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 struct rds_transport *rds_trans_get_preferred(__be32 addr)
  75 {
  76         struct rds_transport *ret = NULL;
  77         int i;
  78
  79         if (IN_LOOPBACK(ntohl(addr)))
  80                 return &rds_loop_transport;
  81
  82         down_read(&rds_trans_sem);
  83         for (i = 0; i < RDS_TRANS_COUNT; i++)
  84         {
  85                 if (transports[i] && (transports[i]->laddr_check(addr) == 0)) {
  86                         ret = transports[i];
  87                         break;
  88                 }
  89         }
  90         up_read(&rds_trans_sem);
  91
  92         return ret;
  93 }
  94
  95 /*
  96  * This returns the number of stats entries in the snapshot and only
  97  * copies them using the iter if there is enough space for them.  The
  98  * caller passes in the global stats so that we can size and copy while
  99  * holding the lock.
 100  */
 101 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
 102                                        unsigned int avail)
 103
 104 {
 105         struct rds_transport *trans;
 106         unsigned int total = 0;
 107         unsigned int part;
 108         int i;
 109
 110         rds_info_iter_unmap(iter);
 111         down_read(&rds_trans_sem);
 112
 113         for (i = 0; i < RDS_TRANS_COUNT; i++)
 114         {
 115                 trans = transports[i];
 116                 if (!trans || !trans->stats_info_copy)
 117                         continue;
 118
 119                 part = trans->stats_info_copy(iter, avail);
 120                 avail -= min(avail, part);
 121                 total += part;
 122         }
 123
 124         up_read(&rds_trans_sem);
 125
 126         return total;
 127 }
 128