds_info_lengths *lens,
  			  int (*visitor)(struct rds_connection *, void *),
  			  size_t item_len)
  {
  	uint64_t buffer[(item_len + 7) / 8];
  	struct hlist_head *head;

  	struct rds_connection *conn;

  	size_t i;

  	rcu_read_lock();

  
  	lens->nr = 0;
  	lens->each = item_len;
  
  	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
  	     i++, head++) {

  		hlist_for_each_entry_rcu(conn, head, c_hash_node) {

  
  			/* XXX no c_lock usage.. */
  			if (!visitor(conn, buffer))
  				continue;
  
  			/* We copy as much as we can fit in the buffer,
  			 * but we count all items so that the caller
  			 * can resize the buffer. */
  			if (len >= item_len) {
  				rds_info_copy(iter, buffer, item_len);
  				len -= item_len;
  			}
  			lens->nr++;
  		}
  	}

  	rcu_read_unlock();

  }

  EXPORT_SYMBOL_GPL(rds_for_each_conn_info);

  static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
  				    struct rds_info_iterator *iter,
  				    struct rds_info_lengths *lens,
  				    int (*visitor)(struct rds_conn_path *, void *),
  				    size_t item_len)

  {
  	u64  buffer[(item_len + 7) / 8];
  	struct hlist_head *head;
  	struct rds_connection *conn;
  	size_t i;
  	int j;
  
  	rcu_read_lock();
  
  	lens->nr = 0;
  	lens->each = item_len;
  
  	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
  	     i++, head++) {
  		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
  			struct rds_conn_path *cp;

  			int npaths;

  			npaths = (conn->c_trans->t_mp_capable ?
  				 RDS_MPATH_WORKERS : 1);
  			for (j = 0; j < npaths; j++) {

  				cp = &conn->c_path[j];
  
  				/* XXX no cp_lock usage.. */
  				if (!visitor(cp, buffer))
  					continue;

  			}
  
  			/* We copy as much as we can fit in the buffer,
  			 * but we count all items so that the caller
  			 * can resize the buffer.
  			 */
  			if (len >= item_len) {
  				rds_info_copy(iter, buffer, item_len);
  				len -= item_len;
  			}
  			lens->nr++;
  		}
  	}
  	rcu_read_unlock();
  }
  
  static int rds_conn_info_visitor(struct rds_conn_path *cp, void *buffer)

  {
  	struct rds_info_connection *cinfo = buffer;

  	cinfo->next_tx_seq = cp->cp_next_tx_seq;
  	cinfo->next_rx_seq = cp->cp_next_rx_seq;
  	cinfo->laddr = cp->cp_conn->c_laddr;
  	cinfo->faddr = cp->cp_conn->c_faddr;
  	strncpy(cinfo->transport, cp->cp_conn->c_trans->t_name,

  		sizeof(cinfo->transport));
  	cinfo->flags = 0;

  	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),

  			  SENDING);

  	/* XXX Future: return the state rather than these funky bits */
  	rds_conn_info_set(cinfo->flags,

  			  atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,

  			  CONNECTING);
  	rds_conn_info_set(cinfo->flags,

  			  atomic_read(&cp->cp_state) == RDS_CONN_UP,

  			  CONNECTED);
  	return 1;
  }
  
  static void rds_conn_info(struct socket *sock, unsigned int len,
  			  struct rds_info_iterator *iter,
  			  struct rds_info_lengths *lens)
  {

  	rds_walk_conn_path_info(sock, len, iter, lens,

  				rds_conn_info_visitor,
  				sizeof(struct rds_info_connection));
  }

  int rds_conn_init(void)

  {
  	rds_conn_slab = kmem_cache_create("rds_connection",
  					  sizeof(struct rds_connection),
  					  0, 0, NULL);

  	if (!rds_conn_slab)

  		return -ENOMEM;
  
  	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
  	rds_info_register_func(RDS_INFO_SEND_MESSAGES,
  			       rds_conn_message_info_send);
  	rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
  			       rds_conn_message_info_retrans);
  
  	return 0;
  }
  
  void rds_conn_exit(void)
  {
  	rds_loop_exit();
  
  	WARN_ON(!hlist_empty(rds_conn_hash));
  
  	kmem_cache_destroy(rds_conn_slab);
  
  	rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
  	rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
  				 rds_conn_message_info_send);
  	rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
  				 rds_conn_message_info_retrans);
  }
  
  /*
   * Force a disconnect
   */

  void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)

  {
  	atomic_set(&cp->cp_state, RDS_CONN_ERROR);

  
  	if (!destroy && cp->cp_conn->c_destroy_in_prog)
  		return;

  	queue_work(rds_wq, &cp->cp_down_w);
  }
  EXPORT_SYMBOL_GPL(rds_conn_path_drop);

  void rds_conn_drop(struct rds_connection *conn)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);

  	rds_conn_path_drop(&conn->c_path[0], false);

  }

  EXPORT_SYMBOL_GPL(rds_conn_drop);

  
  /*

   * If the connection is down, trigger a connect. We may have scheduled a
   * delayed reconnect however - in this case we should not interfere.
   */

  void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
  {
  	if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
  	    !test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
  		queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
  }

  EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);

  void rds_conn_connect_if_down(struct rds_connection *conn)
  {

  	WARN_ON(conn->c_trans->t_mp_capable);
  	rds_conn_path_connect_if_down(&conn->c_path[0]);

  }
  EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);

  void
  __rds_conn_path_error(struct rds_conn_path *cp, const char *fmt, ...)
  {
  	va_list ap;
  
  	va_start(ap, fmt);
  	vprintk(fmt, ap);
  	va_end(ap);

  	rds_conn_path_drop(cp, false);

  }