net/rxrpc/peer.c

   1 /* peer.c: Rx RPC peer management
   2  *
   3  * Copyright (C) 2002 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/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/module.h>
  15 #include <rxrpc/rxrpc.h>
  16 #include <rxrpc/transport.h>
  17 #include <rxrpc/peer.h>
  18 #include <rxrpc/connection.h>
  19 #include <rxrpc/call.h>
  20 #include <rxrpc/message.h>
  21 #include <linux/udp.h>
  22 #include <linux/ip.h>
  23 #include <net/sock.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/div64.h>
  26 #include "internal.h"
  27
  28 __RXACCT_DECL(atomic_t rxrpc_peer_count);
  29 LIST_HEAD(rxrpc_peers);
  30 DECLARE_RWSEM(rxrpc_peers_sem);
  31 unsigned long rxrpc_peer_timeout = 12 * 60 * 60;
  32
  33 static void rxrpc_peer_do_timeout(struct rxrpc_peer *peer);
  34
  35 static void __rxrpc_peer_timeout(rxrpc_timer_t *timer)
  36 {
  37         struct rxrpc_peer *peer =
  38                 list_entry(timer, struct rxrpc_peer, timeout);
  39
  40         _debug("Rx PEER TIMEOUT [%p{u=%d}]", peer, atomic_read(&peer->usage));
  41
  42         rxrpc_peer_do_timeout(peer);
  43 }
  44
  45 static const struct rxrpc_timer_ops rxrpc_peer_timer_ops = {
  46         .timed_out      = __rxrpc_peer_timeout,
  47 };
  48
  49 /*****************************************************************************/
  50 /*
  51  * create a peer record
  52  */
  53 static int __rxrpc_create_peer(struct rxrpc_transport *trans, __be32 addr,
  54                                struct rxrpc_peer **_peer)
  55 {
  56         struct rxrpc_peer *peer;
  57
  58         _enter("%p,%08x", trans, ntohl(addr));
  59
  60         /* allocate and initialise a peer record */
  61         peer = kzalloc(sizeof(struct rxrpc_peer), GFP_KERNEL);
  62         if (!peer) {
  63                 _leave(" = -ENOMEM");
  64                 return -ENOMEM;
  65         }
  66
  67         atomic_set(&peer->usage, 1);
  68
  69         INIT_LIST_HEAD(&peer->link);
  70         INIT_LIST_HEAD(&peer->proc_link);
  71         INIT_LIST_HEAD(&peer->conn_idlist);
  72         INIT_LIST_HEAD(&peer->conn_active);
  73         INIT_LIST_HEAD(&peer->conn_graveyard);
  74         spin_lock_init(&peer->conn_gylock);
  75         init_waitqueue_head(&peer->conn_gy_waitq);
  76         rwlock_init(&peer->conn_idlock);
  77         rwlock_init(&peer->conn_lock);
  78         atomic_set(&peer->conn_count, 0);
  79         spin_lock_init(&peer->lock);
  80         rxrpc_timer_init(&peer->timeout, &rxrpc_peer_timer_ops);
  81
  82         peer->addr.s_addr = addr;
  83
  84         peer->trans = trans;
  85         peer->ops = trans->peer_ops;
  86
  87         __RXACCT(atomic_inc(&rxrpc_peer_count));
  88         *_peer = peer;
  89         _leave(" = 0 (%p)", peer);
  90
  91         return 0;
  92 } /* end __rxrpc_create_peer() */
  93
  94 /*****************************************************************************/
  95 /*
  96  * find a peer record on the specified transport
  97  * - returns (if successful) with peer record usage incremented
  98  * - resurrects it from the graveyard if found there
  99  */
 100 int rxrpc_peer_lookup(struct rxrpc_transport *trans, __be32 addr,
 101                       struct rxrpc_peer **_peer)
 102 {
 103         struct rxrpc_peer *peer, *candidate = NULL;
 104         struct list_head *_p;
 105         int ret;
 106
 107         _enter("%p{%hu},%08x", trans, trans->port, ntohl(addr));
 108
 109         /* [common case] search the transport's active list first */
 110         read_lock(&trans->peer_lock);
 111         list_for_each(_p, &trans->peer_active) {
 112                 peer = list_entry(_p, struct rxrpc_peer, link);
 113                 if (peer->addr.s_addr == addr)
 114                         goto found_active;
 115         }
 116         read_unlock(&trans->peer_lock);
 117
 118         /* [uncommon case] not active - create a candidate for a new record */
 119         ret = __rxrpc_create_peer(trans, addr, &candidate);
 120         if (ret < 0) {
 121                 _leave(" = %d", ret);
 122                 return ret;
 123         }
 124
 125         /* search the active list again, just in case it appeared whilst we
 126          * were busy */
 127         write_lock(&trans->peer_lock);
 128         list_for_each(_p, &trans->peer_active) {
 129                 peer = list_entry(_p, struct rxrpc_peer, link);
 130                 if (peer->addr.s_addr == addr)
 131                         goto found_active_second_chance;
 132         }
 133
 134         /* search the transport's graveyard list */
 135         spin_lock(&trans->peer_gylock);
 136         list_for_each(_p, &trans->peer_graveyard) {
 137                 peer = list_entry(_p, struct rxrpc_peer, link);
 138                 if (peer->addr.s_addr == addr)
 139                         goto found_in_graveyard;
 140         }
 141         spin_unlock(&trans->peer_gylock);
 142
 143         /* we can now add the new candidate to the list
 144          * - tell the application layer that this peer has been added
 145          */
 146         rxrpc_get_transport(trans);
 147         peer = candidate;
 148         candidate = NULL;
 149
 150         if (peer->ops && peer->ops->adding) {
 151                 ret = peer->ops->adding(peer);
 152                 if (ret < 0) {
 153                         write_unlock(&trans->peer_lock);
 154                         __RXACCT(atomic_dec(&rxrpc_peer_count));
 155                         kfree(peer);
 156                         rxrpc_put_transport(trans);
 157                         _leave(" = %d", ret);
 158                         return ret;
 159                 }
 160         }
 161
 162         atomic_inc(&trans->peer_count);
 163
 164  make_active:
 165         list_add_tail(&peer->link, &trans->peer_active);
 166
 167  success_uwfree:
 168         write_unlock(&trans->peer_lock);
 169
 170         if (candidate) {
 171                 __RXACCT(atomic_dec(&rxrpc_peer_count));
 172                 kfree(candidate);
 173         }
 174
 175         if (list_empty(&peer->proc_link)) {
 176                 down_write(&rxrpc_peers_sem);
 177                 list_add_tail(&peer->proc_link, &rxrpc_peers);
 178                 up_write(&rxrpc_peers_sem);
 179         }
 180
 181  success:
 182         *_peer = peer;
 183
 184         _leave(" = 0 (%p{u=%d cc=%d})",
 185                peer,
 186                atomic_read(&peer->usage),
 187                atomic_read(&peer->conn_count));
 188         return 0;
 189
 190         /* handle the peer being found in the active list straight off */
 191  found_active:
 192         rxrpc_get_peer(peer);
 193         read_unlock(&trans->peer_lock);
 194         goto success;
 195
 196         /* handle resurrecting a peer from the graveyard */
 197  found_in_graveyard:
 198         rxrpc_get_peer(peer);
 199         rxrpc_get_transport(peer->trans);
 200         rxrpc_krxtimod_del_timer(&peer->timeout);
 201         list_del_init(&peer->link);
 202         spin_unlock(&trans->peer_gylock);
 203         goto make_active;
 204
 205         /* handle finding the peer on the second time through the active
 206          * list */
 207  found_active_second_chance:
 208         rxrpc_get_peer(peer);
 209         goto success_uwfree;
 210
 211 } /* end rxrpc_peer_lookup() */
 212
 213 /*****************************************************************************/
 214 /*
 215  * finish with a peer record
 216  * - it gets sent to the graveyard from where it can be resurrected or timed
 217  *   out
 218  */
 219 void rxrpc_put_peer(struct rxrpc_peer *peer)
 220 {
 221         struct rxrpc_transport *trans = peer->trans;
 222
 223         _enter("%p{cc=%d a=%08x}",
 224                peer,
 225                atomic_read(&peer->conn_count),
 226                ntohl(peer->addr.s_addr));
 227
 228         /* sanity check */
 229         if (atomic_read(&peer->usage) <= 0)
 230                 BUG();
 231
 232         write_lock(&trans->peer_lock);
 233         spin_lock(&trans->peer_gylock);
 234         if (likely(!atomic_dec_and_test(&peer->usage))) {
 235                 spin_unlock(&trans->peer_gylock);
 236                 write_unlock(&trans->peer_lock);
 237                 _leave("");
 238                 return;
 239         }
 240
 241         /* move to graveyard queue */
 242         list_del(&peer->link);
 243         write_unlock(&trans->peer_lock);
 244
 245         list_add_tail(&peer->link, &trans->peer_graveyard);
 246
 247         BUG_ON(!list_empty(&peer->conn_active));
 248
 249         rxrpc_krxtimod_add_timer(&peer->timeout, rxrpc_peer_timeout * HZ);
 250
 251         spin_unlock(&trans->peer_gylock);
 252
 253         rxrpc_put_transport(trans);
 254
 255         _leave(" [killed]");
 256 } /* end rxrpc_put_peer() */
 257
 258 /*****************************************************************************/
 259 /*
 260  * handle a peer timing out in the graveyard
 261  * - called from krxtimod
 262  */
 263 static void rxrpc_peer_do_timeout(struct rxrpc_peer *peer)
 264 {
 265         struct rxrpc_transport *trans = peer->trans;
 266
 267         _enter("%p{u=%d cc=%d a=%08x}",
 268                peer,
 269                atomic_read(&peer->usage),
 270                atomic_read(&peer->conn_count),
 271                ntohl(peer->addr.s_addr));
 272
 273         BUG_ON(atomic_read(&peer->usage) < 0);
 274
 275         /* remove from graveyard if still dead */
 276         spin_lock(&trans->peer_gylock);
 277         if (atomic_read(&peer->usage) == 0)
 278                 list_del_init(&peer->link);
 279         else
 280                 peer = NULL;
 281         spin_unlock(&trans->peer_gylock);
 282
 283         if (!peer) {
 284                 _leave("");
 285                 return; /* resurrected */
 286         }
 287
 288         /* clear all connections on this peer */
 289         rxrpc_conn_clearall(peer);
 290
 291         BUG_ON(!list_empty(&peer->conn_active));
 292         BUG_ON(!list_empty(&peer->conn_graveyard));
 293
 294         /* inform the application layer */
 295         if (peer->ops && peer->ops->discarding)
 296                 peer->ops->discarding(peer);
 297
 298         if (!list_empty(&peer->proc_link)) {
 299                 down_write(&rxrpc_peers_sem);
 300                 list_del(&peer->proc_link);
 301                 up_write(&rxrpc_peers_sem);
 302         }
 303
 304         __RXACCT(atomic_dec(&rxrpc_peer_count));
 305         kfree(peer);
 306
 307         /* if the graveyard is now empty, wake up anyone waiting for that */
 308         if (atomic_dec_and_test(&trans->peer_count))
 309                 wake_up(&trans->peer_gy_waitq);
 310
 311         _leave(" [destroyed]");
 312 } /* end rxrpc_peer_do_timeout() */
 313
 314 /*****************************************************************************/
 315 /*
 316  * clear all peer records from a transport endpoint
 317  */
 318 void rxrpc_peer_clearall(struct rxrpc_transport *trans)
 319 {
 320         DECLARE_WAITQUEUE(myself,current);
 321
 322         struct rxrpc_peer *peer;
 323         int err;
 324
 325         _enter("%p",trans);
 326
 327         /* there shouldn't be any active peers remaining */
 328         BUG_ON(!list_empty(&trans->peer_active));
 329
 330         /* manually timeout all peers in the graveyard */
 331         spin_lock(&trans->peer_gylock);
 332         while (!list_empty(&trans->peer_graveyard)) {
 333                 peer = list_entry(trans->peer_graveyard.next,
 334                                   struct rxrpc_peer, link);
 335                 _debug("Clearing peer %p\n", peer);
 336                 err = rxrpc_krxtimod_del_timer(&peer->timeout);
 337                 spin_unlock(&trans->peer_gylock);
 338
 339                 if (err == 0)
 340                         rxrpc_peer_do_timeout(peer);
 341
 342                 spin_lock(&trans->peer_gylock);
 343         }
 344         spin_unlock(&trans->peer_gylock);
 345
 346         /* wait for the the peer graveyard to be completely cleared */
 347         set_current_state(TASK_UNINTERRUPTIBLE);
 348         add_wait_queue(&trans->peer_gy_waitq, &myself);
 349
 350         while (atomic_read(&trans->peer_count) != 0) {
 351                 schedule();
 352                 set_current_state(TASK_UNINTERRUPTIBLE);
 353         }
 354
 355         remove_wait_queue(&trans->peer_gy_waitq, &myself);
 356         set_current_state(TASK_RUNNING);
 357
 358         _leave("");
 359 } /* end rxrpc_peer_clearall() */
 360
 361 /*****************************************************************************/
 362 /*
 363  * calculate and cache the Round-Trip-Time for a message and its response
 364  */
 365 void rxrpc_peer_calculate_rtt(struct rxrpc_peer *peer,
 366                               struct rxrpc_message *msg,
 367                               struct rxrpc_message *resp)
 368 {
 369         unsigned long long rtt;
 370         int loop;
 371
 372         _enter("%p,%p,%p", peer, msg, resp);
 373
 374         /* calculate the latest RTT */
 375         rtt = resp->stamp.tv_sec - msg->stamp.tv_sec;
 376         rtt *= 1000000UL;
 377         rtt += resp->stamp.tv_usec - msg->stamp.tv_usec;
 378
 379         /* add to cache */
 380         peer->rtt_cache[peer->rtt_point] = rtt;
 381         peer->rtt_point++;
 382         peer->rtt_point %= RXRPC_RTT_CACHE_SIZE;
 383
 384         if (peer->rtt_usage < RXRPC_RTT_CACHE_SIZE)
 385                 peer->rtt_usage++;
 386
 387         /* recalculate RTT */
 388         rtt = 0;
 389         for (loop = peer->rtt_usage - 1; loop >= 0; loop--)
 390                 rtt += peer->rtt_cache[loop];
 391
 392         do_div(rtt, peer->rtt_usage);
 393         peer->rtt = rtt;
 394
 395         _leave(" RTT=%lu.%lums",
 396                (long) (peer->rtt / 1000), (long) (peer->rtt % 1000));
 397
 398 } /* end rxrpc_peer_calculate_rtt() */