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