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 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         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 }
  61 EXPORT_SYMBOL_GPL(rds_trans_register);
  62
  63 void 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 }
  72 EXPORT_SYMBOL_GPL(rds_trans_unregister);
  73
  74 void rds_trans_put(struct rds_transport *trans)
  75 {
  76         if (trans)
  77                 module_put(trans->t_owner);
  78 }
  79
  80 struct rds_transport *rds_trans_get_preferred(struct net *net, __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(net, 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 struct rds_transport *rds_trans_get(int t_type)
 105 {
 106         struct rds_transport *ret = NULL;
 107         struct rds_transport *trans;
 108         unsigned int i;
 109
 110         down_read(&rds_trans_sem);
 111         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 112                 trans = transports[i];
 113
 114                 if (trans && trans->t_type == t_type &&
 115                     (!trans->t_owner || try_module_get(trans->t_owner))) {
 116                         ret = trans;
 117                         break;
 118                 }
 119         }
 120         up_read(&rds_trans_sem);
 121
 122         return ret;
 123 }
 124
 125 /*
 126  * This returns the number of stats entries in the snapshot and only
 127  * copies them using the iter if there is enough space for them.  The
 128  * caller passes in the global stats so that we can size and copy while
 129  * holding the lock.
 130  */
 131 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
 132                                        unsigned int avail)
 133
 134 {
 135         struct rds_transport *trans;
 136         unsigned int total = 0;
 137         unsigned int part;
 138         int i;
 139
 140         rds_info_iter_unmap(iter);
 141         down_read(&rds_trans_sem);
 142
 143         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 144                 trans = transports[i];
 145                 if (!trans || !trans->stats_info_copy)
 146                         continue;
 147
 148                 part = trans->stats_info_copy(iter, avail);
 149                 avail -= min(avail, part);
 150                 total += part;
 151         }
 152
 153         up_read(&rds_trans_sem);
 154
 155         return total;
 156 }
 157