linux/net/core/datagram.c
<<
>>
Prefs
   1/*
   2 *      SUCS NET3:
   3 *
   4 *      Generic datagram handling routines. These are generic for all
   5 *      protocols. Possibly a generic IP version on top of these would
   6 *      make sense. Not tonight however 8-).
   7 *      This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
   8 *      NetROM layer all have identical poll code and mostly
   9 *      identical recvmsg() code. So we share it here. The poll was
  10 *      shared before but buried in udp.c so I moved it.
  11 *
  12 *      Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>. (datagram_poll() from old
  13 *                                                   udp.c code)
  14 *
  15 *      Fixes:
  16 *              Alan Cox        :       NULL return from skb_peek_copy()
  17 *                                      understood
  18 *              Alan Cox        :       Rewrote skb_read_datagram to avoid the
  19 *                                      skb_peek_copy stuff.
  20 *              Alan Cox        :       Added support for SOCK_SEQPACKET.
  21 *                                      IPX can no longer use the SO_TYPE hack
  22 *                                      but AX.25 now works right, and SPX is
  23 *                                      feasible.
  24 *              Alan Cox        :       Fixed write poll of non IP protocol
  25 *                                      crash.
  26 *              Florian  La Roche:      Changed for my new skbuff handling.
  27 *              Darryl Miles    :       Fixed non-blocking SOCK_SEQPACKET.
  28 *              Linus Torvalds  :       BSD semantic fixes.
  29 *              Alan Cox        :       Datagram iovec handling
  30 *              Darryl Miles    :       Fixed non-blocking SOCK_STREAM.
  31 *              Alan Cox        :       POSIXisms
  32 *              Pete Wyckoff    :       Unconnected accept() fix.
  33 *
  34 */
  35
  36#include <linux/module.h>
  37#include <linux/types.h>
  38#include <linux/kernel.h>
  39#include <asm/uaccess.h>
  40#include <linux/mm.h>
  41#include <linux/interrupt.h>
  42#include <linux/errno.h>
  43#include <linux/sched.h>
  44#include <linux/inet.h>
  45#include <linux/netdevice.h>
  46#include <linux/rtnetlink.h>
  47#include <linux/poll.h>
  48#include <linux/highmem.h>
  49#include <linux/spinlock.h>
  50#include <linux/slab.h>
  51
  52#include <net/protocol.h>
  53#include <linux/skbuff.h>
  54
  55#include <net/checksum.h>
  56#include <net/sock.h>
  57#include <net/tcp_states.h>
  58#include <trace/events/skb.h>
  59
  60/*
  61 *      Is a socket 'connection oriented' ?
  62 */
  63static inline int connection_based(struct sock *sk)
  64{
  65        return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
  66}
  67
  68static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int sync,
  69                                  void *key)
  70{
  71        unsigned long bits = (unsigned long)key;
  72
  73        /*
  74         * Avoid a wakeup if event not interesting for us
  75         */
  76        if (bits && !(bits & (POLLIN | POLLERR)))
  77                return 0;
  78        return autoremove_wake_function(wait, mode, sync, key);
  79}
  80/*
  81 * Wait for a packet..
  82 */
  83static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
  84{
  85        int error;
  86        DEFINE_WAIT_FUNC(wait, receiver_wake_function);
  87
  88        prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
  89
  90        /* Socket errors? */
  91        error = sock_error(sk);
  92        if (error)
  93                goto out_err;
  94
  95        if (!skb_queue_empty(&sk->sk_receive_queue))
  96                goto out;
  97
  98        /* Socket shut down? */
  99        if (sk->sk_shutdown & RCV_SHUTDOWN)
 100                goto out_noerr;
 101
 102        /* Sequenced packets can come disconnected.
 103         * If so we report the problem
 104         */
 105        error = -ENOTCONN;
 106        if (connection_based(sk) &&
 107            !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
 108                goto out_err;
 109
 110        /* handle signals */
 111        if (signal_pending(current))
 112                goto interrupted;
 113
 114        error = 0;
 115        *timeo_p = schedule_timeout(*timeo_p);
 116out:
 117        finish_wait(sk_sleep(sk), &wait);
 118        return error;
 119interrupted:
 120        error = sock_intr_errno(*timeo_p);
 121out_err:
 122        *err = error;
 123        goto out;
 124out_noerr:
 125        *err = 0;
 126        error = 1;
 127        goto out;
 128}
 129
 130/**
 131 *      __skb_recv_datagram - Receive a datagram skbuff
 132 *      @sk: socket
 133 *      @flags: MSG_ flags
 134 *      @off: an offset in bytes to peek skb from. Returns an offset
 135 *            within an skb where data actually starts
 136 *      @peeked: returns non-zero if this packet has been seen before
 137 *      @err: error code returned
 138 *
 139 *      Get a datagram skbuff, understands the peeking, nonblocking wakeups
 140 *      and possible races. This replaces identical code in packet, raw and
 141 *      udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
 142 *      the long standing peek and read race for datagram sockets. If you
 143 *      alter this routine remember it must be re-entrant.
 144 *
 145 *      This function will lock the socket if a skb is returned, so the caller
 146 *      needs to unlock the socket in that case (usually by calling
 147 *      skb_free_datagram)
 148 *
 149 *      * It does not lock socket since today. This function is
 150 *      * free of race conditions. This measure should/can improve
 151 *      * significantly datagram socket latencies at high loads,
 152 *      * when data copying to user space takes lots of time.
 153 *      * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
 154 *      *  8) Great win.)
 155 *      *                                           --ANK (980729)
 156 *
 157 *      The order of the tests when we find no data waiting are specified
 158 *      quite explicitly by POSIX 1003.1g, don't change them without having
 159 *      the standard around please.
 160 */
 161struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 162                                    int *peeked, int *off, int *err)
 163{
 164        struct sk_buff *skb;
 165        long timeo;
 166        /*
 167         * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
 168         */
 169        int error = sock_error(sk);
 170
 171        if (error)
 172                goto no_packet;
 173
 174        timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 175
 176        do {
 177                /* Again only user level code calls this function, so nothing
 178                 * interrupt level will suddenly eat the receive_queue.
 179                 *
 180                 * Look at current nfs client by the way...
 181                 * However, this function was correct in any case. 8)
 182                 */
 183                unsigned long cpu_flags;
 184                struct sk_buff_head *queue = &sk->sk_receive_queue;
 185
 186                spin_lock_irqsave(&queue->lock, cpu_flags);
 187                skb_queue_walk(queue, skb) {
 188                        *peeked = skb->peeked;
 189                        if (flags & MSG_PEEK) {
 190                                if (*off >= skb->len) {
 191                                        *off -= skb->len;
 192                                        continue;
 193                                }
 194                                skb->peeked = 1;
 195                                atomic_inc(&skb->users);
 196                        } else
 197                                __skb_unlink(skb, queue);
 198
 199                        spin_unlock_irqrestore(&queue->lock, cpu_flags);
 200                        return skb;
 201                }
 202                spin_unlock_irqrestore(&queue->lock, cpu_flags);
 203
 204                /* User doesn't want to wait */
 205                error = -EAGAIN;
 206                if (!timeo)
 207                        goto no_packet;
 208
 209        } while (!wait_for_packet(sk, err, &timeo));
 210
 211        return NULL;
 212
 213no_packet:
 214        *err = error;
 215        return NULL;
 216}
 217EXPORT_SYMBOL(__skb_recv_datagram);
 218
 219struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
 220                                  int noblock, int *err)
 221{
 222        int peeked, off = 0;
 223
 224        return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
 225                                   &peeked, &off, err);
 226}
 227EXPORT_SYMBOL(skb_recv_datagram);
 228
 229void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
 230{
 231        consume_skb(skb);
 232        sk_mem_reclaim_partial(sk);
 233}
 234EXPORT_SYMBOL(skb_free_datagram);
 235
 236void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb)
 237{
 238        bool slow;
 239
 240        if (likely(atomic_read(&skb->users) == 1))
 241                smp_rmb();
 242        else if (likely(!atomic_dec_and_test(&skb->users)))
 243                return;
 244
 245        slow = lock_sock_fast(sk);
 246        skb_orphan(skb);
 247        sk_mem_reclaim_partial(sk);
 248        unlock_sock_fast(sk, slow);
 249
 250        /* skb is now orphaned, can be freed outside of locked section */
 251        __kfree_skb(skb);
 252}
 253EXPORT_SYMBOL(skb_free_datagram_locked);
 254
 255/**
 256 *      skb_kill_datagram - Free a datagram skbuff forcibly
 257 *      @sk: socket
 258 *      @skb: datagram skbuff
 259 *      @flags: MSG_ flags
 260 *
 261 *      This function frees a datagram skbuff that was received by
 262 *      skb_recv_datagram.  The flags argument must match the one
 263 *      used for skb_recv_datagram.
 264 *
 265 *      If the MSG_PEEK flag is set, and the packet is still on the
 266 *      receive queue of the socket, it will be taken off the queue
 267 *      before it is freed.
 268 *
 269 *      This function currently only disables BH when acquiring the
 270 *      sk_receive_queue lock.  Therefore it must not be used in a
 271 *      context where that lock is acquired in an IRQ context.
 272 *
 273 *      It returns 0 if the packet was removed by us.
 274 */
 275
 276int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
 277{
 278        int err = 0;
 279
 280        if (flags & MSG_PEEK) {
 281                err = -ENOENT;
 282                spin_lock_bh(&sk->sk_receive_queue.lock);
 283                if (skb == skb_peek(&sk->sk_receive_queue)) {
 284                        __skb_unlink(skb, &sk->sk_receive_queue);
 285                        atomic_dec(&skb->users);
 286                        err = 0;
 287                }
 288                spin_unlock_bh(&sk->sk_receive_queue.lock);
 289        }
 290
 291        kfree_skb(skb);
 292        atomic_inc(&sk->sk_drops);
 293        sk_mem_reclaim_partial(sk);
 294
 295        return err;
 296}
 297EXPORT_SYMBOL(skb_kill_datagram);
 298
 299/**
 300 *      skb_copy_datagram_iovec - Copy a datagram to an iovec.
 301 *      @skb: buffer to copy
 302 *      @offset: offset in the buffer to start copying from
 303 *      @to: io vector to copy to
 304 *      @len: amount of data to copy from buffer to iovec
 305 *
 306 *      Note: the iovec is modified during the copy.
 307 */
 308int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
 309                            struct iovec *to, int len)
 310{
 311        int start = skb_headlen(skb);
 312        int i, copy = start - offset;
 313        struct sk_buff *frag_iter;
 314
 315        trace_skb_copy_datagram_iovec(skb, len);
 316
 317        /* Copy header. */
 318        if (copy > 0) {
 319                if (copy > len)
 320                        copy = len;
 321                if (memcpy_toiovec(to, skb->data + offset, copy))
 322                        goto fault;
 323                if ((len -= copy) == 0)
 324                        return 0;
 325                offset += copy;
 326        }
 327
 328        /* Copy paged appendix. Hmm... why does this look so complicated? */
 329        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 330                int end;
 331                const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 332
 333                WARN_ON(start > offset + len);
 334
 335                end = start + skb_frag_size(frag);
 336                if ((copy = end - offset) > 0) {
 337                        int err;
 338                        u8  *vaddr;
 339                        struct page *page = skb_frag_page(frag);
 340
 341                        if (copy > len)
 342                                copy = len;
 343                        vaddr = kmap(page);
 344                        err = memcpy_toiovec(to, vaddr + frag->page_offset +
 345                                             offset - start, copy);
 346                        kunmap(page);
 347                        if (err)
 348                                goto fault;
 349                        if (!(len -= copy))
 350                                return 0;
 351                        offset += copy;
 352                }
 353                start = end;
 354        }
 355
 356        skb_walk_frags(skb, frag_iter) {
 357                int end;
 358
 359                WARN_ON(start > offset + len);
 360
 361                end = start + frag_iter->len;
 362                if ((copy = end - offset) > 0) {
 363                        if (copy > len)
 364                                copy = len;
 365                        if (skb_copy_datagram_iovec(frag_iter,
 366                                                    offset - start,
 367                                                    to, copy))
 368                                goto fault;
 369                        if ((len -= copy) == 0)
 370                                return 0;
 371                        offset += copy;
 372                }
 373                start = end;
 374        }
 375        if (!len)
 376                return 0;
 377
 378fault:
 379        return -EFAULT;
 380}
 381EXPORT_SYMBOL(skb_copy_datagram_iovec);
 382
 383/**
 384 *      skb_copy_datagram_const_iovec - Copy a datagram to an iovec.
 385 *      @skb: buffer to copy
 386 *      @offset: offset in the buffer to start copying from
 387 *      @to: io vector to copy to
 388 *      @to_offset: offset in the io vector to start copying to
 389 *      @len: amount of data to copy from buffer to iovec
 390 *
 391 *      Returns 0 or -EFAULT.
 392 *      Note: the iovec is not modified during the copy.
 393 */
 394int skb_copy_datagram_const_iovec(const struct sk_buff *skb, int offset,
 395                                  const struct iovec *to, int to_offset,
 396                                  int len)
 397{
 398        int start = skb_headlen(skb);
 399        int i, copy = start - offset;
 400        struct sk_buff *frag_iter;
 401
 402        /* Copy header. */
 403        if (copy > 0) {
 404                if (copy > len)
 405                        copy = len;
 406                if (memcpy_toiovecend(to, skb->data + offset, to_offset, copy))
 407                        goto fault;
 408                if ((len -= copy) == 0)
 409                        return 0;
 410                offset += copy;
 411                to_offset += copy;
 412        }
 413
 414        /* Copy paged appendix. Hmm... why does this look so complicated? */
 415        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 416                int end;
 417                const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 418
 419                WARN_ON(start > offset + len);
 420
 421                end = start + skb_frag_size(frag);
 422                if ((copy = end - offset) > 0) {
 423                        int err;
 424                        u8  *vaddr;
 425                        struct page *page = skb_frag_page(frag);
 426
 427                        if (copy > len)
 428                                copy = len;
 429                        vaddr = kmap(page);
 430                        err = memcpy_toiovecend(to, vaddr + frag->page_offset +
 431                                                offset - start, to_offset, copy);
 432                        kunmap(page);
 433                        if (err)
 434                                goto fault;
 435                        if (!(len -= copy))
 436                                return 0;
 437                        offset += copy;
 438                        to_offset += copy;
 439                }
 440                start = end;
 441        }
 442
 443        skb_walk_frags(skb, frag_iter) {
 444                int end;
 445
 446                WARN_ON(start > offset + len);
 447
 448                end = start + frag_iter->len;
 449                if ((copy = end - offset) > 0) {
 450                        if (copy > len)
 451                                copy = len;
 452                        if (skb_copy_datagram_const_iovec(frag_iter,
 453                                                          offset - start,
 454                                                          to, to_offset,
 455                                                          copy))
 456                                goto fault;
 457                        if ((len -= copy) == 0)
 458                                return 0;
 459                        offset += copy;
 460                        to_offset += copy;
 461                }
 462                start = end;
 463        }
 464        if (!len)
 465                return 0;
 466
 467fault:
 468        return -EFAULT;
 469}
 470EXPORT_SYMBOL(skb_copy_datagram_const_iovec);
 471
 472/**
 473 *      skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
 474 *      @skb: buffer to copy
 475 *      @offset: offset in the buffer to start copying to
 476 *      @from: io vector to copy to
 477 *      @from_offset: offset in the io vector to start copying from
 478 *      @len: amount of data to copy to buffer from iovec
 479 *
 480 *      Returns 0 or -EFAULT.
 481 *      Note: the iovec is not modified during the copy.
 482 */
 483int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
 484                                 const struct iovec *from, int from_offset,
 485                                 int len)
 486{
 487        int start = skb_headlen(skb);
 488        int i, copy = start - offset;
 489        struct sk_buff *frag_iter;
 490
 491        /* Copy header. */
 492        if (copy > 0) {
 493                if (copy > len)
 494                        copy = len;
 495                if (memcpy_fromiovecend(skb->data + offset, from, from_offset,
 496                                        copy))
 497                        goto fault;
 498                if ((len -= copy) == 0)
 499                        return 0;
 500                offset += copy;
 501                from_offset += copy;
 502        }
 503
 504        /* Copy paged appendix. Hmm... why does this look so complicated? */
 505        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 506                int end;
 507                const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 508
 509                WARN_ON(start > offset + len);
 510
 511                end = start + skb_frag_size(frag);
 512                if ((copy = end - offset) > 0) {
 513                        int err;
 514                        u8  *vaddr;
 515                        struct page *page = skb_frag_page(frag);
 516
 517                        if (copy > len)
 518                                copy = len;
 519                        vaddr = kmap(page);
 520                        err = memcpy_fromiovecend(vaddr + frag->page_offset +
 521                                                  offset - start,
 522                                                  from, from_offset, copy);
 523                        kunmap(page);
 524                        if (err)
 525                                goto fault;
 526
 527                        if (!(len -= copy))
 528                                return 0;
 529                        offset += copy;
 530                        from_offset += copy;
 531                }
 532                start = end;
 533        }
 534
 535        skb_walk_frags(skb, frag_iter) {
 536                int end;
 537
 538                WARN_ON(start > offset + len);
 539
 540                end = start + frag_iter->len;
 541                if ((copy = end - offset) > 0) {
 542                        if (copy > len)
 543                                copy = len;
 544                        if (skb_copy_datagram_from_iovec(frag_iter,
 545                                                         offset - start,
 546                                                         from,
 547                                                         from_offset,
 548                                                         copy))
 549                                goto fault;
 550                        if ((len -= copy) == 0)
 551                                return 0;
 552                        offset += copy;
 553                        from_offset += copy;
 554                }
 555                start = end;
 556        }
 557        if (!len)
 558                return 0;
 559
 560fault:
 561        return -EFAULT;
 562}
 563EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
 564
 565static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
 566                                      u8 __user *to, int len,
 567                                      __wsum *csump)
 568{
 569        int start = skb_headlen(skb);
 570        int i, copy = start - offset;
 571        struct sk_buff *frag_iter;
 572        int pos = 0;
 573
 574        /* Copy header. */
 575        if (copy > 0) {
 576                int err = 0;
 577                if (copy > len)
 578                        copy = len;
 579                *csump = csum_and_copy_to_user(skb->data + offset, to, copy,
 580                                               *csump, &err);
 581                if (err)
 582                        goto fault;
 583                if ((len -= copy) == 0)
 584                        return 0;
 585                offset += copy;
 586                to += copy;
 587                pos = copy;
 588        }
 589
 590        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 591                int end;
 592                const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 593
 594                WARN_ON(start > offset + len);
 595
 596                end = start + skb_frag_size(frag);
 597                if ((copy = end - offset) > 0) {
 598                        __wsum csum2;
 599                        int err = 0;
 600                        u8  *vaddr;
 601                        struct page *page = skb_frag_page(frag);
 602
 603                        if (copy > len)
 604                                copy = len;
 605                        vaddr = kmap(page);
 606                        csum2 = csum_and_copy_to_user(vaddr +
 607                                                        frag->page_offset +
 608                                                        offset - start,
 609                                                      to, copy, 0, &err);
 610                        kunmap(page);
 611                        if (err)
 612                                goto fault;
 613                        *csump = csum_block_add(*csump, csum2, pos);
 614                        if (!(len -= copy))
 615                                return 0;
 616                        offset += copy;
 617                        to += copy;
 618                        pos += copy;
 619                }
 620                start = end;
 621        }
 622
 623        skb_walk_frags(skb, frag_iter) {
 624                int end;
 625
 626                WARN_ON(start > offset + len);
 627
 628                end = start + frag_iter->len;
 629                if ((copy = end - offset) > 0) {
 630                        __wsum csum2 = 0;
 631                        if (copy > len)
 632                                copy = len;
 633                        if (skb_copy_and_csum_datagram(frag_iter,
 634                                                       offset - start,
 635                                                       to, copy,
 636                                                       &csum2))
 637                                goto fault;
 638                        *csump = csum_block_add(*csump, csum2, pos);
 639                        if ((len -= copy) == 0)
 640                                return 0;
 641                        offset += copy;
 642                        to += copy;
 643                        pos += copy;
 644                }
 645                start = end;
 646        }
 647        if (!len)
 648                return 0;
 649
 650fault:
 651        return -EFAULT;
 652}
 653
 654__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
 655{
 656        __sum16 sum;
 657
 658        sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
 659        if (likely(!sum)) {
 660                if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
 661                        netdev_rx_csum_fault(skb->dev);
 662                skb->ip_summed = CHECKSUM_UNNECESSARY;
 663        }
 664        return sum;
 665}
 666EXPORT_SYMBOL(__skb_checksum_complete_head);
 667
 668__sum16 __skb_checksum_complete(struct sk_buff *skb)
 669{
 670        return __skb_checksum_complete_head(skb, skb->len);
 671}
 672EXPORT_SYMBOL(__skb_checksum_complete);
 673
 674/**
 675 *      skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
 676 *      @skb: skbuff
 677 *      @hlen: hardware length
 678 *      @iov: io vector
 679 *
 680 *      Caller _must_ check that skb will fit to this iovec.
 681 *
 682 *      Returns: 0       - success.
 683 *               -EINVAL - checksum failure.
 684 *               -EFAULT - fault during copy. Beware, in this case iovec
 685 *                         can be modified!
 686 */
 687int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
 688                                     int hlen, struct iovec *iov)
 689{
 690        __wsum csum;
 691        int chunk = skb->len - hlen;
 692
 693        if (!chunk)
 694                return 0;
 695
 696        /* Skip filled elements.
 697         * Pretty silly, look at memcpy_toiovec, though 8)
 698         */
 699        while (!iov->iov_len)
 700                iov++;
 701
 702        if (iov->iov_len < chunk) {
 703                if (__skb_checksum_complete(skb))
 704                        goto csum_error;
 705                if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
 706                        goto fault;
 707        } else {
 708                csum = csum_partial(skb->data, hlen, skb->csum);
 709                if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
 710                                               chunk, &csum))
 711                        goto fault;
 712                if (csum_fold(csum))
 713                        goto csum_error;
 714                if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
 715                        netdev_rx_csum_fault(skb->dev);
 716                iov->iov_len -= chunk;
 717                iov->iov_base += chunk;
 718        }
 719        return 0;
 720csum_error:
 721        return -EINVAL;
 722fault:
 723        return -EFAULT;
 724}
 725EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
 726
 727/**
 728 *      datagram_poll - generic datagram poll
 729 *      @file: file struct
 730 *      @sock: socket
 731 *      @wait: poll table
 732 *
 733 *      Datagram poll: Again totally generic. This also handles
 734 *      sequenced packet sockets providing the socket receive queue
 735 *      is only ever holding data ready to receive.
 736 *
 737 *      Note: when you _don't_ use this routine for this protocol,
 738 *      and you use a different write policy from sock_writeable()
 739 *      then please supply your own write_space callback.
 740 */
 741unsigned int datagram_poll(struct file *file, struct socket *sock,
 742                           poll_table *wait)
 743{
 744        struct sock *sk = sock->sk;
 745        unsigned int mask;
 746
 747        sock_poll_wait(file, sk_sleep(sk), wait);
 748        mask = 0;
 749
 750        /* exceptional events? */
 751        if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
 752                mask |= POLLERR;
 753        if (sk->sk_shutdown & RCV_SHUTDOWN)
 754                mask |= POLLRDHUP | POLLIN | POLLRDNORM;
 755        if (sk->sk_shutdown == SHUTDOWN_MASK)
 756                mask |= POLLHUP;
 757
 758        /* readable? */
 759        if (!skb_queue_empty(&sk->sk_receive_queue))
 760                mask |= POLLIN | POLLRDNORM;
 761
 762        /* Connection-based need to check for termination and startup */
 763        if (connection_based(sk)) {
 764                if (sk->sk_state == TCP_CLOSE)
 765                        mask |= POLLHUP;
 766                /* connection hasn't started yet? */
 767                if (sk->sk_state == TCP_SYN_SENT)
 768                        return mask;
 769        }
 770
 771        /* writable? */
 772        if (sock_writeable(sk))
 773                mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
 774        else
 775                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 776
 777        return mask;
 778}
 779EXPORT_SYMBOL(datagram_poll);
 780
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.