The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1991, 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_mbuf.c 8.2 (Berkeley) 1/4/94
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/10.1/sys/kern/uipc_mbuf.c 258483 2013-11-22 19:27:17Z glebius $");
   34 
   35 #include "opt_param.h"
   36 #include "opt_mbuf_stress_test.h"
   37 #include "opt_mbuf_profiling.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/kernel.h>
   42 #include <sys/limits.h>
   43 #include <sys/lock.h>
   44 #include <sys/malloc.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/domain.h>
   48 #include <sys/protosw.h>
   49 #include <sys/uio.h>
   50 
   51 int     max_linkhdr;
   52 int     max_protohdr;
   53 int     max_hdr;
   54 int     max_datalen;
   55 #ifdef MBUF_STRESS_TEST
   56 int     m_defragpackets;
   57 int     m_defragbytes;
   58 int     m_defraguseless;
   59 int     m_defragfailure;
   60 int     m_defragrandomfailures;
   61 #endif
   62 
   63 /*
   64  * sysctl(8) exported objects
   65  */
   66 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD,
   67            &max_linkhdr, 0, "Size of largest link layer header");
   68 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD,
   69            &max_protohdr, 0, "Size of largest protocol layer header");
   70 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD,
   71            &max_hdr, 0, "Size of largest link plus protocol header");
   72 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD,
   73            &max_datalen, 0, "Minimum space left in mbuf after max_hdr");
   74 #ifdef MBUF_STRESS_TEST
   75 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
   76            &m_defragpackets, 0, "");
   77 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
   78            &m_defragbytes, 0, "");
   79 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
   80            &m_defraguseless, 0, "");
   81 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
   82            &m_defragfailure, 0, "");
   83 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
   84            &m_defragrandomfailures, 0, "");
   85 #endif
   86 
   87 /*
   88  * Ensure the correct size of various mbuf parameters.  It could be off due
   89  * to compiler-induced padding and alignment artifacts.
   90  */
   91 CTASSERT(sizeof(struct mbuf) == MSIZE);
   92 CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN);
   93 CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN);
   94 
   95 /*
   96  * m_get2() allocates minimum mbuf that would fit "size" argument.
   97  */
   98 struct mbuf *
   99 m_get2(int size, int how, short type, int flags)
  100 {
  101         struct mb_args args;
  102         struct mbuf *m, *n;
  103 
  104         args.flags = flags;
  105         args.type = type;
  106 
  107         if (size <= MHLEN || (size <= MLEN && (flags & M_PKTHDR) == 0))
  108                 return (uma_zalloc_arg(zone_mbuf, &args, how));
  109         if (size <= MCLBYTES)
  110                 return (uma_zalloc_arg(zone_pack, &args, how));
  111 
  112         if (size > MJUMPAGESIZE)
  113                 return (NULL);
  114 
  115         m = uma_zalloc_arg(zone_mbuf, &args, how);
  116         if (m == NULL)
  117                 return (NULL);
  118 
  119         n = uma_zalloc_arg(zone_jumbop, m, how);
  120         if (n == NULL) {
  121                 uma_zfree(zone_mbuf, m);
  122                 return (NULL);
  123         }
  124 
  125         return (m);
  126 }
  127 
  128 /*
  129  * m_getjcl() returns an mbuf with a cluster of the specified size attached.
  130  * For size it takes MCLBYTES, MJUMPAGESIZE, MJUM9BYTES, MJUM16BYTES.
  131  */
  132 struct mbuf *
  133 m_getjcl(int how, short type, int flags, int size)
  134 {
  135         struct mb_args args;
  136         struct mbuf *m, *n;
  137         uma_zone_t zone;
  138 
  139         if (size == MCLBYTES)
  140                 return m_getcl(how, type, flags);
  141 
  142         args.flags = flags;
  143         args.type = type;
  144 
  145         m = uma_zalloc_arg(zone_mbuf, &args, how);
  146         if (m == NULL)
  147                 return (NULL);
  148 
  149         zone = m_getzone(size);
  150         n = uma_zalloc_arg(zone, m, how);
  151         if (n == NULL) {
  152                 uma_zfree(zone_mbuf, m);
  153                 return (NULL);
  154         }
  155         return (m);
  156 }
  157 
  158 /*
  159  * Allocate a given length worth of mbufs and/or clusters (whatever fits
  160  * best) and return a pointer to the top of the allocated chain.  If an
  161  * existing mbuf chain is provided, then we will append the new chain
  162  * to the existing one but still return the top of the newly allocated
  163  * chain.
  164  */
  165 struct mbuf *
  166 m_getm2(struct mbuf *m, int len, int how, short type, int flags)
  167 {
  168         struct mbuf *mb, *nm = NULL, *mtail = NULL;
  169 
  170         KASSERT(len >= 0, ("%s: len is < 0", __func__));
  171 
  172         /* Validate flags. */
  173         flags &= (M_PKTHDR | M_EOR);
  174 
  175         /* Packet header mbuf must be first in chain. */
  176         if ((flags & M_PKTHDR) && m != NULL)
  177                 flags &= ~M_PKTHDR;
  178 
  179         /* Loop and append maximum sized mbufs to the chain tail. */
  180         while (len > 0) {
  181                 if (len > MCLBYTES)
  182                         mb = m_getjcl(how, type, (flags & M_PKTHDR),
  183                             MJUMPAGESIZE);
  184                 else if (len >= MINCLSIZE)
  185                         mb = m_getcl(how, type, (flags & M_PKTHDR));
  186                 else if (flags & M_PKTHDR)
  187                         mb = m_gethdr(how, type);
  188                 else
  189                         mb = m_get(how, type);
  190 
  191                 /* Fail the whole operation if one mbuf can't be allocated. */
  192                 if (mb == NULL) {
  193                         if (nm != NULL)
  194                                 m_freem(nm);
  195                         return (NULL);
  196                 }
  197 
  198                 /* Book keeping. */
  199                 len -= (mb->m_flags & M_EXT) ? mb->m_ext.ext_size :
  200                         ((mb->m_flags & M_PKTHDR) ? MHLEN : MLEN);
  201                 if (mtail != NULL)
  202                         mtail->m_next = mb;
  203                 else
  204                         nm = mb;
  205                 mtail = mb;
  206                 flags &= ~M_PKTHDR;     /* Only valid on the first mbuf. */
  207         }
  208         if (flags & M_EOR)
  209                 mtail->m_flags |= M_EOR;  /* Only valid on the last mbuf. */
  210 
  211         /* If mbuf was supplied, append new chain to the end of it. */
  212         if (m != NULL) {
  213                 for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next)
  214                         ;
  215                 mtail->m_next = nm;
  216                 mtail->m_flags &= ~M_EOR;
  217         } else
  218                 m = nm;
  219 
  220         return (m);
  221 }
  222 
  223 /*
  224  * Free an entire chain of mbufs and associated external buffers, if
  225  * applicable.
  226  */
  227 void
  228 m_freem(struct mbuf *mb)
  229 {
  230 
  231         while (mb != NULL)
  232                 mb = m_free(mb);
  233 }
  234 
  235 /*-
  236  * Configure a provided mbuf to refer to the provided external storage
  237  * buffer and setup a reference count for said buffer.  If the setting
  238  * up of the reference count fails, the M_EXT bit will not be set.  If
  239  * successfull, the M_EXT bit is set in the mbuf's flags.
  240  *
  241  * Arguments:
  242  *    mb     The existing mbuf to which to attach the provided buffer.
  243  *    buf    The address of the provided external storage buffer.
  244  *    size   The size of the provided buffer.
  245  *    freef  A pointer to a routine that is responsible for freeing the
  246  *           provided external storage buffer.
  247  *    args   A pointer to an argument structure (of any type) to be passed
  248  *           to the provided freef routine (may be NULL).
  249  *    flags  Any other flags to be passed to the provided mbuf.
  250  *    type   The type that the external storage buffer should be
  251  *           labeled with.
  252  *
  253  * Returns:
  254  *    Nothing.
  255  */
  256 int
  257 m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
  258     int (*freef)(struct mbuf *, void *, void *), void *arg1, void *arg2,
  259     int flags, int type, int wait)
  260 {
  261         KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
  262 
  263         if (type != EXT_EXTREF)
  264                 mb->m_ext.ref_cnt = uma_zalloc(zone_ext_refcnt, wait);
  265 
  266         if (mb->m_ext.ref_cnt == NULL)
  267                 return (ENOMEM);
  268 
  269         *(mb->m_ext.ref_cnt) = 1;
  270         mb->m_flags |= (M_EXT | flags);
  271         mb->m_ext.ext_buf = buf;
  272         mb->m_data = mb->m_ext.ext_buf;
  273         mb->m_ext.ext_size = size;
  274         mb->m_ext.ext_free = freef;
  275         mb->m_ext.ext_arg1 = arg1;
  276         mb->m_ext.ext_arg2 = arg2;
  277         mb->m_ext.ext_type = type;
  278         mb->m_ext.ext_flags = 0;
  279 
  280         return (0);
  281 }
  282 
  283 /*
  284  * Non-directly-exported function to clean up after mbufs with M_EXT
  285  * storage attached to them if the reference count hits 1.
  286  */
  287 void
  288 mb_free_ext(struct mbuf *m)
  289 {
  290         int skipmbuf;
  291         
  292         KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
  293         KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
  294 
  295         /*
  296          * check if the header is embedded in the cluster
  297          */
  298         skipmbuf = (m->m_flags & M_NOFREE);
  299 
  300         /* Free attached storage if this mbuf is the only reference to it. */
  301         if (*(m->m_ext.ref_cnt) == 1 ||
  302             atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 1) {
  303                 switch (m->m_ext.ext_type) {
  304                 case EXT_PACKET:        /* The packet zone is special. */
  305                         if (*(m->m_ext.ref_cnt) == 0)
  306                                 *(m->m_ext.ref_cnt) = 1;
  307                         uma_zfree(zone_pack, m);
  308                         return;         /* Job done. */
  309                 case EXT_CLUSTER:
  310                         uma_zfree(zone_clust, m->m_ext.ext_buf);
  311                         break;
  312                 case EXT_JUMBOP:
  313                         uma_zfree(zone_jumbop, m->m_ext.ext_buf);
  314                         break;
  315                 case EXT_JUMBO9:
  316                         uma_zfree(zone_jumbo9, m->m_ext.ext_buf);
  317                         break;
  318                 case EXT_JUMBO16:
  319                         uma_zfree(zone_jumbo16, m->m_ext.ext_buf);
  320                         break;
  321                 case EXT_SFBUF:
  322                 case EXT_NET_DRV:
  323                 case EXT_MOD_TYPE:
  324                 case EXT_DISPOSABLE:
  325                         *(m->m_ext.ref_cnt) = 0;
  326                         uma_zfree(zone_ext_refcnt, __DEVOLATILE(u_int *,
  327                                 m->m_ext.ref_cnt));
  328                         /* FALLTHROUGH */
  329                 case EXT_EXTREF:
  330                         KASSERT(m->m_ext.ext_free != NULL,
  331                                 ("%s: ext_free not set", __func__));
  332                         (void)(*(m->m_ext.ext_free))(m, m->m_ext.ext_arg1,
  333                             m->m_ext.ext_arg2);
  334                         break;
  335                 default:
  336                         KASSERT(m->m_ext.ext_type == 0,
  337                                 ("%s: unknown ext_type", __func__));
  338                 }
  339         }
  340         if (skipmbuf)
  341                 return;
  342         
  343         /*
  344          * Free this mbuf back to the mbuf zone with all m_ext
  345          * information purged.
  346          */
  347         m->m_ext.ext_buf = NULL;
  348         m->m_ext.ext_free = NULL;
  349         m->m_ext.ext_arg1 = NULL;
  350         m->m_ext.ext_arg2 = NULL;
  351         m->m_ext.ref_cnt = NULL;
  352         m->m_ext.ext_size = 0;
  353         m->m_ext.ext_type = 0;
  354         m->m_ext.ext_flags = 0;
  355         m->m_flags &= ~M_EXT;
  356         uma_zfree(zone_mbuf, m);
  357 }
  358 
  359 /*
  360  * Attach the cluster from *m to *n, set up m_ext in *n
  361  * and bump the refcount of the cluster.
  362  */
  363 static void
  364 mb_dupcl(struct mbuf *n, struct mbuf *m)
  365 {
  366         KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
  367         KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
  368         KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
  369 
  370         if (*(m->m_ext.ref_cnt) == 1)
  371                 *(m->m_ext.ref_cnt) += 1;
  372         else
  373                 atomic_add_int(m->m_ext.ref_cnt, 1);
  374         n->m_ext.ext_buf = m->m_ext.ext_buf;
  375         n->m_ext.ext_free = m->m_ext.ext_free;
  376         n->m_ext.ext_arg1 = m->m_ext.ext_arg1;
  377         n->m_ext.ext_arg2 = m->m_ext.ext_arg2;
  378         n->m_ext.ext_size = m->m_ext.ext_size;
  379         n->m_ext.ref_cnt = m->m_ext.ref_cnt;
  380         n->m_ext.ext_type = m->m_ext.ext_type;
  381         n->m_ext.ext_flags = m->m_ext.ext_flags;
  382         n->m_flags |= M_EXT;
  383         n->m_flags |= m->m_flags & M_RDONLY;
  384 }
  385 
  386 /*
  387  * Clean up mbuf (chain) from any tags and packet headers.
  388  * If "all" is set then the first mbuf in the chain will be
  389  * cleaned too.
  390  */
  391 void
  392 m_demote(struct mbuf *m0, int all)
  393 {
  394         struct mbuf *m;
  395 
  396         for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
  397                 if (m->m_flags & M_PKTHDR) {
  398                         m_tag_delete_chain(m, NULL);
  399                         m->m_flags &= ~M_PKTHDR;
  400                         bzero(&m->m_pkthdr, sizeof(struct pkthdr));
  401                 }
  402                 if (m != m0 && m->m_nextpkt != NULL) {
  403                         KASSERT(m->m_nextpkt == NULL,
  404                             ("%s: m_nextpkt not NULL", __func__));
  405                         m_freem(m->m_nextpkt);
  406                         m->m_nextpkt = NULL;
  407                 }
  408                 m->m_flags = m->m_flags & (M_EXT|M_RDONLY|M_NOFREE);
  409         }
  410 }
  411 
  412 /*
  413  * Sanity checks on mbuf (chain) for use in KASSERT() and general
  414  * debugging.
  415  * Returns 0 or panics when bad and 1 on all tests passed.
  416  * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
  417  * blow up later.
  418  */
  419 int
  420 m_sanity(struct mbuf *m0, int sanitize)
  421 {
  422         struct mbuf *m;
  423         caddr_t a, b;
  424         int pktlen = 0;
  425 
  426 #ifdef INVARIANTS
  427 #define M_SANITY_ACTION(s)      panic("mbuf %p: " s, m)
  428 #else 
  429 #define M_SANITY_ACTION(s)      printf("mbuf %p: " s, m)
  430 #endif
  431 
  432         for (m = m0; m != NULL; m = m->m_next) {
  433                 /*
  434                  * Basic pointer checks.  If any of these fails then some
  435                  * unrelated kernel memory before or after us is trashed.
  436                  * No way to recover from that.
  437                  */
  438                 a = ((m->m_flags & M_EXT) ? m->m_ext.ext_buf :
  439                         ((m->m_flags & M_PKTHDR) ? (caddr_t)(&m->m_pktdat) :
  440                          (caddr_t)(&m->m_dat)) );
  441                 b = (caddr_t)(a + (m->m_flags & M_EXT ? m->m_ext.ext_size :
  442                         ((m->m_flags & M_PKTHDR) ? MHLEN : MLEN)));
  443                 if ((caddr_t)m->m_data < a)
  444                         M_SANITY_ACTION("m_data outside mbuf data range left");
  445                 if ((caddr_t)m->m_data > b)
  446                         M_SANITY_ACTION("m_data outside mbuf data range right");
  447                 if ((caddr_t)m->m_data + m->m_len > b)
  448                         M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
  449 
  450                 /* m->m_nextpkt may only be set on first mbuf in chain. */
  451                 if (m != m0 && m->m_nextpkt != NULL) {
  452                         if (sanitize) {
  453                                 m_freem(m->m_nextpkt);
  454                                 m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
  455                         } else
  456                                 M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
  457                 }
  458 
  459                 /* packet length (not mbuf length!) calculation */
  460                 if (m0->m_flags & M_PKTHDR)
  461                         pktlen += m->m_len;
  462 
  463                 /* m_tags may only be attached to first mbuf in chain. */
  464                 if (m != m0 && m->m_flags & M_PKTHDR &&
  465                     !SLIST_EMPTY(&m->m_pkthdr.tags)) {
  466                         if (sanitize) {
  467                                 m_tag_delete_chain(m, NULL);
  468                                 /* put in 0xDEADC0DE perhaps? */
  469                         } else
  470                                 M_SANITY_ACTION("m_tags on in-chain mbuf");
  471                 }
  472 
  473                 /* M_PKTHDR may only be set on first mbuf in chain */
  474                 if (m != m0 && m->m_flags & M_PKTHDR) {
  475                         if (sanitize) {
  476                                 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
  477                                 m->m_flags &= ~M_PKTHDR;
  478                                 /* put in 0xDEADCODE and leave hdr flag in */
  479                         } else
  480                                 M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
  481                 }
  482         }
  483         m = m0;
  484         if (pktlen && pktlen != m->m_pkthdr.len) {
  485                 if (sanitize)
  486                         m->m_pkthdr.len = 0;
  487                 else
  488                         M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
  489         }
  490         return 1;
  491 
  492 #undef  M_SANITY_ACTION
  493 }
  494 
  495 
  496 /*
  497  * "Move" mbuf pkthdr from "from" to "to".
  498  * "from" must have M_PKTHDR set, and "to" must be empty.
  499  */
  500 void
  501 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
  502 {
  503 
  504 #if 0
  505         /* see below for why these are not enabled */
  506         M_ASSERTPKTHDR(to);
  507         /* Note: with MAC, this may not be a good assertion. */
  508         KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
  509             ("m_move_pkthdr: to has tags"));
  510 #endif
  511 #ifdef MAC
  512         /*
  513          * XXXMAC: It could be this should also occur for non-MAC?
  514          */
  515         if (to->m_flags & M_PKTHDR)
  516                 m_tag_delete_chain(to, NULL);
  517 #endif
  518         to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
  519         if ((to->m_flags & M_EXT) == 0)
  520                 to->m_data = to->m_pktdat;
  521         to->m_pkthdr = from->m_pkthdr;          /* especially tags */
  522         SLIST_INIT(&from->m_pkthdr.tags);       /* purge tags from src */
  523         from->m_flags &= ~M_PKTHDR;
  524 }
  525 
  526 /*
  527  * Duplicate "from"'s mbuf pkthdr in "to".
  528  * "from" must have M_PKTHDR set, and "to" must be empty.
  529  * In particular, this does a deep copy of the packet tags.
  530  */
  531 int
  532 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
  533 {
  534 
  535 #if 0
  536         /*
  537          * The mbuf allocator only initializes the pkthdr
  538          * when the mbuf is allocated with m_gethdr(). Many users
  539          * (e.g. m_copy*, m_prepend) use m_get() and then
  540          * smash the pkthdr as needed causing these
  541          * assertions to trip.  For now just disable them.
  542          */
  543         M_ASSERTPKTHDR(to);
  544         /* Note: with MAC, this may not be a good assertion. */
  545         KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
  546 #endif
  547         MBUF_CHECKSLEEP(how);
  548 #ifdef MAC
  549         if (to->m_flags & M_PKTHDR)
  550                 m_tag_delete_chain(to, NULL);
  551 #endif
  552         to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
  553         if ((to->m_flags & M_EXT) == 0)
  554                 to->m_data = to->m_pktdat;
  555         to->m_pkthdr = from->m_pkthdr;
  556         SLIST_INIT(&to->m_pkthdr.tags);
  557         return (m_tag_copy_chain(to, from, MBTOM(how)));
  558 }
  559 
  560 /*
  561  * Lesser-used path for M_PREPEND:
  562  * allocate new mbuf to prepend to chain,
  563  * copy junk along.
  564  */
  565 struct mbuf *
  566 m_prepend(struct mbuf *m, int len, int how)
  567 {
  568         struct mbuf *mn;
  569 
  570         if (m->m_flags & M_PKTHDR)
  571                 mn = m_gethdr(how, m->m_type);
  572         else
  573                 mn = m_get(how, m->m_type);
  574         if (mn == NULL) {
  575                 m_freem(m);
  576                 return (NULL);
  577         }
  578         if (m->m_flags & M_PKTHDR)
  579                 m_move_pkthdr(mn, m);
  580         mn->m_next = m;
  581         m = mn;
  582         if(m->m_flags & M_PKTHDR) {
  583                 if (len < MHLEN)
  584                         MH_ALIGN(m, len);
  585         } else {
  586                 if (len < MLEN) 
  587                         M_ALIGN(m, len);
  588         }
  589         m->m_len = len;
  590         return (m);
  591 }
  592 
  593 /*
  594  * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
  595  * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
  596  * The wait parameter is a choice of M_WAITOK/M_NOWAIT from caller.
  597  * Note that the copy is read-only, because clusters are not copied,
  598  * only their reference counts are incremented.
  599  */
  600 struct mbuf *
  601 m_copym(struct mbuf *m, int off0, int len, int wait)
  602 {
  603         struct mbuf *n, **np;
  604         int off = off0;
  605         struct mbuf *top;
  606         int copyhdr = 0;
  607 
  608         KASSERT(off >= 0, ("m_copym, negative off %d", off));
  609         KASSERT(len >= 0, ("m_copym, negative len %d", len));
  610         MBUF_CHECKSLEEP(wait);
  611         if (off == 0 && m->m_flags & M_PKTHDR)
  612                 copyhdr = 1;
  613         while (off > 0) {
  614                 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
  615                 if (off < m->m_len)
  616                         break;
  617                 off -= m->m_len;
  618                 m = m->m_next;
  619         }
  620         np = &top;
  621         top = 0;
  622         while (len > 0) {
  623                 if (m == NULL) {
  624                         KASSERT(len == M_COPYALL, 
  625                             ("m_copym, length > size of mbuf chain"));
  626                         break;
  627                 }
  628                 if (copyhdr)
  629                         n = m_gethdr(wait, m->m_type);
  630                 else
  631                         n = m_get(wait, m->m_type);
  632                 *np = n;
  633                 if (n == NULL)
  634                         goto nospace;
  635                 if (copyhdr) {
  636                         if (!m_dup_pkthdr(n, m, wait))
  637                                 goto nospace;
  638                         if (len == M_COPYALL)
  639                                 n->m_pkthdr.len -= off0;
  640                         else
  641                                 n->m_pkthdr.len = len;
  642                         copyhdr = 0;
  643                 }
  644                 n->m_len = min(len, m->m_len - off);
  645                 if (m->m_flags & M_EXT) {
  646                         n->m_data = m->m_data + off;
  647                         mb_dupcl(n, m);
  648                 } else
  649                         bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
  650                             (u_int)n->m_len);
  651                 if (len != M_COPYALL)
  652                         len -= n->m_len;
  653                 off = 0;
  654                 m = m->m_next;
  655                 np = &n->m_next;
  656         }
  657 
  658         return (top);
  659 nospace:
  660         m_freem(top);
  661         return (NULL);
  662 }
  663 
  664 /*
  665  * Returns mbuf chain with new head for the prepending case.
  666  * Copies from mbuf (chain) n from off for len to mbuf (chain) m
  667  * either prepending or appending the data.
  668  * The resulting mbuf (chain) m is fully writeable.
  669  * m is destination (is made writeable)
  670  * n is source, off is offset in source, len is len from offset
  671  * dir, 0 append, 1 prepend
  672  * how, wait or nowait
  673  */
  674 
  675 static int
  676 m_bcopyxxx(void *s, void *t, u_int len)
  677 {
  678         bcopy(s, t, (size_t)len);
  679         return 0;
  680 }
  681 
  682 struct mbuf *
  683 m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len,
  684     int prep, int how)
  685 {
  686         struct mbuf *mm, *x, *z, *prev = NULL;
  687         caddr_t p;
  688         int i, nlen = 0;
  689         caddr_t buf[MLEN];
  690 
  691         KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source"));
  692         KASSERT(off >= 0, ("m_copymdata, negative off %d", off));
  693         KASSERT(len >= 0, ("m_copymdata, negative len %d", len));
  694         KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep));
  695 
  696         mm = m;
  697         if (!prep) {
  698                 while(mm->m_next) {
  699                         prev = mm;
  700                         mm = mm->m_next;
  701                 }
  702         }
  703         for (z = n; z != NULL; z = z->m_next)
  704                 nlen += z->m_len;
  705         if (len == M_COPYALL)
  706                 len = nlen - off;
  707         if (off + len > nlen || len < 1)
  708                 return NULL;
  709 
  710         if (!M_WRITABLE(mm)) {
  711                 /* XXX: Use proper m_xxx function instead. */
  712                 x = m_getcl(how, MT_DATA, mm->m_flags);
  713                 if (x == NULL)
  714                         return NULL;
  715                 bcopy(mm->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size);
  716                 p = x->m_ext.ext_buf + (mm->m_data - mm->m_ext.ext_buf);
  717                 x->m_data = p;
  718                 mm->m_next = NULL;
  719                 if (mm != m)
  720                         prev->m_next = x;
  721                 m_free(mm);
  722                 mm = x;
  723         }
  724 
  725         /*
  726          * Append/prepend the data.  Allocating mbufs as necessary.
  727          */
  728         /* Shortcut if enough free space in first/last mbuf. */
  729         if (!prep && M_TRAILINGSPACE(mm) >= len) {
  730                 m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) +
  731                          mm->m_len);
  732                 mm->m_len += len;
  733                 mm->m_pkthdr.len += len;
  734                 return m;
  735         }
  736         if (prep && M_LEADINGSPACE(mm) >= len) {
  737                 mm->m_data = mtod(mm, caddr_t) - len;
  738                 m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t));
  739                 mm->m_len += len;
  740                 mm->m_pkthdr.len += len;
  741                 return mm;
  742         }
  743 
  744         /* Expand first/last mbuf to cluster if possible. */
  745         if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) {
  746                 bcopy(mm->m_data, &buf, mm->m_len);
  747                 m_clget(mm, how);
  748                 if (!(mm->m_flags & M_EXT))
  749                         return NULL;
  750                 bcopy(&buf, mm->m_ext.ext_buf, mm->m_len);
  751                 mm->m_data = mm->m_ext.ext_buf;
  752         }
  753         if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) {
  754                 bcopy(mm->m_data, &buf, mm->m_len);
  755                 m_clget(mm, how);
  756                 if (!(mm->m_flags & M_EXT))
  757                         return NULL;
  758                 bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf +
  759                        mm->m_ext.ext_size - mm->m_len, mm->m_len);
  760                 mm->m_data = (caddr_t)mm->m_ext.ext_buf +
  761                               mm->m_ext.ext_size - mm->m_len;
  762         }
  763 
  764         /* Append/prepend as many mbuf (clusters) as necessary to fit len. */
  765         if (!prep && len > M_TRAILINGSPACE(mm)) {
  766                 if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA))
  767                         return NULL;
  768         }
  769         if (prep && len > M_LEADINGSPACE(mm)) {
  770                 if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA)))
  771                         return NULL;
  772                 i = 0;
  773                 for (x = z; x != NULL; x = x->m_next) {
  774                         i += x->m_flags & M_EXT ? x->m_ext.ext_size :
  775                               (x->m_flags & M_PKTHDR ? MHLEN : MLEN);
  776                         if (!x->m_next)
  777                                 break;
  778                 }
  779                 z->m_data += i - len;
  780                 m_move_pkthdr(mm, z);
  781                 x->m_next = mm;
  782                 mm = z;
  783         }
  784 
  785         /* Seek to start position in source mbuf. Optimization for long chains. */
  786         while (off > 0) {
  787                 if (off < n->m_len)
  788                         break;
  789                 off -= n->m_len;
  790                 n = n->m_next;
  791         }
  792 
  793         /* Copy data into target mbuf. */
  794         z = mm;
  795         while (len > 0) {
  796                 KASSERT(z != NULL, ("m_copymdata, falling off target edge"));
  797                 i = M_TRAILINGSPACE(z);
  798                 m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len);
  799                 z->m_len += i;
  800                 /* fixup pkthdr.len if necessary */
  801                 if ((prep ? mm : m)->m_flags & M_PKTHDR)
  802                         (prep ? mm : m)->m_pkthdr.len += i;
  803                 off += i;
  804                 len -= i;
  805                 z = z->m_next;
  806         }
  807         return (prep ? mm : m);
  808 }
  809 
  810 /*
  811  * Copy an entire packet, including header (which must be present).
  812  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
  813  * Note that the copy is read-only, because clusters are not copied,
  814  * only their reference counts are incremented.
  815  * Preserve alignment of the first mbuf so if the creator has left
  816  * some room at the beginning (e.g. for inserting protocol headers)
  817  * the copies still have the room available.
  818  */
  819 struct mbuf *
  820 m_copypacket(struct mbuf *m, int how)
  821 {
  822         struct mbuf *top, *n, *o;
  823 
  824         MBUF_CHECKSLEEP(how);
  825         n = m_get(how, m->m_type);
  826         top = n;
  827         if (n == NULL)
  828                 goto nospace;
  829 
  830         if (!m_dup_pkthdr(n, m, how))
  831                 goto nospace;
  832         n->m_len = m->m_len;
  833         if (m->m_flags & M_EXT) {
  834                 n->m_data = m->m_data;
  835                 mb_dupcl(n, m);
  836         } else {
  837                 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
  838                 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
  839         }
  840 
  841         m = m->m_next;
  842         while (m) {
  843                 o = m_get(how, m->m_type);
  844                 if (o == NULL)
  845                         goto nospace;
  846 
  847                 n->m_next = o;
  848                 n = n->m_next;
  849 
  850                 n->m_len = m->m_len;
  851                 if (m->m_flags & M_EXT) {
  852                         n->m_data = m->m_data;
  853                         mb_dupcl(n, m);
  854                 } else {
  855                         bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
  856                 }
  857 
  858                 m = m->m_next;
  859         }
  860         return top;
  861 nospace:
  862         m_freem(top);
  863         return (NULL);
  864 }
  865 
  866 /*
  867  * Copy data from an mbuf chain starting "off" bytes from the beginning,
  868  * continuing for "len" bytes, into the indicated buffer.
  869  */
  870 void
  871 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
  872 {
  873         u_int count;
  874 
  875         KASSERT(off >= 0, ("m_copydata, negative off %d", off));
  876         KASSERT(len >= 0, ("m_copydata, negative len %d", len));
  877         while (off > 0) {
  878                 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
  879                 if (off < m->m_len)
  880                         break;
  881                 off -= m->m_len;
  882                 m = m->m_next;
  883         }
  884         while (len > 0) {
  885                 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
  886                 count = min(m->m_len - off, len);
  887                 bcopy(mtod(m, caddr_t) + off, cp, count);
  888                 len -= count;
  889                 cp += count;
  890                 off = 0;
  891                 m = m->m_next;
  892         }
  893 }
  894 
  895 /*
  896  * Copy a packet header mbuf chain into a completely new chain, including
  897  * copying any mbuf clusters.  Use this instead of m_copypacket() when
  898  * you need a writable copy of an mbuf chain.
  899  */
  900 struct mbuf *
  901 m_dup(struct mbuf *m, int how)
  902 {
  903         struct mbuf **p, *top = NULL;
  904         int remain, moff, nsize;
  905 
  906         MBUF_CHECKSLEEP(how);
  907         /* Sanity check */
  908         if (m == NULL)
  909                 return (NULL);
  910         M_ASSERTPKTHDR(m);
  911 
  912         /* While there's more data, get a new mbuf, tack it on, and fill it */
  913         remain = m->m_pkthdr.len;
  914         moff = 0;
  915         p = &top;
  916         while (remain > 0 || top == NULL) {     /* allow m->m_pkthdr.len == 0 */
  917                 struct mbuf *n;
  918 
  919                 /* Get the next new mbuf */
  920                 if (remain >= MINCLSIZE) {
  921                         n = m_getcl(how, m->m_type, 0);
  922                         nsize = MCLBYTES;
  923                 } else {
  924                         n = m_get(how, m->m_type);
  925                         nsize = MLEN;
  926                 }
  927                 if (n == NULL)
  928                         goto nospace;
  929 
  930                 if (top == NULL) {              /* First one, must be PKTHDR */
  931                         if (!m_dup_pkthdr(n, m, how)) {
  932                                 m_free(n);
  933                                 goto nospace;
  934                         }
  935                         if ((n->m_flags & M_EXT) == 0)
  936                                 nsize = MHLEN;
  937                 }
  938                 n->m_len = 0;
  939 
  940                 /* Link it into the new chain */
  941                 *p = n;
  942                 p = &n->m_next;
  943 
  944                 /* Copy data from original mbuf(s) into new mbuf */
  945                 while (n->m_len < nsize && m != NULL) {
  946                         int chunk = min(nsize - n->m_len, m->m_len - moff);
  947 
  948                         bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
  949                         moff += chunk;
  950                         n->m_len += chunk;
  951                         remain -= chunk;
  952                         if (moff == m->m_len) {
  953                                 m = m->m_next;
  954                                 moff = 0;
  955                         }
  956                 }
  957 
  958                 /* Check correct total mbuf length */
  959                 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
  960                         ("%s: bogus m_pkthdr.len", __func__));
  961         }
  962         return (top);
  963 
  964 nospace:
  965         m_freem(top);
  966         return (NULL);
  967 }
  968 
  969 /*
  970  * Concatenate mbuf chain n to m.
  971  * Both chains must be of the same type (e.g. MT_DATA).
  972  * Any m_pkthdr is not updated.
  973  */
  974 void
  975 m_cat(struct mbuf *m, struct mbuf *n)
  976 {
  977         while (m->m_next)
  978                 m = m->m_next;
  979         while (n) {
  980                 if (!M_WRITABLE(m) ||
  981                     M_TRAILINGSPACE(m) < n->m_len) {
  982                         /* just join the two chains */
  983                         m->m_next = n;
  984                         return;
  985                 }
  986                 /* splat the data from one into the other */
  987                 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
  988                     (u_int)n->m_len);
  989                 m->m_len += n->m_len;
  990                 n = m_free(n);
  991         }
  992 }
  993 
  994 void
  995 m_adj(struct mbuf *mp, int req_len)
  996 {
  997         int len = req_len;
  998         struct mbuf *m;
  999         int count;
 1000 
 1001         if ((m = mp) == NULL)
 1002                 return;
 1003         if (len >= 0) {
 1004                 /*
 1005                  * Trim from head.
 1006                  */
 1007                 while (m != NULL && len > 0) {
 1008                         if (m->m_len <= len) {
 1009                                 len -= m->m_len;
 1010                                 m->m_len = 0;
 1011                                 m = m->m_next;
 1012                         } else {
 1013                                 m->m_len -= len;
 1014                                 m->m_data += len;
 1015                                 len = 0;
 1016                         }
 1017                 }
 1018                 if (mp->m_flags & M_PKTHDR)
 1019                         mp->m_pkthdr.len -= (req_len - len);
 1020         } else {
 1021                 /*
 1022                  * Trim from tail.  Scan the mbuf chain,
 1023                  * calculating its length and finding the last mbuf.
 1024                  * If the adjustment only affects this mbuf, then just
 1025                  * adjust and return.  Otherwise, rescan and truncate
 1026                  * after the remaining size.
 1027                  */
 1028                 len = -len;
 1029                 count = 0;
 1030                 for (;;) {
 1031                         count += m->m_len;
 1032                         if (m->m_next == (struct mbuf *)0)
 1033                                 break;
 1034                         m = m->m_next;
 1035                 }
 1036                 if (m->m_len >= len) {
 1037                         m->m_len -= len;
 1038                         if (mp->m_flags & M_PKTHDR)
 1039                                 mp->m_pkthdr.len -= len;
 1040                         return;
 1041                 }
 1042                 count -= len;
 1043                 if (count < 0)
 1044                         count = 0;
 1045                 /*
 1046                  * Correct length for chain is "count".
 1047                  * Find the mbuf with last data, adjust its length,
 1048                  * and toss data from remaining mbufs on chain.
 1049                  */
 1050                 m = mp;
 1051                 if (m->m_flags & M_PKTHDR)
 1052                         m->m_pkthdr.len = count;
 1053                 for (; m; m = m->m_next) {
 1054                         if (m->m_len >= count) {
 1055                                 m->m_len = count;
 1056                                 if (m->m_next != NULL) {
 1057                                         m_freem(m->m_next);
 1058                                         m->m_next = NULL;
 1059                                 }
 1060                                 break;
 1061                         }
 1062                         count -= m->m_len;
 1063                 }
 1064         }
 1065 }
 1066 
 1067 /*
 1068  * Rearange an mbuf chain so that len bytes are contiguous
 1069  * and in the data area of an mbuf (so that mtod will work
 1070  * for a structure of size len).  Returns the resulting
 1071  * mbuf chain on success, frees it and returns null on failure.
 1072  * If there is room, it will add up to max_protohdr-len extra bytes to the
 1073  * contiguous region in an attempt to avoid being called next time.
 1074  */
 1075 struct mbuf *
 1076 m_pullup(struct mbuf *n, int len)
 1077 {
 1078         struct mbuf *m;
 1079         int count;
 1080         int space;
 1081 
 1082         /*
 1083          * If first mbuf has no cluster, and has room for len bytes
 1084          * without shifting current data, pullup into it,
 1085          * otherwise allocate a new mbuf to prepend to the chain.
 1086          */
 1087         if ((n->m_flags & M_EXT) == 0 &&
 1088             n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
 1089                 if (n->m_len >= len)
 1090                         return (n);
 1091                 m = n;
 1092                 n = n->m_next;
 1093                 len -= m->m_len;
 1094         } else {
 1095                 if (len > MHLEN)
 1096                         goto bad;
 1097                 m = m_get(M_NOWAIT, n->m_type);
 1098                 if (m == NULL)
 1099                         goto bad;
 1100                 if (n->m_flags & M_PKTHDR)
 1101                         m_move_pkthdr(m, n);
 1102         }
 1103         space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
 1104         do {
 1105                 count = min(min(max(len, max_protohdr), space), n->m_len);
 1106                 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
 1107                   (u_int)count);
 1108                 len -= count;
 1109                 m->m_len += count;
 1110                 n->m_len -= count;
 1111                 space -= count;
 1112                 if (n->m_len)
 1113                         n->m_data += count;
 1114                 else
 1115                         n = m_free(n);
 1116         } while (len > 0 && n);
 1117         if (len > 0) {
 1118                 (void) m_free(m);
 1119                 goto bad;
 1120         }
 1121         m->m_next = n;
 1122         return (m);
 1123 bad:
 1124         m_freem(n);
 1125         return (NULL);
 1126 }
 1127 
 1128 /*
 1129  * Like m_pullup(), except a new mbuf is always allocated, and we allow
 1130  * the amount of empty space before the data in the new mbuf to be specified
 1131  * (in the event that the caller expects to prepend later).
 1132  */
 1133 int MSFail;
 1134 
 1135 struct mbuf *
 1136 m_copyup(struct mbuf *n, int len, int dstoff)
 1137 {
 1138         struct mbuf *m;
 1139         int count, space;
 1140 
 1141         if (len > (MHLEN - dstoff))
 1142                 goto bad;
 1143         m = m_get(M_NOWAIT, n->m_type);
 1144         if (m == NULL)
 1145                 goto bad;
 1146         if (n->m_flags & M_PKTHDR)
 1147                 m_move_pkthdr(m, n);
 1148         m->m_data += dstoff;
 1149         space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
 1150         do {
 1151                 count = min(min(max(len, max_protohdr), space), n->m_len);
 1152                 memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
 1153                     (unsigned)count);
 1154                 len -= count;
 1155                 m->m_len += count;
 1156                 n->m_len -= count;
 1157                 space -= count;
 1158                 if (n->m_len)
 1159                         n->m_data += count;
 1160                 else
 1161                         n = m_free(n);
 1162         } while (len > 0 && n);
 1163         if (len > 0) {
 1164                 (void) m_free(m);
 1165                 goto bad;
 1166         }
 1167         m->m_next = n;
 1168         return (m);
 1169  bad:
 1170         m_freem(n);
 1171         MSFail++;
 1172         return (NULL);
 1173 }
 1174 
 1175 /*
 1176  * Partition an mbuf chain in two pieces, returning the tail --
 1177  * all but the first len0 bytes.  In case of failure, it returns NULL and
 1178  * attempts to restore the chain to its original state.
 1179  *
 1180  * Note that the resulting mbufs might be read-only, because the new
 1181  * mbuf can end up sharing an mbuf cluster with the original mbuf if
 1182  * the "breaking point" happens to lie within a cluster mbuf. Use the
 1183  * M_WRITABLE() macro to check for this case.
 1184  */
 1185 struct mbuf *
 1186 m_split(struct mbuf *m0, int len0, int wait)
 1187 {
 1188         struct mbuf *m, *n;
 1189         u_int len = len0, remain;
 1190 
 1191         MBUF_CHECKSLEEP(wait);
 1192         for (m = m0; m && len > m->m_len; m = m->m_next)
 1193                 len -= m->m_len;
 1194         if (m == NULL)
 1195                 return (NULL);
 1196         remain = m->m_len - len;
 1197         if (m0->m_flags & M_PKTHDR && remain == 0) {
 1198                 n = m_gethdr(wait, m0->m_type);
 1199                 if (n == NULL)
 1200                         return (NULL);
 1201                 n->m_next = m->m_next;
 1202                 m->m_next = NULL;
 1203                 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
 1204                 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
 1205                 m0->m_pkthdr.len = len0;
 1206                 return (n);
 1207         } else if (m0->m_flags & M_PKTHDR) {
 1208                 n = m_gethdr(wait, m0->m_type);
 1209                 if (n == NULL)
 1210                         return (NULL);
 1211                 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
 1212                 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
 1213                 m0->m_pkthdr.len = len0;
 1214                 if (m->m_flags & M_EXT)
 1215                         goto extpacket;
 1216                 if (remain > MHLEN) {
 1217                         /* m can't be the lead packet */
 1218                         MH_ALIGN(n, 0);
 1219                         n->m_next = m_split(m, len, wait);
 1220                         if (n->m_next == NULL) {
 1221                                 (void) m_free(n);
 1222                                 return (NULL);
 1223                         } else {
 1224                                 n->m_len = 0;
 1225                                 return (n);
 1226                         }
 1227                 } else
 1228                         MH_ALIGN(n, remain);
 1229         } else if (remain == 0) {
 1230                 n = m->m_next;
 1231                 m->m_next = NULL;
 1232                 return (n);
 1233         } else {
 1234                 n = m_get(wait, m->m_type);
 1235                 if (n == NULL)
 1236                         return (NULL);
 1237                 M_ALIGN(n, remain);
 1238         }
 1239 extpacket:
 1240         if (m->m_flags & M_EXT) {
 1241                 n->m_data = m->m_data + len;
 1242                 mb_dupcl(n, m);
 1243         } else {
 1244                 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
 1245         }
 1246         n->m_len = remain;
 1247         m->m_len = len;
 1248         n->m_next = m->m_next;
 1249         m->m_next = NULL;
 1250         return (n);
 1251 }
 1252 /*
 1253  * Routine to copy from device local memory into mbufs.
 1254  * Note that `off' argument is offset into first mbuf of target chain from
 1255  * which to begin copying the data to.
 1256  */
 1257 struct mbuf *
 1258 m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
 1259     void (*copy)(char *from, caddr_t to, u_int len))
 1260 {
 1261         struct mbuf *m;
 1262         struct mbuf *top = NULL, **mp = &top;
 1263         int len;
 1264 
 1265         if (off < 0 || off > MHLEN)
 1266                 return (NULL);
 1267 
 1268         while (totlen > 0) {
 1269                 if (top == NULL) {      /* First one, must be PKTHDR */
 1270                         if (totlen + off >= MINCLSIZE) {
 1271                                 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
 1272                                 len = MCLBYTES;
 1273                         } else {
 1274                                 m = m_gethdr(M_NOWAIT, MT_DATA);
 1275                                 len = MHLEN;
 1276 
 1277                                 /* Place initial small packet/header at end of mbuf */
 1278                                 if (m && totlen + off + max_linkhdr <= MLEN) {
 1279                                         m->m_data += max_linkhdr;
 1280                                         len -= max_linkhdr;
 1281                                 }
 1282                         }
 1283                         if (m == NULL)
 1284                                 return NULL;
 1285                         m->m_pkthdr.rcvif = ifp;
 1286                         m->m_pkthdr.len = totlen;
 1287                 } else {
 1288                         if (totlen + off >= MINCLSIZE) {
 1289                                 m = m_getcl(M_NOWAIT, MT_DATA, 0);
 1290                                 len = MCLBYTES;
 1291                         } else {
 1292                                 m = m_get(M_NOWAIT, MT_DATA);
 1293                                 len = MLEN;
 1294                         }
 1295                         if (m == NULL) {
 1296                                 m_freem(top);
 1297                                 return NULL;
 1298                         }
 1299                 }
 1300                 if (off) {
 1301                         m->m_data += off;
 1302                         len -= off;
 1303                         off = 0;
 1304                 }
 1305                 m->m_len = len = min(totlen, len);
 1306                 if (copy)
 1307                         copy(buf, mtod(m, caddr_t), (u_int)len);
 1308                 else
 1309                         bcopy(buf, mtod(m, caddr_t), (u_int)len);
 1310                 buf += len;
 1311                 *mp = m;
 1312                 mp = &m->m_next;
 1313                 totlen -= len;
 1314         }
 1315         return (top);
 1316 }
 1317 
 1318 /*
 1319  * Copy data from a buffer back into the indicated mbuf chain,
 1320  * starting "off" bytes from the beginning, extending the mbuf
 1321  * chain if necessary.
 1322  */
 1323 void
 1324 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
 1325 {
 1326         int mlen;
 1327         struct mbuf *m = m0, *n;
 1328         int totlen = 0;
 1329 
 1330         if (m0 == NULL)
 1331                 return;
 1332         while (off > (mlen = m->m_len)) {
 1333                 off -= mlen;
 1334                 totlen += mlen;
 1335                 if (m->m_next == NULL) {
 1336                         n = m_get(M_NOWAIT, m->m_type);
 1337                         if (n == NULL)
 1338                                 goto out;
 1339                         bzero(mtod(n, caddr_t), MLEN);
 1340                         n->m_len = min(MLEN, len + off);
 1341                         m->m_next = n;
 1342                 }
 1343                 m = m->m_next;
 1344         }
 1345         while (len > 0) {
 1346                 if (m->m_next == NULL && (len > m->m_len - off)) {
 1347                         m->m_len += min(len - (m->m_len - off),
 1348                             M_TRAILINGSPACE(m));
 1349                 }
 1350                 mlen = min (m->m_len - off, len);
 1351                 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
 1352                 cp += mlen;
 1353                 len -= mlen;
 1354                 mlen += off;
 1355                 off = 0;
 1356                 totlen += mlen;
 1357                 if (len == 0)
 1358                         break;
 1359                 if (m->m_next == NULL) {
 1360                         n = m_get(M_NOWAIT, m->m_type);
 1361                         if (n == NULL)
 1362                                 break;
 1363                         n->m_len = min(MLEN, len);
 1364                         m->m_next = n;
 1365                 }
 1366                 m = m->m_next;
 1367         }
 1368 out:    if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
 1369                 m->m_pkthdr.len = totlen;
 1370 }
 1371 
 1372 /*
 1373  * Append the specified data to the indicated mbuf chain,
 1374  * Extend the mbuf chain if the new data does not fit in
 1375  * existing space.
 1376  *
 1377  * Return 1 if able to complete the job; otherwise 0.
 1378  */
 1379 int
 1380 m_append(struct mbuf *m0, int len, c_caddr_t cp)
 1381 {
 1382         struct mbuf *m, *n;
 1383         int remainder, space;
 1384 
 1385         for (m = m0; m->m_next != NULL; m = m->m_next)
 1386                 ;
 1387         remainder = len;
 1388         space = M_TRAILINGSPACE(m);
 1389         if (space > 0) {
 1390                 /*
 1391                  * Copy into available space.
 1392                  */
 1393                 if (space > remainder)
 1394                         space = remainder;
 1395                 bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
 1396                 m->m_len += space;
 1397                 cp += space, remainder -= space;
 1398         }
 1399         while (remainder > 0) {
 1400                 /*
 1401                  * Allocate a new mbuf; could check space
 1402                  * and allocate a cluster instead.
 1403                  */
 1404                 n = m_get(M_NOWAIT, m->m_type);
 1405                 if (n == NULL)
 1406                         break;
 1407                 n->m_len = min(MLEN, remainder);
 1408                 bcopy(cp, mtod(n, caddr_t), n->m_len);
 1409                 cp += n->m_len, remainder -= n->m_len;
 1410                 m->m_next = n;
 1411                 m = n;
 1412         }
 1413         if (m0->m_flags & M_PKTHDR)
 1414                 m0->m_pkthdr.len += len - remainder;
 1415         return (remainder == 0);
 1416 }
 1417 
 1418 /*
 1419  * Apply function f to the data in an mbuf chain starting "off" bytes from
 1420  * the beginning, continuing for "len" bytes.
 1421  */
 1422 int
 1423 m_apply(struct mbuf *m, int off, int len,
 1424     int (*f)(void *, void *, u_int), void *arg)
 1425 {
 1426         u_int count;
 1427         int rval;
 1428 
 1429         KASSERT(off >= 0, ("m_apply, negative off %d", off));
 1430         KASSERT(len >= 0, ("m_apply, negative len %d", len));
 1431         while (off > 0) {
 1432                 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
 1433                 if (off < m->m_len)
 1434                         break;
 1435                 off -= m->m_len;
 1436                 m = m->m_next;
 1437         }
 1438         while (len > 0) {
 1439                 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
 1440                 count = min(m->m_len - off, len);
 1441                 rval = (*f)(arg, mtod(m, caddr_t) + off, count);
 1442                 if (rval)
 1443                         return (rval);
 1444                 len -= count;
 1445                 off = 0;
 1446                 m = m->m_next;
 1447         }
 1448         return (0);
 1449 }
 1450 
 1451 /*
 1452  * Return a pointer to mbuf/offset of location in mbuf chain.
 1453  */
 1454 struct mbuf *
 1455 m_getptr(struct mbuf *m, int loc, int *off)
 1456 {
 1457 
 1458         while (loc >= 0) {
 1459                 /* Normal end of search. */
 1460                 if (m->m_len > loc) {
 1461                         *off = loc;
 1462                         return (m);
 1463                 } else {
 1464                         loc -= m->m_len;
 1465                         if (m->m_next == NULL) {
 1466                                 if (loc == 0) {
 1467                                         /* Point at the end of valid data. */
 1468                                         *off = m->m_len;
 1469                                         return (m);
 1470                                 }
 1471                                 return (NULL);
 1472                         }
 1473                         m = m->m_next;
 1474                 }
 1475         }
 1476         return (NULL);
 1477 }
 1478 
 1479 void
 1480 m_print(const struct mbuf *m, int maxlen)
 1481 {
 1482         int len;
 1483         int pdata;
 1484         const struct mbuf *m2;
 1485 
 1486         if (m == NULL) {
 1487                 printf("mbuf: %p\n", m);
 1488                 return;
 1489         }
 1490 
 1491         if (m->m_flags & M_PKTHDR)
 1492                 len = m->m_pkthdr.len;
 1493         else
 1494                 len = -1;
 1495         m2 = m;
 1496         while (m2 != NULL && (len == -1 || len)) {
 1497                 pdata = m2->m_len;
 1498                 if (maxlen != -1 && pdata > maxlen)
 1499                         pdata = maxlen;
 1500                 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
 1501                     m2->m_next, m2->m_flags, "\2\20freelist\17skipfw"
 1502                     "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
 1503                     "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
 1504                 if (pdata)
 1505                         printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
 1506                 if (len != -1)
 1507                         len -= m2->m_len;
 1508                 m2 = m2->m_next;
 1509         }
 1510         if (len > 0)
 1511                 printf("%d bytes unaccounted for.\n", len);
 1512         return;
 1513 }
 1514 
 1515 u_int
 1516 m_fixhdr(struct mbuf *m0)
 1517 {
 1518         u_int len;
 1519 
 1520         len = m_length(m0, NULL);
 1521         m0->m_pkthdr.len = len;
 1522         return (len);
 1523 }
 1524 
 1525 u_int
 1526 m_length(struct mbuf *m0, struct mbuf **last)
 1527 {
 1528         struct mbuf *m;
 1529         u_int len;
 1530 
 1531         len = 0;
 1532         for (m = m0; m != NULL; m = m->m_next) {
 1533                 len += m->m_len;
 1534                 if (m->m_next == NULL)
 1535                         break;
 1536         }
 1537         if (last != NULL)
 1538                 *last = m;
 1539         return (len);
 1540 }
 1541 
 1542 /*
 1543  * Defragment a mbuf chain, returning the shortest possible
 1544  * chain of mbufs and clusters.  If allocation fails and
 1545  * this cannot be completed, NULL will be returned, but
 1546  * the passed in chain will be unchanged.  Upon success,
 1547  * the original chain will be freed, and the new chain
 1548  * will be returned.
 1549  *
 1550  * If a non-packet header is passed in, the original
 1551  * mbuf (chain?) will be returned unharmed.
 1552  */
 1553 struct mbuf *
 1554 m_defrag(struct mbuf *m0, int how)
 1555 {
 1556         struct mbuf *m_new = NULL, *m_final = NULL;
 1557         int progress = 0, length;
 1558 
 1559         MBUF_CHECKSLEEP(how);
 1560         if (!(m0->m_flags & M_PKTHDR))
 1561                 return (m0);
 1562 
 1563         m_fixhdr(m0); /* Needed sanity check */
 1564 
 1565 #ifdef MBUF_STRESS_TEST
 1566         if (m_defragrandomfailures) {
 1567                 int temp = arc4random() & 0xff;
 1568                 if (temp == 0xba)
 1569                         goto nospace;
 1570         }
 1571 #endif
 1572         
 1573         if (m0->m_pkthdr.len > MHLEN)
 1574                 m_final = m_getcl(how, MT_DATA, M_PKTHDR);
 1575         else
 1576                 m_final = m_gethdr(how, MT_DATA);
 1577 
 1578         if (m_final == NULL)
 1579                 goto nospace;
 1580 
 1581         if (m_dup_pkthdr(m_final, m0, how) == 0)
 1582                 goto nospace;
 1583 
 1584         m_new = m_final;
 1585 
 1586         while (progress < m0->m_pkthdr.len) {
 1587                 length = m0->m_pkthdr.len - progress;
 1588                 if (length > MCLBYTES)
 1589                         length = MCLBYTES;
 1590 
 1591                 if (m_new == NULL) {
 1592                         if (length > MLEN)
 1593                                 m_new = m_getcl(how, MT_DATA, 0);
 1594                         else
 1595                                 m_new = m_get(how, MT_DATA);
 1596                         if (m_new == NULL)
 1597                                 goto nospace;
 1598                 }
 1599 
 1600                 m_copydata(m0, progress, length, mtod(m_new, caddr_t));
 1601                 progress += length;
 1602                 m_new->m_len = length;
 1603                 if (m_new != m_final)
 1604                         m_cat(m_final, m_new);
 1605                 m_new = NULL;
 1606         }
 1607 #ifdef MBUF_STRESS_TEST
 1608         if (m0->m_next == NULL)
 1609                 m_defraguseless++;
 1610 #endif
 1611         m_freem(m0);
 1612         m0 = m_final;
 1613 #ifdef MBUF_STRESS_TEST
 1614         m_defragpackets++;
 1615         m_defragbytes += m0->m_pkthdr.len;
 1616 #endif
 1617         return (m0);
 1618 nospace:
 1619 #ifdef MBUF_STRESS_TEST
 1620         m_defragfailure++;
 1621 #endif
 1622         if (m_final)
 1623                 m_freem(m_final);
 1624         return (NULL);
 1625 }
 1626 
 1627 /*
 1628  * Defragment an mbuf chain, returning at most maxfrags separate
 1629  * mbufs+clusters.  If this is not possible NULL is returned and
 1630  * the original mbuf chain is left in it's present (potentially
 1631  * modified) state.  We use two techniques: collapsing consecutive
 1632  * mbufs and replacing consecutive mbufs by a cluster.
 1633  *
 1634  * NB: this should really be named m_defrag but that name is taken
 1635  */
 1636 struct mbuf *
 1637 m_collapse(struct mbuf *m0, int how, int maxfrags)
 1638 {
 1639         struct mbuf *m, *n, *n2, **prev;
 1640         u_int curfrags;
 1641 
 1642         /*
 1643          * Calculate the current number of frags.
 1644          */
 1645         curfrags = 0;
 1646         for (m = m0; m != NULL; m = m->m_next)
 1647                 curfrags++;
 1648         /*
 1649          * First, try to collapse mbufs.  Note that we always collapse
 1650          * towards the front so we don't need to deal with moving the
 1651          * pkthdr.  This may be suboptimal if the first mbuf has much
 1652          * less data than the following.
 1653          */
 1654         m = m0;
 1655 again:
 1656         for (;;) {
 1657                 n = m->m_next;
 1658                 if (n == NULL)
 1659                         break;
 1660                 if (M_WRITABLE(m) &&
 1661                     n->m_len < M_TRAILINGSPACE(m)) {
 1662                         bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
 1663                                 n->m_len);
 1664                         m->m_len += n->m_len;
 1665                         m->m_next = n->m_next;
 1666                         m_free(n);
 1667                         if (--curfrags <= maxfrags)
 1668                                 return m0;
 1669                 } else
 1670                         m = n;
 1671         }
 1672         KASSERT(maxfrags > 1,
 1673                 ("maxfrags %u, but normal collapse failed", maxfrags));
 1674         /*
 1675          * Collapse consecutive mbufs to a cluster.
 1676          */
 1677         prev = &m0->m_next;             /* NB: not the first mbuf */
 1678         while ((n = *prev) != NULL) {
 1679                 if ((n2 = n->m_next) != NULL &&
 1680                     n->m_len + n2->m_len < MCLBYTES) {
 1681                         m = m_getcl(how, MT_DATA, 0);
 1682                         if (m == NULL)
 1683                                 goto bad;
 1684                         bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
 1685                         bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
 1686                                 n2->m_len);
 1687                         m->m_len = n->m_len + n2->m_len;
 1688                         m->m_next = n2->m_next;
 1689                         *prev = m;
 1690                         m_free(n);
 1691                         m_free(n2);
 1692                         if (--curfrags <= maxfrags)     /* +1 cl -2 mbufs */
 1693                                 return m0;
 1694                         /*
 1695                          * Still not there, try the normal collapse
 1696                          * again before we allocate another cluster.
 1697                          */
 1698                         goto again;
 1699                 }
 1700                 prev = &n->m_next;
 1701         }
 1702         /*
 1703          * No place where we can collapse to a cluster; punt.
 1704          * This can occur if, for example, you request 2 frags
 1705          * but the packet requires that both be clusters (we
 1706          * never reallocate the first mbuf to avoid moving the
 1707          * packet header).
 1708          */
 1709 bad:
 1710         return NULL;
 1711 }
 1712 
 1713 #ifdef MBUF_STRESS_TEST
 1714 
 1715 /*
 1716  * Fragment an mbuf chain.  There's no reason you'd ever want to do
 1717  * this in normal usage, but it's great for stress testing various
 1718  * mbuf consumers.
 1719  *
 1720  * If fragmentation is not possible, the original chain will be
 1721  * returned.
 1722  *
 1723  * Possible length values:
 1724  * 0     no fragmentation will occur
 1725  * > 0  each fragment will be of the specified length
 1726  * -1   each fragment will be the same random value in length
 1727  * -2   each fragment's length will be entirely random
 1728  * (Random values range from 1 to 256)
 1729  */
 1730 struct mbuf *
 1731 m_fragment(struct mbuf *m0, int how, int length)
 1732 {
 1733         struct mbuf *m_new = NULL, *m_final = NULL;
 1734         int progress = 0;
 1735 
 1736         if (!(m0->m_flags & M_PKTHDR))
 1737                 return (m0);
 1738         
 1739         if ((length == 0) || (length < -2))
 1740                 return (m0);
 1741 
 1742         m_fixhdr(m0); /* Needed sanity check */
 1743 
 1744         m_final = m_getcl(how, MT_DATA, M_PKTHDR);
 1745 
 1746         if (m_final == NULL)
 1747                 goto nospace;
 1748 
 1749         if (m_dup_pkthdr(m_final, m0, how) == 0)
 1750                 goto nospace;
 1751 
 1752         m_new = m_final;
 1753 
 1754         if (length == -1)
 1755                 length = 1 + (arc4random() & 255);
 1756 
 1757         while (progress < m0->m_pkthdr.len) {
 1758                 int fraglen;
 1759 
 1760                 if (length > 0)
 1761                         fraglen = length;
 1762                 else
 1763                         fraglen = 1 + (arc4random() & 255);
 1764                 if (fraglen > m0->m_pkthdr.len - progress)
 1765                         fraglen = m0->m_pkthdr.len - progress;
 1766 
 1767                 if (fraglen > MCLBYTES)
 1768                         fraglen = MCLBYTES;
 1769 
 1770                 if (m_new == NULL) {
 1771                         m_new = m_getcl(how, MT_DATA, 0);
 1772                         if (m_new == NULL)
 1773                                 goto nospace;
 1774                 }
 1775 
 1776                 m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
 1777                 progress += fraglen;
 1778                 m_new->m_len = fraglen;
 1779                 if (m_new != m_final)
 1780                         m_cat(m_final, m_new);
 1781                 m_new = NULL;
 1782         }
 1783         m_freem(m0);
 1784         m0 = m_final;
 1785         return (m0);
 1786 nospace:
 1787         if (m_final)
 1788                 m_freem(m_final);
 1789         /* Return the original chain on failure */
 1790         return (m0);
 1791 }
 1792 
 1793 #endif
 1794 
 1795 /*
 1796  * Copy the contents of uio into a properly sized mbuf chain.
 1797  */
 1798 struct mbuf *
 1799 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
 1800 {
 1801         struct mbuf *m, *mb;
 1802         int error, length;
 1803         ssize_t total;
 1804         int progress = 0;
 1805 
 1806         /*
 1807          * len can be zero or an arbitrary large value bound by
 1808          * the total data supplied by the uio.
 1809          */
 1810         if (len > 0)
 1811                 total = min(uio->uio_resid, len);
 1812         else
 1813                 total = uio->uio_resid;
 1814 
 1815         /*
 1816          * The smallest unit returned by m_getm2() is a single mbuf
 1817          * with pkthdr.  We can't align past it.
 1818          */
 1819         if (align >= MHLEN)
 1820                 return (NULL);
 1821 
 1822         /*
 1823          * Give us the full allocation or nothing.
 1824          * If len is zero return the smallest empty mbuf.
 1825          */
 1826         m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
 1827         if (m == NULL)
 1828                 return (NULL);
 1829         m->m_data += align;
 1830 
 1831         /* Fill all mbufs with uio data and update header information. */
 1832         for (mb = m; mb != NULL; mb = mb->m_next) {
 1833                 length = min(M_TRAILINGSPACE(mb), total - progress);
 1834 
 1835                 error = uiomove(mtod(mb, void *), length, uio);
 1836                 if (error) {
 1837                         m_freem(m);
 1838                         return (NULL);
 1839                 }
 1840 
 1841                 mb->m_len = length;
 1842                 progress += length;
 1843                 if (flags & M_PKTHDR)
 1844                         m->m_pkthdr.len += length;
 1845         }
 1846         KASSERT(progress == total, ("%s: progress != total", __func__));
 1847 
 1848         return (m);
 1849 }
 1850 
 1851 /*
 1852  * Copy an mbuf chain into a uio limited by len if set.
 1853  */
 1854 int
 1855 m_mbuftouio(struct uio *uio, struct mbuf *m, int len)
 1856 {
 1857         int error, length, total;
 1858         int progress = 0;
 1859 
 1860         if (len > 0)
 1861                 total = min(uio->uio_resid, len);
 1862         else
 1863                 total = uio->uio_resid;
 1864 
 1865         /* Fill the uio with data from the mbufs. */
 1866         for (; m != NULL; m = m->m_next) {
 1867                 length = min(m->m_len, total - progress);
 1868 
 1869                 error = uiomove(mtod(m, void *), length, uio);
 1870                 if (error)
 1871                         return (error);
 1872 
 1873                 progress += length;
 1874         }
 1875 
 1876         return (0);
 1877 }
 1878 
 1879 /*
 1880  * Set the m_data pointer of a newly-allocated mbuf
 1881  * to place an object of the specified size at the
 1882  * end of the mbuf, longword aligned.
 1883  */
 1884 void
 1885 m_align(struct mbuf *m, int len)
 1886 {
 1887 #ifdef INVARIANTS
 1888         const char *msg = "%s: not a virgin mbuf";
 1889 #endif
 1890         int adjust;
 1891 
 1892         if (m->m_flags & M_EXT) {
 1893                 KASSERT(m->m_data == m->m_ext.ext_buf, (msg, __func__));
 1894                 adjust = m->m_ext.ext_size - len;
 1895         } else if (m->m_flags & M_PKTHDR) {
 1896                 KASSERT(m->m_data == m->m_pktdat, (msg, __func__));
 1897                 adjust = MHLEN - len;
 1898         } else {
 1899                 KASSERT(m->m_data == m->m_dat, (msg, __func__));
 1900                 adjust = MLEN - len;
 1901         }
 1902 
 1903         m->m_data += adjust &~ (sizeof(long)-1);
 1904 }
 1905 
 1906 /*
 1907  * Create a writable copy of the mbuf chain.  While doing this
 1908  * we compact the chain with a goal of producing a chain with
 1909  * at most two mbufs.  The second mbuf in this chain is likely
 1910  * to be a cluster.  The primary purpose of this work is to create
 1911  * a writable packet for encryption, compression, etc.  The
 1912  * secondary goal is to linearize the data so the data can be
 1913  * passed to crypto hardware in the most efficient manner possible.
 1914  */
 1915 struct mbuf *
 1916 m_unshare(struct mbuf *m0, int how)
 1917 {
 1918         struct mbuf *m, *mprev;
 1919         struct mbuf *n, *mfirst, *mlast;
 1920         int len, off;
 1921 
 1922         mprev = NULL;
 1923         for (m = m0; m != NULL; m = mprev->m_next) {
 1924                 /*
 1925                  * Regular mbufs are ignored unless there's a cluster
 1926                  * in front of it that we can use to coalesce.  We do
 1927                  * the latter mainly so later clusters can be coalesced
 1928                  * also w/o having to handle them specially (i.e. convert
 1929                  * mbuf+cluster -> cluster).  This optimization is heavily
 1930                  * influenced by the assumption that we're running over
 1931                  * Ethernet where MCLBYTES is large enough that the max
 1932                  * packet size will permit lots of coalescing into a
 1933                  * single cluster.  This in turn permits efficient
 1934                  * crypto operations, especially when using hardware.
 1935                  */
 1936                 if ((m->m_flags & M_EXT) == 0) {
 1937                         if (mprev && (mprev->m_flags & M_EXT) &&
 1938                             m->m_len <= M_TRAILINGSPACE(mprev)) {
 1939                                 /* XXX: this ignores mbuf types */
 1940                                 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
 1941                                        mtod(m, caddr_t), m->m_len);
 1942                                 mprev->m_len += m->m_len;
 1943                                 mprev->m_next = m->m_next;      /* unlink from chain */
 1944                                 m_free(m);                      /* reclaim mbuf */
 1945 #if 0
 1946                                 newipsecstat.ips_mbcoalesced++;
 1947 #endif
 1948                         } else {
 1949                                 mprev = m;
 1950                         }
 1951                         continue;
 1952                 }
 1953                 /*
 1954                  * Writable mbufs are left alone (for now).
 1955                  */
 1956                 if (M_WRITABLE(m)) {
 1957                         mprev = m;
 1958                         continue;
 1959                 }
 1960 
 1961                 /*
 1962                  * Not writable, replace with a copy or coalesce with
 1963                  * the previous mbuf if possible (since we have to copy
 1964                  * it anyway, we try to reduce the number of mbufs and
 1965                  * clusters so that future work is easier).
 1966                  */
 1967                 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
 1968                 /* NB: we only coalesce into a cluster or larger */
 1969                 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
 1970                     m->m_len <= M_TRAILINGSPACE(mprev)) {
 1971                         /* XXX: this ignores mbuf types */
 1972                         memcpy(mtod(mprev, caddr_t) + mprev->m_len,
 1973                                mtod(m, caddr_t), m->m_len);
 1974                         mprev->m_len += m->m_len;
 1975                         mprev->m_next = m->m_next;      /* unlink from chain */
 1976                         m_free(m);                      /* reclaim mbuf */
 1977 #if 0
 1978                         newipsecstat.ips_clcoalesced++;
 1979 #endif
 1980                         continue;
 1981                 }
 1982 
 1983                 /*
 1984                  * Allocate new space to hold the copy and copy the data.
 1985                  * We deal with jumbo mbufs (i.e. m_len > MCLBYTES) by
 1986                  * splitting them into clusters.  We could just malloc a
 1987                  * buffer and make it external but too many device drivers
 1988                  * don't know how to break up the non-contiguous memory when
 1989                  * doing DMA.
 1990                  */
 1991                 n = m_getcl(how, m->m_type, m->m_flags);
 1992                 if (n == NULL) {
 1993                         m_freem(m0);
 1994                         return (NULL);
 1995                 }
 1996                 len = m->m_len;
 1997                 off = 0;
 1998                 mfirst = n;
 1999                 mlast = NULL;
 2000                 for (;;) {
 2001                         int cc = min(len, MCLBYTES);
 2002                         memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
 2003                         n->m_len = cc;
 2004                         if (mlast != NULL)
 2005                                 mlast->m_next = n;
 2006                         mlast = n;      
 2007 #if 0
 2008                         newipsecstat.ips_clcopied++;
 2009 #endif
 2010 
 2011                         len -= cc;
 2012                         if (len <= 0)
 2013                                 break;
 2014                         off += cc;
 2015 
 2016                         n = m_getcl(how, m->m_type, m->m_flags);
 2017                         if (n == NULL) {
 2018                                 m_freem(mfirst);
 2019                                 m_freem(m0);
 2020                                 return (NULL);
 2021                         }
 2022                 }
 2023                 n->m_next = m->m_next; 
 2024                 if (mprev == NULL)
 2025                         m0 = mfirst;            /* new head of chain */
 2026                 else
 2027                         mprev->m_next = mfirst; /* replace old mbuf */
 2028                 m_free(m);                      /* release old mbuf */
 2029                 mprev = mfirst;
 2030         }
 2031         return (m0);
 2032 }
 2033 
 2034 #ifdef MBUF_PROFILING
 2035 
 2036 #define MP_BUCKETS 32 /* don't just change this as things may overflow.*/
 2037 struct mbufprofile {
 2038         uintmax_t wasted[MP_BUCKETS];
 2039         uintmax_t used[MP_BUCKETS];
 2040         uintmax_t segments[MP_BUCKETS];
 2041 } mbprof;
 2042 
 2043 #define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */
 2044 #define MP_NUMLINES 6
 2045 #define MP_NUMSPERLINE 16
 2046 #define MP_EXTRABYTES 64        /* > strlen("used:\nwasted:\nsegments:\n") */
 2047 /* work out max space needed and add a bit of spare space too */
 2048 #define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
 2049 #define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
 2050 
 2051 char mbprofbuf[MP_BUFSIZE];
 2052 
 2053 void
 2054 m_profile(struct mbuf *m)
 2055 {
 2056         int segments = 0;
 2057         int used = 0;
 2058         int wasted = 0;
 2059         
 2060         while (m) {
 2061                 segments++;
 2062                 used += m->m_len;
 2063                 if (m->m_flags & M_EXT) {
 2064                         wasted += MHLEN - sizeof(m->m_ext) +
 2065                             m->m_ext.ext_size - m->m_len;
 2066                 } else {
 2067                         if (m->m_flags & M_PKTHDR)
 2068                                 wasted += MHLEN - m->m_len;
 2069                         else
 2070                                 wasted += MLEN - m->m_len;
 2071                 }
 2072                 m = m->m_next;
 2073         }
 2074         /* be paranoid.. it helps */
 2075         if (segments > MP_BUCKETS - 1)
 2076                 segments = MP_BUCKETS - 1;
 2077         if (used > 100000)
 2078                 used = 100000;
 2079         if (wasted > 100000)
 2080                 wasted = 100000;
 2081         /* store in the appropriate bucket */
 2082         /* don't bother locking. if it's slightly off, so what? */
 2083         mbprof.segments[segments]++;
 2084         mbprof.used[fls(used)]++;
 2085         mbprof.wasted[fls(wasted)]++;
 2086 }
 2087 
 2088 static void
 2089 mbprof_textify(void)
 2090 {
 2091         int offset;
 2092         char *c;
 2093         uint64_t *p;
 2094         
 2095 
 2096         p = &mbprof.wasted[0];
 2097         c = mbprofbuf;
 2098         offset = snprintf(c, MP_MAXLINE + 10, 
 2099             "wasted:\n"
 2100             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2101             "%ju %ju %ju %ju %ju %ju %ju %ju\n",
 2102             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2103             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2104 #ifdef BIG_ARRAY
 2105         p = &mbprof.wasted[16];
 2106         c += offset;
 2107         offset = snprintf(c, MP_MAXLINE, 
 2108             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2109             "%ju %ju %ju %ju %ju %ju %ju %ju\n",
 2110             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2111             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2112 #endif
 2113         p = &mbprof.used[0];
 2114         c += offset;
 2115         offset = snprintf(c, MP_MAXLINE + 10, 
 2116             "used:\n"
 2117             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2118             "%ju %ju %ju %ju %ju %ju %ju %ju\n",
 2119             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2120             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2121 #ifdef BIG_ARRAY
 2122         p = &mbprof.used[16];
 2123         c += offset;
 2124         offset = snprintf(c, MP_MAXLINE, 
 2125             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2126             "%ju %ju %ju %ju %ju %ju %ju %ju\n",
 2127             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2128             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2129 #endif
 2130         p = &mbprof.segments[0];
 2131         c += offset;
 2132         offset = snprintf(c, MP_MAXLINE + 10, 
 2133             "segments:\n"
 2134             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2135             "%ju %ju %ju %ju %ju %ju %ju %ju\n",
 2136             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2137             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2138 #ifdef BIG_ARRAY
 2139         p = &mbprof.segments[16];
 2140         c += offset;
 2141         offset = snprintf(c, MP_MAXLINE, 
 2142             "%ju %ju %ju %ju %ju %ju %ju %ju "
 2143             "%ju %ju %ju %ju %ju %ju %ju %jju",
 2144             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
 2145             p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
 2146 #endif
 2147 }
 2148 
 2149 static int
 2150 mbprof_handler(SYSCTL_HANDLER_ARGS)
 2151 {
 2152         int error;
 2153 
 2154         mbprof_textify();
 2155         error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
 2156         return (error);
 2157 }
 2158 
 2159 static int
 2160 mbprof_clr_handler(SYSCTL_HANDLER_ARGS)
 2161 {
 2162         int clear, error;
 2163  
 2164         clear = 0;
 2165         error = sysctl_handle_int(oidp, &clear, 0, req);
 2166         if (error || !req->newptr)
 2167                 return (error);
 2168  
 2169         if (clear) {
 2170                 bzero(&mbprof, sizeof(mbprof));
 2171         }
 2172  
 2173         return (error);
 2174 }
 2175 
 2176 
 2177 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
 2178             NULL, 0, mbprof_handler, "A", "mbuf profiling statistics");
 2179 
 2180 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW,
 2181             NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics");
 2182 #endif
 2183 

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