git.oblomov.eu Git - linux-2.6/blob - net/ipv4/inet_connection_sock.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Support for INET connection oriented protocols.
   7  *
   8  * Authors:     See the TCP sources
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or(at your option) any later version.
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/module.h>
  18 #include <linux/jhash.h>
  19
  20 #include <net/inet_connection_sock.h>
  21 #include <net/inet_hashtables.h>
  22 #include <net/inet_timewait_sock.h>
  23 #include <net/ip.h>
  24 #include <net/route.h>
  25 #include <net/tcp_states.h>
  26 #include <net/xfrm.h>
  27
  28 #ifdef INET_CSK_DEBUG
  29 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
  30 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  31 #endif
  32
  33 /*
  34  * This array holds the first and last local port number.
  35  * For high-usage systems, use sysctl to change this to
  36  * 32768-61000
  37  */
  38 int sysctl_local_port_range[2] = { 1024, 4999 };
  39
  40 static inline int inet_csk_bind_conflict(struct sock *sk, struct inet_bind_bucket *tb)
  41 {
  42         const u32 sk_rcv_saddr = inet_rcv_saddr(sk);
  43         struct sock *sk2;
  44         struct hlist_node *node;
  45         int reuse = sk->sk_reuse;
  46
  47         sk_for_each_bound(sk2, node, &tb->owners) {
  48                 if (sk != sk2 &&
  49                     !inet_v6_ipv6only(sk2) &&
  50                     (!sk->sk_bound_dev_if ||
  51                      !sk2->sk_bound_dev_if ||
  52                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
  53                         if (!reuse || !sk2->sk_reuse ||
  54                             sk2->sk_state == TCP_LISTEN) {
  55                                 const u32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
  56                                 if (!sk2_rcv_saddr || !sk_rcv_saddr ||
  57                                     sk2_rcv_saddr == sk_rcv_saddr)
  58                                         break;
  59                         }
  60                 }
  61         }
  62         return node != NULL;
  63 }
  64
  65 /* Obtain a reference to a local port for the given sock,
  66  * if snum is zero it means select any available local port.
  67  */
  68 int inet_csk_get_port(struct inet_hashinfo *hashinfo,
  69                       struct sock *sk, unsigned short snum)
  70 {
  71         struct inet_bind_hashbucket *head;
  72         struct hlist_node *node;
  73         struct inet_bind_bucket *tb;
  74         int ret;
  75
  76         local_bh_disable();
  77         if (!snum) {
  78                 int low = sysctl_local_port_range[0];
  79                 int high = sysctl_local_port_range[1];
  80                 int remaining = (high - low) + 1;
  81                 int rover;
  82
  83                 spin_lock(&hashinfo->portalloc_lock);
  84                 if (hashinfo->port_rover < low)
  85                         rover = low;
  86                 else
  87                         rover = hashinfo->port_rover;
  88                 do {
  89                         rover++;
  90                         if (rover > high)
  91                                 rover = low;
  92                         head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
  93                         spin_lock(&head->lock);
  94                         inet_bind_bucket_for_each(tb, node, &head->chain)
  95                                 if (tb->port == rover)
  96                                         goto next;
  97                         break;
  98                 next:
  99                         spin_unlock(&head->lock);
 100                 } while (--remaining > 0);
 101                 hashinfo->port_rover = rover;
 102                 spin_unlock(&hashinfo->portalloc_lock);
 103
 104                 /* Exhausted local port range during search?  It is not
 105                  * possible for us to be holding one of the bind hash
 106                  * locks if this test triggers, because if 'remaining'
 107                  * drops to zero, we broke out of the do/while loop at
 108                  * the top level, not from the 'break;' statement.
 109                  */
 110                 ret = 1;
 111                 if (remaining <= 0)
 112                         goto fail;
 113
 114                 /* OK, here is the one we will use.  HEAD is
 115                  * non-NULL and we hold it's mutex.
 116                  */
 117                 snum = rover;
 118         } else {
 119                 head = &hashinfo->bhash[inet_bhashfn(snum, hashinfo->bhash_size)];
 120                 spin_lock(&head->lock);
 121                 inet_bind_bucket_for_each(tb, node, &head->chain)
 122                         if (tb->port == snum)
 123                                 goto tb_found;
 124         }
 125         tb = NULL;
 126         goto tb_not_found;
 127 tb_found:
 128         if (!hlist_empty(&tb->owners)) {
 129                 if (sk->sk_reuse > 1)
 130                         goto success;
 131                 if (tb->fastreuse > 0 &&
 132                     sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
 133                         goto success;
 134                 } else {
 135                         ret = 1;
 136                         if (inet_csk_bind_conflict(sk, tb))
 137                                 goto fail_unlock;
 138                 }
 139         }
 140 tb_not_found:
 141         ret = 1;
 142         if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep, head, snum)) == NULL)
 143                 goto fail_unlock;
 144         if (hlist_empty(&tb->owners)) {
 145                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
 146                         tb->fastreuse = 1;
 147                 else
 148                         tb->fastreuse = 0;
 149         } else if (tb->fastreuse &&
 150                    (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
 151                 tb->fastreuse = 0;
 152 success:
 153         if (!inet_csk(sk)->icsk_bind_hash)
 154                 inet_bind_hash(sk, tb, snum);
 155         BUG_TRAP(inet_csk(sk)->icsk_bind_hash == tb);
 156         ret = 0;
 157
 158 fail_unlock:
 159         spin_unlock(&head->lock);
 160 fail:
 161         local_bh_enable();
 162         return ret;
 163 }
 164
 165 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 166
 167 /*
 168  * Wait for an incoming connection, avoid race conditions. This must be called
 169  * with the socket locked.
 170  */
 171 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 172 {
 173         struct inet_connection_sock *icsk = inet_csk(sk);
 174         DEFINE_WAIT(wait);
 175         int err;
 176
 177         /*
 178          * True wake-one mechanism for incoming connections: only
 179          * one process gets woken up, not the 'whole herd'.
 180          * Since we do not 'race & poll' for established sockets
 181          * anymore, the common case will execute the loop only once.
 182          *
 183          * Subtle issue: "add_wait_queue_exclusive()" will be added
 184          * after any current non-exclusive waiters, and we know that
 185          * it will always _stay_ after any new non-exclusive waiters
 186          * because all non-exclusive waiters are added at the
 187          * beginning of the wait-queue. As such, it's ok to "drop"
 188          * our exclusiveness temporarily when we get woken up without
 189          * having to remove and re-insert us on the wait queue.
 190          */
 191         for (;;) {
 192                 prepare_to_wait_exclusive(sk->sk_sleep, &wait,
 193                                           TASK_INTERRUPTIBLE);
 194                 release_sock(sk);
 195                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 196                         timeo = schedule_timeout(timeo);
 197                 lock_sock(sk);
 198                 err = 0;
 199                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 200                         break;
 201                 err = -EINVAL;
 202                 if (sk->sk_state != TCP_LISTEN)
 203                         break;
 204                 err = sock_intr_errno(timeo);
 205                 if (signal_pending(current))
 206                         break;
 207                 err = -EAGAIN;
 208                 if (!timeo)
 209                         break;
 210         }
 211         finish_wait(sk->sk_sleep, &wait);
 212         return err;
 213 }
 214
 215 /*
 216  * This will accept the next outstanding connection.
 217  */
 218 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 219 {
 220         struct inet_connection_sock *icsk = inet_csk(sk);
 221         struct sock *newsk;
 222         int error;
 223
 224         lock_sock(sk);
 225
 226         /* We need to make sure that this socket is listening,
 227          * and that it has something pending.
 228          */
 229         error = -EINVAL;
 230         if (sk->sk_state != TCP_LISTEN)
 231                 goto out_err;
 232
 233         /* Find already established connection */
 234         if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
 235                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 236
 237                 /* If this is a non blocking socket don't sleep */
 238                 error = -EAGAIN;
 239                 if (!timeo)
 240                         goto out_err;
 241
 242                 error = inet_csk_wait_for_connect(sk, timeo);
 243                 if (error)
 244                         goto out_err;
 245         }
 246
 247         newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
 248         BUG_TRAP(newsk->sk_state != TCP_SYN_RECV);
 249 out:
 250         release_sock(sk);
 251         return newsk;
 252 out_err:
 253         newsk = NULL;
 254         *err = error;
 255         goto out;
 256 }
 257
 258 EXPORT_SYMBOL(inet_csk_accept);
 259
 260 /*
 261  * Using different timers for retransmit, delayed acks and probes
 262  * We may wish use just one timer maintaining a list of expire jiffies
 263  * to optimize.
 264  */
 265 void inet_csk_init_xmit_timers(struct sock *sk,
 266                                void (*retransmit_handler)(unsigned long),
 267                                void (*delack_handler)(unsigned long),
 268                                void (*keepalive_handler)(unsigned long))
 269 {
 270         struct inet_connection_sock *icsk = inet_csk(sk);
 271
 272         init_timer(&icsk->icsk_retransmit_timer);
 273         init_timer(&icsk->icsk_delack_timer);
 274         init_timer(&sk->sk_timer);
 275
 276         icsk->icsk_retransmit_timer.function = retransmit_handler;
 277         icsk->icsk_delack_timer.function     = delack_handler;
 278         sk->sk_timer.function                = keepalive_handler;
 279
 280         icsk->icsk_retransmit_timer.data =
 281                 icsk->icsk_delack_timer.data =
 282                         sk->sk_timer.data  = (unsigned long)sk;
 283
 284         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 285 }
 286
 287 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 288
 289 void inet_csk_clear_xmit_timers(struct sock *sk)
 290 {
 291         struct inet_connection_sock *icsk = inet_csk(sk);
 292
 293         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
 294
 295         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 296         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 297         sk_stop_timer(sk, &sk->sk_timer);
 298 }
 299
 300 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 301
 302 void inet_csk_delete_keepalive_timer(struct sock *sk)
 303 {
 304         sk_stop_timer(sk, &sk->sk_timer);
 305 }
 306
 307 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 308
 309 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 310 {
 311         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 312 }
 313
 314 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 315
 316 struct dst_entry* inet_csk_route_req(struct sock *sk,
 317                                      const struct request_sock *req)
 318 {
 319         struct rtable *rt;
 320         const struct inet_request_sock *ireq = inet_rsk(req);
 321         struct ip_options *opt = inet_rsk(req)->opt;
 322         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 323                             .nl_u = { .ip4_u =
 324                                       { .daddr = ((opt && opt->srr) ?
 325                                                   opt->faddr :
 326                                                   ireq->rmt_addr),
 327                                         .saddr = ireq->loc_addr,
 328                                         .tos = RT_CONN_FLAGS(sk) } },
 329                             .proto = sk->sk_protocol,
 330                             .uli_u = { .ports =
 331                                        { .sport = inet_sk(sk)->sport,
 332                                          .dport = ireq->rmt_port } } };
 333
 334         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 335                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 336                 return NULL;
 337         }
 338         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
 339                 ip_rt_put(rt);
 340                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 341                 return NULL;
 342         }
 343         return &rt->u.dst;
 344 }
 345
 346 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 347
 348 static inline u32 inet_synq_hash(const u32 raddr, const u16 rport,
 349                                  const u32 rnd, const u16 synq_hsize)
 350 {
 351         return jhash_2words(raddr, (u32)rport, rnd) & (synq_hsize - 1);
 352 }
 353
 354 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 355 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
 356 #else
 357 #define AF_INET_FAMILY(fam) 1
 358 #endif
 359
 360 struct request_sock *inet_csk_search_req(const struct sock *sk,
 361                                          struct request_sock ***prevp,
 362                                          const __u16 rport, const __u32 raddr,
 363                                          const __u32 laddr)
 364 {
 365         const struct inet_connection_sock *icsk = inet_csk(sk);
 366         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 367         struct request_sock *req, **prev;
 368
 369         for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
 370                                                     lopt->nr_table_entries)];
 371              (req = *prev) != NULL;
 372              prev = &req->dl_next) {
 373                 const struct inet_request_sock *ireq = inet_rsk(req);
 374
 375                 if (ireq->rmt_port == rport &&
 376                     ireq->rmt_addr == raddr &&
 377                     ireq->loc_addr == laddr &&
 378                     AF_INET_FAMILY(req->rsk_ops->family)) {
 379                         BUG_TRAP(!req->sk);
 380                         *prevp = prev;
 381                         break;
 382                 }
 383         }
 384
 385         return req;
 386 }
 387
 388 EXPORT_SYMBOL_GPL(inet_csk_search_req);
 389
 390 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 391                                    const unsigned timeout)
 392 {
 393         struct inet_connection_sock *icsk = inet_csk(sk);
 394         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 395         const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
 396                                      lopt->hash_rnd, lopt->nr_table_entries);
 397
 398         reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
 399         inet_csk_reqsk_queue_added(sk, timeout);
 400 }
 401
 402 /* Only thing we need from tcp.h */
 403 extern int sysctl_tcp_synack_retries;
 404
 405 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 406
 407 void inet_csk_reqsk_queue_prune(struct sock *parent,
 408                                 const unsigned long interval,
 409                                 const unsigned long timeout,
 410                                 const unsigned long max_rto)
 411 {
 412         struct inet_connection_sock *icsk = inet_csk(parent);
 413         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 414         struct listen_sock *lopt = queue->listen_opt;
 415         int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
 416         int thresh = max_retries;
 417         unsigned long now = jiffies;
 418         struct request_sock **reqp, *req;
 419         int i, budget;
 420
 421         if (lopt == NULL || lopt->qlen == 0)
 422                 return;
 423
 424         /* Normally all the openreqs are young and become mature
 425          * (i.e. converted to established socket) for first timeout.
 426          * If synack was not acknowledged for 3 seconds, it means
 427          * one of the following things: synack was lost, ack was lost,
 428          * rtt is high or nobody planned to ack (i.e. synflood).
 429          * When server is a bit loaded, queue is populated with old
 430          * open requests, reducing effective size of queue.
 431          * When server is well loaded, queue size reduces to zero
 432          * after several minutes of work. It is not synflood,
 433          * it is normal operation. The solution is pruning
 434          * too old entries overriding normal timeout, when
 435          * situation becomes dangerous.
 436          *
 437          * Essentially, we reserve half of room for young
 438          * embrions; and abort old ones without pity, if old
 439          * ones are about to clog our table.
 440          */
 441         if (lopt->qlen>>(lopt->max_qlen_log-1)) {
 442                 int young = (lopt->qlen_young<<1);
 443
 444                 while (thresh > 2) {
 445                         if (lopt->qlen < young)
 446                                 break;
 447                         thresh--;
 448                         young <<= 1;
 449                 }
 450         }
 451
 452         if (queue->rskq_defer_accept)
 453                 max_retries = queue->rskq_defer_accept;
 454
 455         budget = 2 * (lopt->nr_table_entries / (timeout / interval));
 456         i = lopt->clock_hand;
 457
 458         do {
 459                 reqp=&lopt->syn_table[i];
 460                 while ((req = *reqp) != NULL) {
 461                         if (time_after_eq(now, req->expires)) {
 462                                 if ((req->retrans < thresh ||
 463                                      (inet_rsk(req)->acked && req->retrans < max_retries))
 464                                     && !req->rsk_ops->rtx_syn_ack(parent, req, NULL)) {
 465                                         unsigned long timeo;
 466
 467                                         if (req->retrans++ == 0)
 468                                                 lopt->qlen_young--;
 469                                         timeo = min((timeout << req->retrans), max_rto);
 470                                         req->expires = now + timeo;
 471                                         reqp = &req->dl_next;
 472                                         continue;
 473                                 }
 474
 475                                 /* Drop this request */
 476                                 inet_csk_reqsk_queue_unlink(parent, req, reqp);
 477                                 reqsk_queue_removed(queue, req);
 478                                 reqsk_free(req);
 479                                 continue;
 480                         }
 481                         reqp = &req->dl_next;
 482                 }
 483
 484                 i = (i + 1) & (lopt->nr_table_entries - 1);
 485
 486         } while (--budget > 0);
 487
 488         lopt->clock_hand = i;
 489
 490         if (lopt->qlen)
 491                 inet_csk_reset_keepalive_timer(parent, interval);
 492 }
 493
 494 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
 495
 496 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
 497                             const unsigned int __nocast priority)
 498 {
 499         struct sock *newsk = sk_clone(sk, priority);
 500
 501         if (newsk != NULL) {
 502                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 503
 504                 newsk->sk_state = TCP_SYN_RECV;
 505                 newicsk->icsk_bind_hash = NULL;
 506
 507                 inet_sk(newsk)->dport = inet_rsk(req)->rmt_port;
 508                 newsk->sk_write_space = sk_stream_write_space;
 509
 510                 newicsk->icsk_retransmits = 0;
 511                 newicsk->icsk_backoff     = 0;
 512                 newicsk->icsk_probes_out  = 0;
 513
 514                 /* Deinitialize accept_queue to trap illegal accesses. */
 515                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 516         }
 517         return newsk;
 518 }
 519
 520 EXPORT_SYMBOL_GPL(inet_csk_clone);
 521
 522 /*
 523  * At this point, there should be no process reference to this
 524  * socket, and thus no user references at all.  Therefore we
 525  * can assume the socket waitqueue is inactive and nobody will
 526  * try to jump onto it.
 527  */
 528 void inet_csk_destroy_sock(struct sock *sk)
 529 {
 530         BUG_TRAP(sk->sk_state == TCP_CLOSE);
 531         BUG_TRAP(sock_flag(sk, SOCK_DEAD));
 532
 533         /* It cannot be in hash table! */
 534         BUG_TRAP(sk_unhashed(sk));
 535
 536         /* If it has not 0 inet_sk(sk)->num, it must be bound */
 537         BUG_TRAP(!inet_sk(sk)->num || inet_csk(sk)->icsk_bind_hash);
 538
 539         sk->sk_prot->destroy(sk);
 540
 541         sk_stream_kill_queues(sk);
 542
 543         xfrm_sk_free_policy(sk);
 544
 545         sk_refcnt_debug_release(sk);
 546
 547         atomic_dec(sk->sk_prot->orphan_count);
 548         sock_put(sk);
 549 }
 550
 551 EXPORT_SYMBOL(inet_csk_destroy_sock);
 552
 553 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
 554 {
 555         struct inet_sock *inet = inet_sk(sk);
 556         struct inet_connection_sock *icsk = inet_csk(sk);
 557         int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
 558
 559         if (rc != 0)
 560                 return rc;
 561
 562         sk->sk_max_ack_backlog = 0;
 563         sk->sk_ack_backlog = 0;
 564         inet_csk_delack_init(sk);
 565
 566         /* There is race window here: we announce ourselves listening,
 567          * but this transition is still not validated by get_port().
 568          * It is OK, because this socket enters to hash table only
 569          * after validation is complete.
 570          */
 571         sk->sk_state = TCP_LISTEN;
 572         if (!sk->sk_prot->get_port(sk, inet->num)) {
 573                 inet->sport = htons(inet->num);
 574
 575                 sk_dst_reset(sk);
 576                 sk->sk_prot->hash(sk);
 577
 578                 return 0;
 579         }
 580
 581         sk->sk_state = TCP_CLOSE;
 582         __reqsk_queue_destroy(&icsk->icsk_accept_queue);
 583         return -EADDRINUSE;
 584 }
 585
 586 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
 587
 588 /*
 589  *      This routine closes sockets which have been at least partially
 590  *      opened, but not yet accepted.
 591  */
 592 void inet_csk_listen_stop(struct sock *sk)
 593 {
 594         struct inet_connection_sock *icsk = inet_csk(sk);
 595         struct request_sock *acc_req;
 596         struct request_sock *req;
 597
 598         inet_csk_delete_keepalive_timer(sk);
 599
 600         /* make all the listen_opt local to us */
 601         acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
 602
 603         /* Following specs, it would be better either to send FIN
 604          * (and enter FIN-WAIT-1, it is normal close)
 605          * or to send active reset (abort).
 606          * Certainly, it is pretty dangerous while synflood, but it is
 607          * bad justification for our negligence 8)
 608          * To be honest, we are not able to make either
 609          * of the variants now.                 --ANK
 610          */
 611         reqsk_queue_destroy(&icsk->icsk_accept_queue);
 612
 613         while ((req = acc_req) != NULL) {
 614                 struct sock *child = req->sk;
 615
 616                 acc_req = req->dl_next;
 617
 618                 local_bh_disable();
 619                 bh_lock_sock(child);
 620                 BUG_TRAP(!sock_owned_by_user(child));
 621                 sock_hold(child);
 622
 623                 sk->sk_prot->disconnect(child, O_NONBLOCK);
 624
 625                 sock_orphan(child);
 626
 627                 atomic_inc(sk->sk_prot->orphan_count);
 628
 629                 inet_csk_destroy_sock(child);
 630
 631                 bh_unlock_sock(child);
 632                 local_bh_enable();
 633                 sock_put(child);
 634
 635                 sk_acceptq_removed(sk);
 636                 __reqsk_free(req);
 637         }
 638         BUG_TRAP(!sk->sk_ack_backlog);
 639 }
 640
 641 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);