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/fs.h>
 256 #include <linux/random.h>
 257 #include <linux/bootmem.h>
 258 #include <linux/cache.h>
 259 #include <linux/err.h>
 260 #include <linux/crypto.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 __read_mostly = 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 __read_mostly;
 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                        tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->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 sk_buff *skb)
 463 {
 464         struct tcp_sock *tp = tcp_sk(sk);
 465         struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
 466
 467         skb->csum    = 0;
 468         tcb->seq     = tcb->end_seq = tp->write_seq;
 469         tcb->flags   = TCPCB_FLAG_ACK;
 470         tcb->sacked  = 0;
 471         skb_header_release(skb);
 472         tcp_add_write_queue_tail(sk, skb);
 473         sk_charge_skb(sk, skb);
 474         if (tp->nonagle & TCP_NAGLE_PUSH)
 475                 tp->nonagle &= ~TCP_NAGLE_PUSH;
 476 }
 477
 478 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
 479                                 struct sk_buff *skb)
 480 {
 481         if (flags & MSG_OOB) {
 482                 tp->urg_mode = 1;
 483                 tp->snd_up = tp->write_seq;
 484                 TCP_SKB_CB(skb)->sacked |= TCPCB_URG;
 485         }
 486 }
 487
 488 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 489                             int nonagle)
 490 {
 491         struct tcp_sock *tp = tcp_sk(sk);
 492
 493         if (tcp_send_head(sk)) {
 494                 struct sk_buff *skb = tcp_write_queue_tail(sk);
 495                 if (!(flags & MSG_MORE) || forced_push(tp))
 496                         tcp_mark_push(tp, skb);
 497                 tcp_mark_urg(tp, flags, skb);
 498                 __tcp_push_pending_frames(sk, mss_now,
 499                                           (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 500         }
 501 }
 502
 503 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
 504                          size_t psize, int flags)
 505 {
 506         struct tcp_sock *tp = tcp_sk(sk);
 507         int mss_now, size_goal;
 508         int err;
 509         ssize_t copied;
 510         long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 511
 512         /* Wait for a connection to finish. */
 513         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 514                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 515                         goto out_err;
 516
 517         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 518
 519         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 520         size_goal = tp->xmit_size_goal;
 521         copied = 0;
 522
 523         err = -EPIPE;
 524         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 525                 goto do_error;
 526
 527         while (psize > 0) {
 528                 struct sk_buff *skb = tcp_write_queue_tail(sk);
 529                 struct page *page = pages[poffset / PAGE_SIZE];
 530                 int copy, i, can_coalesce;
 531                 int offset = poffset % PAGE_SIZE;
 532                 int size = min_t(size_t, psize, PAGE_SIZE - offset);
 533
 534                 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
 535 new_segment:
 536                         if (!sk_stream_memory_free(sk))
 537                                 goto wait_for_sndbuf;
 538
 539                         skb = sk_stream_alloc_pskb(sk, 0, 0,
 540                                                    sk->sk_allocation);
 541                         if (!skb)
 542                                 goto wait_for_memory;
 543
 544                         skb_entail(sk, skb);
 545                         copy = size_goal;
 546                 }
 547
 548                 if (copy > size)
 549                         copy = size;
 550
 551                 i = skb_shinfo(skb)->nr_frags;
 552                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
 553                 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
 554                         tcp_mark_push(tp, skb);
 555                         goto new_segment;
 556                 }
 557                 if (!sk_stream_wmem_schedule(sk, copy))
 558                         goto wait_for_memory;
 559
 560                 if (can_coalesce) {
 561                         skb_shinfo(skb)->frags[i - 1].size += copy;
 562                 } else {
 563                         get_page(page);
 564                         skb_fill_page_desc(skb, i, page, offset, copy);
 565                 }
 566
 567                 skb->len += copy;
 568                 skb->data_len += copy;
 569                 skb->truesize += copy;
 570                 sk->sk_wmem_queued += copy;
 571                 sk->sk_forward_alloc -= copy;
 572                 skb->ip_summed = CHECKSUM_PARTIAL;
 573                 tp->write_seq += copy;
 574                 TCP_SKB_CB(skb)->end_seq += copy;
 575                 skb_shinfo(skb)->gso_segs = 0;
 576
 577                 if (!copied)
 578                         TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 579
 580                 copied += copy;
 581                 poffset += copy;
 582                 if (!(psize -= copy))
 583                         goto out;
 584
 585                 if (skb->len < mss_now || (flags & MSG_OOB))
 586                         continue;
 587
 588                 if (forced_push(tp)) {
 589                         tcp_mark_push(tp, skb);
 590                         __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 591                 } else if (skb == tcp_send_head(sk))
 592                         tcp_push_one(sk, mss_now);
 593                 continue;
 594
 595 wait_for_sndbuf:
 596                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 597 wait_for_memory:
 598                 if (copied)
 599                         tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 600
 601                 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 602                         goto do_error;
 603
 604                 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 605                 size_goal = tp->xmit_size_goal;
 606         }
 607
 608 out:
 609         if (copied)
 610                 tcp_push(sk, flags, mss_now, tp->nonagle);
 611         return copied;
 612
 613 do_error:
 614         if (copied)
 615                 goto out;
 616 out_err:
 617         return sk_stream_error(sk, flags, err);
 618 }
 619
 620 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
 621                      size_t size, int flags)
 622 {
 623         ssize_t res;
 624         struct sock *sk = sock->sk;
 625
 626         if (!(sk->sk_route_caps & NETIF_F_SG) ||
 627             !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
 628                 return sock_no_sendpage(sock, page, offset, size, flags);
 629
 630         lock_sock(sk);
 631         TCP_CHECK_TIMER(sk);
 632         res = do_tcp_sendpages(sk, &page, offset, size, flags);
 633         TCP_CHECK_TIMER(sk);
 634         release_sock(sk);
 635         return res;
 636 }
 637
 638 #define TCP_PAGE(sk)    (sk->sk_sndmsg_page)
 639 #define TCP_OFF(sk)     (sk->sk_sndmsg_off)
 640
 641 static inline int select_size(struct sock *sk)
 642 {
 643         struct tcp_sock *tp = tcp_sk(sk);
 644         int tmp = tp->mss_cache;
 645
 646         if (sk->sk_route_caps & NETIF_F_SG) {
 647                 if (sk_can_gso(sk))
 648                         tmp = 0;
 649                 else {
 650                         int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
 651
 652                         if (tmp >= pgbreak &&
 653                             tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
 654                                 tmp = pgbreak;
 655                 }
 656         }
 657
 658         return tmp;
 659 }
 660
 661 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 662                 size_t size)
 663 {
 664         struct iovec *iov;
 665         struct tcp_sock *tp = tcp_sk(sk);
 666         struct sk_buff *skb;
 667         int iovlen, flags;
 668         int mss_now, size_goal;
 669         int err, copied;
 670         long timeo;
 671
 672         lock_sock(sk);
 673         TCP_CHECK_TIMER(sk);
 674
 675         flags = msg->msg_flags;
 676         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 677
 678         /* Wait for a connection to finish. */
 679         if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 680                 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 681                         goto out_err;
 682
 683         /* This should be in poll */
 684         clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 685
 686         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 687         size_goal = tp->xmit_size_goal;
 688
 689         /* Ok commence sending. */
 690         iovlen = msg->msg_iovlen;
 691         iov = msg->msg_iov;
 692         copied = 0;
 693
 694         err = -EPIPE;
 695         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 696                 goto do_error;
 697
 698         while (--iovlen >= 0) {
 699                 int seglen = iov->iov_len;
 700                 unsigned char __user *from = iov->iov_base;
 701
 702                 iov++;
 703
 704                 while (seglen > 0) {
 705                         int copy;
 706
 707                         skb = tcp_write_queue_tail(sk);
 708
 709                         if (!tcp_send_head(sk) ||
 710                             (copy = size_goal - skb->len) <= 0) {
 711
 712 new_segment:
 713                                 /* Allocate new segment. If the interface is SG,
 714                                  * allocate skb fitting to single page.
 715                                  */
 716                                 if (!sk_stream_memory_free(sk))
 717                                         goto wait_for_sndbuf;
 718
 719                                 skb = sk_stream_alloc_pskb(sk, select_size(sk),
 720                                                            0, sk->sk_allocation);
 721                                 if (!skb)
 722                                         goto wait_for_memory;
 723
 724                                 /*
 725                                  * Check whether we can use HW checksum.
 726                                  */
 727                                 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
 728                                         skb->ip_summed = CHECKSUM_PARTIAL;
 729
 730                                 skb_entail(sk, skb);
 731                                 copy = size_goal;
 732                         }
 733
 734                         /* Try to append data to the end of skb. */
 735                         if (copy > seglen)
 736                                 copy = seglen;
 737
 738                         /* Where to copy to? */
 739                         if (skb_tailroom(skb) > 0) {
 740                                 /* We have some space in skb head. Superb! */
 741                                 if (copy > skb_tailroom(skb))
 742                                         copy = skb_tailroom(skb);
 743                                 if ((err = skb_add_data(skb, from, copy)) != 0)
 744                                         goto do_fault;
 745                         } else {
 746                                 int merge = 0;
 747                                 int i = skb_shinfo(skb)->nr_frags;
 748                                 struct page *page = TCP_PAGE(sk);
 749                                 int off = TCP_OFF(sk);
 750
 751                                 if (skb_can_coalesce(skb, i, page, off) &&
 752                                     off != PAGE_SIZE) {
 753                                         /* We can extend the last page
 754                                          * fragment. */
 755                                         merge = 1;
 756                                 } else if (i == MAX_SKB_FRAGS ||
 757                                            (!i &&
 758                                            !(sk->sk_route_caps & NETIF_F_SG))) {
 759                                         /* Need to add new fragment and cannot
 760                                          * do this because interface is non-SG,
 761                                          * or because all the page slots are
 762                                          * busy. */
 763                                         tcp_mark_push(tp, skb);
 764                                         goto new_segment;
 765                                 } else if (page) {
 766                                         if (off == PAGE_SIZE) {
 767                                                 put_page(page);
 768                                                 TCP_PAGE(sk) = page = NULL;
 769                                                 off = 0;
 770                                         }
 771                                 } else
 772                                         off = 0;
 773
 774                                 if (copy > PAGE_SIZE - off)
 775                                         copy = PAGE_SIZE - off;
 776
 777                                 if (!sk_stream_wmem_schedule(sk, copy))
 778                                         goto wait_for_memory;
 779
 780                                 if (!page) {
 781                                         /* Allocate new cache page. */
 782                                         if (!(page = sk_stream_alloc_page(sk)))
 783                                                 goto wait_for_memory;
 784                                 }
 785
 786                                 /* Time to copy data. We are close to
 787                                  * the end! */
 788                                 err = skb_copy_to_page(sk, from, skb, page,
 789                                                        off, copy);
 790                                 if (err) {
 791                                         /* If this page was new, give it to the
 792                                          * socket so it does not get leaked.
 793                                          */
 794                                         if (!TCP_PAGE(sk)) {
 795                                                 TCP_PAGE(sk) = page;
 796                                                 TCP_OFF(sk) = 0;
 797                                         }
 798                                         goto do_error;
 799                                 }
 800
 801                                 /* Update the skb. */
 802                                 if (merge) {
 803                                         skb_shinfo(skb)->frags[i - 1].size +=
 804                                                                         copy;
 805                                 } else {
 806                                         skb_fill_page_desc(skb, i, page, off, copy);
 807                                         if (TCP_PAGE(sk)) {
 808                                                 get_page(page);
 809                                         } else if (off + copy < PAGE_SIZE) {
 810                                                 get_page(page);
 811                                                 TCP_PAGE(sk) = page;
 812                                         }
 813                                 }
 814
 815                                 TCP_OFF(sk) = off + copy;
 816                         }
 817
 818                         if (!copied)
 819                                 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
 820
 821                         tp->write_seq += copy;
 822                         TCP_SKB_CB(skb)->end_seq += copy;
 823                         skb_shinfo(skb)->gso_segs = 0;
 824
 825                         from += copy;
 826                         copied += copy;
 827                         if ((seglen -= copy) == 0 && iovlen == 0)
 828                                 goto out;
 829
 830                         if (skb->len < mss_now || (flags & MSG_OOB))
 831                                 continue;
 832
 833                         if (forced_push(tp)) {
 834                                 tcp_mark_push(tp, skb);
 835                                 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
 836                         } else if (skb == tcp_send_head(sk))
 837                                 tcp_push_one(sk, mss_now);
 838                         continue;
 839
 840 wait_for_sndbuf:
 841                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 842 wait_for_memory:
 843                         if (copied)
 844                                 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
 845
 846                         if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
 847                                 goto do_error;
 848
 849                         mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
 850                         size_goal = tp->xmit_size_goal;
 851                 }
 852         }
 853
 854 out:
 855         if (copied)
 856                 tcp_push(sk, flags, mss_now, tp->nonagle);
 857         TCP_CHECK_TIMER(sk);
 858         release_sock(sk);
 859         return copied;
 860
 861 do_fault:
 862         if (!skb->len) {
 863                 tcp_unlink_write_queue(skb, sk);
 864                 /* It is the one place in all of TCP, except connection
 865                  * reset, where we can be unlinking the send_head.
 866                  */
 867                 tcp_check_send_head(sk, skb);
 868                 sk_stream_free_skb(sk, skb);
 869         }
 870
 871 do_error:
 872         if (copied)
 873                 goto out;
 874 out_err:
 875         err = sk_stream_error(sk, flags, err);
 876         TCP_CHECK_TIMER(sk);
 877         release_sock(sk);
 878         return err;
 879 }
 880
 881 /*
 882  *      Handle reading urgent data. BSD has very simple semantics for
 883  *      this, no blocking and very strange errors 8)
 884  */
 885
 886 static int tcp_recv_urg(struct sock *sk, long timeo,
 887                         struct msghdr *msg, int len, int flags,
 888                         int *addr_len)
 889 {
 890         struct tcp_sock *tp = tcp_sk(sk);
 891
 892         /* No URG data to read. */
 893         if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
 894             tp->urg_data == TCP_URG_READ)
 895                 return -EINVAL; /* Yes this is right ! */
 896
 897         if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
 898                 return -ENOTCONN;
 899
 900         if (tp->urg_data & TCP_URG_VALID) {
 901                 int err = 0;
 902                 char c = tp->urg_data;
 903
 904                 if (!(flags & MSG_PEEK))
 905                         tp->urg_data = TCP_URG_READ;
 906
 907                 /* Read urgent data. */
 908                 msg->msg_flags |= MSG_OOB;
 909
 910                 if (len > 0) {
 911                         if (!(flags & MSG_TRUNC))
 912                                 err = memcpy_toiovec(msg->msg_iov, &c, 1);
 913                         len = 1;
 914                 } else
 915                         msg->msg_flags |= MSG_TRUNC;
 916
 917                 return err ? -EFAULT : len;
 918         }
 919
 920         if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
 921                 return 0;
 922
 923         /* Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
 924          * the available implementations agree in this case:
 925          * this call should never block, independent of the
 926          * blocking state of the socket.
 927          * Mike <pall@rz.uni-karlsruhe.de>
 928          */
 929         return -EAGAIN;
 930 }
 931
 932 /* Clean up the receive buffer for full frames taken by the user,
 933  * then send an ACK if necessary.  COPIED is the number of bytes
 934  * tcp_recvmsg has given to the user so far, it speeds up the
 935  * calculation of whether or not we must ACK for the sake of
 936  * a window update.
 937  */
 938 void tcp_cleanup_rbuf(struct sock *sk, int copied)
 939 {
 940         struct tcp_sock *tp = tcp_sk(sk);
 941         int time_to_ack = 0;
 942
 943 #if TCP_DEBUG
 944         struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 945
 946         BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
 947 #endif
 948
 949         if (inet_csk_ack_scheduled(sk)) {
 950                 const struct inet_connection_sock *icsk = inet_csk(sk);
 951                    /* Delayed ACKs frequently hit locked sockets during bulk
 952                     * receive. */
 953                 if (icsk->icsk_ack.blocked ||
 954                     /* Once-per-two-segments ACK was not sent by tcp_input.c */
 955                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
 956                     /*
 957                      * If this read emptied read buffer, we send ACK, if
 958                      * connection is not bidirectional, user drained
 959                      * receive buffer and there was a small segment
 960                      * in queue.
 961                      */
 962                     (copied > 0 &&
 963                      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
 964                       ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
 965                        !icsk->icsk_ack.pingpong)) &&
 966                       !atomic_read(&sk->sk_rmem_alloc)))
 967                         time_to_ack = 1;
 968         }
 969
 970         /* We send an ACK if we can now advertise a non-zero window
 971          * which has been raised "significantly".
 972          *
 973          * Even if window raised up to infinity, do not send window open ACK
 974          * in states, where we will not receive more. It is useless.
 975          */
 976         if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
 977                 __u32 rcv_window_now = tcp_receive_window(tp);
 978
 979                 /* Optimize, __tcp_select_window() is not cheap. */
 980                 if (2*rcv_window_now <= tp->window_clamp) {
 981                         __u32 new_window = __tcp_select_window(sk);
 982
 983                         /* Send ACK now, if this read freed lots of space
 984                          * in our buffer. Certainly, new_window is new window.
 985                          * We can advertise it now, if it is not less than current one.
 986                          * "Lots" means "at least twice" here.
 987                          */
 988                         if (new_window && new_window >= 2 * rcv_window_now)
 989                                 time_to_ack = 1;
 990                 }
 991         }
 992         if (time_to_ack)
 993                 tcp_send_ack(sk);
 994 }
 995
 996 static void tcp_prequeue_process(struct sock *sk)
 997 {
 998         struct sk_buff *skb;
 999         struct tcp_sock *tp = tcp_sk(sk);
1000
1001         NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
1002
1003         /* RX process wants to run with disabled BHs, though it is not
1004          * necessary */
1005         local_bh_disable();
1006         while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1007                 sk->sk_backlog_rcv(sk, skb);
1008         local_bh_enable();
1009
1010         /* Clear memory counter. */
1011         tp->ucopy.memory = 0;
1012 }
1013
1014 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1015 {
1016         struct sk_buff *skb;
1017         u32 offset;
1018
1019         skb_queue_walk(&sk->sk_receive_queue, skb) {
1020                 offset = seq - TCP_SKB_CB(skb)->seq;
1021                 if (tcp_hdr(skb)->syn)
1022                         offset--;
1023                 if (offset < skb->len || tcp_hdr(skb)->fin) {
1024                         *off = offset;
1025                         return skb;
1026                 }
1027         }
1028         return NULL;
1029 }
1030
1031 /*
1032  * This routine provides an alternative to tcp_recvmsg() for routines
1033  * that would like to handle copying from skbuffs directly in 'sendfile'
1034  * fashion.
1035  * Note:
1036  *      - It is assumed that the socket was locked by the caller.
1037  *      - The routine does not block.
1038  *      - At present, there is no support for reading OOB data
1039  *        or for 'peeking' the socket using this routine
1040  *        (although both would be easy to implement).
1041  */
1042 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1043                   sk_read_actor_t recv_actor)
1044 {
1045         struct sk_buff *skb;
1046         struct tcp_sock *tp = tcp_sk(sk);
1047         u32 seq = tp->copied_seq;
1048         u32 offset;
1049         int copied = 0;
1050
1051         if (sk->sk_state == TCP_LISTEN)
1052                 return -ENOTCONN;
1053         while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1054                 if (offset < skb->len) {
1055                         size_t used, len;
1056
1057                         len = skb->len - offset;
1058                         /* Stop reading if we hit a patch of urgent data */
1059                         if (tp->urg_data) {
1060                                 u32 urg_offset = tp->urg_seq - seq;
1061                                 if (urg_offset < len)
1062                                         len = urg_offset;
1063                                 if (!len)
1064                                         break;
1065                         }
1066                         used = recv_actor(desc, skb, offset, len);
1067                         if (used < 0) {
1068                                 if (!copied)
1069                                         copied = used;
1070                                 break;
1071                         } else if (used <= len) {
1072                                 seq += used;
1073                                 copied += used;
1074                                 offset += used;
1075                         }
1076                         if (offset != skb->len)
1077                                 break;
1078                 }
1079                 if (tcp_hdr(skb)->fin) {
1080                         sk_eat_skb(sk, skb, 0);
1081                         ++seq;
1082                         break;
1083                 }
1084                 sk_eat_skb(sk, skb, 0);
1085                 if (!desc->count)
1086                         break;
1087         }
1088         tp->copied_seq = seq;
1089
1090         tcp_rcv_space_adjust(sk);
1091
1092         /* Clean up data we have read: This will do ACK frames. */
1093         if (copied > 0)
1094                 tcp_cleanup_rbuf(sk, copied);
1095         return copied;
1096 }
1097
1098 /*
1099  *      This routine copies from a sock struct into the user buffer.
1100  *
1101  *      Technical note: in 2.3 we work on _locked_ socket, so that
1102  *      tricks with *seq access order and skb->users are not required.
1103  *      Probably, code can be easily improved even more.
1104  */
1105
1106 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1107                 size_t len, int nonblock, int flags, int *addr_len)
1108 {
1109         struct tcp_sock *tp = tcp_sk(sk);
1110         int copied = 0;
1111         u32 peek_seq;
1112         u32 *seq;
1113         unsigned long used;
1114         int err;
1115         int target;             /* Read at least this many bytes */
1116         long timeo;
1117         struct task_struct *user_recv = NULL;
1118         int copied_early = 0;
1119
1120         lock_sock(sk);
1121
1122         TCP_CHECK_TIMER(sk);
1123
1124         err = -ENOTCONN;
1125         if (sk->sk_state == TCP_LISTEN)
1126                 goto out;
1127
1128         timeo = sock_rcvtimeo(sk, nonblock);
1129
1130         /* Urgent data needs to be handled specially. */
1131         if (flags & MSG_OOB)
1132                 goto recv_urg;
1133
1134         seq = &tp->copied_seq;
1135         if (flags & MSG_PEEK) {
1136                 peek_seq = tp->copied_seq;
1137                 seq = &peek_seq;
1138         }
1139
1140         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1141
1142 #ifdef CONFIG_NET_DMA
1143         tp->ucopy.dma_chan = NULL;
1144         preempt_disable();
1145         if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
1146             !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) {
1147                 preempt_enable_no_resched();
1148                 tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len);
1149         } else
1150                 preempt_enable_no_resched();
1151 #endif
1152
1153         do {
1154                 struct sk_buff *skb;
1155                 u32 offset;
1156
1157                 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1158                 if (tp->urg_data && tp->urg_seq == *seq) {
1159                         if (copied)
1160                                 break;
1161                         if (signal_pending(current)) {
1162                                 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1163                                 break;
1164                         }
1165                 }
1166
1167                 /* Next get a buffer. */
1168
1169                 skb = skb_peek(&sk->sk_receive_queue);
1170                 do {
1171                         if (!skb)
1172                                 break;
1173
1174                         /* Now that we have two receive queues this
1175                          * shouldn't happen.
1176                          */
1177                         if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1178                                 printk(KERN_INFO "recvmsg bug: copied %X "
1179                                        "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1180                                 break;
1181                         }
1182                         offset = *seq - TCP_SKB_CB(skb)->seq;
1183                         if (tcp_hdr(skb)->syn)
1184                                 offset--;
1185                         if (offset < skb->len)
1186                                 goto found_ok_skb;
1187                         if (tcp_hdr(skb)->fin)
1188                                 goto found_fin_ok;
1189                         BUG_TRAP(flags & MSG_PEEK);
1190                         skb = skb->next;
1191                 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1192
1193                 /* Well, if we have backlog, try to process it now yet. */
1194
1195                 if (copied >= target && !sk->sk_backlog.tail)
1196                         break;
1197
1198                 if (copied) {
1199                         if (sk->sk_err ||
1200                             sk->sk_state == TCP_CLOSE ||
1201                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
1202                             !timeo ||
1203                             signal_pending(current) ||
1204                             (flags & MSG_PEEK))
1205                                 break;
1206                 } else {
1207                         if (sock_flag(sk, SOCK_DONE))
1208                                 break;
1209
1210                         if (sk->sk_err) {
1211                                 copied = sock_error(sk);
1212                                 break;
1213                         }
1214
1215                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1216                                 break;
1217
1218                         if (sk->sk_state == TCP_CLOSE) {
1219                                 if (!sock_flag(sk, SOCK_DONE)) {
1220                                         /* This occurs when user tries to read
1221                                          * from never connected socket.
1222                                          */
1223                                         copied = -ENOTCONN;
1224                                         break;
1225                                 }
1226                                 break;
1227                         }
1228
1229                         if (!timeo) {
1230                                 copied = -EAGAIN;
1231                                 break;
1232                         }
1233
1234                         if (signal_pending(current)) {
1235                                 copied = sock_intr_errno(timeo);
1236                                 break;
1237                         }
1238                 }
1239
1240                 tcp_cleanup_rbuf(sk, copied);
1241
1242                 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1243                         /* Install new reader */
1244                         if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1245                                 user_recv = current;
1246                                 tp->ucopy.task = user_recv;
1247                                 tp->ucopy.iov = msg->msg_iov;
1248                         }
1249
1250                         tp->ucopy.len = len;
1251
1252                         BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1253                                  (flags & (MSG_PEEK | MSG_TRUNC)));
1254
1255                         /* Ugly... If prequeue is not empty, we have to
1256                          * process it before releasing socket, otherwise
1257                          * order will be broken at second iteration.
1258                          * More elegant solution is required!!!
1259                          *
1260                          * Look: we have the following (pseudo)queues:
1261                          *
1262                          * 1. packets in flight
1263                          * 2. backlog
1264                          * 3. prequeue
1265                          * 4. receive_queue
1266                          *
1267                          * Each queue can be processed only if the next ones
1268                          * are empty. At this point we have empty receive_queue.
1269                          * But prequeue _can_ be not empty after 2nd iteration,
1270                          * when we jumped to start of loop because backlog
1271                          * processing added something to receive_queue.
1272                          * We cannot release_sock(), because backlog contains
1273                          * packets arrived _after_ prequeued ones.
1274                          *
1275                          * Shortly, algorithm is clear --- to process all
1276                          * the queues in order. We could make it more directly,
1277                          * requeueing packets from backlog to prequeue, if
1278                          * is not empty. It is more elegant, but eats cycles,
1279                          * unfortunately.
1280                          */
1281                         if (!skb_queue_empty(&tp->ucopy.prequeue))
1282                                 goto do_prequeue;
1283
1284                         /* __ Set realtime policy in scheduler __ */
1285                 }
1286
1287                 if (copied >= target) {
1288                         /* Do not sleep, just process backlog. */
1289                         release_sock(sk);
1290                         lock_sock(sk);
1291                 } else
1292                         sk_wait_data(sk, &timeo);
1293
1294 #ifdef CONFIG_NET_DMA
1295                 tp->ucopy.wakeup = 0;
1296 #endif
1297
1298                 if (user_recv) {
1299                         int chunk;
1300
1301                         /* __ Restore normal policy in scheduler __ */
1302
1303                         if ((chunk = len - tp->ucopy.len) != 0) {
1304                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1305                                 len -= chunk;
1306                                 copied += chunk;
1307                         }
1308
1309                         if (tp->rcv_nxt == tp->copied_seq &&
1310                             !skb_queue_empty(&tp->ucopy.prequeue)) {
1311 do_prequeue:
1312                                 tcp_prequeue_process(sk);
1313
1314                                 if ((chunk = len - tp->ucopy.len) != 0) {
1315                                         NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1316                                         len -= chunk;
1317                                         copied += chunk;
1318                                 }
1319                         }
1320                 }
1321                 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1322                         if (net_ratelimit())
1323                                 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1324                                        current->comm, current->pid);
1325                         peek_seq = tp->copied_seq;
1326                 }
1327                 continue;
1328
1329         found_ok_skb:
1330                 /* Ok so how much can we use? */
1331                 used = skb->len - offset;
1332                 if (len < used)
1333                         used = len;
1334
1335                 /* Do we have urgent data here? */
1336                 if (tp->urg_data) {
1337                         u32 urg_offset = tp->urg_seq - *seq;
1338                         if (urg_offset < used) {
1339                                 if (!urg_offset) {
1340                                         if (!sock_flag(sk, SOCK_URGINLINE)) {
1341                                                 ++*seq;
1342                                                 offset++;
1343                                                 used--;
1344                                                 if (!used)
1345                                                         goto skip_copy;
1346                                         }
1347                                 } else
1348                                         used = urg_offset;
1349                         }
1350                 }
1351
1352                 if (!(flags & MSG_TRUNC)) {
1353 #ifdef CONFIG_NET_DMA
1354                         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1355                                 tp->ucopy.dma_chan = get_softnet_dma();
1356
1357                         if (tp->ucopy.dma_chan) {
1358                                 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
1359                                         tp->ucopy.dma_chan, skb, offset,
1360                                         msg->msg_iov, used,
1361                                         tp->ucopy.pinned_list);
1362
1363                                 if (tp->ucopy.dma_cookie < 0) {
1364
1365                                         printk(KERN_ALERT "dma_cookie < 0\n");
1366
1367                                         /* Exception. Bailout! */
1368                                         if (!copied)
1369                                                 copied = -EFAULT;
1370                                         break;
1371                                 }
1372                                 if ((offset + used) == skb->len)
1373                                         copied_early = 1;
1374
1375                         } else
1376 #endif
1377                         {
1378                                 err = skb_copy_datagram_iovec(skb, offset,
1379                                                 msg->msg_iov, used);
1380                                 if (err) {
1381                                         /* Exception. Bailout! */
1382                                         if (!copied)
1383                                                 copied = -EFAULT;
1384                                         break;
1385                                 }
1386                         }
1387                 }
1388
1389                 *seq += used;
1390                 copied += used;
1391                 len -= used;
1392
1393                 tcp_rcv_space_adjust(sk);
1394
1395 skip_copy:
1396                 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1397                         tp->urg_data = 0;
1398                         tcp_fast_path_check(sk);
1399                 }
1400                 if (used + offset < skb->len)
1401                         continue;
1402
1403                 if (tcp_hdr(skb)->fin)
1404                         goto found_fin_ok;
1405                 if (!(flags & MSG_PEEK)) {
1406                         sk_eat_skb(sk, skb, copied_early);
1407                         copied_early = 0;
1408                 }
1409                 continue;
1410
1411         found_fin_ok:
1412                 /* Process the FIN. */
1413                 ++*seq;
1414                 if (!(flags & MSG_PEEK)) {
1415                         sk_eat_skb(sk, skb, copied_early);
1416                         copied_early = 0;
1417                 }
1418                 break;
1419         } while (len > 0);
1420
1421         if (user_recv) {
1422                 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1423                         int chunk;
1424
1425                         tp->ucopy.len = copied > 0 ? len : 0;
1426
1427                         tcp_prequeue_process(sk);
1428
1429                         if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1430                                 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1431                                 len -= chunk;
1432                                 copied += chunk;
1433                         }
1434                 }
1435
1436                 tp->ucopy.task = NULL;
1437                 tp->ucopy.len = 0;
1438         }
1439
1440 #ifdef CONFIG_NET_DMA
1441         if (tp->ucopy.dma_chan) {
1442                 struct sk_buff *skb;
1443                 dma_cookie_t done, used;
1444
1445                 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
1446
1447                 while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
1448                                                  tp->ucopy.dma_cookie, &done,
1449                                                  &used) == DMA_IN_PROGRESS) {
1450                         /* do partial cleanup of sk_async_wait_queue */
1451                         while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
1452                                (dma_async_is_complete(skb->dma_cookie, done,
1453                                                       used) == DMA_SUCCESS)) {
1454                                 __skb_dequeue(&sk->sk_async_wait_queue);
1455                                 kfree_skb(skb);
1456                         }
1457                 }
1458
1459                 /* Safe to free early-copied skbs now */
1460                 __skb_queue_purge(&sk->sk_async_wait_queue);
1461                 dma_chan_put(tp->ucopy.dma_chan);
1462                 tp->ucopy.dma_chan = NULL;
1463         }
1464         if (tp->ucopy.pinned_list) {
1465                 dma_unpin_iovec_pages(tp->ucopy.pinned_list);
1466                 tp->ucopy.pinned_list = NULL;
1467         }
1468 #endif
1469
1470         /* According to UNIX98, msg_name/msg_namelen are ignored
1471          * on connected socket. I was just happy when found this 8) --ANK
1472          */
1473
1474         /* Clean up data we have read: This will do ACK frames. */
1475         tcp_cleanup_rbuf(sk, copied);
1476
1477         TCP_CHECK_TIMER(sk);
1478         release_sock(sk);
1479         return copied;
1480
1481 out:
1482         TCP_CHECK_TIMER(sk);
1483         release_sock(sk);
1484         return err;
1485
1486 recv_urg:
1487         err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1488         goto out;
1489 }
1490
1491 /*
1492  *      State processing on a close. This implements the state shift for
1493  *      sending our FIN frame. Note that we only send a FIN for some
1494  *      states. A shutdown() may have already sent the FIN, or we may be
1495  *      closed.
1496  */
1497
1498 static const unsigned char new_state[16] = {
1499   /* current state:        new state:      action:      */
1500   /* (Invalid)          */ TCP_CLOSE,
1501   /* TCP_ESTABLISHED    */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1502   /* TCP_SYN_SENT       */ TCP_CLOSE,
1503   /* TCP_SYN_RECV       */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1504   /* TCP_FIN_WAIT1      */ TCP_FIN_WAIT1,
1505   /* TCP_FIN_WAIT2      */ TCP_FIN_WAIT2,
1506   /* TCP_TIME_WAIT      */ TCP_CLOSE,
1507   /* TCP_CLOSE          */ TCP_CLOSE,
1508   /* TCP_CLOSE_WAIT     */ TCP_LAST_ACK  | TCP_ACTION_FIN,
1509   /* TCP_LAST_ACK       */ TCP_LAST_ACK,
1510   /* TCP_LISTEN         */ TCP_CLOSE,
1511   /* TCP_CLOSING        */ TCP_CLOSING,
1512 };
1513
1514 static int tcp_close_state(struct sock *sk)
1515 {
1516         int next = (int)new_state[sk->sk_state];
1517         int ns = next & TCP_STATE_MASK;
1518
1519         tcp_set_state(sk, ns);
1520
1521         return next & TCP_ACTION_FIN;
1522 }
1523
1524 /*
1525  *      Shutdown the sending side of a connection. Much like close except
1526  *      that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
1527  */
1528
1529 void tcp_shutdown(struct sock *sk, int how)
1530 {
1531         /*      We need to grab some memory, and put together a FIN,
1532          *      and then put it into the queue to be sent.
1533          *              Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1534          */
1535         if (!(how & SEND_SHUTDOWN))
1536                 return;
1537
1538         /* If we've already sent a FIN, or it's a closed state, skip this. */
1539         if ((1 << sk->sk_state) &
1540             (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1541              TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1542                 /* Clear out any half completed packets.  FIN if needed. */
1543                 if (tcp_close_state(sk))
1544                         tcp_send_fin(sk);
1545         }
1546 }
1547
1548 void tcp_close(struct sock *sk, long timeout)
1549 {
1550         struct sk_buff *skb;
1551         int data_was_unread = 0;
1552         int state;
1553
1554         lock_sock(sk);
1555         sk->sk_shutdown = SHUTDOWN_MASK;
1556
1557         if (sk->sk_state == TCP_LISTEN) {
1558                 tcp_set_state(sk, TCP_CLOSE);
1559
1560                 /* Special case. */
1561                 inet_csk_listen_stop(sk);
1562
1563                 goto adjudge_to_death;
1564         }
1565
1566         /*  We need to flush the recv. buffs.  We do this only on the
1567          *  descriptor close, not protocol-sourced closes, because the
1568          *  reader process may not have drained the data yet!
1569          */
1570         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1571                 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1572                           tcp_hdr(skb)->fin;
1573                 data_was_unread += len;
1574                 __kfree_skb(skb);
1575         }
1576
1577         sk_stream_mem_reclaim(sk);
1578
1579         /* As outlined in RFC 2525, section 2.17, we send a RST here because
1580          * data was lost. To witness the awful effects of the old behavior of
1581          * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
1582          * GET in an FTP client, suspend the process, wait for the client to
1583          * advertise a zero window, then kill -9 the FTP client, wheee...
1584          * Note: timeout is always zero in such a case.
1585          */
1586         if (data_was_unread) {
1587                 /* Unread data was tossed, zap the connection. */
1588                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1589                 tcp_set_state(sk, TCP_CLOSE);
1590                 tcp_send_active_reset(sk, GFP_KERNEL);
1591         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1592                 /* Check zero linger _after_ checking for unread data. */
1593                 sk->sk_prot->disconnect(sk, 0);
1594                 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1595         } else if (tcp_close_state(sk)) {
1596                 /* We FIN if the application ate all the data before
1597                  * zapping the connection.
1598                  */
1599
1600                 /* RED-PEN. Formally speaking, we have broken TCP state
1601                  * machine. State transitions:
1602                  *
1603                  * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1604                  * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1605                  * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1606                  *
1607                  * are legal only when FIN has been sent (i.e. in window),
1608                  * rather than queued out of window. Purists blame.
1609                  *
1610                  * F.e. "RFC state" is ESTABLISHED,
1611                  * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1612                  *
1613                  * The visible declinations are that sometimes
1614                  * we enter time-wait state, when it is not required really
1615                  * (harmless), do not send active resets, when they are
1616                  * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1617                  * they look as CLOSING or LAST_ACK for Linux)
1618                  * Probably, I missed some more holelets.
1619                  *                                              --ANK
1620                  */
1621                 tcp_send_fin(sk);
1622         }
1623
1624         sk_stream_wait_close(sk, timeout);
1625
1626 adjudge_to_death:
1627         state = sk->sk_state;
1628         sock_hold(sk);
1629         sock_orphan(sk);
1630         atomic_inc(sk->sk_prot->orphan_count);
1631
1632         /* It is the last release_sock in its life. It will remove backlog. */
1633         release_sock(sk);
1634
1635
1636         /* Now socket is owned by kernel and we acquire BH lock
1637            to finish close. No need to check for user refs.
1638          */
1639         local_bh_disable();
1640         bh_lock_sock(sk);
1641         BUG_TRAP(!sock_owned_by_user(sk));
1642
1643         /* Have we already been destroyed by a softirq or backlog? */
1644         if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1645                 goto out;
1646
1647         /*      This is a (useful) BSD violating of the RFC. There is a
1648          *      problem with TCP as specified in that the other end could
1649          *      keep a socket open forever with no application left this end.
1650          *      We use a 3 minute timeout (about the same as BSD) then kill
1651          *      our end. If they send after that then tough - BUT: long enough
1652          *      that we won't make the old 4*rto = almost no time - whoops
1653          *      reset mistake.
1654          *
1655          *      Nope, it was not mistake. It is really desired behaviour
1656          *      f.e. on http servers, when such sockets are useless, but
1657          *      consume significant resources. Let's do it with special
1658          *      linger2 option.                                 --ANK
1659          */
1660
1661         if (sk->sk_state == TCP_FIN_WAIT2) {
1662                 struct tcp_sock *tp = tcp_sk(sk);
1663                 if (tp->linger2 < 0) {
1664                         tcp_set_state(sk, TCP_CLOSE);
1665                         tcp_send_active_reset(sk, GFP_ATOMIC);
1666                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1667                 } else {
1668                         const int tmo = tcp_fin_time(sk);
1669
1670                         if (tmo > TCP_TIMEWAIT_LEN) {
1671                                 inet_csk_reset_keepalive_timer(sk,
1672                                                 tmo - TCP_TIMEWAIT_LEN);
1673                         } else {
1674                                 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1675                                 goto out;
1676                         }
1677                 }
1678         }
1679         if (sk->sk_state != TCP_CLOSE) {
1680                 sk_stream_mem_reclaim(sk);
1681                 if (tcp_too_many_orphans(sk,
1682                                 atomic_read(sk->sk_prot->orphan_count))) {
1683                         if (net_ratelimit())
1684                                 printk(KERN_INFO "TCP: too many of orphaned "
1685                                        "sockets\n");
1686                         tcp_set_state(sk, TCP_CLOSE);
1687                         tcp_send_active_reset(sk, GFP_ATOMIC);
1688                         NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1689                 }
1690         }
1691
1692         if (sk->sk_state == TCP_CLOSE)
1693                 inet_csk_destroy_sock(sk);
1694         /* Otherwise, socket is reprieved until protocol close. */
1695
1696 out:
1697         bh_unlock_sock(sk);
1698         local_bh_enable();
1699         sock_put(sk);
1700 }
1701
1702 /* These states need RST on ABORT according to RFC793 */
1703
1704 static inline int tcp_need_reset(int state)
1705 {
1706         return (1 << state) &
1707                (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1708                 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1709 }
1710
1711 int tcp_disconnect(struct sock *sk, int flags)
1712 {
1713         struct inet_sock *inet = inet_sk(sk);
1714         struct inet_connection_sock *icsk = inet_csk(sk);
1715         struct tcp_sock *tp = tcp_sk(sk);
1716         int err = 0;
1717         int old_state = sk->sk_state;
1718
1719         if (old_state != TCP_CLOSE)
1720                 tcp_set_state(sk, TCP_CLOSE);
1721
1722         /* ABORT function of RFC793 */
1723         if (old_state == TCP_LISTEN) {
1724                 inet_csk_listen_stop(sk);
1725         } else if (tcp_need_reset(old_state) ||
1726                    (tp->snd_nxt != tp->write_seq &&
1727                     (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1728                 /* The last check adjusts for discrepancy of Linux wrt. RFC
1729                  * states
1730                  */
1731                 tcp_send_active_reset(sk, gfp_any());
1732                 sk->sk_err = ECONNRESET;
1733         } else if (old_state == TCP_SYN_SENT)
1734                 sk->sk_err = ECONNRESET;
1735
1736         tcp_clear_xmit_timers(sk);
1737         __skb_queue_purge(&sk->sk_receive_queue);
1738         tcp_write_queue_purge(sk);
1739         __skb_queue_purge(&tp->out_of_order_queue);
1740 #ifdef CONFIG_NET_DMA
1741         __skb_queue_purge(&sk->sk_async_wait_queue);
1742 #endif
1743
1744         inet->dport = 0;
1745
1746         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1747                 inet_reset_saddr(sk);
1748
1749         sk->sk_shutdown = 0;
1750         sock_reset_flag(sk, SOCK_DONE);
1751         tp->srtt = 0;
1752         if ((tp->write_seq += tp->max_window + 2) == 0)
1753                 tp->write_seq = 1;
1754         icsk->icsk_backoff = 0;
1755         tp->snd_cwnd = 2;
1756         icsk->icsk_probes_out = 0;
1757         tp->packets_out = 0;
1758         tp->snd_ssthresh = 0x7fffffff;
1759         tp->snd_cwnd_cnt = 0;
1760         tp->bytes_acked = 0;
1761         tcp_set_ca_state(sk, TCP_CA_Open);
1762         tcp_clear_retrans(tp);
1763         inet_csk_delack_init(sk);
1764         tcp_init_send_head(sk);
1765         memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
1766         __sk_dst_reset(sk);
1767
1768         BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1769
1770         sk->sk_error_report(sk);
1771         return err;
1772 }
1773
1774 /*
1775  *      Socket option code for TCP.
1776  */
1777 static int do_tcp_setsockopt(struct sock *sk, int level,
1778                 int optname, char __user *optval, int optlen)
1779 {
1780         struct tcp_sock *tp = tcp_sk(sk);
1781         struct inet_connection_sock *icsk = inet_csk(sk);
1782         int val;
1783         int err = 0;
1784
1785         /* This is a string value all the others are int's */
1786         if (optname == TCP_CONGESTION) {
1787                 char name[TCP_CA_NAME_MAX];
1788
1789                 if (optlen < 1)
1790                         return -EINVAL;
1791
1792                 val = strncpy_from_user(name, optval,
1793                                         min(TCP_CA_NAME_MAX-1, optlen));
1794                 if (val < 0)
1795                         return -EFAULT;
1796                 name[val] = 0;
1797
1798                 lock_sock(sk);
1799                 err = tcp_set_congestion_control(sk, name);
1800                 release_sock(sk);
1801                 return err;
1802         }
1803
1804         if (optlen < sizeof(int))
1805                 return -EINVAL;
1806
1807         if (get_user(val, (int __user *)optval))
1808                 return -EFAULT;
1809
1810         lock_sock(sk);
1811
1812         switch (optname) {
1813         case TCP_MAXSEG:
1814                 /* Values greater than interface MTU won't take effect. However
1815                  * at the point when this call is done we typically don't yet
1816                  * know which interface is going to be used */
1817                 if (val < 8 || val > MAX_TCP_WINDOW) {
1818                         err = -EINVAL;
1819                         break;
1820                 }
1821                 tp->rx_opt.user_mss = val;
1822                 break;
1823
1824         case TCP_NODELAY:
1825                 if (val) {
1826                         /* TCP_NODELAY is weaker than TCP_CORK, so that
1827                          * this option on corked socket is remembered, but
1828                          * it is not activated until cork is cleared.
1829                          *
1830                          * However, when TCP_NODELAY is set we make
1831                          * an explicit push, which overrides even TCP_CORK
1832                          * for currently queued segments.
1833                          */
1834                         tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
1835                         tcp_push_pending_frames(sk);
1836                 } else {
1837                         tp->nonagle &= ~TCP_NAGLE_OFF;
1838                 }
1839                 break;
1840
1841         case TCP_CORK:
1842                 /* When set indicates to always queue non-full frames.
1843                  * Later the user clears this option and we transmit
1844                  * any pending partial frames in the queue.  This is
1845                  * meant to be used alongside sendfile() to get properly
1846                  * filled frames when the user (for example) must write
1847                  * out headers with a write() call first and then use
1848                  * sendfile to send out the data parts.
1849                  *
1850                  * TCP_CORK can be set together with TCP_NODELAY and it is
1851                  * stronger than TCP_NODELAY.
1852                  */
1853                 if (val) {
1854                         tp->nonagle |= TCP_NAGLE_CORK;
1855                 } else {
1856                         tp->nonagle &= ~TCP_NAGLE_CORK;
1857                         if (tp->nonagle&TCP_NAGLE_OFF)
1858                                 tp->nonagle |= TCP_NAGLE_PUSH;
1859                         tcp_push_pending_frames(sk);
1860                 }
1861                 break;
1862
1863         case TCP_KEEPIDLE:
1864                 if (val < 1 || val > MAX_TCP_KEEPIDLE)
1865                         err = -EINVAL;
1866                 else {
1867                         tp->keepalive_time = val * HZ;
1868                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
1869                             !((1 << sk->sk_state) &
1870                               (TCPF_CLOSE | TCPF_LISTEN))) {
1871                                 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
1872                                 if (tp->keepalive_time > elapsed)
1873                                         elapsed = tp->keepalive_time - elapsed;
1874                                 else
1875                                         elapsed = 0;
1876                                 inet_csk_reset_keepalive_timer(sk, elapsed);
1877                         }
1878                 }
1879                 break;
1880         case TCP_KEEPINTVL:
1881                 if (val < 1 || val > MAX_TCP_KEEPINTVL)
1882                         err = -EINVAL;
1883                 else
1884                         tp->keepalive_intvl = val * HZ;
1885                 break;
1886         case TCP_KEEPCNT:
1887                 if (val < 1 || val > MAX_TCP_KEEPCNT)
1888                         err = -EINVAL;
1889                 else
1890                         tp->keepalive_probes = val;
1891                 break;
1892         case TCP_SYNCNT:
1893                 if (val < 1 || val > MAX_TCP_SYNCNT)
1894                         err = -EINVAL;
1895                 else
1896                         icsk->icsk_syn_retries = val;
1897                 break;
1898
1899         case TCP_LINGER2:
1900                 if (val < 0)
1901                         tp->linger2 = -1;
1902                 else if (val > sysctl_tcp_fin_timeout / HZ)
1903                         tp->linger2 = 0;
1904                 else
1905                         tp->linger2 = val * HZ;
1906                 break;
1907
1908         case TCP_DEFER_ACCEPT:
1909                 icsk->icsk_accept_queue.rskq_defer_accept = 0;
1910                 if (val > 0) {
1911                         /* Translate value in seconds to number of
1912                          * retransmits */
1913                         while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
1914                                val > ((TCP_TIMEOUT_INIT / HZ) <<
1915                                        icsk->icsk_accept_queue.rskq_defer_accept))
1916                                 icsk->icsk_accept_queue.rskq_defer_accept++;
1917                         icsk->icsk_accept_queue.rskq_defer_accept++;
1918                 }
1919                 break;
1920
1921         case TCP_WINDOW_CLAMP:
1922                 if (!val) {
1923                         if (sk->sk_state != TCP_CLOSE) {
1924                                 err = -EINVAL;
1925                                 break;
1926                         }
1927                         tp->window_clamp = 0;
1928                 } else
1929                         tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
1930                                                 SOCK_MIN_RCVBUF / 2 : val;
1931                 break;
1932
1933         case TCP_QUICKACK:
1934                 if (!val) {
1935                         icsk->icsk_ack.pingpong = 1;
1936                 } else {
1937                         icsk->icsk_ack.pingpong = 0;
1938                         if ((1 << sk->sk_state) &
1939                             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
1940                             inet_csk_ack_scheduled(sk)) {
1941                                 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
1942                                 tcp_cleanup_rbuf(sk, 1);
1943                                 if (!(val & 1))
1944                                         icsk->icsk_ack.pingpong = 1;
1945                         }
1946                 }
1947                 break;
1948
1949 #ifdef CONFIG_TCP_MD5SIG
1950         case TCP_MD5SIG:
1951                 /* Read the IP->Key mappings from userspace */
1952                 err = tp->af_specific->md5_parse(sk, optval, optlen);
1953                 break;
1954 #endif
1955
1956         default:
1957                 err = -ENOPROTOOPT;
1958                 break;
1959         }
1960
1961         release_sock(sk);
1962         return err;
1963 }
1964
1965 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
1966                    int optlen)
1967 {
1968         struct inet_connection_sock *icsk = inet_csk(sk);
1969
1970         if (level != SOL_TCP)
1971                 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1972                                                      optval, optlen);
1973         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1974 }
1975
1976 #ifdef CONFIG_COMPAT
1977 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
1978                           char __user *optval, int optlen)
1979 {
1980         if (level != SOL_TCP)
1981                 return inet_csk_compat_setsockopt(sk, level, optname,
1982                                                   optval, optlen);
1983         return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1984 }
1985
1986 EXPORT_SYMBOL(compat_tcp_setsockopt);
1987 #endif
1988
1989 /* Return information about state of tcp endpoint in API format. */
1990 void tcp_get_info(struct sock *sk, struct tcp_info *info)
1991 {
1992         struct tcp_sock *tp = tcp_sk(sk);
1993         const struct inet_connection_sock *icsk = inet_csk(sk);
1994         u32 now = tcp_time_stamp;
1995
1996         memset(info, 0, sizeof(*info));
1997
1998         info->tcpi_state = sk->sk_state;
1999         info->tcpi_ca_state = icsk->icsk_ca_state;
2000         info->tcpi_retransmits = icsk->icsk_retransmits;
2001         info->tcpi_probes = icsk->icsk_probes_out;
2002         info->tcpi_backoff = icsk->icsk_backoff;
2003
2004         if (tp->rx_opt.tstamp_ok)
2005                 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
2006         if (tp->rx_opt.sack_ok)
2007                 info->tcpi_options |= TCPI_OPT_SACK;
2008         if (tp->rx_opt.wscale_ok) {
2009                 info->tcpi_options |= TCPI_OPT_WSCALE;
2010                 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
2011                 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
2012         }
2013
2014         if (tp->ecn_flags&TCP_ECN_OK)
2015                 info->tcpi_options |= TCPI_OPT_ECN;
2016
2017         info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
2018         info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
2019         info->tcpi_snd_mss = tp->mss_cache;
2020         info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
2021
2022         info->tcpi_unacked = tp->packets_out;
2023         info->tcpi_sacked = tp->sacked_out;
2024         info->tcpi_lost = tp->lost_out;
2025         info->tcpi_retrans = tp->retrans_out;
2026         info->tcpi_fackets = tp->fackets_out;
2027
2028         info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
2029         info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
2030         info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
2031
2032         info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
2033         info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
2034         info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
2035         info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
2036         info->tcpi_snd_ssthresh = tp->snd_ssthresh;
2037         info->tcpi_snd_cwnd = tp->snd_cwnd;
2038         info->tcpi_advmss = tp->advmss;
2039         info->tcpi_reordering = tp->reordering;
2040
2041         info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
2042         info->tcpi_rcv_space = tp->rcvq_space.space;
2043
2044         info->tcpi_total_retrans = tp->total_retrans;
2045 }
2046
2047 EXPORT_SYMBOL_GPL(tcp_get_info);
2048
2049 static int do_tcp_getsockopt(struct sock *sk, int level,
2050                 int optname, char __user *optval, int __user *optlen)
2051 {
2052         struct inet_connection_sock *icsk = inet_csk(sk);
2053         struct tcp_sock *tp = tcp_sk(sk);
2054         int val, len;
2055
2056         if (get_user(len, optlen))
2057                 return -EFAULT;
2058
2059         len = min_t(unsigned int, len, sizeof(int));
2060
2061         if (len < 0)
2062                 return -EINVAL;
2063
2064         switch (optname) {
2065         case TCP_MAXSEG:
2066                 val = tp->mss_cache;
2067                 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
2068                         val = tp->rx_opt.user_mss;
2069                 break;
2070         case TCP_NODELAY:
2071                 val = !!(tp->nonagle&TCP_NAGLE_OFF);
2072                 break;
2073         case TCP_CORK:
2074                 val = !!(tp->nonagle&TCP_NAGLE_CORK);
2075                 break;
2076         case TCP_KEEPIDLE:
2077                 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
2078                 break;
2079         case TCP_KEEPINTVL:
2080                 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
2081                 break;
2082         case TCP_KEEPCNT:
2083                 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
2084                 break;
2085         case TCP_SYNCNT:
2086                 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
2087                 break;
2088         case TCP_LINGER2:
2089                 val = tp->linger2;
2090                 if (val >= 0)
2091                         val = (val ? : sysctl_tcp_fin_timeout) / HZ;
2092                 break;
2093         case TCP_DEFER_ACCEPT:
2094                 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2095                         ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2096                 break;
2097         case TCP_WINDOW_CLAMP:
2098                 val = tp->window_clamp;
2099                 break;
2100         case TCP_INFO: {
2101                 struct tcp_info info;
2102
2103                 if (get_user(len, optlen))
2104                         return -EFAULT;
2105
2106                 tcp_get_info(sk, &info);
2107
2108                 len = min_t(unsigned int, len, sizeof(info));
2109                 if (put_user(len, optlen))
2110                         return -EFAULT;
2111                 if (copy_to_user(optval, &info, len))
2112                         return -EFAULT;
2113                 return 0;
2114         }
2115         case TCP_QUICKACK:
2116                 val = !icsk->icsk_ack.pingpong;
2117                 break;
2118
2119         case TCP_CONGESTION:
2120                 if (get_user(len, optlen))
2121                         return -EFAULT;
2122                 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2123                 if (put_user(len, optlen))
2124                         return -EFAULT;
2125                 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2126                         return -EFAULT;
2127                 return 0;
2128         default:
2129                 return -ENOPROTOOPT;
2130         }
2131
2132         if (put_user(len, optlen))
2133                 return -EFAULT;
2134         if (copy_to_user(optval, &val, len))
2135                 return -EFAULT;
2136         return 0;
2137 }
2138
2139 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2140                    int __user *optlen)
2141 {
2142         struct inet_connection_sock *icsk = inet_csk(sk);
2143
2144         if (level != SOL_TCP)
2145                 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2146                                                      optval, optlen);
2147         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2148 }
2149
2150 #ifdef CONFIG_COMPAT
2151 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2152                           char __user *optval, int __user *optlen)
2153 {
2154         if (level != SOL_TCP)
2155                 return inet_csk_compat_getsockopt(sk, level, optname,
2156                                                   optval, optlen);
2157         return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2158 }
2159
2160 EXPORT_SYMBOL(compat_tcp_getsockopt);
2161 #endif
2162
2163 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2164 {
2165         struct sk_buff *segs = ERR_PTR(-EINVAL);
2166         struct tcphdr *th;
2167         unsigned thlen;
2168         unsigned int seq;
2169         __be32 delta;
2170         unsigned int oldlen;
2171         unsigned int len;
2172
2173         if (!pskb_may_pull(skb, sizeof(*th)))
2174                 goto out;
2175
2176         th = tcp_hdr(skb);
2177         thlen = th->doff * 4;
2178         if (thlen < sizeof(*th))
2179                 goto out;
2180
2181         if (!pskb_may_pull(skb, thlen))
2182                 goto out;
2183
2184         oldlen = (u16)~skb->len;
2185         __skb_pull(skb, thlen);
2186
2187         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2188                 /* Packet is from an untrusted source, reset gso_segs. */
2189                 int type = skb_shinfo(skb)->gso_type;
2190                 int mss;
2191
2192                 if (unlikely(type &
2193                              ~(SKB_GSO_TCPV4 |
2194                                SKB_GSO_DODGY |
2195                                SKB_GSO_TCP_ECN |
2196                                SKB_GSO_TCPV6 |
2197                                0) ||
2198                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
2199                         goto out;
2200
2201                 mss = skb_shinfo(skb)->gso_size;
2202                 skb_shinfo(skb)->gso_segs = (skb->len + mss - 1) / mss;
2203
2204                 segs = NULL;
2205                 goto out;
2206         }
2207
2208         segs = skb_segment(skb, features);
2209         if (IS_ERR(segs))
2210                 goto out;
2211
2212         len = skb_shinfo(skb)->gso_size;
2213         delta = htonl(oldlen + (thlen + len));
2214
2215         skb = segs;
2216         th = tcp_hdr(skb);
2217         seq = ntohl(th->seq);
2218
2219         do {
2220                 th->fin = th->psh = 0;
2221
2222                 th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2223                                        (__force u32)delta));
2224                 if (skb->ip_summed != CHECKSUM_PARTIAL)
2225                         th->check =
2226                              csum_fold(csum_partial(skb_transport_header(skb),
2227                                                     thlen, skb->csum));
2228
2229                 seq += len;
2230                 skb = skb->next;
2231                 th = tcp_hdr(skb);
2232
2233                 th->seq = htonl(seq);
2234                 th->cwr = 0;
2235         } while (skb->next);
2236
2237         delta = htonl(oldlen + (skb->tail - skb->transport_header) +
2238                       skb->data_len);
2239         th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
2240                                 (__force u32)delta));
2241         if (skb->ip_summed != CHECKSUM_PARTIAL)
2242                 th->check = csum_fold(csum_partial(skb_transport_header(skb),
2243                                                    thlen, skb->csum));
2244
2245 out:
2246         return segs;
2247 }
2248 EXPORT_SYMBOL(tcp_tso_segment);
2249
2250 #ifdef CONFIG_TCP_MD5SIG
2251 static unsigned long tcp_md5sig_users;
2252 static struct tcp_md5sig_pool **tcp_md5sig_pool;
2253 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
2254
2255 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool)
2256 {
2257         int cpu;
2258         for_each_possible_cpu(cpu) {
2259                 struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu);
2260                 if (p) {
2261                         if (p->md5_desc.tfm)
2262                                 crypto_free_hash(p->md5_desc.tfm);
2263                         kfree(p);
2264                         p = NULL;
2265                 }
2266         }
2267         free_percpu(pool);
2268 }
2269
2270 void tcp_free_md5sig_pool(void)
2271 {
2272         struct tcp_md5sig_pool **pool = NULL;
2273
2274         spin_lock_bh(&tcp_md5sig_pool_lock);
2275         if (--tcp_md5sig_users == 0) {
2276                 pool = tcp_md5sig_pool;
2277                 tcp_md5sig_pool = NULL;
2278         }
2279         spin_unlock_bh(&tcp_md5sig_pool_lock);
2280         if (pool)
2281                 __tcp_free_md5sig_pool(pool);
2282 }
2283
2284 EXPORT_SYMBOL(tcp_free_md5sig_pool);
2285
2286 static struct tcp_md5sig_pool **__tcp_alloc_md5sig_pool(void)
2287 {
2288         int cpu;
2289         struct tcp_md5sig_pool **pool;
2290
2291         pool = alloc_percpu(struct tcp_md5sig_pool *);
2292         if (!pool)
2293                 return NULL;
2294
2295         for_each_possible_cpu(cpu) {
2296                 struct tcp_md5sig_pool *p;
2297                 struct crypto_hash *hash;
2298
2299                 p = kzalloc(sizeof(*p), GFP_KERNEL);
2300                 if (!p)
2301                         goto out_free;
2302                 *per_cpu_ptr(pool, cpu) = p;
2303
2304                 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
2305                 if (!hash || IS_ERR(hash))
2306                         goto out_free;
2307
2308                 p->md5_desc.tfm = hash;
2309         }
2310         return pool;
2311 out_free:
2312         __tcp_free_md5sig_pool(pool);
2313         return NULL;
2314 }
2315
2316 struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void)
2317 {
2318         struct tcp_md5sig_pool **pool;
2319         int alloc = 0;
2320
2321 retry:
2322         spin_lock_bh(&tcp_md5sig_pool_lock);
2323         pool = tcp_md5sig_pool;
2324         if (tcp_md5sig_users++ == 0) {
2325                 alloc = 1;
2326                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2327         } else if (!pool) {
2328                 tcp_md5sig_users--;
2329                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2330                 cpu_relax();
2331                 goto retry;
2332         } else
2333                 spin_unlock_bh(&tcp_md5sig_pool_lock);
2334
2335         if (alloc) {
2336                 /* we cannot hold spinlock here because this may sleep. */
2337                 struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool();
2338                 spin_lock_bh(&tcp_md5sig_pool_lock);
2339                 if (!p) {
2340                         tcp_md5sig_users--;
2341                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2342                         return NULL;
2343                 }
2344                 pool = tcp_md5sig_pool;
2345                 if (pool) {
2346                         /* oops, it has already been assigned. */
2347                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2348                         __tcp_free_md5sig_pool(p);
2349                 } else {
2350                         tcp_md5sig_pool = pool = p;
2351                         spin_unlock_bh(&tcp_md5sig_pool_lock);
2352                 }
2353         }
2354         return pool;
2355 }
2356
2357 EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
2358
2359 struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu)
2360 {
2361         struct tcp_md5sig_pool **p;
2362         spin_lock_bh(&tcp_md5sig_pool_lock);
2363         p = tcp_md5sig_pool;
2364         if (p)
2365                 tcp_md5sig_users++;
2366         spin_unlock_bh(&tcp_md5sig_pool_lock);
2367         return (p ? *per_cpu_ptr(p, cpu) : NULL);
2368 }
2369
2370 EXPORT_SYMBOL(__tcp_get_md5sig_pool);
2371
2372 void __tcp_put_md5sig_pool(void)
2373 {
2374         tcp_free_md5sig_pool();
2375 }
2376
2377 EXPORT_SYMBOL(__tcp_put_md5sig_pool);
2378 #endif
2379
2380 void tcp_done(struct sock *sk)
2381 {
2382         if(sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
2383                 TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
2384
2385         tcp_set_state(sk, TCP_CLOSE);
2386         tcp_clear_xmit_timers(sk);
2387
2388         sk->sk_shutdown = SHUTDOWN_MASK;
2389
2390         if (!sock_flag(sk, SOCK_DEAD))
2391                 sk->sk_state_change(sk);
2392         else
2393                 inet_csk_destroy_sock(sk);
2394 }
2395 EXPORT_SYMBOL_GPL(tcp_done);
2396
2397 extern void __skb_cb_too_small_for_tcp(int, int);
2398 extern struct tcp_congestion_ops tcp_reno;
2399
2400 static __initdata unsigned long thash_entries;
2401 static int __init set_thash_entries(char *str)
2402 {
2403         if (!str)
2404                 return 0;
2405         thash_entries = simple_strtoul(str, &str, 0);
2406         return 1;
2407 }
2408 __setup("thash_entries=", set_thash_entries);
2409
2410 void __init tcp_init(void)
2411 {
2412         struct sk_buff *skb = NULL;
2413         unsigned long limit;
2414         int order, i, max_share;
2415
2416         if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
2417                 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
2418                                            sizeof(skb->cb));
2419
2420         tcp_hashinfo.bind_bucket_cachep =
2421                 kmem_cache_create("tcp_bind_bucket",
2422                                   sizeof(struct inet_bind_bucket), 0,
2423                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
2424
2425         /* Size and allocate the main established and bind bucket
2426          * hash tables.
2427          *
2428          * The methodology is similar to that of the buffer cache.
2429          */
2430         tcp_hashinfo.ehash =
2431                 alloc_large_system_hash("TCP established",
2432                                         sizeof(struct inet_ehash_bucket),
2433                                         thash_entries,
2434                                         (num_physpages >= 128 * 1024) ?
2435                                         13 : 15,
2436                                         0,
2437                                         &tcp_hashinfo.ehash_size,
2438                                         NULL,
2439                                         0);
2440         tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
2441         for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
2442                 rwlock_init(&tcp_hashinfo.ehash[i].lock);
2443                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2444                 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain);
2445         }
2446
2447         tcp_hashinfo.bhash =
2448                 alloc_large_system_hash("TCP bind",
2449                                         sizeof(struct inet_bind_hashbucket),
2450                                         tcp_hashinfo.ehash_size,
2451                                         (num_physpages >= 128 * 1024) ?
2452                                         13 : 15,
2453                                         0,
2454                                         &tcp_hashinfo.bhash_size,
2455                                         NULL,
2456                                         64 * 1024);
2457         tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2458         for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2459                 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2460                 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2461         }
2462
2463         /* Try to be a bit smarter and adjust defaults depending
2464          * on available memory.
2465          */
2466         for (order = 0; ((1 << order) << PAGE_SHIFT) <
2467                         (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2468                         order++)
2469                 ;
2470         if (order >= 4) {
2471                 tcp_death_row.sysctl_max_tw_buckets = 180000;
2472                 sysctl_tcp_max_orphans = 4096 << (order - 4);
2473                 sysctl_max_syn_backlog = 1024;
2474         } else if (order < 3) {
2475                 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2476                 sysctl_tcp_max_orphans >>= (3 - order);
2477                 sysctl_max_syn_backlog = 128;
2478         }
2479
2480         /* Set the pressure threshold to be a fraction of global memory that
2481          * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
2482          * memory, with a floor of 128 pages.
2483          */
2484         limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
2485         limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
2486         limit = max(limit, 128UL);
2487         sysctl_tcp_mem[0] = limit / 4 * 3;
2488         sysctl_tcp_mem[1] = limit;
2489         sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
2490
2491         /* Set per-socket limits to no more than 1/128 the pressure threshold */
2492         limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2493         max_share = min(4UL*1024*1024, limit);
2494
2495         sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM;
2496         sysctl_tcp_wmem[1] = 16*1024;
2497         sysctl_tcp_wmem[2] = max(64*1024, max_share);
2498
2499         sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM;
2500         sysctl_tcp_rmem[1] = 87380;
2501         sysctl_tcp_rmem[2] = max(87380, max_share);
2502
2503         printk(KERN_INFO "TCP: Hash tables configured "
2504                "(established %d bind %d)\n",
2505                tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size);
2506
2507         tcp_register_congestion_control(&tcp_reno);
2508 }
2509
2510 EXPORT_SYMBOL(tcp_close);
2511 EXPORT_SYMBOL(tcp_disconnect);
2512 EXPORT_SYMBOL(tcp_getsockopt);
2513 EXPORT_SYMBOL(tcp_ioctl);
2514 EXPORT_SYMBOL(tcp_poll);
2515 EXPORT_SYMBOL(tcp_read_sock);
2516 EXPORT_SYMBOL(tcp_recvmsg);
2517 EXPORT_SYMBOL(tcp_sendmsg);
2518 EXPORT_SYMBOL(tcp_sendpage);
2519 EXPORT_SYMBOL(tcp_setsockopt);
2520 EXPORT_SYMBOL(tcp_shutdown);
2521 EXPORT_SYMBOL(tcp_statistics);