net/ipv4/tcp.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  *              Implementation of the Transmission Control Protocol(TCP).
   7  *
   8  * Version:     $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *              Corey Minyard <wf-rch!minyard@relay.EU.net>
  14  *              Florian La Roche, <flla@stud.uni-sb.de>
  15  *              Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
  16  *              Linus Torvalds, <torvalds@cs.helsinki.fi>
  17  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  18  *              Matthew Dillon, <dillon@apollo.west.oic.com>
  19  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  20  *              Jorge Cwik, <jorge@laser.satlink.net>
  21  *
  22  * Fixes:
  23  *              Alan Cox        :       Numerous verify_area() calls
  24  *              Alan Cox        :       Set the ACK bit on a reset
  25  *              Alan Cox        :       Stopped it crashing if it closed while
  26  *                                      sk->inuse=1 and was trying to connect
  27  *                                      (tcp_err()).
  28  *              Alan Cox        :       All icmp error handling was broken
  29  *                                      pointers passed where wrong and the
  30  *                                      socket was looked up backwards. Nobody
  31  *                                      tested any icmp error code obviously.
  32  *              Alan Cox        :       tcp_err() now handled properly. It
  33  *                                      wakes people on errors. poll
  34  *                                      behaves and the icmp error race
  35  *                                      has gone by moving it into sock.c
  36  *              Alan Cox        :       tcp_send_reset() fixed to work for
  37  *                                      everything not just packets for
  38  *                                      unknown sockets.
  39  *              Alan Cox        :       tcp option processing.
  40  *              Alan Cox        :       Reset tweaked (still not 100%) [Had
  41  *                                      syn rule wrong]
  42  *              Herp Rosmanith  :       More reset fixes
  43  *              Alan Cox        :       No longer acks invalid rst frames.
  44  *                                      Acking any kind of RST is right out.
  45  *              Alan Cox        :       Sets an ignore me flag on an rst
  46  *                                      receive otherwise odd bits of prattle
  47  *                                      escape still
  48  *              Alan Cox        :       Fixed another acking RST frame bug.
  49  *                                      Should stop LAN workplace lockups.
  50  *              Alan Cox        :       Some tidyups using the new skb list
  51  *                                      facilities
  52  *              Alan Cox        :       sk->keepopen now seems to work
  53  *              Alan Cox        :       Pulls options out correctly on accepts
  54  *              Alan Cox        :       Fixed assorted sk->rqueue->next errors
  55  *              Alan Cox        :       PSH doesn't end a TCP read. Switched a
  56  *                                      bit to skb ops.
  57  *              Alan Cox        :       Tidied tcp_data to avoid a potential
  58  *                                      nasty.
  59  *              Alan Cox        :       Added some better commenting, as the
  60  *                                      tcp is hard to follow
  61  *              Alan Cox        :       Removed incorrect check for 20 * psh
  62  *      Michael O'Reilly        :       ack < copied bug fix.
  63  *      Johannes Stille         :       Misc tcp fixes (not all in yet).
  64  *              Alan Cox        :       FIN with no memory -> CRASH
  65  *              Alan Cox        :       Added socket option proto entries.
  66  *                                      Also added awareness of them to accept.
  67  *              Alan Cox        :       Added TCP options (SOL_TCP)
  68  *              Alan Cox        :       Switched wakeup calls to callbacks,
  69  *                                      so the kernel can layer network
  70  *                                      sockets.
  71  *              Alan Cox        :       Use ip_tos/ip_ttl settings.
  72  *              Alan Cox        :       Handle FIN (more) properly (we hope).
  73  *              Alan Cox        :       RST frames sent on unsynchronised
  74  *                                      state ack error.
  75  *              Alan Cox        :       Put in missing check for SYN bit.
  76  *              Alan Cox        :       Added tcp_select_window() aka NET2E
  77  *                                      window non shrink trick.
  78  *              Alan Cox        :       Added a couple of small NET2E timer
  79  *                                      fixes
  80  *              Charles Hedrick :       TCP fixes
  81  *              Toomas Tamm     :       TCP window fixes
  82  *              Alan Cox        :       Small URG fix to rlogin ^C ack fight
  83  *              Charles Hedrick :       Rewrote most of it to actually work
  84  *              Linus           :       Rewrote tcp_read() and URG handling
  85  *                                      completely
  86  *              Gerhard Koerting:       Fixed some missing timer handling
  87  *              Matthew Dillon  :       Reworked TCP machine states as per RFC
  88  *              Gerhard Koerting:       PC/TCP workarounds
  89  *              Adam Caldwell   :       Assorted timer/timing errors
  90  *              Matthew Dillon  :       Fixed another RST bug
  91  *              Alan Cox        :       Move to kernel side addressing changes.
  92  *              Alan Cox        :       Beginning work on TCP fastpathing
  93  *                                      (not yet usable)
  94  *              Arnt Gulbrandsen:       Turbocharged tcp_check() routine.
  95  *              Alan Cox        :       TCP fast path debugging
  96  *              Alan Cox        :       Window clamping
  97  *              Michael Riepe   :       Bug in tcp_check()
  98  *              Matt Dillon     :       More TCP improvements and RST bug fixes
  99  *              Matt Dillon     :       Yet more small nasties remove from the
 100  *                                      TCP code (Be very nice to this man if
 101  *                                      tcp finally works 100%) 8)
 102  *              Alan Cox        :       BSD accept semantics.
 103  *              Alan Cox        :       Reset on closedown bug.
 104  *      Peter De Schrijver      :       ENOTCONN check missing in tcp_sendto().
 105  *              Michael Pall    :       Handle poll() after URG properly in
 106  *                                      all cases.
 107  *              Michael Pall    :       Undo the last fix in tcp_read_urg()
 108  *                                      (multi URG PUSH broke rlogin).
 109  *              Michael Pall    :       Fix the multi URG PUSH problem in
 110  *                                      tcp_readable(), poll() after URG
 111  *                                      works now.
 112  *              Michael Pall    :       recv(...,MSG_OOB) never blocks in the
 113  *                                      BSD api.
 114  *              Alan Cox        :       Changed the semantics of sk->socket to
 115  *                                      fix a race and a signal problem with
 116  *                                      accept() and async I/O.
 117  *              Alan Cox        :       Relaxed the rules on tcp_sendto().
 118  *              Yury Shevchuk   :       Really fixed accept() blocking problem.
 119  *              Craig I. Hagan  :       Allow for BSD compatible TIME_WAIT for
 120  *                                      clients/servers which listen in on
 121  *                                      fixed ports.
 122  *              Alan Cox        :       Cleaned the above up and shrank it to
 123  *                                      a sensible code size.
 124  *              Alan Cox        :       Self connect lockup fix.
 125  *              Alan Cox        :       No connect to multicast.
 126  *              Ross Biro       :       Close unaccepted children on master
 127  *                                      socket close.
 128  *              Alan Cox        :       Reset tracing code.
 129  *              Alan Cox        :       Spurious resets on shutdown.
 130  *              Alan Cox        :       Giant 15 minute/60 second timer error
 131  *              Alan Cox        :       Small whoops in polling before an
 132  *                                      accept.
 133  *              Alan Cox        :       Kept the state trace facility since
 134  *                                      it's handy for debugging.
 135  *              Alan Cox        :       More reset handler fixes.
 136  *              Alan Cox        :       Started rewriting the code based on
 137  *                                      the RFC's for other useful protocol
 138  *                                      references see: Comer, KA9Q NOS, and
 139  *                                      for a reference on the difference
 140  *                                      between specifications and how BSD
 141  *                                      works see the 4.4lite source.
 142  *              A.N.Kuznetsov   :       Don't time wait on completion of tidy
 143  *                                      close.
 144  *              Linus Torvalds  :       Fin/Shutdown & copied_seq changes.
 145  *              Linus Torvalds  :       Fixed BSD port reuse to work first syn
 146  *              Alan Cox        :       Reimplemented timers as per the RFC
 147  *                                      and using multiple timers for sanity.
 148  *              Alan Cox        :       Small bug fixes, and a lot of new
 149  *                                      comments.
 150  *              Alan Cox        :       Fixed dual reader crash by locking
 151  *                                      the buffers (much like datagram.c)
 152  *              Alan Cox        :       Fixed stuck sockets in probe. A probe
 153  *                                      now gets fed up of retrying without
 154  *                                      (even a no space) answer.
 155  *              Alan Cox        :       Extracted closing code better
 156  *              Alan Cox        :       Fixed the closing state machine to
 157  *                                      resemble the RFC.
 158  *              Alan Cox        :       More 'per spec' fixes.
 159  *              Jorge Cwik      :       Even faster checksumming.
 160  *              Alan Cox        :       tcp_data() doesn't ack illegal PSH
 161  *                                      only frames. At least one pc tcp stack
 162  *                                      generates them.
 163  *              Alan Cox        :       Cache last socket.
 164  *              Alan Cox        :       Per route irtt.
 165  *              Matt Day        :       poll()->select() match BSD precisely on error
 166  *              Alan Cox        :       New buffers
 167  *              Marc Tamsky     :       Various sk->prot->retransmits and
 168  *                                      sk->retransmits misupdating fixed.
 169  *                                      Fixed tcp_write_timeout: stuck close,
 170  *                                      and TCP syn retries gets used now.
 171  *              Mark Yarvis     :       In tcp_read_wakeup(), don't send an
 172  *                                      ack if state is TCP_CLOSED.
 173  *              Alan Cox        :       Look up device on a retransmit - routes may
 174  *                                      change. Doesn't yet cope with MSS shrink right
 175  *                                      but it's a start!
 176  *              Marc Tamsky     :       Closing in closing fixes.
 177  *              Mike Shaver     :       RFC1122 verifications.
 178  *              Alan Cox        :       rcv_saddr errors.
 179  *              Alan Cox        :       Block double connect().
 180  *              Alan Cox        :       Small hooks for enSKIP.
 181  *              Alexey Kuznetsov:       Path MTU discovery.
 182  *              Alan Cox        :       Support soft errors.
 183  *              Alan Cox        :       Fix MTU discovery pathological case
 184  *                                      when the remote claims no mtu!
 185  *              Marc Tamsky     :       TCP_CLOSE fix.
 186  *              Colin (G3TNE)   :       Send a reset on syn ack replies in
 187  *                                      window but wrong (fixes NT lpd problems)
 188  *              Pedro Roque     :       Better TCP window handling, delayed ack.
 189  *              Joerg Reuter    :       No modification of locked buffers in
 190  *                                      tcp_do_retransmit()
 191  *              Eric Schenk     :       Changed receiver side silly window
 192  *                                      avoidance algorithm to BSD style
 193  *                                      algorithm. This doubles throughput
 194  *                                      against machines running Solaris,
 195  *                                      and seems to result in general
 196  *                                      improvement.
 197  *      Stefan Magdalinski      :       adjusted tcp_readable() to fix FIONREAD
 198  *      Willy Konynenberg       :       Transparent proxying support.
 199  *      Mike McLagan            :       Routing by source
 200  *              Keith Owens     :       Do proper merging with partial SKB's in
 201  *                                      tcp_do_sendmsg to avoid burstiness.
 202  *              Eric Schenk     :       Fix fast close down bug with
 203  *                                      shutdown() followed by close().
 204  *              Andi Kleen      :       Make poll agree with SIGIO
 205  *      Salvatore Sanfilippo    :       Support SO_LINGER with linger == 1 and
 206  *                                      lingertime == 0 (RFC 793 ABORT Call)
 207  *      Hirokazu Takahashi      :       Use copy_from_user() instead of
 208  *                                      csum_and_copy_from_user() if possible.
 209  *
 210  *              This program is free software; you can redistribute it and/or
 211  *              modify it under the terms of the GNU General Public License
 212  *              as published by the Free Software Foundation; either version
 213  *              2 of the License, or(at your option) any later version.
 214  *
 215  * Description of States:
 216  *
 217  *      TCP_SYN_SENT            sent a connection request, waiting for ack
 218  *
 219  *      TCP_SYN_RECV            received a connection request, sent ack,
 220  *                              waiting for final ack in three-way handshake.
 221  *
 222  *      TCP_ESTABLISHED         connection established
 223  *
 224  *      TCP_FIN_WAIT1           our side has shutdown, waiting to complete
 225  *                              transmission of remaining buffered data
 226  *
 227  *      TCP_FIN_WAIT2           all buffered data sent, waiting for remote
 228  *                              to shutdown
 229  *
 230  *      TCP_CLOSING             both sides have shutdown but we still have
 231  *                              data we have to finish sending
 232  *
 233  *      TCP_TIME_WAIT           timeout to catch resent junk before entering
 234  *                              closed, can only be entered from FIN_WAIT2
 235  *                              or CLOSING.  Required because the other end
 236  *                              may not have gotten our last ACK causing it
 237  *                              to retransmit the data packet (which we ignore)
 238  *
 239  *      TCP_CLOSE_WAIT          remote side has shutdown and is waiting for
 240  *                              us to finish writing our data and to shutdown
 241  *                              (we have to close() to move on to LAST_ACK)
 242  *
 243  *      TCP_LAST_ACK            out side has shutdown after remote has
 244  *                              shutdown.  There may still be data in our
 245  *                              buffer that we have to finish sending
 246  *
 247  *      TCP_CLOSE               socket is finished
 248  */
 249
 250 #include <linux/module.h>
 251 #include <linux/types.h>
 252 #include <linux/fcntl.h>
 253 #include <linux/poll.h>
 254 #include <linux/init.h>
 255 #include <linux/smp_lock.h>
 256 #include <linux/fs.h>
 257 #include <linux/random.h>
 258 #include <linux/bootmem.h>
 259 #include <linux/cache.h>
 260 #include <linux/err.h>
 261
 262 #include <net/icmp.h>
 263 #include <net/tcp.h>
 264 #include <net/xfrm.h>
 265 #include <net/ip.h>
 266 #include <net/netdma.h>
 267
 268 #include <asm/uaccess.h>
 269 #include <asm/ioctls.h>
 270
 271 int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
 272
 273 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
 274
 275 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
 276
 277 EXPORT_SYMBOL_GPL(tcp_orphan_count);
 278
 279 int sysctl_tcp_mem[3] __read_mostly;
 280 int sysctl_tcp_wmem[3] __read_mostly;
 281 int sysctl_tcp_rmem[3] __read_mostly;
 282
 283 EXPORT_SYMBOL(sysctl_tcp_mem);
 284 EXPORT_SYMBOL(sysctl_tcp_rmem);
 285 EXPORT_SYMBOL(sysctl_tcp_wmem);
 286
 287 atomic_t tcp_memory_allocated;  /* Current allocated memory. */
 288 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
 289
 290 EXPORT_SYMBOL(tcp_memory_allocated);
 291 EXPORT_SYMBOL(tcp_sockets_allocated);
 292
 293 /*
 294  * Pressure flag: try to collapse.
 295  * Technical note: it is used by multiple contexts non atomically.
 296  * All the sk_stream_mem_schedule() is of this nature: accounting
 297  * is strict, actions are advisory and have some latency.
 298  */
 299 int tcp_memory_pressure;
 300
 301 EXPORT_SYMBOL(tcp_memory_pressure);
 302
 303 void tcp_enter_memory_pressure(void)
 304 {
 305         if (!tcp_memory_pressure) {
 306                 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
 307                 tcp_memory_pressure = 1;
 308         }
 309 }
 310
 311 EXPORT_SYMBOL(tcp_enter_memory_pressure);
 312
 313 /*
 314  *      Wait for a TCP event.
 315  *
 316  *      Note that we don't need to lock the socket, as the upper poll layers
 317  *      take care of normal races (between the test and the event) and we don't
 318  *      go look at any of the socket buffers directly.
 319  */
 320 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 321 {
 322         unsigned int mask;
 323         struct sock *sk = sock->sk;
 324         struct tcp_sock *tp = tcp_sk(sk);
 325
 326         poll_wait(file, sk->sk_sleep, wait);
 327         if (sk->sk_state == TCP_LISTEN)
 328                 return inet_csk_listen_poll(sk);
 329
 330         /* Socket is not locked. We are protected from async events
 331            by poll logic and correct handling of state changes
 332            made by another threads is impossible in any case.
 333          */
 334
 335         mask = 0;
 336         if (sk->sk_err)
 337                 mask = POLLERR;
 338
 339         /*
 340          * POLLHUP is certainly not done right. But poll() doesn't
 341          * have a notion of HUP in just one direction, and for a
 342          * socket the read side is more interesting.
 343          *
 344          * Some poll() documentation says that POLLHUP is incompatible
 345          * with the POLLOUT/POLLWR flags, so somebody should check this
 346          * all. But careful, it tends to be safer to return too many
 347          * bits than too few, and you can easily break real applications
 348          * if you don't tell them that something has hung up!
 349          *
 350          * Check-me.
 351          *
 352          * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
 353          * our fs/select.c). It means that after we received EOF,
 354          * poll always returns immediately, making impossible poll() on write()
 355          * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
 356          * if and only if shutdown has been made in both directions.
 357          * Actually, it is interesting to look how Solaris and DUX
 358          * solve this dilemma. I would prefer, if PULLHUP were maskable,
 359          * then we could set it on SND_SHUTDOWN. BTW examples given
 360          * in Stevens' books assume exactly this behaviour, it explains
 361          * why PULLHUP is incompatible with POLLOUT.    --ANK
 362          *
 363          * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
 364          * blocking on fresh not-connected or disconnected socket. --ANK
 365          */
 366         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
 367                 mask |= POLLHUP;
 368         if (sk->sk_shutdown & RCV_SHUTDOWN)
 369                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 370
 371         /* Connected? */
 372         if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
 373                 /* Potential race condition. If read of tp below will
 374                  * escape above sk->sk_state, we can be illegally awaken
 375                  * in SYN_* states. */
 376                 if ((tp->rcv_nxt != tp->copied_seq) &&
 377                     (tp->urg_seq != tp->copied_seq ||
 378                      tp->rcv_nxt != tp->copied_seq + 1 ||
 379                      sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
 380                         mask |= POLLIN | POLLRDNORM;
 381
 382                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 383                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 384                                 mask |= POLLOUT | POLLWRNORM;
 385                         } else {  /* send SIGIO later */
 386                                 set_bit(SOCK_ASYNC_NOSPACE,
 387                                         &sk->sk_socket->flags);
 388                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 389
 390                                 /* Race breaker. If space is freed after
 391                                  * wspace test but before the flags are set,
 392                                  * IO signal will be lost.
 393                                  */
 394                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 395                                         mask |= POLLOUT | POLLWRNORM;
 396                         }
 397                 }
 398
 399                 if (tp->urg_data & TCP_URG_VALID)
 400                         mask |= POLLPRI;
 401         }
 402         return mask;
 403 }
 404
 405 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 406 {
 407         struct tcp_sock *tp = tcp_sk(sk);
 408         int answ;
 409
 410         switch (cmd) {
 411         case SIOCINQ:
 412                 if (sk->sk_state == TCP_LISTEN)
 413                         return -EINVAL;
 414
 415                 lock_sock(sk);
 416                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 417                         answ = 0;
 418                 else if (sock_flag(sk, SOCK_URGINLINE) ||
 419                          !tp->urg_data ||
 420                          before(tp->urg_seq, tp->copied_seq) ||
 421                          !before(tp->urg_seq, tp->rcv_nxt)) {
 422                         answ = tp->rcv_nxt - tp->copied_seq;
 423
 424                         /* Subtract 1, if FIN is in queue. */
 425                         if (answ && !skb_queue_empty(&sk->sk_receive_queue))
 426                                 answ -=
 427                        ((struct sk_buff *)sk->sk_receive_queue.prev)->h.th->fin;
 428                 } else
 429                         answ = tp->urg_seq - tp->copied_seq;
 430                 release_sock(sk);
 431                 break;
 432         case SIOCATMARK:
 433                 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
 434                 break;
 435         case SIOCOUTQ:
 436                 if (sk->sk_state == TCP_LISTEN)
 437                         return -EINVAL;
 438
 439                 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
 440                         answ = 0;
 441                 else
 442                         answ = tp->write_seq - tp->snd_una;
 443                 break;
 444         default:
 445                 return -ENOIOCTLCMD;
 446         };
 447
 448         return put_user(answ, (int __user *)arg);
 449 }
 450
 451 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 452 {
 453         TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
 454         tp->pushed_seq = tp->write_seq;
 455 }
 456
 457 static inline int forced_push(struct tcp_sock *tp)
 458 {
 459         return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 460 }
 461
 462 static inline void skb_entail(struct sock *sk, struct tcp_sock *tp,
 463                               struct sk_buff *skb)
 464 {
 465         skb->csum = 0;
 466         TCP_SKB_CB(skb)->seq = tp->write_seq;
 467         TCP_SKB_CB(skb)->end_seq = tp->write_seq;
 468         TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
 469         TCP_SKB_CB(skb)->sacked = 0;
 470         skb_header_release(skb);
 471         __skb_queue_tail(&sk->sk_write_queue, skb);
 472         sk_charge_skb(sk, skb);
 473         if (!sk->sk_send_head)
 474                 sk->sk_send_head = skb;
 475         if (tp->nonagle & TCP_NAGLE_PUSH)
 476                 tp->nonagle &= ~TCP_NAGLE_PUSH;
 477 }
 478
 479 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
 480                                 struct sk_buff *skb)
 481 {
 482         if (flags & MSG_OOB) {
 483                 tp->urg_mode = 1;
 484                 tp->snd_up = tp->write_seq;
 485                 TCP_SKB_CB(skb)->sacked |= TCPCB_URG;
 486         }
 487 }
 488
 489 static inline void tcp_push(struct sock *sk, struct tcp_sock *tp, int flags,
 490                             int mss_now, int nonagle)
 491 {
 492         if (sk->sk_send_head) {
 493                 struct sk_buff *skb = sk->sk_write_queue.prev;
 494                 if (!(flags & MSG_MORE) || forced_push(tp))
 495                         tcp_mark_push(tp, skb);
 496                 tcp_mark_urg(tp, flags, skb);
 497                 __tcp_push_pending_frames(sk, tp, mss_now,
 498                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 499         }
 500 }
 501
 502 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 503                          size_t psize, int flags)
 504 {
 505         struct tcp_sock *tp = tcp_sk(sk);
 506         int mss_now, size_goal;
 507         int err;
 508         ssize_t copied;
 509         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 510
 511         /* Wait for a connection to finish. */
 512         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 513                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 514                         goto out_err;
 515
 516         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 517
 518         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 519         size_goal = tp->xmit_size_goal;
 520         copied = 0;
 521
 522         err = -EPIPE;
 523         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 524                 goto do_error;
 525
 526         while (psize > 0) {
 527                 struct sk_buff *skb = sk->sk_write_queue.prev;
 528                 struct page *page = pages[poffset / PAGE_SIZE];
 529                 int copy, i, can_coalesce;
 530                 int offset = poffset % PAGE_SIZE;
 531                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
 532
 533                 if (!sk->sk_send_head || (copy = size_goal - skb->len) <= 0) {
 534 new_segment:
 535                         if (!sk_stream_memory_free(sk))
 536                                 goto wait_for_sndbuf;
 537
 538                         skb = sk_stream_alloc_pskb(sk, 0, 0,
 539                                                    sk->sk_allocation);
 540                         if (!skb)
 541                                 goto wait_for_memory;
 542
 543                         skb_entail(sk, tp, skb);
 544                         copy = size_goal;
 545                 }
 546
 547                 if (copy > size)
 548                         copy = size;
 549
 550                 i = skb_shinfo(skb)->nr_frags;
 551                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
 552                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 553                         tcp_mark_push(tp, skb);
 554                         goto new_segment;
 555                 }
 556                 if (!sk_stream_wmem_schedule(sk, copy))
 557                         goto wait_for_memory;
 558
 559                 if (can_coalesce) {
 560                         skb_shinfo(skb)->frags[i - 1].size += copy;
 561                 } else {
 562                         get_page(page);
 563                         skb_fill_page_desc(skb, i, page, offset, copy);
 564                 }
 565
 566                 skb->len += copy;
 567                 skb->data_len += copy;
 568                 skb->truesize += copy;
 569                 sk->sk_wmem_queued += copy;
 570                 sk->sk_forward_alloc -= copy;
 571                 skb->ip_summed = CHECKSUM_HW;
 572                 tp->write_seq += copy;
 573                 TCP_SKB_CB(skb)->end_seq += copy;
 574                 skb_shinfo(skb)->gso_segs = 0;
 575
 576                 if (!copied)
 577                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 578
 579                 copied += copy;
 580                 poffset += copy;
 581                 if (!(psize -= copy))
 582                         goto out;
 583
 584                 if (skb->len < mss_now || (flags & MSG_OOB))
 585                         continue;
 586
 587                 if (forced_push(tp)) {
 588                         tcp_mark_push(tp, skb);
 589                         __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
 590                 } else if (skb == sk->sk_send_head)
 591                         tcp_push_one(sk, mss_now);
 592                 continue;
 593
 594 wait_for_sndbuf:
 595                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 596 wait_for_memory:
 597                 if (copied)
 598                         tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 599
 600                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 601                         goto do_error;
 602
 603                 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 604                 size_goal = tp->xmit_size_goal;
 605         }
 606
 607 out:
 608         if (copied)
 609                 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
 610         return copied;
 611
 612 do_error:
 613         if (copied)
 614                 goto out;
 615 out_err:
 616         return sk_stream_error(sk, flags, err);
 617 }
 618
 619 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 620                      size_t size, int flags)
 621 {
 622         ssize_t res;
 623         struct sock *sk = sock->sk;
 624
 625         if (!(sk->sk_route_caps & NETIF_F_SG) ||
 626             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 627                 return sock_no_sendpage(sock, page, offset, size, flags);
 628
 629         lock_sock(sk);
 630         TCP_CHECK_TIMER(sk);
 631         res = do_tcp_sendpages(sk, &page, offset, size, flags);
 632         TCP_CHECK_TIMER(sk);
 633         release_sock(sk);
 634         return res;
 635 }
 636
 637 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 638 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 639
 640 static inline int select_size(struct sock *sk, struct tcp_sock *tp)
 641 {
 642         int tmp = tp->mss_cache;
 643
 644         if (sk->sk_route_caps & NETIF_F_SG) {
 645                 if (sk_can_gso(sk))
 646                         tmp = 0;
 647                 else {
 648                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 649
 650                         if (tmp >= pgbreak &&
 651                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 652                                 tmp = pgbreak;
 653                 }
 654         }
 655
 656         return tmp;
 657 }
 658
 659 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 660                 size_t size)
 661 {
 662         struct iovec *iov;
 663         struct tcp_sock *tp = tcp_sk(sk);
 664         struct sk_buff *skb;
 665         int iovlen, flags;
 666         int mss_now, size_goal;
 667         int err, copied;
 668         long timeo;
 669
 670         lock_sock(sk);
 671         TCP_CHECK_TIMER(sk);
 672
 673         flags = msg->msg_flags;
 674         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 675
 676         /* Wait for a connection to finish. */
 677         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 678                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 679                         goto out_err;
 680
 681         /* This should be in poll */
 682         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 683
 684         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 685         size_goal = tp->xmit_size_goal;
 686
 687         /* Ok commence sending. */
 688         iovlen = msg->msg_iovlen;
 689         iov = msg->msg_iov;
 690         copied = 0;
 691
 692         err = -EPIPE;
 693         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 694                 goto do_error;
 695
 696         while (--iovlen >= 0) {
 697                 int seglen = iov->iov_len;
 698                 unsigned char __user *from = iov->iov_base;
 699
 700                 iov++;
 701
 702                 while (seglen > 0) {
 703                         int copy;
 704
 705                         skb = sk->sk_write_queue.prev;
 706
 707                         if (!sk->sk_send_head ||
 708                             (copy = size_goal - skb->len) <= 0) {
 709
 710 new_segment:
 711                                 /* Allocate new segment. If the interface is SG,
 712                                  * allocate skb fitting to single page.
 713                                  */
 714                                 if (!sk_stream_memory_free(sk))
 715                                         goto wait_for_sndbuf;
 716
 717                                 skb = sk_stream_alloc_pskb(sk, select_size(sk, tp),
 718                                                            0, sk->sk_allocation);
 719                                 if (!skb)
 720                                         goto wait_for_memory;
 721
 722                                 /*
 723                                  * Check whether we can use HW checksum.
 724                                  */
 725                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 726                                         skb->ip_summed = CHECKSUM_HW;
 727
 728                                 skb_entail(sk, tp, skb);
 729                                 copy = size_goal;
 730                         }
 731
 732                         /* Try to append data to the end of skb. */
 733                         if (copy > seglen)
 734                                 copy = seglen;
 735
 736                         /* Where to copy to? */
 737                         if (skb_tailroom(skb) > 0) {
 738                                 /* We have some space in skb head. Superb! */
 739                                 if (copy > skb_tailroom(skb))
 740                                         copy = skb_tailroom(skb);
 741                                 if ((err = skb_add_data(skb, from, copy)) != 0)
 742                                         goto do_fault;
 743                         } else {
 744                                 int merge = 0;
 745                                 int i = skb_shinfo(skb)->nr_frags;
 746                                 struct page *page = TCP_PAGE(sk);
 747                                 int off = TCP_OFF(sk);
 748
 749                                 if (skb_can_coalesce(skb, i, page, off) &&
 750                                     off != PAGE_SIZE) {
 751                                         /* We can extend the last page
 752                                          * fragment. */
 753                                         merge = 1;
 754                                 } else if (i == MAX_SKB_FRAGS ||
 755                                            (!i &&
 756                                            !(sk->sk_route_caps & NETIF_F_SG))) {
 757                                         /* Need to add new fragment and cannot
 758                                          * do this because interface is non-SG,
 759                                          * or because all the page slots are
 760                                          * busy. */
 761                                         tcp_mark_push(tp, skb);
 762                                         goto new_segment;
 763                                 } else if (page) {
 764                                         if (off == PAGE_SIZE) {
 765                                                 put_page(page);
 766                                                 TCP_PAGE(sk) = page = NULL;
 767                                                 off = 0;
 768                                         }
 769                                 } else
 770                                         off = 0;
 771
 772                                 if (copy > PAGE_SIZE - off)
 773                                         copy = PAGE_SIZE - off;
 774
 775                                 if (!sk_stream_wmem_schedule(sk, copy))
 776                                         goto wait_for_memory;
 777
 778                                 if (!page) {
 779                                         /* Allocate new cache page. */
 780                                         if (!(page = sk_stream_alloc_page(sk)))
 781                                                 goto wait_for_memory;
 782                                 }
 783
 784                                 /* Time to copy data. We are close to
 785                                  * the end! */
 786                                 err = skb_copy_to_page(sk, from, skb, page,
 787                                                        off, copy);
 788                                 if (err) {
 789                                         /* If this page was new, give it to the
 790                                          * socket so it does not get leaked.
 791                                          */
 792                                         if (!TCP_PAGE(sk)) {
 793                                                 TCP_PAGE(sk) = page;
 794                                                 TCP_OFF(sk) = 0;
 795                                         }
 796                                         goto do_error;
 797                                 }
 798
 799                                 /* Update the skb. */
 800                                 if (merge) {
 801                                         skb_shinfo(skb)->frags[i - 1].size +=
 802                                                                         copy;
 803                                 } else {
 804                                         skb_fill_page_desc(skb, i, page, off, copy);
 805                                         if (TCP_PAGE(sk)) {
 806                                                 get_page(page);
 807                                         } else if (off + copy < PAGE_SIZE) {
 808                                                 get_page(page);
 809                                                 TCP_PAGE(sk) = page;
 810                                         }
 811                                 }
 812
 813                                 TCP_OFF(sk) = off + copy;
 814                         }
 815
 816                         if (!copied)
 817                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 818
 819                         tp->write_seq += copy;
 820                         TCP_SKB_CB(skb)->end_seq += copy;
 821                         skb_shinfo(skb)->gso_segs = 0;
 822
 823                         from += copy;
 824                         copied += copy;
 825                         if ((seglen -= copy) == 0 && iovlen == 0)
 826                                 goto out;
 827
 828                         if (skb->len < mss_now || (flags & MSG_OOB))
 829                                 continue;
 830
 831                         if (forced_push(tp)) {
 832                                 tcp_mark_push(tp, skb);
 833                                 __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
 834                         } else if (skb == sk->sk_send_head)
 835                                 tcp_push_one(sk, mss_now);
 836                         continue;
 837
 838 wait_for_sndbuf:
 839                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 840 wait_for_memory:
 841                         if (copied)
 842                                 tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 843
 844                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 845                                 goto do_error;
 846
 847                         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 848                         size_goal = tp->xmit_size_goal;
 849                 }
 850         }
 851
 852 out:
 853         if (copied)
 854                 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
 855         TCP_CHECK_TIMER(sk);
 856         release_sock(sk);
 857         return copied;
 858
 859 do_fault:
 860         if (!skb->len) {
 861                 if (sk->sk_send_head == skb)
 862                         sk->sk_send_head = NULL;
 863                 __skb_unlink(skb, &sk->sk_write_queue);
 864                 sk_stream_free_skb(sk, skb);
 865         }
 866
 867 do_error:
 868         if (copied)
 869                 goto out;
 870 out_err:
 871         err = sk_stream_error(sk, flags, err);
 872         TCP_CHECK_TIMER(sk);
 873         release_sock(sk);
 874         return err;
 875 }
 876
 877 /*
 878  *      Handle reading urgent data. BSD has very simple semantics for
 879  *      this, no blocking and very strange errors 8)
 880  */
 881
 882 static int tcp_recv_urg(struct sock *sk, long timeo,
 883                         struct msghdr *msg, int len, int flags,
 884                         int *addr_len)
 885 {
 886         struct tcp_sock *tp = tcp_sk(sk);
 887
 888         /* No URG data to read. */
 889         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
 890             tp->urg_data == TCP_URG_READ)
 891                 return -EINVAL; /* Yes this is right ! */
 892
 893         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
 894                 return -ENOTCONN;
 895
 896         if (tp->urg_data & TCP_URG_VALID) {
 897                 int err = 0;
 898                 char c = tp->urg_data;
 899
 900                 if (!(flags & MSG_PEEK))
 901                         tp->urg_data = TCP_URG_READ;
 902
 903                 /* Read urgent data. */
 904                 msg->msg_flags |= MSG_OOB;
 905
 906                 if (len > 0) {
 907                         if (!(flags & MSG_TRUNC))
 908                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
 909                         len = 1;
 910                 } else
 911                         msg->msg_flags |= MSG_TRUNC;
 912
 913                 return err ? -EFAULT : len;
 914         }
 915
 916         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
 917                 return 0;
 918
 919         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
 920          * the available implementations agree in this case:
 921          * this call should never block, independent of the
 922          * blocking state of the socket.
 923          * Mike <pall@rz.uni-karlsruhe.de>
 924          */
 925         return -EAGAIN;
 926 }
 927
 928 /* Clean up the receive buffer for full frames taken by the user,
 929  * then send an ACK if necessary.  COPIED is the number of bytes
 930  * tcp_recvmsg has given to the user so far, it speeds up the
 931  * calculation of whether or not we must ACK for the sake of
 932  * a window update.
 933  */
 934 void tcp_cleanup_rbuf(struct sock *sk, int copied)
 935 {
 936         struct tcp_sock *tp = tcp_sk(sk);
 937         int time_to_ack = 0;
 938
 939 #if TCP_DEBUG
 940         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 941
 942         BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
 943 #endif
 944
 945         if (inet_csk_ack_scheduled(sk)) {
 946                 const struct inet_connection_sock *icsk = inet_csk(sk);
 947                    /* Delayed ACKs frequently hit locked sockets during bulk
 948                     * receive. */
 949                 if (icsk->icsk_ack.blocked ||
 950                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
 951                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
 952                     /*
 953                      * If this read emptied read buffer, we send ACK, if
 954                      * connection is not bidirectional, user drained
 955                      * receive buffer and there was a small segment
 956                      * in queue.
 957                      */
 958                     (copied > 0 && (icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
 959                      !icsk->icsk_ack.pingpong && !atomic_read(&sk->sk_rmem_alloc)))
 960                         time_to_ack = 1;
 961         }
 962
 963         /* We send an ACK if we can now advertise a non-zero window
 964          * which has been raised "significantly".
 965          *
 966          * Even if window raised up to infinity, do not send window open ACK
 967          * in states, where we will not receive more. It is useless.
 968          */
 969         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
 970                 __u32 rcv_window_now = tcp_receive_window(tp);
 971
 972                 /* Optimize, __tcp_select_window() is not cheap. */
 973                 if (2*rcv_window_now <= tp->window_clamp) {
 974                         __u32 new_window = __tcp_select_window(sk);
 975
 976                         /* Send ACK now, if this read freed lots of space
 977                          * in our buffer. Certainly, new_window is new window.
 978                          * We can advertise it now, if it is not less than current one.
 979                          * "Lots" means "at least twice" here.
 980                          */
 981                         if (new_window && new_window >= 2 * rcv_window_now)
 982                                 time_to_ack = 1;
 983                 }
 984         }
 985         if (time_to_ack)
 986                 tcp_send_ack(sk);
 987 }
 988
 989 static void tcp_prequeue_process(struct sock *sk)
 990 {
 991         struct sk_buff *skb;
 992         struct tcp_sock *tp = tcp_sk(sk);
 993
 994         NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
 995
 996         /* RX process wants to run with disabled BHs, though it is not
 997          * necessary */
 998         local_bh_disable();
 999         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1000                 sk->sk_backlog_rcv(sk, skb);
1001         local_bh_enable();
1002
1003         /* Clear memory counter. */
1004         tp->ucopy.memory = 0;
1005 }
1006
1007 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1008 {
1009         struct sk_buff *skb;
1010         u32 offset;
1011
1012         skb_queue_walk(&sk->sk_receive_queue, skb) {
1013                 offset = seq - TCP_SKB_CB(skb)->seq;
1014                 if (skb->h.th->syn)
1015                         offset--;
1016                 if (offset < skb->len || skb->h.th->fin) {
1017                         *off = offset;
1018                         return skb;
1019                 }
1020         }
1021         return NULL;
1022 }
1023
1024 /*
1025  * This routine provides an alternative to tcp_recvmsg() for routines
1026  * that would like to handle copying from skbuffs directly in 'sendfile'
1027  * fashion.
1028  * Note:
1029  *      - It is assumed that the socket was locked by the caller.
1030  *      - The routine does not block.
1031  *      - At present, there is no support for reading OOB data
1032  *        or for 'peeking' the socket using this routine
1033  *        (although both would be easy to implement).
1034  */
1035 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1036                   sk_read_actor_t recv_actor)
1037 {
1038         struct sk_buff *skb;
1039         struct tcp_sock *tp = tcp_sk(sk);
1040         u32 seq = tp->copied_seq;
1041         u32 offset;
1042         int copied = 0;
1043
1044         if (sk->sk_state == TCP_LISTEN)
1045                 return -ENOTCONN;
1046         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1047                 if (offset < skb->len) {
1048                         size_t used, len;
1049
1050                         len = skb->len - offset;
1051                         /* Stop reading if we hit a patch of urgent data */
1052                         if (tp->urg_data) {
1053                                 u32 urg_offset = tp->urg_seq - seq;
1054                                 if (urg_offset < len)
1055                                         len = urg_offset;
1056                                 if (!len)
1057                                         break;
1058                         }
1059                         used = recv_actor(desc, skb, offset, len);
1060                         if (used <= len) {
1061                                 seq += used;
1062                                 copied += used;
1063                                 offset += used;
1064                         }
1065                         if (offset != skb->len)
1066                                 break;
1067                 }
1068                 if (skb->h.th->fin) {
1069                         sk_eat_skb(sk, skb, 0);
1070                         ++seq;
1071                         break;
1072                 }
1073                 sk_eat_skb(sk, skb, 0);
1074                 if (!desc->count)
1075                         break;
1076         }
1077         tp->copied_seq = seq;
1078
1079         tcp_rcv_space_adjust(sk);
1080
1081         /* Clean up data we have read: This will do ACK frames. */
1082         if (copied)
1083                 tcp_cleanup_rbuf(sk, copied);
1084         return copied;
1085 }
1086
1087 /*
1088  *      This routine copies from a sock struct into the user buffer.
1089  *
1090  *      Technical note: in 2.3 we work on _locked_ socket, so that
1091  *      tricks with *seq access order and skb->users are not required.
1092  *      Probably, code can be easily improved even more.
1093  */
1094
1095 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1096                 size_t len, int nonblock, int flags, int *addr_len)
1097 {
1098         struct tcp_sock *tp = tcp_sk(sk);
1099         int copied = 0;
1100         u32 peek_seq;
1101         u32 *seq;
1102         unsigned long used;
1103         int err;
1104         int target;             /* Read at least this many bytes */
1105         long timeo;
1106         struct task_struct *user_recv = NULL;
1107         int copied_early = 0;
1108
1109         lock_sock(sk);
1110
1111         TCP_CHECK_TIMER(sk);
1112
1113         err = -ENOTCONN;
1114         if (sk->sk_state == TCP_LISTEN)
1115                 goto out;
1116
1117         timeo = sock_rcvtimeo(sk, nonblock);
1118
1119         /* Urgent data needs to be handled specially. */
1120         if (flags & MSG_OOB)
1121                 goto recv_urg;
1122
1123         seq = &tp->copied_seq;
1124         if (flags & MSG_PEEK) {
1125                 peek_seq = tp->copied_seq;
1126                 seq = &peek_seq;
1127         }
1128
1129         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1130
1131 #ifdef CONFIG_NET_DMA
1132         tp->ucopy.dma_chan = NULL;
1133         preempt_disable();
1134         if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1135             !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) {
1136                 preempt_enable_no_resched();
1137                 tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len);
1138         } else
1139                 preempt_enable_no_resched();
1140 #endif
1141
1142         do {
1143                 struct sk_buff *skb;
1144                 u32 offset;
1145
1146                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1147                 if (tp->urg_data && tp->urg_seq == *seq) {
1148                         if (copied)
1149                                 break;
1150                         if (signal_pending(current)) {
1151                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1152                                 break;
1153                         }
1154                 }
1155
1156                 /* Next get a buffer. */
1157
1158                 skb = skb_peek(&sk->sk_receive_queue);
1159                 do {
1160                         if (!skb)
1161                                 break;
1162
1163                         /* Now that we have two receive queues this
1164                          * shouldn't happen.
1165                          */
1166                         if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1167                                 printk(KERN_INFO "recvmsg bug: copied %X "
1168                                        "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1169                                 break;
1170                         }
1171                         offset = *seq - TCP_SKB_CB(skb)->seq;
1172                         if (skb->h.th->syn)
1173                                 offset--;
1174                         if (offset < skb->len)
1175                                 goto found_ok_skb;
1176                         if (skb->h.th->fin)
1177                                 goto found_fin_ok;
1178                         BUG_TRAP(flags & MSG_PEEK);
1179                         skb = skb->next;
1180                 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1181
1182                 /* Well, if we have backlog, try to process it now yet. */
1183
1184                 if (copied >= target && !sk->sk_backlog.tail)
1185                         break;
1186
1187                 if (copied) {
1188                         if (sk->sk_err ||
1189                             sk->sk_state == TCP_CLOSE ||
1190                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1191                             !timeo ||
1192                             signal_pending(current) ||
1193                             (flags & MSG_PEEK))
1194                                 break;
1195                 } else {
1196                         if (sock_flag(sk, SOCK_DONE))
1197                                 break;
1198
1199                         if (sk->sk_err) {
1200                                 copied = sock_error(sk);
1201                                 break;
1202                         }
1203
1204                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1205                                 break;
1206
1207                         if (sk->sk_state == TCP_CLOSE) {
1208                                 if (!sock_flag(sk, SOCK_DONE)) {
1209                                         /* This occurs when user tries to read
1210                                          * from never connected socket.
1211                                          */
1212                                         copied = -ENOTCONN;
1213                                         break;
1214                                 }
1215                                 break;
1216                         }
1217
1218                         if (!timeo) {
1219                                 copied = -EAGAIN;
1220                                 break;
1221                         }
1222
1223                         if (signal_pending(current)) {
1224                                 copied = sock_intr_errno(timeo);
1225                                 break;
1226                         }
1227                 }
1228
1229                 tcp_cleanup_rbuf(sk, copied);
1230
1231                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1232                         /* Install new reader */
1233                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1234                                 user_recv = current;
1235                                 tp->ucopy.task = user_recv;
1236                                 tp->ucopy.iov = msg->msg_iov;
1237                         }
1238
1239                         tp->ucopy.len = len;
1240
1241                         BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1242                                  (flags & (MSG_PEEK | MSG_TRUNC)));
1243
1244                         /* Ugly... If prequeue is not empty, we have to
1245                          * process it before releasing socket, otherwise
1246                          * order will be broken at second iteration.
1247                          * More elegant solution is required!!!
1248                          *
1249                          * Look: we have the following (pseudo)queues:
1250                          *
1251                          * 1. packets in flight
1252                          * 2. backlog
1253                          * 3. prequeue
1254                          * 4. receive_queue
1255                          *
1256                          * Each queue can be processed only if the next ones
1257                          * are empty. At this point we have empty receive_queue.
1258                          * But prequeue _can_ be not empty after 2nd iteration,
1259                          * when we jumped to start of loop because backlog
1260                          * processing added something to receive_queue.
1261                          * We cannot release_sock(), because backlog contains
1262                          * packets arrived _after_ prequeued ones.
1263                          *
1264                          * Shortly, algorithm is clear --- to process all
1265                          * the queues in order. We could make it more directly,
1266                          * requeueing packets from backlog to prequeue, if
1267                          * is not empty. It is more elegant, but eats cycles,
1268                          * unfortunately.
1269                          */
1270                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1271                                 goto do_prequeue;
1272
1273                         /* __ Set realtime policy in scheduler __ */
1274                 }
1275
1276                 if (copied >= target) {
1277                         /* Do not sleep, just process backlog. */
1278                         release_sock(sk);
1279                         lock_sock(sk);
1280                 } else
1281                         sk_wait_data(sk, &timeo);
1282
1283 #ifdef CONFIG_NET_DMA
1284                 tp->ucopy.wakeup = 0;
1285 #endif
1286
1287                 if (user_recv) {
1288                         int chunk;
1289
1290                         /* __ Restore normal policy in scheduler __ */
1291
1292                         if ((chunk = len - tp->ucopy.len) != 0) {
1293                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1294                                 len -= chunk;
1295                                 copied += chunk;
1296                         }
1297
1298                         if (tp->rcv_nxt == tp->copied_seq &&
1299                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1300 do_prequeue:
1301                                 tcp_prequeue_process(sk);
1302
1303                                 if ((chunk = len - tp->ucopy.len) != 0) {
1304                                         NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1305                                         len -= chunk;
1306                                         copied += chunk;
1307                                 }
1308                         }
1309                 }
1310                 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1311                         if (net_ratelimit())
1312                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1313                                        current->comm, current->pid);
1314                         peek_seq = tp->copied_seq;
1315                 }
1316                 continue;
1317
1318         found_ok_skb:
1319                 /* Ok so how much can we use? */
1320                 used = skb->len - offset;
1321                 if (len < used)
1322                         used = len;
1323
1324                 /* Do we have urgent data here? */
1325                 if (tp->urg_data) {
1326                         u32 urg_offset = tp->urg_seq - *seq;
1327                         if (urg_offset < used) {
1328                                 if (!urg_offset) {
1329                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1330                                                 ++*seq;
1331                                                 offset++;
1332                                                 used--;
1333                                                 if (!used)
1334                                                         goto skip_copy;
1335                                         }
1336                                 } else
1337                                         used = urg_offset;
1338                         }
1339                 }
1340
1341                 if (!(flags & MSG_TRUNC)) {
1342 #ifdef CONFIG_NET_DMA
1343                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1344                                 tp->ucopy.dma_chan = get_softnet_dma();
1345
1346                         if (tp->ucopy.dma_chan) {
1347                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1348                                         tp->ucopy.dma_chan, skb, offset,
1349                                         msg->msg_iov, used,
1350                                         tp->ucopy.pinned_list);
1351
1352                                 if (tp->ucopy.dma_cookie < 0) {
1353
1354                                         printk(KERN_ALERT "dma_cookie < 0\n");
1355
1356                                         /* Exception. Bailout! */
1357                                         if (!copied)
1358                                                 copied = -EFAULT;
1359                                         break;
1360                                 }
1361                                 if ((offset + used) == skb->len)
1362                                         copied_early = 1;
1363
1364                         } else
1365 #endif
1366                         {
1367                                 err = skb_copy_datagram_iovec(skb, offset,
1368                                                 msg->msg_iov, used);
1369                                 if (err) {
1370                                         /* Exception. Bailout! */
1371                                         if (!copied)
1372                                                 copied = -EFAULT;
1373                                         break;
1374                                 }
1375                         }
1376                 }
1377
1378                 *seq += used;
1379                 copied += used;
1380                 len -= used;
1381
1382                 tcp_rcv_space_adjust(sk);
1383
1384 skip_copy:
1385                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1386                         tp->urg_data = 0;
1387                         tcp_fast_path_check(sk, tp);
1388                 }
1389                 if (used + offset < skb->len)
1390                         continue;
1391
1392                 if (skb->h.th->fin)
1393                         goto found_fin_ok;
1394                 if (!(flags & MSG_PEEK)) {
1395                         sk_eat_skb(sk, skb, copied_early);
1396                         copied_early = 0;
1397                 }
1398                 continue;
1399
1400         found_fin_ok:
1401                 /* Process the FIN. */
1402                 ++*seq;
1403                 if (!(flags & MSG_PEEK)) {
1404                         sk_eat_skb(sk, skb, copied_early);
1405                         copied_early = 0;
1406                 }
1407                 break;
1408         } while (len > 0);
1409
1410         if (user_recv) {
1411                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1412                         int chunk;
1413
1414                         tp->ucopy.len = copied > 0 ? len : 0;
1415
1416                         tcp_prequeue_process(sk);
1417
1418                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1419                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1420                                 len -= chunk;
1421                                 copied += chunk;
1422                         }
1423                 }
1424
1425                 tp->ucopy.task = NULL;
1426                 tp->ucopy.len = 0;
1427         }
1428
1429 #ifdef CONFIG_NET_DMA
1430         if (tp->ucopy.dma_chan) {
1431                 struct sk_buff *skb;
1432                 dma_cookie_t done, used;
1433
1434                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1435
1436                 while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1437                                                  tp->ucopy.dma_cookie, &done,
1438                                                  &used) == DMA_IN_PROGRESS) {
1439                         /* do partial cleanup of sk_async_wait_queue */
1440                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1441                                (dma_async_is_complete(skb->dma_cookie, done,
1442                                                       used) == DMA_SUCCESS)) {
1443                                 __skb_dequeue(&sk->sk_async_wait_queue);
1444                                 kfree_skb(skb);
1445                         }
1446                 }
1447
1448                 /* Safe to free early-copied skbs now */
1449                 __skb_queue_purge(&sk->sk_async_wait_queue);
1450                 dma_chan_put(tp->ucopy.dma_chan);
1451                 tp->ucopy.dma_chan = NULL;
1452         }
1453         if (tp->ucopy.pinned_list) {
1454                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1455                 tp->ucopy.pinned_list = NULL;
1456         }
1457 #endif
1458
1459         /* According to UNIX98, msg_name/msg_namelen are ignored
1460          * on connected socket. I was just happy when found this 8) --ANK
1461          */
1462
1463         /* Clean up data we have read: This will do ACK frames. */
1464         tcp_cleanup_rbuf(sk, copied);
1465
1466         TCP_CHECK_TIMER(sk);
1467         release_sock(sk);
1468         return copied;
1469
1470 out:
1471         TCP_CHECK_TIMER(sk);
1472         release_sock(sk);
1473         return err;
1474
1475 recv_urg:
1476         err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1477         goto out;
1478 }
1479
1480 /*
1481  *      State processing on a close. This implements the state shift for
1482  *      sending our FIN frame. Note that we only send a FIN for some
1483  *      states. A shutdown() may have already sent the FIN, or we may be
1484  *      closed.
1485  */
1486
1487 static const unsigned char new_state[16] = {
1488   /* current state:        new state:      action:      */
1489   /* (Invalid)          */ TCP_CLOSE,
1490   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1491   /* TCP_SYN_SENT       */ TCP_CLOSE,
1492   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1493   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1494   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1495   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1496   /* TCP_CLOSE          */ TCP_CLOSE,
1497   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1498   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1499   /* TCP_LISTEN         */ TCP_CLOSE,
1500   /* TCP_CLOSING        */ TCP_CLOSING,
1501 };
1502
1503 static int tcp_close_state(struct sock *sk)
1504 {
1505         int next = (int)new_state[sk->sk_state];
1506         int ns = next & TCP_STATE_MASK;
1507
1508         tcp_set_state(sk, ns);
1509
1510         return next & TCP_ACTION_FIN;
1511 }
1512
1513 /*
1514  *      Shutdown the sending side of a connection. Much like close except
1515  *      that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
1516  */
1517
1518 void tcp_shutdown(struct sock *sk, int how)
1519 {
1520         /*      We need to grab some memory, and put together a FIN,
1521          *      and then put it into the queue to be sent.
1522          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1523          */
1524         if (!(how & SEND_SHUTDOWN))
1525                 return;
1526
1527         /* If we've already sent a FIN, or it's a closed state, skip this. */
1528         if ((1 << sk->sk_state) &
1529             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1530              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1531                 /* Clear out any half completed packets.  FIN if needed. */
1532                 if (tcp_close_state(sk))
1533                         tcp_send_fin(sk);
1534         }
1535 }
1536
1537 void tcp_close(struct sock *sk, long timeout)
1538 {
1539         struct sk_buff *skb;
1540         int data_was_unread = 0;
1541         int state;
1542
1543         lock_sock(sk);
1544         sk->sk_shutdown = SHUTDOWN_MASK;
1545
1546         if (sk->sk_state == TCP_LISTEN) {
1547                 tcp_set_state(sk, TCP_CLOSE);
1548
1549                 /* Special case. */
1550                 inet_csk_listen_stop(sk);
1551
1552                 goto adjudge_to_death;
1553         }
1554
1555         /*  We need to flush the recv. buffs.  We do this only on the
1556          *  descriptor close, not protocol-sourced closes, because the
1557          *  reader process may not have drained the data yet!
1558          */
1559         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1560                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1561                           skb->h.th->fin;
1562                 data_was_unread += len;
1563                 __kfree_skb(skb);
1564         }
1565
1566         sk_stream_mem_reclaim(sk);
1567
1568         /* As outlined in draft-ietf-tcpimpl-prob-03.txt, section
1569          * 3.10, we send a RST here because data was lost.  To
1570          * witness the awful effects of the old behavior of always
1571          * doing a FIN, run an older 2.1.x kernel or 2.0.x, start
1572          * a bulk GET in an FTP client, suspend the process, wait
1573          * for the client to advertise a zero window, then kill -9
1574          * the FTP client, wheee...  Note: timeout is always zero
1575          * in such a case.
1576          */
1577         if (data_was_unread) {
1578                 /* Unread data was tossed, zap the connection. */
1579                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1580                 tcp_set_state(sk, TCP_CLOSE);
1581                 tcp_send_active_reset(sk, GFP_KERNEL);
1582         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1583                 /* Check zero linger _after_ checking for unread data. */
1584                 sk->sk_prot->disconnect(sk, 0);
1585                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1586         } else if (tcp_close_state(sk)) {
1587                 /* We FIN if the application ate all the data before
1588                  * zapping the connection.
1589                  */
1590
1591                 /* RED-PEN. Formally speaking, we have broken TCP state
1592                  * machine. State transitions:
1593                  *
1594                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1595                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1596                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1597                  *
1598                  * are legal only when FIN has been sent (i.e. in window),
1599                  * rather than queued out of window. Purists blame.
1600                  *
1601                  * F.e. "RFC state" is ESTABLISHED,
1602                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1603                  *
1604                  * The visible declinations are that sometimes
1605                  * we enter time-wait state, when it is not required really
1606                  * (harmless), do not send active resets, when they are
1607                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1608                  * they look as CLOSING or LAST_ACK for Linux)
1609                  * Probably, I missed some more holelets.
1610                  *                                              --ANK
1611                  */
1612                 tcp_send_fin(sk);
1613         }
1614
1615         sk_stream_wait_close(sk, timeout);
1616
1617 adjudge_to_death:
1618         state = sk->sk_state;
1619         sock_hold(sk);
1620         sock_orphan(sk);
1621         atomic_inc(sk->sk_prot->orphan_count);
1622
1623         /* It is the last release_sock in its life. It will remove backlog. */
1624         release_sock(sk);
1625
1626
1627         /* Now socket is owned by kernel and we acquire BH lock
1628            to finish close. No need to check for user refs.
1629          */
1630         local_bh_disable();
1631         bh_lock_sock(sk);
1632         BUG_TRAP(!sock_owned_by_user(sk));
1633
1634         /* Have we already been destroyed by a softirq or backlog? */
1635         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1636                 goto out;
1637
1638         /*      This is a (useful) BSD violating of the RFC. There is a
1639          *      problem with TCP as specified in that the other end could
1640          *      keep a socket open forever with no application left this end.
1641          *      We use a 3 minute timeout (about the same as BSD) then kill
1642          *      our end. If they send after that then tough - BUT: long enough
1643          *      that we won't make the old 4*rto = almost no time - whoops
1644          *      reset mistake.
1645          *
1646          *      Nope, it was not mistake. It is really desired behaviour
1647          *      f.e. on http servers, when such sockets are useless, but
1648          *      consume significant resources. Let's do it with special
1649          *      linger2 option.                                 --ANK
1650          */
1651
1652         if (sk->sk_state == TCP_FIN_WAIT2) {
1653                 struct tcp_sock *tp = tcp_sk(sk);
1654                 if (tp->linger2 < 0) {
1655                         tcp_set_state(sk, TCP_CLOSE);
1656                         tcp_send_active_reset(sk, GFP_ATOMIC);
1657                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1658                 } else {
1659                         const int tmo = tcp_fin_time(sk);
1660
1661                         if (tmo > TCP_TIMEWAIT_LEN) {
1662                                 inet_csk_reset_keepalive_timer(sk,
1663                                                 tmo - TCP_TIMEWAIT_LEN);
1664                         } else {
1665                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1666                                 goto out;
1667                         }
1668                 }
1669         }
1670         if (sk->sk_state != TCP_CLOSE) {
1671                 sk_stream_mem_reclaim(sk);
1672                 if (atomic_read(sk->sk_prot->orphan_count) > sysctl_tcp_max_orphans ||
1673                     (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
1674                      atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) {
1675                         if (net_ratelimit())
1676                                 printk(KERN_INFO "TCP: too many of orphaned "
1677                                        "sockets\n");
1678                         tcp_set_state(sk, TCP_CLOSE);
1679                         tcp_send_active_reset(sk, GFP_ATOMIC);
1680                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1681                 }
1682         }
1683
1684         if (sk->sk_state == TCP_CLOSE)
1685                 inet_csk_destroy_sock(sk);
1686         /* Otherwise, socket is reprieved until protocol close. */
1687
1688 out:
1689         bh_unlock_sock(sk);
1690         local_bh_enable();
1691         sock_put(sk);
1692 }
1693
1694 /* These states need RST on ABORT according to RFC793 */
1695
1696 static inline int tcp_need_reset(int state)
1697 {
1698         return (1 << state) &
1699                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1700                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1701 }
1702
1703 int tcp_disconnect(struct sock *sk, int flags)
1704 {
1705         struct inet_sock *inet = inet_sk(sk);
1706         struct inet_connection_sock *icsk = inet_csk(sk);
1707         struct tcp_sock *tp = tcp_sk(sk);
1708         int err = 0;
1709         int old_state = sk->sk_state;
1710
1711         if (old_state != TCP_CLOSE)
1712                 tcp_set_state(sk, TCP_CLOSE);
1713
1714         /* ABORT function of RFC793 */
1715         if (old_state == TCP_LISTEN) {
1716                 inet_csk_listen_stop(sk);
1717         } else if (tcp_need_reset(old_state) ||
1718                    (tp->snd_nxt != tp->write_seq &&
1719                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1720                 /* The last check adjusts for discrepancy of Linux wrt. RFC
1721                  * states
1722                  */
1723                 tcp_send_active_reset(sk, gfp_any());
1724                 sk->sk_err = ECONNRESET;
1725         } else if (old_state == TCP_SYN_SENT)
1726                 sk->sk_err = ECONNRESET;
1727
1728         tcp_clear_xmit_timers(sk);
1729         __skb_queue_purge(&sk->sk_receive_queue);
1730         sk_stream_writequeue_purge(sk);
1731         __skb_queue_purge(&tp->out_of_order_queue);
1732 #ifdef CONFIG_NET_DMA
1733         __skb_queue_purge(&sk->sk_async_wait_queue);
1734 #endif
1735
1736         inet->dport = 0;
1737
1738         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1739                 inet_reset_saddr(sk);
1740
1741         sk->sk_shutdown = 0;
1742         sock_reset_flag(sk, SOCK_DONE);
1743         tp->srtt = 0;
1744         if ((tp->write_seq += tp->max_window + 2) == 0)
1745                 tp->write_seq = 1;
1746         icsk->icsk_backoff = 0;
1747         tp->snd_cwnd = 2;
1748         icsk->icsk_probes_out = 0;
1749         tp->packets_out = 0;
1750         tp->snd_ssthresh = 0x7fffffff;
1751         tp->snd_cwnd_cnt = 0;
1752         tp->bytes_acked = 0;
1753         tcp_set_ca_state(sk, TCP_CA_Open);
1754         tcp_clear_retrans(tp);
1755         inet_csk_delack_init(sk);
1756         sk->sk_send_head = NULL;
1757         tp->rx_opt.saw_tstamp = 0;
1758         tcp_sack_reset(&tp->rx_opt);
1759         __sk_dst_reset(sk);
1760
1761         BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1762
1763         sk->sk_error_report(sk);
1764         return err;
1765 }
1766
1767 /*
1768  *      Socket option code for TCP.
1769  */
1770 static int do_tcp_setsockopt(struct sock *sk, int level,
1771                 int optname, char __user *optval, int optlen)
1772 {
1773         struct tcp_sock *tp = tcp_sk(sk);
1774         struct inet_connection_sock *icsk = inet_csk(sk);
1775         int val;
1776         int err = 0;
1777
1778         /* This is a string value all the others are int's */
1779         if (optname == TCP_CONGESTION) {
1780                 char name[TCP_CA_NAME_MAX];
1781
1782                 if (optlen < 1)
1783                         return -EINVAL;
1784
1785                 val = strncpy_from_user(name, optval,
1786                                         min(TCP_CA_NAME_MAX-1, optlen));
1787                 if (val < 0)
1788                         return -EFAULT;
1789                 name[val] = 0;
1790
1791                 lock_sock(sk);
1792                 err = tcp_set_congestion_control(sk, name);
1793                 release_sock(sk);
1794                 return err;
1795         }
1796
1797         if (optlen < sizeof(int))
1798                 return -EINVAL;
1799
1800         if (get_user(val, (int __user *)optval))
1801                 return -EFAULT;
1802
1803         lock_sock(sk);
1804
1805         switch (optname) {
1806         case TCP_MAXSEG:
1807                 /* Values greater than interface MTU won't take effect. However
1808                  * at the point when this call is done we typically don't yet
1809                  * know which interface is going to be used */
1810                 if (val < 8 || val > MAX_TCP_WINDOW) {
1811                         err = -EINVAL;
1812                         break;
1813                 }
1814                 tp->rx_opt.user_mss = val;
1815                 break;
1816
1817         case TCP_NODELAY:
1818                 if (val) {
1819                         /* TCP_NODELAY is weaker than TCP_CORK, so that
1820                          * this option on corked socket is remembered, but
1821                          * it is not activated until cork is cleared.
1822                          *
1823                          * However, when TCP_NODELAY is set we make
1824                          * an explicit push, which overrides even TCP_CORK
1825                          * for currently queued segments.
1826                          */
1827                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
1828                         tcp_push_pending_frames(sk, tp);
1829                 } else {
1830                         tp->nonagle &= ~TCP_NAGLE_OFF;
1831                 }
1832                 break;
1833
1834         case TCP_CORK:
1835                 /* When set indicates to always queue non-full frames.
1836                  * Later the user clears this option and we transmit
1837                  * any pending partial frames in the queue.  This is
1838                  * meant to be used alongside sendfile() to get properly
1839                  * filled frames when the user (for example) must write
1840                  * out headers with a write() call first and then use
1841                  * sendfile to send out the data parts.
1842                  *
1843                  * TCP_CORK can be set together with TCP_NODELAY and it is
1844                  * stronger than TCP_NODELAY.
1845                  */
1846                 if (val) {
1847                         tp->nonagle |= TCP_NAGLE_CORK;
1848                 } else {
1849                         tp->nonagle &= ~TCP_NAGLE_CORK;
1850                         if (tp->nonagle&TCP_NAGLE_OFF)
1851                                 tp->nonagle |= TCP_NAGLE_PUSH;
1852                         tcp_push_pending_frames(sk, tp);
1853                 }
1854                 break;
1855
1856         case TCP_KEEPIDLE:
1857                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
1858                         err = -EINVAL;
1859                 else {
1860                         tp->keepalive_time = val * HZ;
1861                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
1862                             !((1 << sk->sk_state) &
1863                               (TCPF_CLOSE | TCPF_LISTEN))) {
1864                                 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
1865                                 if (tp->keepalive_time > elapsed)
1866                                         elapsed = tp->keepalive_time - elapsed;
1867                                 else
1868                                         elapsed = 0;
1869                                 inet_csk_reset_keepalive_timer(sk, elapsed);
1870                         }
1871                 }
1872                 break;
1873         case TCP_KEEPINTVL:
1874                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
1875                         err = -EINVAL;
1876                 else
1877                         tp->keepalive_intvl = val * HZ;
1878                 break;
1879         case TCP_KEEPCNT:
1880                 if (val < 1 || val > MAX_TCP_KEEPCNT)
1881                         err = -EINVAL;
1882                 else
1883                         tp->keepalive_probes = val;
1884                 break;
1885         case TCP_SYNCNT:
1886                 if (val < 1 || val > MAX_TCP_SYNCNT)
1887                         err = -EINVAL;
1888                 else
1889                         icsk->icsk_syn_retries = val;
1890                 break;
1891
1892         case TCP_LINGER2:
1893                 if (val < 0)
1894                         tp->linger2 = -1;
1895                 else if (val > sysctl_tcp_fin_timeout / HZ)
1896                         tp->linger2 = 0;
1897                 else
1898                         tp->linger2 = val * HZ;
1899                 break;
1900
1901         case TCP_DEFER_ACCEPT:
1902                 icsk->icsk_accept_queue.rskq_defer_accept = 0;
1903                 if (val > 0) {
1904                         /* Translate value in seconds to number of
1905                          * retransmits */
1906                         while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
1907                                val > ((TCP_TIMEOUT_INIT / HZ) <<
1908                                        icsk->icsk_accept_queue.rskq_defer_accept))
1909                                 icsk->icsk_accept_queue.rskq_defer_accept++;
1910                         icsk->icsk_accept_queue.rskq_defer_accept++;
1911                 }
1912                 break;
1913
1914         case TCP_WINDOW_CLAMP:
1915                 if (!val) {
1916                         if (sk->sk_state != TCP_CLOSE) {
1917                                 err = -EINVAL;
1918                                 break;
1919                         }
1920                         tp->window_clamp = 0;
1921                 } else
1922                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
1923                                                 SOCK_MIN_RCVBUF / 2 : val;
1924                 break;
1925
1926         case TCP_QUICKACK:
1927                 if (!val) {
1928                         icsk->icsk_ack.pingpong = 1;
1929                 } else {
1930                         icsk->icsk_ack.pingpong = 0;
1931                         if ((1 << sk->sk_state) &
1932                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
1933                             inet_csk_ack_scheduled(sk)) {
1934                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
1935                                 tcp_cleanup_rbuf(sk, 1);
1936                                 if (!(val & 1))
1937                                         icsk->icsk_ack.pingpong = 1;
1938                         }
1939                 }
1940                 break;
1941
1942         default:
1943                 err = -ENOPROTOOPT;
1944                 break;
1945         };
1946         release_sock(sk);
1947         return err;
1948 }
1949
1950 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
1951                    int optlen)
1952 {
1953         struct inet_connection_sock *icsk = inet_csk(sk);
1954
1955         if (level != SOL_TCP)
1956                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1957                                                      optval, optlen);
1958         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1959 }
1960
1961 #ifdef CONFIG_COMPAT
1962 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
1963                           char __user *optval, int optlen)
1964 {
1965         if (level != SOL_TCP)
1966                 return inet_csk_compat_setsockopt(sk, level, optname,
1967                                                   optval, optlen);
1968         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1969 }
1970
1971 EXPORT_SYMBOL(compat_tcp_setsockopt);
1972 #endif
1973
1974 /* Return information about state of tcp endpoint in API format. */
1975 void tcp_get_info(struct sock *sk, struct tcp_info *info)
1976 {
1977         struct tcp_sock *tp = tcp_sk(sk);
1978         const struct inet_connection_sock *icsk = inet_csk(sk);
1979         u32 now = tcp_time_stamp;
1980
1981         memset(info, 0, sizeof(*info));
1982
1983         info->tcpi_state = sk->sk_state;
1984         info->tcpi_ca_state = icsk->icsk_ca_state;
1985         info->tcpi_retransmits = icsk->icsk_retransmits;
1986         info->tcpi_probes = icsk->icsk_probes_out;
1987         info->tcpi_backoff = icsk->icsk_backoff;
1988
1989         if (tp->rx_opt.tstamp_ok)
1990                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
1991         if (tp->rx_opt.sack_ok)
1992                 info->tcpi_options |= TCPI_OPT_SACK;
1993         if (tp->rx_opt.wscale_ok) {
1994                 info->tcpi_options |= TCPI_OPT_WSCALE;
1995                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
1996                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
1997         }
1998
1999         if (tp->ecn_flags&TCP_ECN_OK)
2000                 info->tcpi_options |= TCPI_OPT_ECN;
2001
2002         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2003         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2004         info->tcpi_snd_mss = tp->mss_cache;
2005         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2006
2007         info->tcpi_unacked = tp->packets_out;
2008         info->tcpi_sacked = tp->sacked_out;
2009         info->tcpi_lost = tp->lost_out;
2010         info->tcpi_retrans = tp->retrans_out;
2011         info->tcpi_fackets = tp->fackets_out;
2012
2013         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2014         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2015         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2016
2017         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2018         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2019         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2020         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2021         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2022         info->tcpi_snd_cwnd = tp->snd_cwnd;
2023         info->tcpi_advmss = tp->advmss;
2024         info->tcpi_reordering = tp->reordering;
2025
2026         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2027         info->tcpi_rcv_space = tp->rcvq_space.space;
2028
2029         info->tcpi_total_retrans = tp->total_retrans;
2030 }
2031
2032 EXPORT_SYMBOL_GPL(tcp_get_info);
2033
2034 static int do_tcp_getsockopt(struct sock *sk, int level,
2035                 int optname, char __user *optval, int __user *optlen)
2036 {
2037         struct inet_connection_sock *icsk = inet_csk(sk);
2038         struct tcp_sock *tp = tcp_sk(sk);
2039         int val, len;
2040
2041         if (get_user(len, optlen))
2042                 return -EFAULT;
2043
2044         len = min_t(unsigned int, len, sizeof(int));
2045
2046         if (len < 0)
2047                 return -EINVAL;
2048
2049         switch (optname) {
2050         case TCP_MAXSEG:
2051                 val = tp->mss_cache;
2052                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2053                         val = tp->rx_opt.user_mss;
2054                 break;
2055         case TCP_NODELAY:
2056                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2057                 break;
2058         case TCP_CORK:
2059                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2060                 break;
2061         case TCP_KEEPIDLE:
2062                 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
2063                 break;
2064         case TCP_KEEPINTVL:
2065                 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
2066                 break;
2067         case TCP_KEEPCNT:
2068                 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
2069                 break;
2070         case TCP_SYNCNT:
2071                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2072                 break;
2073         case TCP_LINGER2:
2074                 val = tp->linger2;
2075                 if (val >= 0)
2076                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2077                 break;
2078         case TCP_DEFER_ACCEPT:
2079                 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2080                         ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2081                 break;
2082         case TCP_WINDOW_CLAMP:
2083                 val = tp->window_clamp;
2084                 break;
2085         case TCP_INFO: {
2086                 struct tcp_info info;
2087
2088                 if (get_user(len, optlen))
2089                         return -EFAULT;
2090
2091                 tcp_get_info(sk, &info);
2092
2093                 len = min_t(unsigned int, len, sizeof(info));
2094                 if (put_user(len, optlen))
2095                         return -EFAULT;
2096                 if (copy_to_user(optval, &info, len))
2097                         return -EFAULT;
2098                 return 0;
2099         }
2100         case TCP_QUICKACK:
2101                 val = !icsk->icsk_ack.pingpong;
2102                 break;
2103
2104         case TCP_CONGESTION:
2105                 if (get_user(len, optlen))
2106                         return -EFAULT;
2107                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2108                 if (put_user(len, optlen))
2109                         return -EFAULT;
2110                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2111                         return -EFAULT;
2112                 return 0;
2113         default:
2114                 return -ENOPROTOOPT;
2115         };
2116
2117         if (put_user(len, optlen))
2118                 return -EFAULT;
2119         if (copy_to_user(optval, &val, len))
2120                 return -EFAULT;
2121         return 0;
2122 }
2123
2124 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2125                    int __user *optlen)
2126 {
2127         struct inet_connection_sock *icsk = inet_csk(sk);
2128
2129         if (level != SOL_TCP)
2130                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2131                                                      optval, optlen);
2132         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2133 }
2134
2135 #ifdef CONFIG_COMPAT
2136 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2137                           char __user *optval, int __user *optlen)
2138 {
2139         if (level != SOL_TCP)
2140                 return inet_csk_compat_getsockopt(sk, level, optname,
2141                                                   optval, optlen);
2142         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2143 }
2144
2145 EXPORT_SYMBOL(compat_tcp_getsockopt);
2146 #endif
2147
2148 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2149 {
2150         struct sk_buff *segs = ERR_PTR(-EINVAL);
2151         struct tcphdr *th;
2152         unsigned thlen;
2153         unsigned int seq;
2154         unsigned int delta;
2155         unsigned int oldlen;
2156         unsigned int len;
2157
2158         if (!pskb_may_pull(skb, sizeof(*th)))
2159                 goto out;
2160
2161         th = skb->h.th;
2162         thlen = th->doff * 4;
2163         if (thlen < sizeof(*th))
2164                 goto out;
2165
2166         if (!pskb_may_pull(skb, thlen))
2167                 goto out;
2168
2169         oldlen = (u16)~skb->len;
2170         __skb_pull(skb, thlen);
2171
2172         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2173                 /* Packet is from an untrusted source, reset gso_segs. */
2174                 int type = skb_shinfo(skb)->gso_type;
2175                 int mss;
2176
2177                 if (unlikely(type &
2178                              ~(SKB_GSO_TCPV4 |
2179                                SKB_GSO_DODGY |
2180                                SKB_GSO_TCP_ECN |
2181                                SKB_GSO_TCPV6 |
2182                                0) ||
2183                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2184                         goto out;
2185
2186                 mss = skb_shinfo(skb)->gso_size;
2187                 skb_shinfo(skb)->gso_segs = (skb->len + mss - 1) / mss;
2188
2189                 segs = NULL;
2190                 goto out;
2191         }
2192
2193         segs = skb_segment(skb, features);
2194         if (IS_ERR(segs))
2195                 goto out;
2196
2197         len = skb_shinfo(skb)->gso_size;
2198         delta = htonl(oldlen + (thlen + len));
2199
2200         skb = segs;
2201         th = skb->h.th;
2202         seq = ntohl(th->seq);
2203
2204         do {
2205                 th->fin = th->psh = 0;
2206
2207                 th->check = ~csum_fold(th->check + delta);
2208                 if (skb->ip_summed != CHECKSUM_HW)
2209                         th->check = csum_fold(csum_partial(skb->h.raw, thlen,
2210                                                            skb->csum));
2211
2212                 seq += len;
2213                 skb = skb->next;
2214                 th = skb->h.th;
2215
2216                 th->seq = htonl(seq);
2217                 th->cwr = 0;
2218         } while (skb->next);
2219
2220         delta = htonl(oldlen + (skb->tail - skb->h.raw) + skb->data_len);
2221         th->check = ~csum_fold(th->check + delta);
2222         if (skb->ip_summed != CHECKSUM_HW)
2223                 th->check = csum_fold(csum_partial(skb->h.raw, thlen,
2224                                                    skb->csum));
2225
2226 out:
2227         return segs;
2228 }
2229 EXPORT_SYMBOL(tcp_tso_segment);
2230
2231 extern void __skb_cb_too_small_for_tcp(int, int);
2232 extern struct tcp_congestion_ops tcp_reno;
2233
2234 static __initdata unsigned long thash_entries;
2235 static int __init set_thash_entries(char *str)
2236 {
2237         if (!str)
2238                 return 0;
2239         thash_entries = simple_strtoul(str, &str, 0);
2240         return 1;
2241 }
2242 __setup("thash_entries=", set_thash_entries);
2243
2244 void __init tcp_init(void)
2245 {
2246         struct sk_buff *skb = NULL;
2247         unsigned long limit;
2248         int order, i, max_share;
2249
2250         if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
2251                 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
2252                                            sizeof(skb->cb));
2253
2254         tcp_hashinfo.bind_bucket_cachep =
2255                 kmem_cache_create("tcp_bind_bucket",
2256                                   sizeof(struct inet_bind_bucket), 0,
2257                                   SLAB_HWCACHE_ALIGN, NULL, NULL);
2258         if (!tcp_hashinfo.bind_bucket_cachep)
2259                 panic("tcp_init: Cannot alloc tcp_bind_bucket cache.");
2260
2261         /* Size and allocate the main established and bind bucket
2262          * hash tables.
2263          *
2264          * The methodology is similar to that of the buffer cache.
2265          */
2266         tcp_hashinfo.ehash =
2267                 alloc_large_system_hash("TCP established",
2268                                         sizeof(struct inet_ehash_bucket),
2269                                         thash_entries,
2270                                         (num_physpages >= 128 * 1024) ?
2271                                         13 : 15,
2272                                         HASH_HIGHMEM,
2273                                         &tcp_hashinfo.ehash_size,
2274                                         NULL,
2275                                         0);
2276         tcp_hashinfo.ehash_size = (1 << tcp_hashinfo.ehash_size) >> 1;
2277         for (i = 0; i < (tcp_hashinfo.ehash_size << 1); i++) {
2278                 rwlock_init(&tcp_hashinfo.ehash[i].lock);
2279                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2280         }
2281
2282         tcp_hashinfo.bhash =
2283                 alloc_large_system_hash("TCP bind",
2284                                         sizeof(struct inet_bind_hashbucket),
2285                                         tcp_hashinfo.ehash_size,
2286                                         (num_physpages >= 128 * 1024) ?
2287                                         13 : 15,
2288                                         HASH_HIGHMEM,
2289                                         &tcp_hashinfo.bhash_size,
2290                                         NULL,
2291                                         64 * 1024);
2292         tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2293         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2294                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2295                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2296         }
2297
2298         /* Try to be a bit smarter and adjust defaults depending
2299          * on available memory.
2300          */
2301         for (order = 0; ((1 << order) << PAGE_SHIFT) <
2302                         (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2303                         order++)
2304                 ;
2305         if (order >= 4) {
2306                 sysctl_local_port_range[0] = 32768;
2307                 sysctl_local_port_range[1] = 61000;
2308                 tcp_death_row.sysctl_max_tw_buckets = 180000;
2309                 sysctl_tcp_max_orphans = 4096 << (order - 4);
2310                 sysctl_max_syn_backlog = 1024;
2311         } else if (order < 3) {
2312                 sysctl_local_port_range[0] = 1024 * (3 - order);
2313                 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2314                 sysctl_tcp_max_orphans >>= (3 - order);
2315                 sysctl_max_syn_backlog = 128;
2316         }
2317
2318         sysctl_tcp_mem[0] =  768 << order;
2319         sysctl_tcp_mem[1] = 1024 << order;
2320         sysctl_tcp_mem[2] = 1536 << order;
2321
2322         limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2323         max_share = min(4UL*1024*1024, limit);
2324
2325         sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM;
2326         sysctl_tcp_wmem[1] = 16*1024;
2327         sysctl_tcp_wmem[2] = max(64*1024, max_share);
2328
2329         sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM;
2330         sysctl_tcp_rmem[1] = 87380;
2331         sysctl_tcp_rmem[2] = max(87380, max_share);
2332
2333         printk(KERN_INFO "TCP: Hash tables configured "
2334                "(established %d bind %d)\n",
2335                tcp_hashinfo.ehash_size << 1, tcp_hashinfo.bhash_size);
2336
2337         tcp_register_congestion_control(&tcp_reno);
2338 }
2339
2340 EXPORT_SYMBOL(tcp_close);
2341 EXPORT_SYMBOL(tcp_disconnect);
2342 EXPORT_SYMBOL(tcp_getsockopt);
2343 EXPORT_SYMBOL(tcp_ioctl);
2344 EXPORT_SYMBOL(tcp_poll);
2345 EXPORT_SYMBOL(tcp_read_sock);
2346 EXPORT_SYMBOL(tcp_recvmsg);
2347 EXPORT_SYMBOL(tcp_sendmsg);
2348 EXPORT_SYMBOL(tcp_sendpage);
2349 EXPORT_SYMBOL(tcp_setsockopt);
2350 EXPORT_SYMBOL(tcp_shutdown);
2351 EXPORT_SYMBOL(tcp_statistics);