/*

   * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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/module.h>
  #include <linux/in.h>

  #include <linux/ipv6.h>

  
  #include "rds.h"
  #include "loop.h"

  static char * const rds_trans_modules[] = {
  	[RDS_TRANS_IB] = "rds_rdma",
  	[RDS_TRANS_GAP] = NULL,
  	[RDS_TRANS_TCP] = "rds_tcp",
  };

  static struct rds_transport *transports[RDS_TRANS_COUNT];

  static DECLARE_RWSEM(rds_trans_sem);

  void rds_trans_register(struct rds_transport *trans)

  {
  	BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ);
  
  	down_write(&rds_trans_sem);

  	if (transports[trans->t_type])
  		printk(KERN_ERR "RDS Transport type %d already registered
  ",
  			trans->t_type);
  	else {
  		transports[trans->t_type] = trans;
  		printk(KERN_INFO "Registered RDS/%s transport
  ", trans->t_name);
  	}

  
  	up_write(&rds_trans_sem);

  }

  EXPORT_SYMBOL_GPL(rds_trans_register);

  
  void rds_trans_unregister(struct rds_transport *trans)
  {
  	down_write(&rds_trans_sem);

  	transports[trans->t_type] = NULL;

  	printk(KERN_INFO "Unregistered RDS/%s transport
  ", trans->t_name);
  
  	up_write(&rds_trans_sem);
  }

  EXPORT_SYMBOL_GPL(rds_trans_unregister);

  void rds_trans_put(struct rds_transport *trans)
  {

  	if (trans)

  		module_put(trans->t_owner);
  }

  struct rds_transport *rds_trans_get_preferred(struct net *net,
  					      const struct in6_addr *addr,
  					      __u32 scope_id)

  {

  	struct rds_transport *ret = NULL;

  	struct rds_transport *trans;
  	unsigned int i;

  	if (ipv6_addr_v4mapped(addr)) {
  		if (*(u_int8_t *)&addr->s6_addr32[3] == IN_LOOPBACKNET)
  			return &rds_loop_transport;
  	} else if (ipv6_addr_loopback(addr)) {

  		return &rds_loop_transport;

  	}

  
  	down_read(&rds_trans_sem);

  	for (i = 0; i < RDS_TRANS_COUNT; i++) {
  		trans = transports[i];

  		if (trans && (trans->laddr_check(net, addr, scope_id) == 0) &&

  		    (!trans->t_owner || try_module_get(trans->t_owner))) {
  			ret = trans;

  			break;
  		}
  	}
  	up_read(&rds_trans_sem);
  
  	return ret;
  }

  struct rds_transport *rds_trans_get(int t_type)
  {
  	struct rds_transport *ret = NULL;
  	struct rds_transport *trans;

  
  	down_read(&rds_trans_sem);

  	trans = transports[t_type];
  	if (!trans) {
  		up_read(&rds_trans_sem);
  		if (rds_trans_modules[t_type])
  			request_module(rds_trans_modules[t_type]);
  		down_read(&rds_trans_sem);
  		trans = transports[t_type];

  	}

  	if (trans && trans->t_type == t_type &&
  	    (!trans->t_owner || try_module_get(trans->t_owner)))
  		ret = trans;

  	up_read(&rds_trans_sem);
  
  	return ret;
  }

  /*
   * This returns the number of stats entries in the snapshot and only
   * copies them using the iter if there is enough space for them.  The
   * caller passes in the global stats so that we can size and copy while
   * holding the lock.
   */
  unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
  				       unsigned int avail)
  
  {
  	struct rds_transport *trans;
  	unsigned int total = 0;
  	unsigned int part;

  	int i;

  
  	rds_info_iter_unmap(iter);
  	down_read(&rds_trans_sem);

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

  		trans = transports[i];
  		if (!trans || !trans->stats_info_copy)

  			continue;
  
  		part = trans->stats_info_copy(iter, avail);
  		avail -= min(avail, part);
  		total += part;
  	}
  
  	up_read(&rds_trans_sem);
  
  	return total;
  }