net/rds/transport.c

   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
  40 static LIST_HEAD(rds_transports);
  41 static DECLARE_RWSEM(rds_trans_sem);
  42
  43 int 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         list_add_tail(&trans->t_item, &rds_transports);
  50         printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
  51
  52         up_write(&rds_trans_sem);
  53
  54         return 0;
  55 }
  56
  57 void rds_trans_unregister(struct rds_transport *trans)
  58 {
  59         down_write(&rds_trans_sem);
  60
  61         list_del_init(&trans->t_item);
  62         printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
  63
  64         up_write(&rds_trans_sem);
  65 }
  66
  67 struct rds_transport *rds_trans_get_preferred(__be32 addr)
  68 {
  69         struct rds_transport *trans;
  70         struct rds_transport *ret = NULL;
  71
  72         if (IN_LOOPBACK(ntohl(addr)))
  73                 return &rds_loop_transport;
  74
  75         down_read(&rds_trans_sem);
  76         list_for_each_entry(trans, &rds_transports, t_item) {
  77                 if (trans->laddr_check(addr) == 0) {
  78                         ret = trans;
  79                         break;
  80                 }
  81         }
  82         up_read(&rds_trans_sem);
  83
  84         return ret;
  85 }
  86
  87 /*
  88  * This returns the number of stats entries in the snapshot and only
  89  * copies them using the iter if there is enough space for them.  The
  90  * caller passes in the global stats so that we can size and copy while
  91  * holding the lock.
  92  */
  93 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
  94                                        unsigned int avail)
  95
  96 {
  97         struct rds_transport *trans;
  98         unsigned int total = 0;
  99         unsigned int part;
 100
 101         rds_info_iter_unmap(iter);
 102         down_read(&rds_trans_sem);
 103
 104         list_for_each_entry(trans, &rds_transports, t_item) {
 105                 if (trans->stats_info_copy == NULL)
 106                         continue;
 107
 108                 part = trans->stats_info_copy(iter, avail);
 109                 avail -= min(avail, part);
 110                 total += part;
 111         }
 112
 113         up_read(&rds_trans_sem);
 114
 115         return total;
 116 }
 117