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