net/rxrpc/ar-transport.c

   1 /* RxRPC point-to-point transport session management
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/net.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/slab.h>
  16 #include <net/sock.h>
  17 #include <net/af_rxrpc.h>
  18 #include "ar-internal.h"
  19
  20 /*
  21  * Time after last use at which transport record is cleaned up.
  22  */
  23 unsigned int rxrpc_transport_expiry = 3600 * 24;
  24
  25 static void rxrpc_transport_reaper(struct work_struct *work);
  26
  27 static LIST_HEAD(rxrpc_transports);
  28 static DEFINE_RWLOCK(rxrpc_transport_lock);
  29 static DECLARE_DELAYED_WORK(rxrpc_transport_reap, rxrpc_transport_reaper);
  30
  31 /*
  32  * allocate a new transport session manager
  33  */
  34 static struct rxrpc_transport *rxrpc_alloc_transport(struct rxrpc_local *local,
  35                                                      struct rxrpc_peer *peer,
  36                                                      gfp_t gfp)
  37 {
  38         struct rxrpc_transport *trans;
  39
  40         _enter("");
  41
  42         trans = kzalloc(sizeof(struct rxrpc_transport), gfp);
  43         if (trans) {
  44                 trans->local = local;
  45                 trans->peer = peer;
  46                 INIT_LIST_HEAD(&trans->link);
  47                 trans->bundles = RB_ROOT;
  48                 trans->client_conns = RB_ROOT;
  49                 trans->server_conns = RB_ROOT;
  50                 skb_queue_head_init(&trans->error_queue);
  51                 spin_lock_init(&trans->client_lock);
  52                 rwlock_init(&trans->conn_lock);
  53                 atomic_set(&trans->usage, 1);
  54                 trans->conn_idcounter = peer->srx.srx_service << 16;
  55                 trans->debug_id = atomic_inc_return(&rxrpc_debug_id);
  56
  57                 if (peer->srx.transport.family == AF_INET) {
  58                         switch (peer->srx.transport_type) {
  59                         case SOCK_DGRAM:
  60                                 INIT_WORK(&trans->error_handler,
  61                                           rxrpc_UDP_error_handler);
  62                                 break;
  63                         default:
  64                                 BUG();
  65                                 break;
  66                         }
  67                 } else {
  68                         BUG();
  69                 }
  70         }
  71
  72         _leave(" = %p", trans);
  73         return trans;
  74 }
  75
  76 /*
  77  * obtain a transport session for the nominated endpoints
  78  */
  79 struct rxrpc_transport *rxrpc_get_transport(struct rxrpc_local *local,
  80                                             struct rxrpc_peer *peer,
  81                                             gfp_t gfp)
  82 {
  83         struct rxrpc_transport *trans, *candidate;
  84         const char *new = "old";
  85         int usage;
  86
  87         _enter("{%pI4+%hu},{%pI4+%hu},",
  88                &local->srx.transport.sin.sin_addr,
  89                ntohs(local->srx.transport.sin.sin_port),
  90                &peer->srx.transport.sin.sin_addr,
  91                ntohs(peer->srx.transport.sin.sin_port));
  92
  93         /* search the transport list first */
  94         read_lock_bh(&rxrpc_transport_lock);
  95         list_for_each_entry(trans, &rxrpc_transports, link) {
  96                 if (trans->local == local && trans->peer == peer)
  97                         goto found_extant_transport;
  98         }
  99         read_unlock_bh(&rxrpc_transport_lock);
 100
 101         /* not yet present - create a candidate for a new record and then
 102          * redo the search */
 103         candidate = rxrpc_alloc_transport(local, peer, gfp);
 104         if (!candidate) {
 105                 _leave(" = -ENOMEM");
 106                 return ERR_PTR(-ENOMEM);
 107         }
 108
 109         write_lock_bh(&rxrpc_transport_lock);
 110
 111         list_for_each_entry(trans, &rxrpc_transports, link) {
 112                 if (trans->local == local && trans->peer == peer)
 113                         goto found_extant_second;
 114         }
 115
 116         /* we can now add the new candidate to the list */
 117         trans = candidate;
 118         candidate = NULL;
 119         usage = atomic_read(&trans->usage);
 120
 121         rxrpc_get_local(trans->local);
 122         atomic_inc(&trans->peer->usage);
 123         list_add_tail(&trans->link, &rxrpc_transports);
 124         write_unlock_bh(&rxrpc_transport_lock);
 125         new = "new";
 126
 127 success:
 128         _net("TRANSPORT %s %d local %d -> peer %d",
 129              new,
 130              trans->debug_id,
 131              trans->local->debug_id,
 132              trans->peer->debug_id);
 133
 134         _leave(" = %p {u=%d}", trans, usage);
 135         return trans;
 136
 137         /* we found the transport in the list immediately */
 138 found_extant_transport:
 139         usage = atomic_inc_return(&trans->usage);
 140         read_unlock_bh(&rxrpc_transport_lock);
 141         goto success;
 142
 143         /* we found the transport on the second time through the list */
 144 found_extant_second:
 145         usage = atomic_inc_return(&trans->usage);
 146         write_unlock_bh(&rxrpc_transport_lock);
 147         kfree(candidate);
 148         goto success;
 149 }
 150
 151 /*
 152  * find the transport connecting two endpoints
 153  */
 154 struct rxrpc_transport *rxrpc_find_transport(struct rxrpc_local *local,
 155                                              struct rxrpc_peer *peer)
 156 {
 157         struct rxrpc_transport *trans;
 158
 159         _enter("{%pI4+%hu},{%pI4+%hu},",
 160                &local->srx.transport.sin.sin_addr,
 161                ntohs(local->srx.transport.sin.sin_port),
 162                &peer->srx.transport.sin.sin_addr,
 163                ntohs(peer->srx.transport.sin.sin_port));
 164
 165         /* search the transport list */
 166         read_lock_bh(&rxrpc_transport_lock);
 167
 168         list_for_each_entry(trans, &rxrpc_transports, link) {
 169                 if (trans->local == local && trans->peer == peer)
 170                         goto found_extant_transport;
 171         }
 172
 173         read_unlock_bh(&rxrpc_transport_lock);
 174         _leave(" = NULL");
 175         return NULL;
 176
 177 found_extant_transport:
 178         atomic_inc(&trans->usage);
 179         read_unlock_bh(&rxrpc_transport_lock);
 180         _leave(" = %p", trans);
 181         return trans;
 182 }
 183
 184 /*
 185  * release a transport session
 186  */
 187 void rxrpc_put_transport(struct rxrpc_transport *trans)
 188 {
 189         _enter("%p{u=%d}", trans, atomic_read(&trans->usage));
 190
 191         ASSERTCMP(atomic_read(&trans->usage), >, 0);
 192
 193         trans->put_time = ktime_get_seconds();
 194         if (unlikely(atomic_dec_and_test(&trans->usage))) {
 195                 _debug("zombie");
 196                 /* let the reaper determine the timeout to avoid a race with
 197                  * overextending the timeout if the reaper is running at the
 198                  * same time */
 199                 rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
 200         }
 201         _leave("");
 202 }
 203
 204 /*
 205  * clean up a transport session
 206  */
 207 static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
 208 {
 209         _net("DESTROY TRANS %d", trans->debug_id);
 210
 211         rxrpc_purge_queue(&trans->error_queue);
 212
 213         rxrpc_put_local(trans->local);
 214         rxrpc_put_peer(trans->peer);
 215         kfree(trans);
 216 }
 217
 218 /*
 219  * reap dead transports that have passed their expiry date
 220  */
 221 static void rxrpc_transport_reaper(struct work_struct *work)
 222 {
 223         struct rxrpc_transport *trans, *_p;
 224         unsigned long now, earliest, reap_time;
 225
 226         LIST_HEAD(graveyard);
 227
 228         _enter("");
 229
 230         now = ktime_get_seconds();
 231         earliest = ULONG_MAX;
 232
 233         /* extract all the transports that have been dead too long */
 234         write_lock_bh(&rxrpc_transport_lock);
 235         list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
 236                 _debug("reap TRANS %d { u=%d t=%ld }",
 237                        trans->debug_id, atomic_read(&trans->usage),
 238                        (long) now - (long) trans->put_time);
 239
 240                 if (likely(atomic_read(&trans->usage) > 0))
 241                         continue;
 242
 243                 reap_time = trans->put_time + rxrpc_transport_expiry;
 244                 if (reap_time <= now)
 245                         list_move_tail(&trans->link, &graveyard);
 246                 else if (reap_time < earliest)
 247                         earliest = reap_time;
 248         }
 249         write_unlock_bh(&rxrpc_transport_lock);
 250
 251         if (earliest != ULONG_MAX) {
 252                 _debug("reschedule reaper %ld", (long) earliest - now);
 253                 ASSERTCMP(earliest, >, now);
 254                 rxrpc_queue_delayed_work(&rxrpc_transport_reap,
 255                                          (earliest - now) * HZ);
 256         }
 257
 258         /* then destroy all those pulled out */
 259         while (!list_empty(&graveyard)) {
 260                 trans = list_entry(graveyard.next, struct rxrpc_transport,
 261                                    link);
 262                 list_del_init(&trans->link);
 263
 264                 ASSERTCMP(atomic_read(&trans->usage), ==, 0);
 265                 rxrpc_cleanup_transport(trans);
 266         }
 267
 268         _leave("");
 269 }
 270
 271 /*
 272  * preemptively destroy all the transport session records rather than waiting
 273  * for them to time out
 274  */
 275 void __exit rxrpc_destroy_all_transports(void)
 276 {
 277         _enter("");
 278
 279         rxrpc_transport_expiry = 0;
 280         cancel_delayed_work(&rxrpc_transport_reap);
 281         rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
 282
 283         _leave("");
 284 }