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 static atomic_t rds_tcp_unloading = ATOMIC_INIT(0);
  53
  54 static struct kmem_cache *rds_tcp_conn_slab;
  55
  56 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
  57                                  void __user *buffer, size_t *lenp,
  58                                  loff_t *fpos);
  59
  60 static int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
  61 static int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
  62
  63 static struct ctl_table rds_tcp_sysctl_table[] = {
  64 #define RDS_TCP_SNDBUF  0
  65         {
  66                 .procname       = "rds_tcp_sndbuf",
  67                 /* data is per-net pointer */
  68                 .maxlen         = sizeof(int),
  69                 .mode           = 0644,
  70                 .proc_handler   = rds_tcp_skbuf_handler,
  71                 .extra1         = &rds_tcp_min_sndbuf,
  72         },
  73 #define RDS_TCP_RCVBUF  1
  74         {
  75                 .procname       = "rds_tcp_rcvbuf",
  76                 /* data is per-net pointer */
  77                 .maxlen         = sizeof(int),
  78                 .mode           = 0644,
  79                 .proc_handler   = rds_tcp_skbuf_handler,
  80                 .extra1         = &rds_tcp_min_rcvbuf,
  81         },
  82         { }
  83 };
  84
  85 /* doing it this way avoids calling tcp_sk() */
  86 void rds_tcp_nonagle(struct socket *sock)
  87 {
  88         int val = 1;
  89
  90         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (void *)&val,
  91                               sizeof(val));
  92 }
  93
  94 u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
  95 {
  96         /* seq# of the last byte of data in tcp send buffer */
  97         return tcp_sk(tc->t_sock->sk)->write_seq;
  98 }
  99
 100 u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)
 101 {
 102         return tcp_sk(tc->t_sock->sk)->snd_una;
 103 }
 104
 105 void rds_tcp_restore_callbacks(struct socket *sock,
 106                                struct rds_tcp_connection *tc)
 107 {
 108         rdsdebug("restoring sock %p callbacks from tc %p\n", sock, tc);
 109         write_lock_bh(&sock->sk->sk_callback_lock);
 110
 111         /* done under the callback_lock to serialize with write_space */
 112         spin_lock(&rds_tcp_tc_list_lock);
 113         list_del_init(&tc->t_list_item);
 114         rds_tcp_tc_count--;
 115         spin_unlock(&rds_tcp_tc_list_lock);
 116
 117         tc->t_sock = NULL;
 118
 119         sock->sk->sk_write_space = tc->t_orig_write_space;
 120         sock->sk->sk_data_ready = tc->t_orig_data_ready;
 121         sock->sk->sk_state_change = tc->t_orig_state_change;
 122         sock->sk->sk_user_data = NULL;
 123
 124         write_unlock_bh(&sock->sk->sk_callback_lock);
 125 }
 126
 127 /*
 128  * rds_tcp_reset_callbacks() switches the to the new sock and
 129  * returns the existing tc->t_sock.
 130  *
 131  * The only functions that set tc->t_sock are rds_tcp_set_callbacks
 132  * and rds_tcp_reset_callbacks.  Send and receive trust that
 133  * it is set.  The absence of RDS_CONN_UP bit protects those paths
 134  * from being called while it isn't set.
 135  */
 136 void rds_tcp_reset_callbacks(struct socket *sock,
 137                              struct rds_conn_path *cp)
 138 {
 139         struct rds_tcp_connection *tc = cp->cp_transport_data;
 140         struct socket *osock = tc->t_sock;
 141
 142         if (!osock)
 143                 goto newsock;
 144
 145         /* Need to resolve a duelling SYN between peers.
 146          * We have an outstanding SYN to this peer, which may
 147          * potentially have transitioned to the RDS_CONN_UP state,
 148          * so we must quiesce any send threads before resetting
 149          * cp_transport_data. We quiesce these threads by setting
 150          * cp_state to something other than RDS_CONN_UP, and then
 151          * waiting for any existing threads in rds_send_xmit to
 152          * complete release_in_xmit(). (Subsequent threads entering
 153          * rds_send_xmit() will bail on !rds_conn_up().
 154          *
 155          * However an incoming syn-ack at this point would end up
 156          * marking the conn as RDS_CONN_UP, and would again permit
 157          * rds_send_xmi() threads through, so ideally we would
 158          * synchronize on RDS_CONN_UP after lock_sock(), but cannot
 159          * do that: waiting on !RDS_IN_XMIT after lock_sock() may
 160          * end up deadlocking with tcp_sendmsg(), and the RDS_IN_XMIT
 161          * would not get set. As a result, we set c_state to
 162          * RDS_CONN_RESETTTING, to ensure that rds_tcp_state_change
 163          * cannot mark rds_conn_path_up() in the window before lock_sock()
 164          */
 165         atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
 166         wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
 167         lock_sock(osock->sk);
 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         if (tc->t_tinc) {
 172                 rds_inc_put(&tc->t_tinc->ti_inc);
 173                 tc->t_tinc = NULL;
 174         }
 175         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 176         tc->t_tinc_data_rem = 0;
 177         rds_tcp_restore_callbacks(osock, tc);
 178         release_sock(osock->sk);
 179         sock_release(osock);
 180 newsock:
 181         rds_send_path_reset(cp);
 182         lock_sock(sock->sk);
 183         rds_tcp_set_callbacks(sock, cp);
 184         release_sock(sock->sk);
 185 }
 186
 187 /* Add tc to rds_tcp_tc_list and set tc->t_sock. See comments
 188  * above rds_tcp_reset_callbacks for notes about synchronization
 189  * with data path
 190  */
 191 void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)
 192 {
 193         struct rds_tcp_connection *tc = cp->cp_transport_data;
 194
 195         rdsdebug("setting sock %p callbacks to tc %p\n", sock, tc);
 196         write_lock_bh(&sock->sk->sk_callback_lock);
 197
 198         /* done under the callback_lock to serialize with write_space */
 199         spin_lock(&rds_tcp_tc_list_lock);
 200         list_add_tail(&tc->t_list_item, &rds_tcp_tc_list);
 201         rds_tcp_tc_count++;
 202         spin_unlock(&rds_tcp_tc_list_lock);
 203
 204         /* accepted sockets need our listen data ready undone */
 205         if (sock->sk->sk_data_ready == rds_tcp_listen_data_ready)
 206                 sock->sk->sk_data_ready = sock->sk->sk_user_data;
 207
 208         tc->t_sock = sock;
 209         tc->t_cpath = cp;
 210         tc->t_orig_data_ready = sock->sk->sk_data_ready;
 211         tc->t_orig_write_space = sock->sk->sk_write_space;
 212         tc->t_orig_state_change = sock->sk->sk_state_change;
 213
 214         sock->sk->sk_user_data = cp;
 215         sock->sk->sk_data_ready = rds_tcp_data_ready;
 216         sock->sk->sk_write_space = rds_tcp_write_space;
 217         sock->sk->sk_state_change = rds_tcp_state_change;
 218
 219         write_unlock_bh(&sock->sk->sk_callback_lock);
 220 }
 221
 222 static void rds_tcp_tc_info(struct socket *rds_sock, unsigned int len,
 223                             struct rds_info_iterator *iter,
 224                             struct rds_info_lengths *lens)
 225 {
 226         struct rds_info_tcp_socket tsinfo;
 227         struct rds_tcp_connection *tc;
 228         unsigned long flags;
 229         struct sockaddr_in sin;
 230         int sinlen;
 231         struct socket *sock;
 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 = tc->t_sock;
 241                 if (sock) {
 242                         sock->ops->getname(sock, (struct sockaddr *)&sin,
 243                                            &sinlen, 0);
 244                         tsinfo.local_addr = sin.sin_addr.s_addr;
 245                         tsinfo.local_port = sin.sin_port;
 246                         sock->ops->getname(sock, (struct sockaddr *)&sin,
 247                                            &sinlen, 1);
 248                         tsinfo.peer_addr = sin.sin_addr.s_addr;
 249                         tsinfo.peer_port = sin.sin_port;
 250                 }
 251
 252                 tsinfo.hdr_rem = tc->t_tinc_hdr_rem;
 253                 tsinfo.data_rem = tc->t_tinc_data_rem;
 254                 tsinfo.last_sent_nxt = tc->t_last_sent_nxt;
 255                 tsinfo.last_expected_una = tc->t_last_expected_una;
 256                 tsinfo.last_seen_una = tc->t_last_seen_una;
 257
 258                 rds_info_copy(iter, &tsinfo, sizeof(tsinfo));
 259         }
 260
 261 out:
 262         lens->nr = rds_tcp_tc_count;
 263         lens->each = sizeof(tsinfo);
 264
 265         spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
 266 }
 267
 268 static int rds_tcp_laddr_check(struct net *net, __be32 addr)
 269 {
 270         if (inet_addr_type(net, addr) == RTN_LOCAL)
 271                 return 0;
 272         return -EADDRNOTAVAIL;
 273 }
 274
 275 static void rds_tcp_conn_free(void *arg)
 276 {
 277         struct rds_tcp_connection *tc = arg;
 278
 279         rdsdebug("freeing tc %p\n", tc);
 280
 281         spin_lock_bh(&rds_tcp_conn_lock);
 282         if (!tc->t_tcp_node_detached)
 283                 list_del(&tc->t_tcp_node);
 284         spin_unlock_bh(&rds_tcp_conn_lock);
 285
 286         kmem_cache_free(rds_tcp_conn_slab, tc);
 287 }
 288
 289 static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 290 {
 291         struct rds_tcp_connection *tc;
 292         int i, j;
 293         int ret = 0;
 294
 295         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 296                 tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
 297                 if (!tc) {
 298                         ret = -ENOMEM;
 299                         goto fail;
 300                 }
 301                 mutex_init(&tc->t_conn_path_lock);
 302                 tc->t_sock = NULL;
 303                 tc->t_tinc = NULL;
 304                 tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 305                 tc->t_tinc_data_rem = 0;
 306
 307                 conn->c_path[i].cp_transport_data = tc;
 308                 tc->t_cpath = &conn->c_path[i];
 309                 tc->t_tcp_node_detached = true;
 310
 311                 rdsdebug("rds_conn_path [%d] tc %p\n", i,
 312                          conn->c_path[i].cp_transport_data);
 313         }
 314         spin_lock_bh(&rds_tcp_conn_lock);
 315         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 316                 tc = conn->c_path[i].cp_transport_data;
 317                 tc->t_tcp_node_detached = false;
 318                 list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
 319         }
 320         spin_unlock_bh(&rds_tcp_conn_lock);
 321 fail:
 322         if (ret) {
 323                 for (j = 0; j < i; j++)
 324                         rds_tcp_conn_free(conn->c_path[j].cp_transport_data);
 325         }
 326         return ret;
 327 }
 328
 329 static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
 330 {
 331         struct rds_tcp_connection *tc, *_tc;
 332
 333         list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
 334                 if (tc->t_cpath->cp_conn == conn)
 335                         return true;
 336         }
 337         return false;
 338 }
 339
 340 static void rds_tcp_set_unloading(void)
 341 {
 342         atomic_set(&rds_tcp_unloading, 1);
 343 }
 344
 345 static bool rds_tcp_is_unloading(struct rds_connection *conn)
 346 {
 347         return atomic_read(&rds_tcp_unloading) != 0;
 348 }
 349
 350 static void rds_tcp_destroy_conns(void)
 351 {
 352         struct rds_tcp_connection *tc, *_tc;
 353         LIST_HEAD(tmp_list);
 354
 355         /* avoid calling conn_destroy with irqs off */
 356         spin_lock_irq(&rds_tcp_conn_lock);
 357         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 358                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
 359                         list_move_tail(&tc->t_tcp_node, &tmp_list);
 360         }
 361         spin_unlock_irq(&rds_tcp_conn_lock);
 362
 363         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
 364                 rds_conn_destroy(tc->t_cpath->cp_conn);
 365 }
 366
 367 static void rds_tcp_exit(void);
 368
 369 struct rds_transport rds_tcp_transport = {
 370         .laddr_check            = rds_tcp_laddr_check,
 371         .xmit_path_prepare      = rds_tcp_xmit_path_prepare,
 372         .xmit_path_complete     = rds_tcp_xmit_path_complete,
 373         .xmit                   = rds_tcp_xmit,
 374         .recv_path              = rds_tcp_recv_path,
 375         .conn_alloc             = rds_tcp_conn_alloc,
 376         .conn_free              = rds_tcp_conn_free,
 377         .conn_path_connect      = rds_tcp_conn_path_connect,
 378         .conn_path_shutdown     = rds_tcp_conn_path_shutdown,
 379         .inc_copy_to_user       = rds_tcp_inc_copy_to_user,
 380         .inc_free               = rds_tcp_inc_free,
 381         .stats_info_copy        = rds_tcp_stats_info_copy,
 382         .exit                   = rds_tcp_exit,
 383         .t_owner                = THIS_MODULE,
 384         .t_name                 = "tcp",
 385         .t_type                 = RDS_TRANS_TCP,
 386         .t_prefer_loopback      = 1,
 387         .t_mp_capable           = 1,
 388         .t_unloading            = rds_tcp_is_unloading,
 389 };
 390
 391 static unsigned int rds_tcp_netid;
 392
 393 /* per-network namespace private data for this module */
 394 struct rds_tcp_net {
 395         struct socket *rds_tcp_listen_sock;
 396         struct work_struct rds_tcp_accept_w;
 397         struct ctl_table_header *rds_tcp_sysctl;
 398         struct ctl_table *ctl_table;
 399         int sndbuf_size;
 400         int rcvbuf_size;
 401 };
 402
 403 /* All module specific customizations to the RDS-TCP socket should be done in
 404  * rds_tcp_tune() and applied after socket creation.
 405  */
 406 void rds_tcp_tune(struct socket *sock)
 407 {
 408         struct sock *sk = sock->sk;
 409         struct net *net = sock_net(sk);
 410         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 411
 412         rds_tcp_nonagle(sock);
 413         lock_sock(sk);
 414         if (rtn->sndbuf_size > 0) {
 415                 sk->sk_sndbuf = rtn->sndbuf_size;
 416                 sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
 417         }
 418         if (rtn->rcvbuf_size > 0) {
 419                 sk->sk_sndbuf = rtn->rcvbuf_size;
 420                 sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
 421         }
 422         release_sock(sk);
 423 }
 424
 425 static void rds_tcp_accept_worker(struct work_struct *work)
 426 {
 427         struct rds_tcp_net *rtn = container_of(work,
 428                                                struct rds_tcp_net,
 429                                                rds_tcp_accept_w);
 430
 431         while (rds_tcp_accept_one(rtn->rds_tcp_listen_sock) == 0)
 432                 cond_resched();
 433 }
 434
 435 void rds_tcp_accept_work(struct sock *sk)
 436 {
 437         struct net *net = sock_net(sk);
 438         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 439
 440         queue_work(rds_wq, &rtn->rds_tcp_accept_w);
 441 }
 442
 443 static __net_init int rds_tcp_init_net(struct net *net)
 444 {
 445         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 446         struct ctl_table *tbl;
 447         int err = 0;
 448
 449         memset(rtn, 0, sizeof(*rtn));
 450
 451         /* {snd, rcv}buf_size default to 0, which implies we let the
 452          * stack pick the value, and permit auto-tuning of buffer size.
 453          */
 454         if (net == &init_net) {
 455                 tbl = rds_tcp_sysctl_table;
 456         } else {
 457                 tbl = kmemdup(rds_tcp_sysctl_table,
 458                               sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
 459                 if (!tbl) {
 460                         pr_warn("could not set allocate syctl table\n");
 461                         return -ENOMEM;
 462                 }
 463                 rtn->ctl_table = tbl;
 464         }
 465         tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
 466         tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
 467         rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
 468         if (!rtn->rds_tcp_sysctl) {
 469                 pr_warn("could not register sysctl\n");
 470                 err = -ENOMEM;
 471                 goto fail;
 472         }
 473         rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net);
 474         if (!rtn->rds_tcp_listen_sock) {
 475                 pr_warn("could not set up listen sock\n");
 476                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
 477                 rtn->rds_tcp_sysctl = NULL;
 478                 err = -EAFNOSUPPORT;
 479                 goto fail;
 480         }
 481         INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
 482         return 0;
 483
 484 fail:
 485         if (net != &init_net)
 486                 kfree(tbl);
 487         return err;
 488 }
 489
 490 static void __net_exit rds_tcp_exit_net(struct net *net)
 491 {
 492         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 493
 494         if (rtn->rds_tcp_sysctl)
 495                 unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
 496
 497         if (net != &init_net && rtn->ctl_table)
 498                 kfree(rtn->ctl_table);
 499
 500         /* If rds_tcp_exit_net() is called as a result of netns deletion,
 501          * the rds_tcp_kill_sock() device notifier would already have cleaned
 502          * up the listen socket, thus there is no work to do in this function.
 503          *
 504          * If rds_tcp_exit_net() is called as a result of module unload,
 505          * i.e., due to rds_tcp_exit() -> unregister_pernet_subsys(), then
 506          * we do need to clean up the listen socket here.
 507          */
 508         if (rtn->rds_tcp_listen_sock) {
 509                 struct socket *lsock = rtn->rds_tcp_listen_sock;
 510
 511                 rtn->rds_tcp_listen_sock = NULL;
 512                 rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
 513         }
 514 }
 515
 516 static struct pernet_operations rds_tcp_net_ops = {
 517         .init = rds_tcp_init_net,
 518         .exit = rds_tcp_exit_net,
 519         .id = &rds_tcp_netid,
 520         .size = sizeof(struct rds_tcp_net),
 521 };
 522
 523 static void rds_tcp_kill_sock(struct net *net)
 524 {
 525         struct rds_tcp_connection *tc, *_tc;
 526         LIST_HEAD(tmp_list);
 527         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 528         struct socket *lsock = rtn->rds_tcp_listen_sock;
 529
 530         rtn->rds_tcp_listen_sock = NULL;
 531         rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
 532         spin_lock_bh(&rds_tcp_conn_lock);
 533         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 534                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 535
 536                 if (net != c_net || !tc->t_sock)
 537                         continue;
 538                 if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) {
 539                         list_move_tail(&tc->t_tcp_node, &tmp_list);
 540                 } else {
 541                         list_del(&tc->t_tcp_node);
 542                         tc->t_tcp_node_detached = true;
 543                 }
 544         }
 545         spin_unlock_bh(&rds_tcp_conn_lock);
 546         list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
 547                 rds_conn_destroy(tc->t_cpath->cp_conn);
 548 }
 549
 550 void *rds_tcp_listen_sock_def_readable(struct net *net)
 551 {
 552         struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 553         struct socket *lsock = rtn->rds_tcp_listen_sock;
 554
 555         if (!lsock)
 556                 return NULL;
 557
 558         return lsock->sk->sk_user_data;
 559 }
 560
 561 static int rds_tcp_dev_event(struct notifier_block *this,
 562                              unsigned long event, void *ptr)
 563 {
 564         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 565
 566         /* rds-tcp registers as a pernet subys, so the ->exit will only
 567          * get invoked after network acitivity has quiesced. We need to
 568          * clean up all sockets  to quiesce network activity, and use
 569          * the unregistration of the per-net loopback device as a trigger
 570          * to start that cleanup.
 571          */
 572         if (event == NETDEV_UNREGISTER_FINAL &&
 573             dev->ifindex == LOOPBACK_IFINDEX)
 574                 rds_tcp_kill_sock(dev_net(dev));
 575
 576         return NOTIFY_DONE;
 577 }
 578
 579 static struct notifier_block rds_tcp_dev_notifier = {
 580         .notifier_call        = rds_tcp_dev_event,
 581         .priority = -10, /* must be called after other network notifiers */
 582 };
 583
 584 /* when sysctl is used to modify some kernel socket parameters,this
 585  * function  resets the RDS connections in that netns  so that we can
 586  * restart with new parameters.  The assumption is that such reset
 587  * events are few and far-between.
 588  */
 589 static void rds_tcp_sysctl_reset(struct net *net)
 590 {
 591         struct rds_tcp_connection *tc, *_tc;
 592
 593         spin_lock_bh(&rds_tcp_conn_lock);
 594         list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
 595                 struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 596
 597                 if (net != c_net || !tc->t_sock)
 598                         continue;
 599
 600                 /* reconnect with new parameters */
 601                 rds_conn_path_drop(tc->t_cpath, false);
 602         }
 603         spin_unlock_bh(&rds_tcp_conn_lock);
 604 }
 605
 606 static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
 607                                  void __user *buffer, size_t *lenp,
 608                                  loff_t *fpos)
 609 {
 610         struct net *net = current->nsproxy->net_ns;
 611         int err;
 612
 613         err = proc_dointvec_minmax(ctl, write, buffer, lenp, fpos);
 614         if (err < 0) {
 615                 pr_warn("Invalid input. Must be >= %d\n",
 616                         *(int *)(ctl->extra1));
 617                 return err;
 618         }
 619         if (write)
 620                 rds_tcp_sysctl_reset(net);
 621         return 0;
 622 }
 623
 624 static void rds_tcp_exit(void)
 625 {
 626         rds_tcp_set_unloading();
 627         synchronize_rcu();
 628         rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
 629         unregister_pernet_subsys(&rds_tcp_net_ops);
 630         if (unregister_netdevice_notifier(&rds_tcp_dev_notifier))
 631                 pr_warn("could not unregister rds_tcp_dev_notifier\n");
 632         rds_tcp_destroy_conns();
 633         rds_trans_unregister(&rds_tcp_transport);
 634         rds_tcp_recv_exit();
 635         kmem_cache_destroy(rds_tcp_conn_slab);
 636 }
 637 module_exit(rds_tcp_exit);
 638
 639 static int rds_tcp_init(void)
 640 {
 641         int ret;
 642
 643         rds_tcp_conn_slab = kmem_cache_create("rds_tcp_connection",
 644                                               sizeof(struct rds_tcp_connection),
 645                                               0, 0, NULL);
 646         if (!rds_tcp_conn_slab) {
 647                 ret = -ENOMEM;
 648                 goto out;
 649         }
 650
 651         ret = rds_tcp_recv_init();
 652         if (ret)
 653                 goto out_slab;
 654
 655         ret = register_pernet_subsys(&rds_tcp_net_ops);
 656         if (ret)
 657                 goto out_recv;
 658
 659         ret = register_netdevice_notifier(&rds_tcp_dev_notifier);
 660         if (ret) {
 661                 pr_warn("could not register rds_tcp_dev_notifier\n");
 662                 goto out_pernet;
 663         }
 664
 665         rds_trans_register(&rds_tcp_transport);
 666
 667         rds_info_register_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
 668
 669         goto out;
 670
 671 out_pernet:
 672         unregister_pernet_subsys(&rds_tcp_net_ops);
 673 out_recv:
 674         rds_tcp_recv_exit();
 675 out_slab:
 676         kmem_cache_destroy(rds_tcp_conn_slab);
 677 out:
 678         return ret;
 679 }
 680 module_init(rds_tcp_init);
 681
 682 MODULE_AUTHOR("Oracle Corporation <rds-devel@oss.oracle.com>");
 683 MODULE_DESCRIPTION("RDS: TCP transport");
 684 MODULE_LICENSE("Dual BSD/GPL");
 685