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 struct rds_transport *transports[RDS_TRANS_COUNT];
  41 static DECLARE_RWSEM(rds_trans_sem);
  42
  43 void 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 EXPORT_SYMBOL_GPL(rds_trans_register);
  60
  61 void rds_trans_unregister(struct rds_transport *trans)
  62 {
  63         down_write(&rds_trans_sem);
  64
  65         transports[trans->t_type] = NULL;
  66         printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
  67
  68         up_write(&rds_trans_sem);
  69 }
  70 EXPORT_SYMBOL_GPL(rds_trans_unregister);
  71
  72 void rds_trans_put(struct rds_transport *trans)
  73 {
  74         if (trans)
  75                 module_put(trans->t_owner);
  76 }
  77
  78 struct rds_transport *rds_trans_get_preferred(struct net *net, __be32 addr)
  79 {
  80         struct rds_transport *ret = NULL;
  81         struct rds_transport *trans;
  82         unsigned int i;
  83
  84         if (IN_LOOPBACK(ntohl(addr)))
  85                 return &rds_loop_transport;
  86
  87         down_read(&rds_trans_sem);
  88         for (i = 0; i < RDS_TRANS_COUNT; i++) {
  89                 trans = transports[i];
  90
  91                 if (trans && (trans->laddr_check(net, addr) == 0) &&
  92                     (!trans->t_owner || try_module_get(trans->t_owner))) {
  93                         ret = trans;
  94                         break;
  95                 }
  96         }
  97         up_read(&rds_trans_sem);
  98
  99         return ret;
 100 }
 101
 102 struct rds_transport *rds_trans_get(int t_type)
 103 {
 104         struct rds_transport *ret = NULL;
 105         struct rds_transport *trans;
 106         unsigned int i;
 107
 108         down_read(&rds_trans_sem);
 109         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 110                 trans = transports[i];
 111
 112                 if (trans && trans->t_type == t_type &&
 113                     (!trans->t_owner || try_module_get(trans->t_owner))) {
 114                         ret = trans;
 115                         break;
 116                 }
 117         }
 118         up_read(&rds_trans_sem);
 119
 120         return ret;
 121 }
 122
 123 /*
 124  * This returns the number of stats entries in the snapshot and only
 125  * copies them using the iter if there is enough space for them.  The
 126  * caller passes in the global stats so that we can size and copy while
 127  * holding the lock.
 128  */
 129 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
 130                                        unsigned int avail)
 131
 132 {
 133         struct rds_transport *trans;
 134         unsigned int total = 0;
 135         unsigned int part;
 136         int i;
 137
 138         rds_info_iter_unmap(iter);
 139         down_read(&rds_trans_sem);
 140
 141         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 142                 trans = transports[i];
 143                 if (!trans || !trans->stats_info_copy)
 144                         continue;
 145
 146                 part = trans->stats_info_copy(iter, avail);
 147                 avail -= min(avail, part);
 148                 total += part;
 149         }
 150
 151         up_read(&rds_trans_sem);
 152
 153         return total;
 154 }
 155