linux/net/rds/transport.c
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   1/*
   2 * Copyright (c) 2006 Oracle.  All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <linux/module.h>
  35#include <linux/in.h>
  36
  37#include "rds.h"
  38#include "loop.h"
  39
  40static struct rds_transport *transports[RDS_TRANS_COUNT];
  41static DECLARE_RWSEM(rds_trans_sem);
  42
  43int rds_trans_register(struct rds_transport *trans)
  44{
  45        BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ);
  46
  47        down_write(&rds_trans_sem);
  48
  49        if (transports[trans->t_type])
  50                printk(KERN_ERR "RDS Transport type %d already registered\n",
  51                        trans->t_type);
  52        else {
  53                transports[trans->t_type] = trans;
  54                printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
  55        }
  56
  57        up_write(&rds_trans_sem);
  58
  59        return 0;
  60}
  61EXPORT_SYMBOL_GPL(rds_trans_register);
  62
  63void rds_trans_unregister(struct rds_transport *trans)
  64{
  65        down_write(&rds_trans_sem);
  66
  67        transports[trans->t_type] = NULL;
  68        printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
  69
  70        up_write(&rds_trans_sem);
  71}
  72EXPORT_SYMBOL_GPL(rds_trans_unregister);
  73
  74void rds_trans_put(struct rds_transport *trans)
  75{
  76        if (trans && trans->t_owner)
  77                module_put(trans->t_owner);
  78}
  79
  80struct rds_transport *rds_trans_get_preferred(__be32 addr)
  81{
  82        struct rds_transport *ret = NULL;
  83        struct rds_transport *trans;
  84        unsigned int i;
  85
  86        if (IN_LOOPBACK(ntohl(addr)))
  87                return &rds_loop_transport;
  88
  89        down_read(&rds_trans_sem);
  90        for (i = 0; i < RDS_TRANS_COUNT; i++) {
  91                trans = transports[i];
  92
  93                if (trans && (trans->laddr_check(addr) == 0) &&
  94                    (!trans->t_owner || try_module_get(trans->t_owner))) {
  95                        ret = trans;
  96                        break;
  97                }
  98        }
  99        up_read(&rds_trans_sem);
 100
 101        return ret;
 102}
 103
 104/*
 105 * This returns the number of stats entries in the snapshot and only
 106 * copies them using the iter if there is enough space for them.  The
 107 * caller passes in the global stats so that we can size and copy while
 108 * holding the lock.
 109 */
 110unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
 111                                       unsigned int avail)
 112
 113{
 114        struct rds_transport *trans;
 115        unsigned int total = 0;
 116        unsigned int part;
 117        int i;
 118
 119        rds_info_iter_unmap(iter);
 120        down_read(&rds_trans_sem);
 121
 122        for (i = 0; i < RDS_TRANS_COUNT; i++)
 123        {
 124                trans = transports[i];
 125                if (!trans || !trans->stats_info_copy)
 126                        continue;
 127
 128                part = trans->stats_info_copy(iter, avail);
 129                avail -= min(avail, part);
 130                total += part;
 131        }
 132
 133        up_read(&rds_trans_sem);
 134
 135        return total;
 136}
 137
 138
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