The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sockbuf.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)uipc_socket2.c      8.1 (Berkeley) 6/10/93
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: stable/10/sys/kern/uipc_sockbuf.c 274043 2014-11-03 12:38:29Z hselasky $");
   34 
   35 #include "opt_param.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/aio.h> /* for aio_swake proto */
   39 #include <sys/kernel.h>
   40 #include <sys/lock.h>
   41 #include <sys/mbuf.h>
   42 #include <sys/mutex.h>
   43 #include <sys/proc.h>
   44 #include <sys/protosw.h>
   45 #include <sys/resourcevar.h>
   46 #include <sys/signalvar.h>
   47 #include <sys/socket.h>
   48 #include <sys/socketvar.h>
   49 #include <sys/sx.h>
   50 #include <sys/sysctl.h>
   51 
   52 /*
   53  * Function pointer set by the AIO routines so that the socket buffer code
   54  * can call back into the AIO module if it is loaded.
   55  */
   56 void    (*aio_swake)(struct socket *, struct sockbuf *);
   57 
   58 /*
   59  * Primitive routines for operating on socket buffers
   60  */
   61 
   62 u_long  sb_max = SB_MAX;
   63 u_long sb_max_adj =
   64        (quad_t)SB_MAX * MCLBYTES / (MSIZE + MCLBYTES); /* adjusted sb_max */
   65 
   66 static  u_long sb_efficiency = 8;       /* parameter for sbreserve() */
   67 
   68 static struct mbuf      *sbcut_internal(struct sockbuf *sb, int len);
   69 static void     sbflush_internal(struct sockbuf *sb);
   70 
   71 /*
   72  * Socantsendmore indicates that no more data will be sent on the socket; it
   73  * would normally be applied to a socket when the user informs the system
   74  * that no more data is to be sent, by the protocol code (in case
   75  * PRU_SHUTDOWN).  Socantrcvmore indicates that no more data will be
   76  * received, and will normally be applied to the socket by a protocol when it
   77  * detects that the peer will send no more data.  Data queued for reading in
   78  * the socket may yet be read.
   79  */
   80 void
   81 socantsendmore_locked(struct socket *so)
   82 {
   83 
   84         SOCKBUF_LOCK_ASSERT(&so->so_snd);
   85 
   86         so->so_snd.sb_state |= SBS_CANTSENDMORE;
   87         sowwakeup_locked(so);
   88         mtx_assert(SOCKBUF_MTX(&so->so_snd), MA_NOTOWNED);
   89 }
   90 
   91 void
   92 socantsendmore(struct socket *so)
   93 {
   94 
   95         SOCKBUF_LOCK(&so->so_snd);
   96         socantsendmore_locked(so);
   97         mtx_assert(SOCKBUF_MTX(&so->so_snd), MA_NOTOWNED);
   98 }
   99 
  100 void
  101 socantrcvmore_locked(struct socket *so)
  102 {
  103 
  104         SOCKBUF_LOCK_ASSERT(&so->so_rcv);
  105 
  106         so->so_rcv.sb_state |= SBS_CANTRCVMORE;
  107         sorwakeup_locked(so);
  108         mtx_assert(SOCKBUF_MTX(&so->so_rcv), MA_NOTOWNED);
  109 }
  110 
  111 void
  112 socantrcvmore(struct socket *so)
  113 {
  114 
  115         SOCKBUF_LOCK(&so->so_rcv);
  116         socantrcvmore_locked(so);
  117         mtx_assert(SOCKBUF_MTX(&so->so_rcv), MA_NOTOWNED);
  118 }
  119 
  120 /*
  121  * Wait for data to arrive at/drain from a socket buffer.
  122  */
  123 int
  124 sbwait(struct sockbuf *sb)
  125 {
  126 
  127         SOCKBUF_LOCK_ASSERT(sb);
  128 
  129         sb->sb_flags |= SB_WAIT;
  130         return (msleep_sbt(&sb->sb_cc, &sb->sb_mtx,
  131             (sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK | PCATCH, "sbwait",
  132             sb->sb_timeo, 0, 0));
  133 }
  134 
  135 int
  136 sblock(struct sockbuf *sb, int flags)
  137 {
  138 
  139         KASSERT((flags & SBL_VALID) == flags,
  140             ("sblock: flags invalid (0x%x)", flags));
  141 
  142         if (flags & SBL_WAIT) {
  143                 if ((sb->sb_flags & SB_NOINTR) ||
  144                     (flags & SBL_NOINTR)) {
  145                         sx_xlock(&sb->sb_sx);
  146                         return (0);
  147                 }
  148                 return (sx_xlock_sig(&sb->sb_sx));
  149         } else {
  150                 if (sx_try_xlock(&sb->sb_sx) == 0)
  151                         return (EWOULDBLOCK);
  152                 return (0);
  153         }
  154 }
  155 
  156 void
  157 sbunlock(struct sockbuf *sb)
  158 {
  159 
  160         sx_xunlock(&sb->sb_sx);
  161 }
  162 
  163 /*
  164  * Wakeup processes waiting on a socket buffer.  Do asynchronous notification
  165  * via SIGIO if the socket has the SS_ASYNC flag set.
  166  *
  167  * Called with the socket buffer lock held; will release the lock by the end
  168  * of the function.  This allows the caller to acquire the socket buffer lock
  169  * while testing for the need for various sorts of wakeup and hold it through
  170  * to the point where it's no longer required.  We currently hold the lock
  171  * through calls out to other subsystems (with the exception of kqueue), and
  172  * then release it to avoid lock order issues.  It's not clear that's
  173  * correct.
  174  */
  175 void
  176 sowakeup(struct socket *so, struct sockbuf *sb)
  177 {
  178         int ret;
  179 
  180         SOCKBUF_LOCK_ASSERT(sb);
  181 
  182         selwakeuppri(&sb->sb_sel, PSOCK);
  183         if (!SEL_WAITING(&sb->sb_sel))
  184                 sb->sb_flags &= ~SB_SEL;
  185         if (sb->sb_flags & SB_WAIT) {
  186                 sb->sb_flags &= ~SB_WAIT;
  187                 wakeup(&sb->sb_cc);
  188         }
  189         KNOTE_LOCKED(&sb->sb_sel.si_note, 0);
  190         if (sb->sb_upcall != NULL) {
  191                 ret = sb->sb_upcall(so, sb->sb_upcallarg, M_NOWAIT);
  192                 if (ret == SU_ISCONNECTED) {
  193                         KASSERT(sb == &so->so_rcv,
  194                             ("SO_SND upcall returned SU_ISCONNECTED"));
  195                         soupcall_clear(so, SO_RCV);
  196                 }
  197         } else
  198                 ret = SU_OK;
  199         if (sb->sb_flags & SB_AIO)
  200                 aio_swake(so, sb);
  201         SOCKBUF_UNLOCK(sb);
  202         if (ret == SU_ISCONNECTED)
  203                 soisconnected(so);
  204         if ((so->so_state & SS_ASYNC) && so->so_sigio != NULL)
  205                 pgsigio(&so->so_sigio, SIGIO, 0);
  206         mtx_assert(SOCKBUF_MTX(sb), MA_NOTOWNED);
  207 }
  208 
  209 /*
  210  * Socket buffer (struct sockbuf) utility routines.
  211  *
  212  * Each socket contains two socket buffers: one for sending data and one for
  213  * receiving data.  Each buffer contains a queue of mbufs, information about
  214  * the number of mbufs and amount of data in the queue, and other fields
  215  * allowing select() statements and notification on data availability to be
  216  * implemented.
  217  *
  218  * Data stored in a socket buffer is maintained as a list of records.  Each
  219  * record is a list of mbufs chained together with the m_next field.  Records
  220  * are chained together with the m_nextpkt field. The upper level routine
  221  * soreceive() expects the following conventions to be observed when placing
  222  * information in the receive buffer:
  223  *
  224  * 1. If the protocol requires each message be preceded by the sender's name,
  225  *    then a record containing that name must be present before any
  226  *    associated data (mbuf's must be of type MT_SONAME).
  227  * 2. If the protocol supports the exchange of ``access rights'' (really just
  228  *    additional data associated with the message), and there are ``rights''
  229  *    to be received, then a record containing this data should be present
  230  *    (mbuf's must be of type MT_RIGHTS).
  231  * 3. If a name or rights record exists, then it must be followed by a data
  232  *    record, perhaps of zero length.
  233  *
  234  * Before using a new socket structure it is first necessary to reserve
  235  * buffer space to the socket, by calling sbreserve().  This should commit
  236  * some of the available buffer space in the system buffer pool for the
  237  * socket (currently, it does nothing but enforce limits).  The space should
  238  * be released by calling sbrelease() when the socket is destroyed.
  239  */
  240 int
  241 soreserve(struct socket *so, u_long sndcc, u_long rcvcc)
  242 {
  243         struct thread *td = curthread;
  244 
  245         SOCKBUF_LOCK(&so->so_snd);
  246         SOCKBUF_LOCK(&so->so_rcv);
  247         if (sbreserve_locked(&so->so_snd, sndcc, so, td) == 0)
  248                 goto bad;
  249         if (sbreserve_locked(&so->so_rcv, rcvcc, so, td) == 0)
  250                 goto bad2;
  251         if (so->so_rcv.sb_lowat == 0)
  252                 so->so_rcv.sb_lowat = 1;
  253         if (so->so_snd.sb_lowat == 0)
  254                 so->so_snd.sb_lowat = MCLBYTES;
  255         if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
  256                 so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
  257         SOCKBUF_UNLOCK(&so->so_rcv);
  258         SOCKBUF_UNLOCK(&so->so_snd);
  259         return (0);
  260 bad2:
  261         sbrelease_locked(&so->so_snd, so);
  262 bad:
  263         SOCKBUF_UNLOCK(&so->so_rcv);
  264         SOCKBUF_UNLOCK(&so->so_snd);
  265         return (ENOBUFS);
  266 }
  267 
  268 static int
  269 sysctl_handle_sb_max(SYSCTL_HANDLER_ARGS)
  270 {
  271         int error = 0;
  272         u_long tmp_sb_max = sb_max;
  273 
  274         error = sysctl_handle_long(oidp, &tmp_sb_max, arg2, req);
  275         if (error || !req->newptr)
  276                 return (error);
  277         if (tmp_sb_max < MSIZE + MCLBYTES)
  278                 return (EINVAL);
  279         sb_max = tmp_sb_max;
  280         sb_max_adj = (u_quad_t)sb_max * MCLBYTES / (MSIZE + MCLBYTES);
  281         return (0);
  282 }
  283         
  284 /*
  285  * Allot mbufs to a sockbuf.  Attempt to scale mbmax so that mbcnt doesn't
  286  * become limiting if buffering efficiency is near the normal case.
  287  */
  288 int
  289 sbreserve_locked(struct sockbuf *sb, u_long cc, struct socket *so,
  290     struct thread *td)
  291 {
  292         rlim_t sbsize_limit;
  293 
  294         SOCKBUF_LOCK_ASSERT(sb);
  295 
  296         /*
  297          * When a thread is passed, we take into account the thread's socket
  298          * buffer size limit.  The caller will generally pass curthread, but
  299          * in the TCP input path, NULL will be passed to indicate that no
  300          * appropriate thread resource limits are available.  In that case,
  301          * we don't apply a process limit.
  302          */
  303         if (cc > sb_max_adj)
  304                 return (0);
  305         if (td != NULL) {
  306                 PROC_LOCK(td->td_proc);
  307                 sbsize_limit = lim_cur(td->td_proc, RLIMIT_SBSIZE);
  308                 PROC_UNLOCK(td->td_proc);
  309         } else
  310                 sbsize_limit = RLIM_INFINITY;
  311         if (!chgsbsize(so->so_cred->cr_uidinfo, &sb->sb_hiwat, cc,
  312             sbsize_limit))
  313                 return (0);
  314         sb->sb_mbmax = min(cc * sb_efficiency, sb_max);
  315         if (sb->sb_lowat > sb->sb_hiwat)
  316                 sb->sb_lowat = sb->sb_hiwat;
  317         return (1);
  318 }
  319 
  320 int
  321 sbreserve(struct sockbuf *sb, u_long cc, struct socket *so, 
  322     struct thread *td)
  323 {
  324         int error;
  325 
  326         SOCKBUF_LOCK(sb);
  327         error = sbreserve_locked(sb, cc, so, td);
  328         SOCKBUF_UNLOCK(sb);
  329         return (error);
  330 }
  331 
  332 /*
  333  * Free mbufs held by a socket, and reserved mbuf space.
  334  */
  335 void
  336 sbrelease_internal(struct sockbuf *sb, struct socket *so)
  337 {
  338 
  339         sbflush_internal(sb);
  340         (void)chgsbsize(so->so_cred->cr_uidinfo, &sb->sb_hiwat, 0,
  341             RLIM_INFINITY);
  342         sb->sb_mbmax = 0;
  343 }
  344 
  345 void
  346 sbrelease_locked(struct sockbuf *sb, struct socket *so)
  347 {
  348 
  349         SOCKBUF_LOCK_ASSERT(sb);
  350 
  351         sbrelease_internal(sb, so);
  352 }
  353 
  354 void
  355 sbrelease(struct sockbuf *sb, struct socket *so)
  356 {
  357 
  358         SOCKBUF_LOCK(sb);
  359         sbrelease_locked(sb, so);
  360         SOCKBUF_UNLOCK(sb);
  361 }
  362 
  363 void
  364 sbdestroy(struct sockbuf *sb, struct socket *so)
  365 {
  366 
  367         sbrelease_internal(sb, so);
  368 }
  369 
  370 /*
  371  * Routines to add and remove data from an mbuf queue.
  372  *
  373  * The routines sbappend() or sbappendrecord() are normally called to append
  374  * new mbufs to a socket buffer, after checking that adequate space is
  375  * available, comparing the function sbspace() with the amount of data to be
  376  * added.  sbappendrecord() differs from sbappend() in that data supplied is
  377  * treated as the beginning of a new record.  To place a sender's address,
  378  * optional access rights, and data in a socket receive buffer,
  379  * sbappendaddr() should be used.  To place access rights and data in a
  380  * socket receive buffer, sbappendrights() should be used.  In either case,
  381  * the new data begins a new record.  Note that unlike sbappend() and
  382  * sbappendrecord(), these routines check for the caller that there will be
  383  * enough space to store the data.  Each fails if there is not enough space,
  384  * or if it cannot find mbufs to store additional information in.
  385  *
  386  * Reliable protocols may use the socket send buffer to hold data awaiting
  387  * acknowledgement.  Data is normally copied from a socket send buffer in a
  388  * protocol with m_copy for output to a peer, and then removing the data from
  389  * the socket buffer with sbdrop() or sbdroprecord() when the data is
  390  * acknowledged by the peer.
  391  */
  392 #ifdef SOCKBUF_DEBUG
  393 void
  394 sblastrecordchk(struct sockbuf *sb, const char *file, int line)
  395 {
  396         struct mbuf *m = sb->sb_mb;
  397 
  398         SOCKBUF_LOCK_ASSERT(sb);
  399 
  400         while (m && m->m_nextpkt)
  401                 m = m->m_nextpkt;
  402 
  403         if (m != sb->sb_lastrecord) {
  404                 printf("%s: sb_mb %p sb_lastrecord %p last %p\n",
  405                         __func__, sb->sb_mb, sb->sb_lastrecord, m);
  406                 printf("packet chain:\n");
  407                 for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt)
  408                         printf("\t%p\n", m);
  409                 panic("%s from %s:%u", __func__, file, line);
  410         }
  411 }
  412 
  413 void
  414 sblastmbufchk(struct sockbuf *sb, const char *file, int line)
  415 {
  416         struct mbuf *m = sb->sb_mb;
  417         struct mbuf *n;
  418 
  419         SOCKBUF_LOCK_ASSERT(sb);
  420 
  421         while (m && m->m_nextpkt)
  422                 m = m->m_nextpkt;
  423 
  424         while (m && m->m_next)
  425                 m = m->m_next;
  426 
  427         if (m != sb->sb_mbtail) {
  428                 printf("%s: sb_mb %p sb_mbtail %p last %p\n",
  429                         __func__, sb->sb_mb, sb->sb_mbtail, m);
  430                 printf("packet tree:\n");
  431                 for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt) {
  432                         printf("\t");
  433                         for (n = m; n != NULL; n = n->m_next)
  434                                 printf("%p ", n);
  435                         printf("\n");
  436                 }
  437                 panic("%s from %s:%u", __func__, file, line);
  438         }
  439 }
  440 #endif /* SOCKBUF_DEBUG */
  441 
  442 #define SBLINKRECORD(sb, m0) do {                                       \
  443         SOCKBUF_LOCK_ASSERT(sb);                                        \
  444         if ((sb)->sb_lastrecord != NULL)                                \
  445                 (sb)->sb_lastrecord->m_nextpkt = (m0);                  \
  446         else                                                            \
  447                 (sb)->sb_mb = (m0);                                     \
  448         (sb)->sb_lastrecord = (m0);                                     \
  449 } while (/*CONSTCOND*/0)
  450 
  451 /*
  452  * Append mbuf chain m to the last record in the socket buffer sb.  The
  453  * additional space associated the mbuf chain is recorded in sb.  Empty mbufs
  454  * are discarded and mbufs are compacted where possible.
  455  */
  456 void
  457 sbappend_locked(struct sockbuf *sb, struct mbuf *m)
  458 {
  459         struct mbuf *n;
  460 
  461         SOCKBUF_LOCK_ASSERT(sb);
  462 
  463         if (m == 0)
  464                 return;
  465 
  466         SBLASTRECORDCHK(sb);
  467         n = sb->sb_mb;
  468         if (n) {
  469                 while (n->m_nextpkt)
  470                         n = n->m_nextpkt;
  471                 do {
  472                         if (n->m_flags & M_EOR) {
  473                                 sbappendrecord_locked(sb, m); /* XXXXXX!!!! */
  474                                 return;
  475                         }
  476                 } while (n->m_next && (n = n->m_next));
  477         } else {
  478                 /*
  479                  * XXX Would like to simply use sb_mbtail here, but
  480                  * XXX I need to verify that I won't miss an EOR that
  481                  * XXX way.
  482                  */
  483                 if ((n = sb->sb_lastrecord) != NULL) {
  484                         do {
  485                                 if (n->m_flags & M_EOR) {
  486                                         sbappendrecord_locked(sb, m); /* XXXXXX!!!! */
  487                                         return;
  488                                 }
  489                         } while (n->m_next && (n = n->m_next));
  490                 } else {
  491                         /*
  492                          * If this is the first record in the socket buffer,
  493                          * it's also the last record.
  494                          */
  495                         sb->sb_lastrecord = m;
  496                 }
  497         }
  498         sbcompress(sb, m, n);
  499         SBLASTRECORDCHK(sb);
  500 }
  501 
  502 /*
  503  * Append mbuf chain m to the last record in the socket buffer sb.  The
  504  * additional space associated the mbuf chain is recorded in sb.  Empty mbufs
  505  * are discarded and mbufs are compacted where possible.
  506  */
  507 void
  508 sbappend(struct sockbuf *sb, struct mbuf *m)
  509 {
  510 
  511         SOCKBUF_LOCK(sb);
  512         sbappend_locked(sb, m);
  513         SOCKBUF_UNLOCK(sb);
  514 }
  515 
  516 /*
  517  * This version of sbappend() should only be used when the caller absolutely
  518  * knows that there will never be more than one record in the socket buffer,
  519  * that is, a stream protocol (such as TCP).
  520  */
  521 void
  522 sbappendstream_locked(struct sockbuf *sb, struct mbuf *m)
  523 {
  524         SOCKBUF_LOCK_ASSERT(sb);
  525 
  526         KASSERT(m->m_nextpkt == NULL,("sbappendstream 0"));
  527         KASSERT(sb->sb_mb == sb->sb_lastrecord,("sbappendstream 1"));
  528 
  529         SBLASTMBUFCHK(sb);
  530 
  531         /* Remove all packet headers and mbuf tags to get a pure data chain. */
  532         m_demote(m, 1);
  533         
  534         sbcompress(sb, m, sb->sb_mbtail);
  535 
  536         sb->sb_lastrecord = sb->sb_mb;
  537         SBLASTRECORDCHK(sb);
  538 }
  539 
  540 /*
  541  * This version of sbappend() should only be used when the caller absolutely
  542  * knows that there will never be more than one record in the socket buffer,
  543  * that is, a stream protocol (such as TCP).
  544  */
  545 void
  546 sbappendstream(struct sockbuf *sb, struct mbuf *m)
  547 {
  548 
  549         SOCKBUF_LOCK(sb);
  550         sbappendstream_locked(sb, m);
  551         SOCKBUF_UNLOCK(sb);
  552 }
  553 
  554 #ifdef SOCKBUF_DEBUG
  555 void
  556 sbcheck(struct sockbuf *sb)
  557 {
  558         struct mbuf *m;
  559         struct mbuf *n = 0;
  560         u_long len = 0, mbcnt = 0;
  561 
  562         SOCKBUF_LOCK_ASSERT(sb);
  563 
  564         for (m = sb->sb_mb; m; m = n) {
  565             n = m->m_nextpkt;
  566             for (; m; m = m->m_next) {
  567                 len += m->m_len;
  568                 mbcnt += MSIZE;
  569                 if (m->m_flags & M_EXT) /*XXX*/ /* pretty sure this is bogus */
  570                         mbcnt += m->m_ext.ext_size;
  571             }
  572         }
  573         if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
  574                 printf("cc %ld != %u || mbcnt %ld != %u\n", len, sb->sb_cc,
  575                     mbcnt, sb->sb_mbcnt);
  576                 panic("sbcheck");
  577         }
  578 }
  579 #endif
  580 
  581 /*
  582  * As above, except the mbuf chain begins a new record.
  583  */
  584 void
  585 sbappendrecord_locked(struct sockbuf *sb, struct mbuf *m0)
  586 {
  587         struct mbuf *m;
  588 
  589         SOCKBUF_LOCK_ASSERT(sb);
  590 
  591         if (m0 == 0)
  592                 return;
  593         /*
  594          * Put the first mbuf on the queue.  Note this permits zero length
  595          * records.
  596          */
  597         sballoc(sb, m0);
  598         SBLASTRECORDCHK(sb);
  599         SBLINKRECORD(sb, m0);
  600         sb->sb_mbtail = m0;
  601         m = m0->m_next;
  602         m0->m_next = 0;
  603         if (m && (m0->m_flags & M_EOR)) {
  604                 m0->m_flags &= ~M_EOR;
  605                 m->m_flags |= M_EOR;
  606         }
  607         /* always call sbcompress() so it can do SBLASTMBUFCHK() */
  608         sbcompress(sb, m, m0);
  609 }
  610 
  611 /*
  612  * As above, except the mbuf chain begins a new record.
  613  */
  614 void
  615 sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
  616 {
  617 
  618         SOCKBUF_LOCK(sb);
  619         sbappendrecord_locked(sb, m0);
  620         SOCKBUF_UNLOCK(sb);
  621 }
  622 
  623 /* Helper routine that appends data, control, and address to a sockbuf. */
  624 static int
  625 sbappendaddr_locked_internal(struct sockbuf *sb, const struct sockaddr *asa,
  626     struct mbuf *m0, struct mbuf *control, struct mbuf *ctrl_last)
  627 {
  628         struct mbuf *m, *n, *nlast;
  629 #if MSIZE <= 256
  630         if (asa->sa_len > MLEN)
  631                 return (0);
  632 #endif
  633         m = m_get(M_NOWAIT, MT_SONAME);
  634         if (m == NULL)
  635                 return (0);
  636         m->m_len = asa->sa_len;
  637         bcopy(asa, mtod(m, caddr_t), asa->sa_len);
  638         if (ctrl_last)
  639                 ctrl_last->m_next = m0; /* concatenate data to control */
  640         else
  641                 control = m0;
  642         m->m_next = control;
  643         for (n = m; n->m_next != NULL; n = n->m_next)
  644                 sballoc(sb, n);
  645         sballoc(sb, n);
  646         nlast = n;
  647         SBLINKRECORD(sb, m);
  648 
  649         sb->sb_mbtail = nlast;
  650         SBLASTMBUFCHK(sb);
  651 
  652         SBLASTRECORDCHK(sb);
  653         return (1);
  654 }
  655 
  656 /*
  657  * Append address and data, and optionally, control (ancillary) data to the
  658  * receive queue of a socket.  If present, m0 must include a packet header
  659  * with total length.  Returns 0 if no space in sockbuf or insufficient
  660  * mbufs.
  661  */
  662 int
  663 sbappendaddr_locked(struct sockbuf *sb, const struct sockaddr *asa,
  664     struct mbuf *m0, struct mbuf *control)
  665 {
  666         struct mbuf *ctrl_last;
  667         int space = asa->sa_len;
  668 
  669         SOCKBUF_LOCK_ASSERT(sb);
  670 
  671         if (m0 && (m0->m_flags & M_PKTHDR) == 0)
  672                 panic("sbappendaddr_locked");
  673         if (m0)
  674                 space += m0->m_pkthdr.len;
  675         space += m_length(control, &ctrl_last);
  676 
  677         if (space > sbspace(sb))
  678                 return (0);
  679         return (sbappendaddr_locked_internal(sb, asa, m0, control, ctrl_last));
  680 }
  681 
  682 /*
  683  * Append address and data, and optionally, control (ancillary) data to the
  684  * receive queue of a socket.  If present, m0 must include a packet header
  685  * with total length.  Returns 0 if insufficient mbufs.  Does not validate space
  686  * on the receiving sockbuf.
  687  */
  688 int
  689 sbappendaddr_nospacecheck_locked(struct sockbuf *sb, const struct sockaddr *asa,
  690     struct mbuf *m0, struct mbuf *control)
  691 {
  692         struct mbuf *ctrl_last;
  693 
  694         SOCKBUF_LOCK_ASSERT(sb);
  695 
  696         ctrl_last = (control == NULL) ? NULL : m_last(control);
  697         return (sbappendaddr_locked_internal(sb, asa, m0, control, ctrl_last));
  698 }
  699 
  700 /*
  701  * Append address and data, and optionally, control (ancillary) data to the
  702  * receive queue of a socket.  If present, m0 must include a packet header
  703  * with total length.  Returns 0 if no space in sockbuf or insufficient
  704  * mbufs.
  705  */
  706 int
  707 sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa,
  708     struct mbuf *m0, struct mbuf *control)
  709 {
  710         int retval;
  711 
  712         SOCKBUF_LOCK(sb);
  713         retval = sbappendaddr_locked(sb, asa, m0, control);
  714         SOCKBUF_UNLOCK(sb);
  715         return (retval);
  716 }
  717 
  718 int
  719 sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
  720     struct mbuf *control)
  721 {
  722         struct mbuf *m, *n, *mlast;
  723         int space;
  724 
  725         SOCKBUF_LOCK_ASSERT(sb);
  726 
  727         if (control == 0)
  728                 panic("sbappendcontrol_locked");
  729         space = m_length(control, &n) + m_length(m0, NULL);
  730 
  731         if (space > sbspace(sb))
  732                 return (0);
  733         n->m_next = m0;                 /* concatenate data to control */
  734 
  735         SBLASTRECORDCHK(sb);
  736 
  737         for (m = control; m->m_next; m = m->m_next)
  738                 sballoc(sb, m);
  739         sballoc(sb, m);
  740         mlast = m;
  741         SBLINKRECORD(sb, control);
  742 
  743         sb->sb_mbtail = mlast;
  744         SBLASTMBUFCHK(sb);
  745 
  746         SBLASTRECORDCHK(sb);
  747         return (1);
  748 }
  749 
  750 int
  751 sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
  752 {
  753         int retval;
  754 
  755         SOCKBUF_LOCK(sb);
  756         retval = sbappendcontrol_locked(sb, m0, control);
  757         SOCKBUF_UNLOCK(sb);
  758         return (retval);
  759 }
  760 
  761 /*
  762  * Append the data in mbuf chain (m) into the socket buffer sb following mbuf
  763  * (n).  If (n) is NULL, the buffer is presumed empty.
  764  *
  765  * When the data is compressed, mbufs in the chain may be handled in one of
  766  * three ways:
  767  *
  768  * (1) The mbuf may simply be dropped, if it contributes nothing (no data, no
  769  *     record boundary, and no change in data type).
  770  *
  771  * (2) The mbuf may be coalesced -- i.e., data in the mbuf may be copied into
  772  *     an mbuf already in the socket buffer.  This can occur if an
  773  *     appropriate mbuf exists, there is room, and no merging of data types
  774  *     will occur.
  775  *
  776  * (3) The mbuf may be appended to the end of the existing mbuf chain.
  777  *
  778  * If any of the new mbufs is marked as M_EOR, mark the last mbuf appended as
  779  * end-of-record.
  780  */
  781 void
  782 sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
  783 {
  784         int eor = 0;
  785         struct mbuf *o;
  786 
  787         SOCKBUF_LOCK_ASSERT(sb);
  788 
  789         while (m) {
  790                 eor |= m->m_flags & M_EOR;
  791                 if (m->m_len == 0 &&
  792                     (eor == 0 ||
  793                      (((o = m->m_next) || (o = n)) &&
  794                       o->m_type == m->m_type))) {
  795                         if (sb->sb_lastrecord == m)
  796                                 sb->sb_lastrecord = m->m_next;
  797                         m = m_free(m);
  798                         continue;
  799                 }
  800                 if (n && (n->m_flags & M_EOR) == 0 &&
  801                     M_WRITABLE(n) &&
  802                     ((sb->sb_flags & SB_NOCOALESCE) == 0) &&
  803                     m->m_len <= MCLBYTES / 4 && /* XXX: Don't copy too much */
  804                     m->m_len <= M_TRAILINGSPACE(n) &&
  805                     n->m_type == m->m_type) {
  806                         bcopy(mtod(m, caddr_t), mtod(n, caddr_t) + n->m_len,
  807                             (unsigned)m->m_len);
  808                         n->m_len += m->m_len;
  809                         sb->sb_cc += m->m_len;
  810                         if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
  811                                 /* XXX: Probably don't need.*/
  812                                 sb->sb_ctl += m->m_len;
  813                         m = m_free(m);
  814                         continue;
  815                 }
  816                 if (n)
  817                         n->m_next = m;
  818                 else
  819                         sb->sb_mb = m;
  820                 sb->sb_mbtail = m;
  821                 sballoc(sb, m);
  822                 n = m;
  823                 m->m_flags &= ~M_EOR;
  824                 m = m->m_next;
  825                 n->m_next = 0;
  826         }
  827         if (eor) {
  828                 KASSERT(n != NULL, ("sbcompress: eor && n == NULL"));
  829                 n->m_flags |= eor;
  830         }
  831         SBLASTMBUFCHK(sb);
  832 }
  833 
  834 /*
  835  * Free all mbufs in a sockbuf.  Check that all resources are reclaimed.
  836  */
  837 static void
  838 sbflush_internal(struct sockbuf *sb)
  839 {
  840 
  841         while (sb->sb_mbcnt) {
  842                 /*
  843                  * Don't call sbdrop(sb, 0) if the leading mbuf is non-empty:
  844                  * we would loop forever. Panic instead.
  845                  */
  846                 if (!sb->sb_cc && (sb->sb_mb == NULL || sb->sb_mb->m_len))
  847                         break;
  848                 m_freem(sbcut_internal(sb, (int)sb->sb_cc));
  849         }
  850         if (sb->sb_cc || sb->sb_mb || sb->sb_mbcnt)
  851                 panic("sbflush_internal: cc %u || mb %p || mbcnt %u",
  852                     sb->sb_cc, (void *)sb->sb_mb, sb->sb_mbcnt);
  853 }
  854 
  855 void
  856 sbflush_locked(struct sockbuf *sb)
  857 {
  858 
  859         SOCKBUF_LOCK_ASSERT(sb);
  860         sbflush_internal(sb);
  861 }
  862 
  863 void
  864 sbflush(struct sockbuf *sb)
  865 {
  866 
  867         SOCKBUF_LOCK(sb);
  868         sbflush_locked(sb);
  869         SOCKBUF_UNLOCK(sb);
  870 }
  871 
  872 /*
  873  * Cut data from (the front of) a sockbuf.
  874  */
  875 static struct mbuf *
  876 sbcut_internal(struct sockbuf *sb, int len)
  877 {
  878         struct mbuf *m, *n, *next, *mfree;
  879 
  880         next = (m = sb->sb_mb) ? m->m_nextpkt : 0;
  881         mfree = NULL;
  882 
  883         while (len > 0) {
  884                 if (m == 0) {
  885                         if (next == 0)
  886                                 panic("sbdrop");
  887                         m = next;
  888                         next = m->m_nextpkt;
  889                         continue;
  890                 }
  891                 if (m->m_len > len) {
  892                         m->m_len -= len;
  893                         m->m_data += len;
  894                         sb->sb_cc -= len;
  895                         if (sb->sb_sndptroff != 0)
  896                                 sb->sb_sndptroff -= len;
  897                         if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
  898                                 sb->sb_ctl -= len;
  899                         break;
  900                 }
  901                 len -= m->m_len;
  902                 sbfree(sb, m);
  903                 n = m->m_next;
  904                 m->m_next = mfree;
  905                 mfree = m;
  906                 m = n;
  907         }
  908         while (m && m->m_len == 0) {
  909                 sbfree(sb, m);
  910                 n = m->m_next;
  911                 m->m_next = mfree;
  912                 mfree = m;
  913                 m = n;
  914         }
  915         if (m) {
  916                 sb->sb_mb = m;
  917                 m->m_nextpkt = next;
  918         } else
  919                 sb->sb_mb = next;
  920         /*
  921          * First part is an inline SB_EMPTY_FIXUP().  Second part makes sure
  922          * sb_lastrecord is up-to-date if we dropped part of the last record.
  923          */
  924         m = sb->sb_mb;
  925         if (m == NULL) {
  926                 sb->sb_mbtail = NULL;
  927                 sb->sb_lastrecord = NULL;
  928         } else if (m->m_nextpkt == NULL) {
  929                 sb->sb_lastrecord = m;
  930         }
  931 
  932         return (mfree);
  933 }
  934 
  935 /*
  936  * Drop data from (the front of) a sockbuf.
  937  */
  938 void
  939 sbdrop_locked(struct sockbuf *sb, int len)
  940 {
  941 
  942         SOCKBUF_LOCK_ASSERT(sb);
  943         m_freem(sbcut_internal(sb, len));
  944 }
  945 
  946 /*
  947  * Drop data from (the front of) a sockbuf,
  948  * and return it to caller.
  949  */
  950 struct mbuf *
  951 sbcut_locked(struct sockbuf *sb, int len)
  952 {
  953 
  954         SOCKBUF_LOCK_ASSERT(sb);
  955         return (sbcut_internal(sb, len));
  956 }
  957 
  958 void
  959 sbdrop(struct sockbuf *sb, int len)
  960 {
  961         struct mbuf *mfree;
  962 
  963         SOCKBUF_LOCK(sb);
  964         mfree = sbcut_internal(sb, len);
  965         SOCKBUF_UNLOCK(sb);
  966 
  967         m_freem(mfree);
  968 }
  969 
  970 /*
  971  * Maintain a pointer and offset pair into the socket buffer mbuf chain to
  972  * avoid traversal of the entire socket buffer for larger offsets.
  973  */
  974 struct mbuf *
  975 sbsndptr(struct sockbuf *sb, u_int off, u_int len, u_int *moff)
  976 {
  977         struct mbuf *m, *ret;
  978 
  979         KASSERT(sb->sb_mb != NULL, ("%s: sb_mb is NULL", __func__));
  980         KASSERT(off + len <= sb->sb_cc, ("%s: beyond sb", __func__));
  981         KASSERT(sb->sb_sndptroff <= sb->sb_cc, ("%s: sndptroff broken", __func__));
  982 
  983         /*
  984          * Is off below stored offset? Happens on retransmits.
  985          * Just return, we can't help here.
  986          */
  987         if (sb->sb_sndptroff > off) {
  988                 *moff = off;
  989                 return (sb->sb_mb);
  990         }
  991 
  992         /* Return closest mbuf in chain for current offset. */
  993         *moff = off - sb->sb_sndptroff;
  994         m = ret = sb->sb_sndptr ? sb->sb_sndptr : sb->sb_mb;
  995         if (*moff == m->m_len) {
  996                 *moff = 0;
  997                 sb->sb_sndptroff += m->m_len;
  998                 m = ret = m->m_next;
  999                 KASSERT(ret->m_len > 0,
 1000                     ("mbuf %p in sockbuf %p chain has no valid data", ret, sb));
 1001         }
 1002 
 1003         /* Advance by len to be as close as possible for the next transmit. */
 1004         for (off = off - sb->sb_sndptroff + len - 1;
 1005              off > 0 && m != NULL && off >= m->m_len;
 1006              m = m->m_next) {
 1007                 sb->sb_sndptroff += m->m_len;
 1008                 off -= m->m_len;
 1009         }
 1010         if (off > 0 && m == NULL)
 1011                 panic("%s: sockbuf %p and mbuf %p clashing", __func__, sb, ret);
 1012         sb->sb_sndptr = m;
 1013 
 1014         return (ret);
 1015 }
 1016 
 1017 /*
 1018  * Return the first mbuf and the mbuf data offset for the provided
 1019  * send offset without changing the "sb_sndptroff" field.
 1020  */
 1021 struct mbuf *
 1022 sbsndmbuf(struct sockbuf *sb, u_int off, u_int *moff)
 1023 {
 1024         struct mbuf *m;
 1025 
 1026         KASSERT(sb->sb_mb != NULL, ("%s: sb_mb is NULL", __func__));
 1027 
 1028         /*
 1029          * If the "off" is below the stored offset, which happens on
 1030          * retransmits, just use "sb_mb":
 1031          */
 1032         if (sb->sb_sndptr == NULL || sb->sb_sndptroff > off) {
 1033                 m = sb->sb_mb;
 1034         } else {
 1035                 m = sb->sb_sndptr;
 1036                 off -= sb->sb_sndptroff;
 1037         }
 1038         while (off > 0 && m != NULL) {
 1039                 if (off < m->m_len)
 1040                         break;
 1041                 off -= m->m_len;
 1042                 m = m->m_next;
 1043         }
 1044         *moff = off;
 1045         return (m);
 1046 }
 1047 
 1048 /*
 1049  * Drop a record off the front of a sockbuf and move the next record to the
 1050  * front.
 1051  */
 1052 void
 1053 sbdroprecord_locked(struct sockbuf *sb)
 1054 {
 1055         struct mbuf *m;
 1056 
 1057         SOCKBUF_LOCK_ASSERT(sb);
 1058 
 1059         m = sb->sb_mb;
 1060         if (m) {
 1061                 sb->sb_mb = m->m_nextpkt;
 1062                 do {
 1063                         sbfree(sb, m);
 1064                         m = m_free(m);
 1065                 } while (m);
 1066         }
 1067         SB_EMPTY_FIXUP(sb);
 1068 }
 1069 
 1070 /*
 1071  * Drop a record off the front of a sockbuf and move the next record to the
 1072  * front.
 1073  */
 1074 void
 1075 sbdroprecord(struct sockbuf *sb)
 1076 {
 1077 
 1078         SOCKBUF_LOCK(sb);
 1079         sbdroprecord_locked(sb);
 1080         SOCKBUF_UNLOCK(sb);
 1081 }
 1082 
 1083 /*
 1084  * Create a "control" mbuf containing the specified data with the specified
 1085  * type for presentation on a socket buffer.
 1086  */
 1087 struct mbuf *
 1088 sbcreatecontrol(caddr_t p, int size, int type, int level)
 1089 {
 1090         struct cmsghdr *cp;
 1091         struct mbuf *m;
 1092 
 1093         if (CMSG_SPACE((u_int)size) > MCLBYTES)
 1094                 return ((struct mbuf *) NULL);
 1095         if (CMSG_SPACE((u_int)size) > MLEN)
 1096                 m = m_getcl(M_NOWAIT, MT_CONTROL, 0);
 1097         else
 1098                 m = m_get(M_NOWAIT, MT_CONTROL);
 1099         if (m == NULL)
 1100                 return ((struct mbuf *) NULL);
 1101         cp = mtod(m, struct cmsghdr *);
 1102         m->m_len = 0;
 1103         KASSERT(CMSG_SPACE((u_int)size) <= M_TRAILINGSPACE(m),
 1104             ("sbcreatecontrol: short mbuf"));
 1105         /*
 1106          * Don't leave the padding between the msg header and the
 1107          * cmsg data and the padding after the cmsg data un-initialized.
 1108          */
 1109         bzero(cp, CMSG_SPACE((u_int)size));
 1110         if (p != NULL)
 1111                 (void)memcpy(CMSG_DATA(cp), p, size);
 1112         m->m_len = CMSG_SPACE(size);
 1113         cp->cmsg_len = CMSG_LEN(size);
 1114         cp->cmsg_level = level;
 1115         cp->cmsg_type = type;
 1116         return (m);
 1117 }
 1118 
 1119 /*
 1120  * This does the same for socket buffers that sotoxsocket does for sockets:
 1121  * generate an user-format data structure describing the socket buffer.  Note
 1122  * that the xsockbuf structure, since it is always embedded in a socket, does
 1123  * not include a self pointer nor a length.  We make this entry point public
 1124  * in case some other mechanism needs it.
 1125  */
 1126 void
 1127 sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb)
 1128 {
 1129 
 1130         xsb->sb_cc = sb->sb_cc;
 1131         xsb->sb_hiwat = sb->sb_hiwat;
 1132         xsb->sb_mbcnt = sb->sb_mbcnt;
 1133         xsb->sb_mcnt = sb->sb_mcnt;     
 1134         xsb->sb_ccnt = sb->sb_ccnt;
 1135         xsb->sb_mbmax = sb->sb_mbmax;
 1136         xsb->sb_lowat = sb->sb_lowat;
 1137         xsb->sb_flags = sb->sb_flags;
 1138         xsb->sb_timeo = sb->sb_timeo;
 1139 }
 1140 
 1141 /* This takes the place of kern.maxsockbuf, which moved to kern.ipc. */
 1142 static int dummy;
 1143 SYSCTL_INT(_kern, KERN_DUMMY, dummy, CTLFLAG_RW, &dummy, 0, "");
 1144 SYSCTL_OID(_kern_ipc, KIPC_MAXSOCKBUF, maxsockbuf, CTLTYPE_ULONG|CTLFLAG_RW,
 1145     &sb_max, 0, sysctl_handle_sb_max, "LU", "Maximum socket buffer size");
 1146 SYSCTL_ULONG(_kern_ipc, KIPC_SOCKBUF_WASTE, sockbuf_waste_factor, CTLFLAG_RW,
 1147     &sb_efficiency, 0, "Socket buffer size waste factor");

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