net/rds/transport.c

   1 /*
   2  * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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 #include <linux/ipv6.h>
  37
  38 #include "rds.h"
  39 #include "loop.h"
  40
  41 static char * const rds_trans_modules[] = {
  42         [RDS_TRANS_IB] = "rds_rdma",
  43         [RDS_TRANS_GAP] = NULL,
  44         [RDS_TRANS_TCP] = "rds_tcp",
  45 };
  46
  47 static struct rds_transport *transports[RDS_TRANS_COUNT];
  48 static DECLARE_RWSEM(rds_trans_sem);
  49
  50 void rds_trans_register(struct rds_transport *trans)
  51 {
  52         BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ);
  53
  54         down_write(&rds_trans_sem);
  55
  56         if (transports[trans->t_type])
  57                 printk(KERN_ERR "RDS Transport type %d already registered\n",
  58                         trans->t_type);
  59         else {
  60                 transports[trans->t_type] = trans;
  61                 printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
  62         }
  63
  64         up_write(&rds_trans_sem);
  65 }
  66 EXPORT_SYMBOL_GPL(rds_trans_register);
  67
  68 void rds_trans_unregister(struct rds_transport *trans)
  69 {
  70         down_write(&rds_trans_sem);
  71
  72         transports[trans->t_type] = NULL;
  73         printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
  74
  75         up_write(&rds_trans_sem);
  76 }
  77 EXPORT_SYMBOL_GPL(rds_trans_unregister);
  78
  79 void rds_trans_put(struct rds_transport *trans)
  80 {
  81         if (trans)
  82                 module_put(trans->t_owner);
  83 }
  84
  85 struct rds_transport *rds_trans_get_preferred(struct net *net,
  86                                               const struct in6_addr *addr,
  87                                               __u32 scope_id)
  88 {
  89         struct rds_transport *ret = NULL;
  90         struct rds_transport *trans;
  91         unsigned int i;
  92
  93         if (ipv6_addr_v4mapped(addr)) {
  94                 if (*(u_int8_t *)&addr->s6_addr32[3] == IN_LOOPBACKNET)
  95                         return &rds_loop_transport;
  96         } else if (ipv6_addr_loopback(addr)) {
  97                 return &rds_loop_transport;
  98         }
  99
 100         down_read(&rds_trans_sem);
 101         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 102                 trans = transports[i];
 103
 104                 if (trans && (trans->laddr_check(net, addr, scope_id) == 0) &&
 105                     (!trans->t_owner || try_module_get(trans->t_owner))) {
 106                         ret = trans;
 107                         break;
 108                 }
 109         }
 110         up_read(&rds_trans_sem);
 111
 112         return ret;
 113 }
 114
 115 struct rds_transport *rds_trans_get(int t_type)
 116 {
 117         struct rds_transport *ret = NULL;
 118         struct rds_transport *trans;
 119
 120         down_read(&rds_trans_sem);
 121         trans = transports[t_type];
 122         if (!trans) {
 123                 up_read(&rds_trans_sem);
 124                 if (rds_trans_modules[t_type])
 125                         request_module(rds_trans_modules[t_type]);
 126                 down_read(&rds_trans_sem);
 127                 trans = transports[t_type];
 128         }
 129         if (trans && trans->t_type == t_type &&
 130             (!trans->t_owner || try_module_get(trans->t_owner)))
 131                 ret = trans;
 132
 133         up_read(&rds_trans_sem);
 134
 135         return ret;
 136 }
 137
 138 /*
 139  * This returns the number of stats entries in the snapshot and only
 140  * copies them using the iter if there is enough space for them.  The
 141  * caller passes in the global stats so that we can size and copy while
 142  * holding the lock.
 143  */
 144 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
 145                                        unsigned int avail)
 146
 147 {
 148         struct rds_transport *trans;
 149         unsigned int total = 0;
 150         unsigned int part;
 151         int i;
 152
 153         rds_info_iter_unmap(iter);
 154         down_read(&rds_trans_sem);
 155
 156         for (i = 0; i < RDS_TRANS_COUNT; i++) {
 157                 trans = transports[i];
 158                 if (!trans || !trans->stats_info_copy)
 159                         continue;
 160
 161                 part = trans->stats_info_copy(iter, avail);
 162                 avail -= min(avail, part);
 163                 total += part;
 164         }
 165
 166         up_read(&rds_trans_sem);
 167
 168         return total;
 169 }