net/rds/tcp.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/slab.h>
  35 #include <linux/in.h>
  36 #include <linux/module.h>
  37 #include <net/tcp.h>
  38 #include <net/net_namespace.h>
  39 #include <net/netns/generic.h>
  40
  41 #include "rds.h"
  42 #include "tcp.h"
  43
  44 /* only for info exporting */
  45 static DEFINE_SPINLOCK(rds_tcp_tc_list_lock);
  46 static LIST_HEAD(rds_tcp_tc_list);
  47 static unsigned int rds_tcp_tc_count;
  48
  49 /* Track rds_tcp_connection structs so they can be cleaned up */
  50 static DEFINE_SPINLOCK(rds_tcp_conn_lock);
  51 static LIST_HEAD(rds_tcp_conn_list);
  52
  53 static struct kmem_cache *rds_tcp_conn_slab;
  54
  55 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
  56                                  void __user *buffer, size_t *lenp,
  57                                  loff_t *fpos);
  58
  59 static int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
  60 static int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
  61
  62 static struct ctl_table rds_tcp_sysctl_table[] = {
  63 #define RDS_TCP_SNDBUF  0
  64         {
  65                 .procname       = "rds_tcp_sndbuf",
  66                 /* data is per-net pointer */
  67                 .maxlen         = sizeof(int),
  68                 .mode           = 0644,
  69                 .proc_handler   = rds_tcp_skbuf_handler,
  70                 .extra1         = &rds_tcp_min_sndbuf,
  71         },
  72 #define RDS_TCP_RCVBUF  1
  73         {
  74                 .procname       = "rds_tcp_rcvbuf",
  75                 /* data is per-net pointer */
  76                 .maxlen         = sizeof(int),
  77                 .mode           = 0644,
  78                 .proc_handler   = rds_tcp_skbuf_handler,
  79                 .extra1         = &rds_tcp_min_rcvbuf,
  80         },
  81         { }
  82 };
  83
  84 /* doing it this way avoids calling tcp_sk() */
  85 void rds_tcp_nonagle(struct socket *sock)
  86 {
  87         mm_segment_t oldfs = get_fs();
  88         int val = 1;
  89
  90         set_fs(KERNEL_DS);
  91         sock->ops->setsockopt(sock, SOL_TCP, TCP_NODELAY, (char __user *)&val,
  92                               sizeof(val));
  93         set_fs(oldfs);
  94 }
  95
  96 u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc)
  97 {
  98         return tcp_sk(tc->t_sock->sk)->snd_nxt;
  99 }
 100
 101 u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)
 102 {
 103         return tcp_sk(tc->t_sock->sk)->snd_una;
 104 }
 105
 106 void rds_tcp_restore_callbacks(struct socket *sock,
 107                                struct rds_tcp_connection *tc)
 108 {
 109         rdsdebug("restoring sock %p callbacks from tc %p\n", sock, tc);
 110         write_lock_bh(&sock->sk->sk_callback_lock);
 111
 112         /* done under the callback_lock to serialize with write_space */
 113         spin_lock(&rds_tcp_tc_list_lock);
 114         list_del_init(&tc->t_list_item);
 115         rds_tcp_tc_count--;
 116         spin_unlock(&rds_tcp_tc_list_lock);
 117
 118         tc->t_sock = NULL;
 119
 120         sock->sk->sk_write_space = tc->t_orig_write_space;
 121         sock->sk->sk_data_ready = tc->t_orig_data_ready;
 122         sock->sk->sk_state_change = tc->t_orig_state_change;
 123         sock->sk->sk_user_data = NULL;
 124
 125         write_unlock_bh(&sock->sk->sk_callback_lock);
 126 }
 127
 128 /*
 129  * rds_tcp_reset_callbacks() switches the to the new sock and
 130  * returns the existing tc->t_sock.
 131  *
 132  * The only functions that set tc->t_sock are rds_tcp_set_callbacks
 133  * and rds_tcp_reset_callbacks.  Send and receive trust that
 134  * it is set.  The absence of RDS_CONN_UP bit protects those paths
 135  * from being called while it isn't set.
 136  */
 137 void rds_tcp_reset_callbacks(struct socket *sock,
 138                              struct rds_conn_path *cp)
 139 {
 140         struct rds_tcp_connection *tc = cp->cp_transport_data;
 141         struct socket *osock = tc->t_sock;
 142
 143         if (!osock)
 144                 goto newsock;
 145
 146         /* Need to resolve a duelling SYN between peers.
 147          * We have an outstanding SYN to this peer, which may
 148          * potentially have transitioned to the RDS_CONN_UP state,
 149          * so we must quiesce any send threads before resetting
 150          * cp_transport_data. We quiesce these threads by setting
 151          * cp_state to something other than RDS_CONN_UP, and then
 152          * waiting for any existing threads in rds_send_xmit to
 153          * complete release_in_xmit(). (Subsequent threads entering
 154          * rds_send_xmit() will bail on !rds_conn_up().
 155          *
 156          * However an incoming syn-ack at this point would end up
 157          * marking the conn as RDS_CONN_UP, and would again permit
 158          * rds_send_xmi() threads through, so ideally we would
 159          * synchronize on RDS_CONN_UP after lock_sock(), but cannot
 160          * do that: waiting on !RDS_IN_XMIT after lock_sock() may
 161          * end up deadlocking with tcp_sendmsg(), and the RDS_IN_XMIT
 162          * would not get set. As a result, we set c_state to
 163          * RDS_CONN_RESETTTING, to ensure that rds_tcp_state_change
 164          * cannot mark rds_conn_path_up() in the window before lock_sock()
 165          */
 166         atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
 167         wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
 168         /* reset receive side state for rds_tcp_data_recv() for osock  */
 169         cancel_delayed_work_sync(&cp->cp_send_w);
 170         cancel_delayed_work_sync(&cp->cp_recv_w);
 171         lock_sock(osock->sk);
 172         if (tc->t_tinc) {
 173                 rds_inc_put(&tc->t_tinc->ti_inc);
 174                 tc->t_tinc = NULL;
 175         }
 176         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 177         tc->t_tinc_data_rem = 0;
 178         rds_tcp_restore_callbacks(osock, tc);
 179         release_sock(osock->sk);
 180         sock_release(osock);
 181 newsock:
 182         rds_send_path_reset(cp);
 183         lock_sock(sock->sk);
 184         rds_tcp_set_callbacks(sock, cp);
 185         release_sock(sock->sk);
 186 }
 187
 188 /* Add tc to rds_tcp_tc_list and set tc->t_sock. See comments
 189  * above rds_tcp_reset_callbacks for notes about synchronization
 190  * with data path
 191  */
 192 void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)
 193 {
 194         struct rds_tcp_connection *tc = cp->cp_transport_data;
 195
 196         rdsdebug("setting sock %p callbacks to tc %p\n", sock, tc);
 197         write_lock_bh(&sock->sk->sk_callback_lock);
 198
 199         /* done under the callback_lock to serialize with write_space */
 200         spin_lock(&rds_tcp_tc_list_lock);
 201         list_add_tail(&tc->t_list_item, &rds_tcp_tc_list);
 202         rds_tcp_tc_count++;
 203         spin_unlock(&rds_tcp_tc_list_lock);
 204
 205         /* accepted sockets need our listen data ready undone */
 206         if (sock->sk->sk_data_ready == rds_tcp_listen_data_ready)
 207                 sock->sk->sk_data_ready = sock->sk->sk_user_data;
 208
 209         tc->t_sock = sock;
 210         tc->t_cpath = cp;
 211         tc->t_orig_data_ready = sock->sk->sk_data_ready;
 212         tc->t_orig_write_space = sock->sk->sk_write_space;
 213         tc->t_orig_state_change = sock->sk->sk_state_change;
 214
 215         sock->sk->sk_user_data = cp;
 216         sock->sk->sk_data_ready = rds_tcp_data_ready;
 217         sock->sk->sk_write_space = rds_tcp_write_space;
 218         sock->sk->sk_state_change = rds_tcp_state_change;
 219
 220         write_unlock_bh(&sock->sk->sk_callback_lock);
 221 }
 222
 223 static void rds_tcp_tc_info(struct socket *sock, unsigned int len,
 224                             struct rds_info_iterator *iter,
 225                             struct rds_info_lengths *lens)
 226 {
 227         struct rds_info_tcp_socket tsinfo;
 228         struct rds_tcp_connection *tc;
 229         unsigned long flags;
 230         struct sockaddr_in sin;
 231         int sinlen;
 232
 233         spin_lock_irqsave(&rds_tcp_tc_list_lock, flags);
 234
 235         if (len / sizeof(tsinfo) < rds_tcp_tc_count)
 236                 goto out;
 237
 238         list_for_each_entry(tc, &rds_tcp_tc_list, t_list_item) {
 239
 240                 sock->ops->getname(sock, (struct sockaddr *)&sin, &sinlen, 0);
 241                 tsinfo.local_addr = sin.sin_addr.s_addr;
 242                 tsinfo.local_port = sin.sin_port;
 243                 sock->ops->getname(sock, (struct sockaddr *)&sin, &sinlen, 1);
 244                 tsinfo.peer_addr = sin.sin_addr.s_addr;
 245                 tsinfo.peer_port = sin.sin_port;
 246
 247                 tsinfo.hdr_rem = tc->t_tinc_hdr_rem;
 248                 tsinfo.data_rem = tc->t_tinc_data_rem;
 249                 tsinfo.last_sent_nxt = tc->t_last_sent_nxt;
 250                 tsinfo.last_expected_una = tc->t_last_expected_una;
 251                 tsinfo.last_seen_una = tc->t_last_seen_una;
 252
 253                 rds_info_copy(iter, &tsinfo, sizeof(tsinfo));
 254         }
 255
 256 out:
 257         lens->nr = rds_tcp_tc_count;
 258         lens->each = sizeof(tsinfo);
 259
 260         spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
 261 }
 262
 263 static int rds_tcp_laddr_check(struct net *net, __be32 addr)
 264 {
 265         if (inet_addr_type(net, addr) == RTN_LOCAL)
 266                 return 0;
 267         return -EADDRNOTAVAIL;
 268 }
 269
 270 static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 271 {
 272         struct rds_tcp_connection *tc;
 273         int i;
 274
 275         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 276                 tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
 277                 if (!tc)
 278                         return -ENOMEM;
 279
 280                 mutex_init(&tc->t_conn_path_lock);
 281                 tc->t_sock = NULL;
 282                 tc->t_tinc = NULL;
 283                 tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 284                 tc->t_tinc_data_rem = 0;
 285
 286                 conn->c_path[i].cp_transport_data = tc;
 287                 tc->t_cpath = &conn->c_path[i];
 288
 289                 spin_lock_irq(&rds_tcp_conn_lock);
 290                 list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
 291                 spin_unlock_irq(&rds_tcp_conn_lock);
 292                 rdsdebug("rds_conn_path [%d] tc %p\n", i,
 293                          conn->c_path[i].cp_transport_data);
 294         }
 295
 296         return 0;
 297 }
 298
 299 static void rds_tcp_conn_free(void *arg)
 300 {
 301         struct rds_tcp_connection *tc = arg;
 302         unsigned long flags;
 303         rdsdebug("freeing tc %p\n", tc);
 304
 305         spin_lock_irqsave(&rds_tcp_conn_lock, flags);
 306         if (!tc->t_tcp_node_detached)
 307                 list_del(&tc->t_tcp_node);
 308         spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
 309
 310         kmem_cache_free(rds_tcp_conn_slab, tc);
 311 }
 312
 313 static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
 314 {
 315         struct rds_tcp_connection *tc, *_tc;
 316
 317         list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
 318                 if (tc->t_cpath->cp_conn == conn)
 319                         return true;
 320         }
 321         return false;
 322 }
 323
 324 static void rds_tcp_destroy_conns(void)
 325 {
 326         struct rds_tcp_connection *tc, *_tc;
 327         LIST_HEAD(tmp_list);
 328
 329         /* avoid calling conn_destroy with irqs off */
 330         spin_lock_irq(&rds_tcp_conn_lock);
 331         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 332                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
 333                         list_move_tail(&tc->t_tcp_node, &tmp_list);
 334         }
 335         spin_unlock_irq(&rds_tcp_conn_lock);
 336
 337         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
 338                 rds_conn_destroy(tc->t_cpath->cp_conn);
 339 }
 340
 341 static void rds_tcp_exit(void);
 342
 343 struct rds_transport rds_tcp_transport = {
 344         .laddr_check            = rds_tcp_laddr_check,
 345         .xmit_path_prepare      = rds_tcp_xmit_path_prepare,
 346         .xmit_path_complete     = rds_tcp_xmit_path_complete,
 347         .xmit                   = rds_tcp_xmit,
 348         .recv_path              = rds_tcp_recv_path,
 349         .conn_alloc             = rds_tcp_conn_alloc,
 350         .conn_free              = rds_tcp_conn_free,
 351         .conn_path_connect      = rds_tcp_conn_path_connect,
 352         .conn_path_shutdown     = rds_tcp_conn_path_shutdown,
 353         .inc_copy_to_user       = rds_tcp_inc_copy_to_user,
 354         .inc_free               = rds_tcp_inc_free,
 355         .stats_info_copy        = rds_tcp_stats_info_copy,
 356         .exit                   = rds_tcp_exit,
 357         .t_owner                = THIS_MODULE,
 358         .t_name                 = "tcp",
 359         .t_type                 = RDS_TRANS_TCP,
 360         .t_prefer_loopback      = 1,
 361         .t_mp_capable           = 1,
 362 };
 363
 364 static int rds_tcp_netid;
 365
 366 /* per-network namespace private data for this module */
 367 struct rds_tcp_net {
 368         struct socket *rds_tcp_listen_sock;
 369         struct work_struct rds_tcp_accept_w;
 370         struct ctl_table_header *rds_tcp_sysctl;
 371         struct ctl_table *ctl_table;
 372         int sndbuf_size;
 373         int rcvbuf_size;
 374 };
 375
 376 /* All module specific customizations to the RDS-TCP socket should be done in
 377  * rds_tcp_tune() and applied after socket creation.
 378  */
 379 void rds_tcp_tune(struct socket *sock)
 380 {
 381         struct sock *sk = sock->sk;
 382         struct net *net = sock_net(sk);
 383         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 384
 385         rds_tcp_nonagle(sock);
 386         lock_sock(sk);
 387         if (rtn->sndbuf_size > 0) {
 388                 sk->sk_sndbuf = rtn->sndbuf_size;
 389                 sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
 390         }
 391         if (rtn->rcvbuf_size > 0) {
 392                 sk->sk_rcvbuf = rtn->rcvbuf_size;
 393                 sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
 394         }
 395         release_sock(sk);
 396 }
 397
 398 static void rds_tcp_accept_worker(struct work_struct *work)
 399 {
 400         struct rds_tcp_net *rtn = container_of(work,
 401                                                struct rds_tcp_net,
 402                                                rds_tcp_accept_w);
 403
 404         while (rds_tcp_accept_one(rtn->rds_tcp_listen_sock) == 0)
 405                 cond_resched();
 406 }
 407
 408 void rds_tcp_accept_work(struct sock *sk)
 409 {
 410         struct net *net = sock_net(sk);
 411         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 412
 413         queue_work(rds_wq, &rtn->rds_tcp_accept_w);
 414 }
 415
 416 static __net_init int rds_tcp_init_net(struct net *net)
 417 {
 418         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 419         struct ctl_table *tbl;
 420         int err = 0;
 421
 422         memset(rtn, 0, sizeof(*rtn));
 423
 424         /* {snd, rcv}buf_size default to 0, which implies we let the
 425          * stack pick the value, and permit auto-tuning of buffer size.
 426          */
 427         if (net == &init_net) {
 428                 tbl = rds_tcp_sysctl_table;
 429         } else {
 430                 tbl = kmemdup(rds_tcp_sysctl_table,
 431                               sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
 432                 if (!tbl) {
 433                         pr_warn("could not set allocate syctl table\n");
 434                         return -ENOMEM;
 435                 }
 436                 rtn->ctl_table = tbl;
 437         }
 438         tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
 439         tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
 440         rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
 441         if (!rtn->rds_tcp_sysctl) {
 442                 pr_warn("could not register sysctl\n");
 443                 err = -ENOMEM;
 444                 goto fail;
 445         }
 446         rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net);
 447         if (!rtn->rds_tcp_listen_sock) {
 448                 pr_warn("could not set up listen sock\n");
 449                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
 450                 rtn->rds_tcp_sysctl = NULL;
 451                 err = -EAFNOSUPPORT;
 452                 goto fail;
 453         }
 454         INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
 455         return 0;
 456
 457 fail:
 458         if (net != &init_net)
 459                 kfree(tbl);
 460         return err;
 461 }
 462
 463 static void __net_exit rds_tcp_exit_net(struct net *net)
 464 {
 465         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 466
 467         if (rtn->rds_tcp_sysctl)
 468                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
 469
 470         if (net != &init_net && rtn->ctl_table)
 471                 kfree(rtn->ctl_table);
 472
 473         /* If rds_tcp_exit_net() is called as a result of netns deletion,
 474          * the rds_tcp_kill_sock() device notifier would already have cleaned
 475          * up the listen socket, thus there is no work to do in this function.
 476          *
 477          * If rds_tcp_exit_net() is called as a result of module unload,
 478          * i.e., due to rds_tcp_exit() -> unregister_pernet_subsys(), then
 479          * we do need to clean up the listen socket here.
 480          */
 481         if (rtn->rds_tcp_listen_sock) {
 482                 struct socket *lsock = rtn->rds_tcp_listen_sock;
 483
 484                 rtn->rds_tcp_listen_sock = NULL;
 485                 rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
 486         }
 487 }
 488
 489 static struct pernet_operations rds_tcp_net_ops = {
 490         .init = rds_tcp_init_net,
 491         .exit = rds_tcp_exit_net,
 492         .id = &rds_tcp_netid,
 493         .size = sizeof(struct rds_tcp_net),
 494 };
 495
 496 /* explicitly send a RST on each socket, thereby releasing any socket refcnts
 497  * that may otherwise hold up netns deletion.
 498  */
 499 static void rds_tcp_conn_paths_destroy(struct rds_connection *conn)
 500 {
 501         struct rds_conn_path *cp;
 502         struct rds_tcp_connection *tc;
 503         int i;
 504         struct sock *sk;
 505
 506         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 507                 cp = &conn->c_path[i];
 508                 tc = cp->cp_transport_data;
 509                 if (!tc->t_sock)
 510                         continue;
 511                 sk = tc->t_sock->sk;
 512                 sk->sk_prot->disconnect(sk, 0);
 513                 tcp_done(sk);
 514         }
 515 }
 516
 517 static void rds_tcp_kill_sock(struct net *net)
 518 {
 519         struct rds_tcp_connection *tc, *_tc;
 520         LIST_HEAD(tmp_list);
 521         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 522         struct socket *lsock = rtn->rds_tcp_listen_sock;
 523
 524         rtn->rds_tcp_listen_sock = NULL;
 525         rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
 526         spin_lock_irq(&rds_tcp_conn_lock);
 527         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 528                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 529
 530                 if (net != c_net)
 531                         continue;
 532                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) {
 533                         list_move_tail(&tc->t_tcp_node, &tmp_list);
 534                 } else {
 535                         list_del(&tc->t_tcp_node);
 536                         tc->t_tcp_node_detached = true;
 537                 }
 538         }
 539         spin_unlock_irq(&rds_tcp_conn_lock);
 540         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {
 541                 rds_tcp_conn_paths_destroy(tc->t_cpath->cp_conn);
 542                 rds_conn_destroy(tc->t_cpath->cp_conn);
 543         }
 544 }
 545
 546 void *rds_tcp_listen_sock_def_readable(struct net *net)
 547 {
 548         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 549         struct socket *lsock = rtn->rds_tcp_listen_sock;
 550
 551         if (!lsock)
 552                 return NULL;
 553
 554         return lsock->sk->sk_user_data;
 555 }
 556
 557 static int rds_tcp_dev_event(struct notifier_block *this,
 558                              unsigned long event, void *ptr)
 559 {
 560         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 561
 562         /* rds-tcp registers as a pernet subys, so the ->exit will only
 563          * get invoked after network acitivity has quiesced. We need to
 564          * clean up all sockets  to quiesce network activity, and use
 565          * the unregistration of the per-net loopback device as a trigger
 566          * to start that cleanup.
 567          */
 568         if (event == NETDEV_UNREGISTER_FINAL &&
 569             dev->ifindex == LOOPBACK_IFINDEX)
 570                 rds_tcp_kill_sock(dev_net(dev));
 571
 572         return NOTIFY_DONE;
 573 }
 574
 575 static struct notifier_block rds_tcp_dev_notifier = {
 576         .notifier_call        = rds_tcp_dev_event,
 577         .priority = -10, /* must be called after other network notifiers */
 578 };
 579
 580 /* when sysctl is used to modify some kernel socket parameters,this
 581  * function  resets the RDS connections in that netns  so that we can
 582  * restart with new parameters.  The assumption is that such reset
 583  * events are few and far-between.
 584  */
 585 static void rds_tcp_sysctl_reset(struct net *net)
 586 {
 587         struct rds_tcp_connection *tc, *_tc;
 588
 589         spin_lock_irq(&rds_tcp_conn_lock);
 590         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 591                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 592
 593                 if (net != c_net || !tc->t_sock)
 594                         continue;
 595
 596                 /* reconnect with new parameters */
 597                 rds_conn_path_drop(tc->t_cpath);
 598         }
 599         spin_unlock_irq(&rds_tcp_conn_lock);
 600 }
 601
 602 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
 603                                  void __user *buffer, size_t *lenp,
 604                                  loff_t *fpos)
 605 {
 606         struct net *net = current->nsproxy->net_ns;
 607         int err;
 608
 609         err = proc_dointvec_minmax(ctl, write, buffer, lenp, fpos);
 610         if (err < 0) {
 611                 pr_warn("Invalid input. Must be >= %d\n",
 612                         *(int *)(ctl->extra1));
 613                 return err;
 614         }
 615         if (write)
 616                 rds_tcp_sysctl_reset(net);
 617         return 0;
 618 }
 619
 620 static void rds_tcp_exit(void)
 621 {
 622         rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
 623         unregister_pernet_subsys(&rds_tcp_net_ops);
 624         if (unregister_netdevice_notifier(&rds_tcp_dev_notifier))
 625                 pr_warn("could not unregister rds_tcp_dev_notifier\n");
 626         rds_tcp_destroy_conns();
 627         rds_trans_unregister(&rds_tcp_transport);
 628         rds_tcp_recv_exit();
 629         kmem_cache_destroy(rds_tcp_conn_slab);
 630 }
 631 module_exit(rds_tcp_exit);
 632
 633 static int rds_tcp_init(void)
 634 {
 635         int ret;
 636
 637         rds_tcp_conn_slab = kmem_cache_create("rds_tcp_connection",
 638                                               sizeof(struct rds_tcp_connection),
 639                                               0, 0, NULL);
 640         if (!rds_tcp_conn_slab) {
 641                 ret = -ENOMEM;
 642                 goto out;
 643         }
 644
 645         ret = register_netdevice_notifier(&rds_tcp_dev_notifier);
 646         if (ret) {
 647                 pr_warn("could not register rds_tcp_dev_notifier\n");
 648                 goto out;
 649         }
 650
 651         ret = register_pernet_subsys(&rds_tcp_net_ops);
 652         if (ret)
 653                 goto out_slab;
 654
 655         ret = rds_tcp_recv_init();
 656         if (ret)
 657                 goto out_pernet;
 658
 659         ret = rds_trans_register(&rds_tcp_transport);
 660         if (ret)
 661                 goto out_recv;
 662
 663         rds_info_register_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
 664
 665         goto out;
 666
 667 out_recv:
 668         rds_tcp_recv_exit();
 669 out_pernet:
 670         unregister_pernet_subsys(&rds_tcp_net_ops);
 671 out_slab:
 672         if (unregister_netdevice_notifier(&rds_tcp_dev_notifier))
 673                 pr_warn("could not unregister rds_tcp_dev_notifier\n");
 674         kmem_cache_destroy(rds_tcp_conn_slab);
 675 out:
 676         return ret;
 677 }
 678 module_init(rds_tcp_init);
 679
 680 MODULE_AUTHOR("Oracle Corporation <rds-devel@oss.oracle.com>");
 681 MODULE_DESCRIPTION("RDS: TCP transport");
 682 MODULE_LICENSE("Dual BSD/GPL");
 683