transport.c

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/*
 * 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/module.h>
#include <linux/in.h>

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

static struct rds_transport *transports[RDS_TRANS_COUNT];
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);

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

    up_write(&rds_trans_sem);

    return 0;
}
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\n", trans->t_name);

    up_write(&rds_trans_sem);
}
EXPORT_SYMBOL_GPL(rds_trans_unregister);

void rds_trans_put(struct rds_transport *trans)
{
    if (trans && trans->t_owner)
        module_put(trans->t_owner);
}

struct rds_transport *rds_trans_get_preferred(__be32 addr)
{
    struct rds_transport *ret = NULL;
    struct rds_transport *trans;
    unsigned int i;

    if (IN_LOOPBACK(ntohl(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(addr) == 0) &&
            (!trans->t_owner || try_module_get(trans->t_owner))) {
            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;
    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;
}