RDS: Transport code

/*

 * 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

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#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/in.h>

#include "rds.h"

#include "loop.h"

static LIST_HEAD(rds_transports);

static DECLARE_RWSEM(rds_trans_sem);

int rds_trans_register(struct rds_transport *trans)

{

	BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ);

	down_write(&rds_trans_sem);

	list_add_tail(&trans->t_item, &rds_transports);

	printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);

	up_write(&rds_trans_sem);

	return 0;

}

void rds_trans_unregister(struct rds_transport *trans)

{

	down_write(&rds_trans_sem);

	list_del_init(&trans->t_item);

	printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);

	up_write(&rds_trans_sem);

}

struct rds_transport *rds_trans_get_preferred(__be32 addr)

{

	struct rds_transport *trans;

	struct rds_transport *ret = NULL;

	if (IN_LOOPBACK(ntohl(addr)))

		return &rds_loop_transport;

	down_read(&rds_trans_sem);

	list_for_each_entry(trans, &rds_transports, t_item) {

		if (trans->laddr_check(addr) == 0) {

			ret = trans;

			break;

		}

	}

	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;

	rds_info_iter_unmap(iter);

	down_read(&rds_trans_sem);

	list_for_each_entry(trans, &rds_transports, t_item) {

		if (trans->stats_info_copy == NULL)

			continue;

		part = trans->stats_info_copy(iter, avail);

		avail -= min(avail, part);

		total += part;

	}

	up_read(&rds_trans_sem);

	return total;

}