uipc_mbuf2.c

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    1 /*      $FreeBSD$       */
    2 /*      $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $     */
    3 /*      $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $   */
    4 
    5 /*
    6  * Copyright (C) 1999 WIDE Project.
    7  * All rights reserved.
    8  * 
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. Neither the name of the project nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  * 
   21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  */
   33 
   34 /*
   35  * Copyright (c) 1982, 1986, 1988, 1991, 1993
   36  *      The Regents of the University of California.  All rights reserved.
   37  *
   38  * Redistribution and use in source and binary forms, with or without
   39  * modification, are permitted provided that the following conditions
   40  * are met:
   41  * 1. Redistributions of source code must retain the above copyright
   42  *    notice, this list of conditions and the following disclaimer.
   43  * 2. Redistributions in binary form must reproduce the above copyright
   44  *    notice, this list of conditions and the following disclaimer in the
   45  *    documentation and/or other materials provided with the distribution.
   46  * 3. All advertising materials mentioning features or use of this software
   47  *    must display the following acknowledgement:
   48  *      This product includes software developed by the University of
   49  *      California, Berkeley and its contributors.
   50  * 4. Neither the name of the University nor the names of its contributors
   51  *    may be used to endorse or promote products derived from this software
   52  *    without specific prior written permission.
   53  *
   54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   64  * SUCH DAMAGE.
   65  *
   66  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
   67  */
   68 
   69 /*#define PULLDOWN_DEBUG*/
   70 
   71 #include <sys/param.h>
   72 #include <sys/systm.h>
   73 #include <sys/kernel.h>
   74 #include <sys/proc.h>
   75 #include <sys/malloc.h>
   76 #include <sys/mbuf.h>
   77 
   78 #define M_SHAREDCLUSTER(m) \
   79         (((m)->m_flags & M_EXT) != 0 && \
   80          ((m)->m_ext.ext_free || mclrefcnt[mtocl((m)->m_ext.ext_buf)] > 1))
   81 
   82 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
   83 
   84 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
   85 static struct mbuf *m_dup1 __P((struct mbuf *, int, int, int));
   86 
   87 /*
   88  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
   89  * packet chain before "off" is kept untouched.
   90  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
   91  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
   92  *
   93  * on error return (NULL return value), original "m" will be freed.
   94  *
   95  * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
   96  */
   97 struct mbuf *
   98 m_pulldown(m, off, len, offp)
   99         struct mbuf *m;
  100         int off, len;
  101         int *offp;
  102 {
  103         struct mbuf *n, *o;
  104         int hlen, tlen, olen;
  105         int sharedcluster;
  106 
  107         /* check invalid arguments. */
  108         if (m == NULL)
  109                 panic("m == NULL in m_pulldown()");
  110         if (len > MCLBYTES) {
  111                 m_freem(m);
  112                 return NULL;    /* impossible */
  113         }
  114 
  115 #ifdef PULLDOWN_DEBUG
  116     {
  117         struct mbuf *t;
  118         printf("before:");
  119         for (t = m; t; t = t->m_next)
  120                 printf(" %d", t->m_len);
  121         printf("\n");
  122     }
  123 #endif
  124         n = m;
  125         while (n != NULL && off > 0) {
  126                 if (n->m_len > off)
  127                         break;
  128                 off -= n->m_len;
  129                 n = n->m_next;
  130         }
  131         /* be sure to point non-empty mbuf */
  132         while (n != NULL && n->m_len == 0)
  133                 n = n->m_next;
  134         if (!n) {
  135                 m_freem(m);
  136                 return NULL;    /* mbuf chain too short */
  137         }
  138 
  139         sharedcluster = M_SHAREDCLUSTER(n);
  140 
  141         /*
  142          * the target data is on <n, off>.
  143          * if we got enough data on the mbuf "n", we're done.
  144          */
  145         if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
  146                 goto ok;
  147 
  148         /*
  149          * when len <= n->m_len - off and off != 0, it is a special case.
  150          * len bytes from <n, off> sits in single mbuf, but the caller does
  151          * not like the starting position (off).
  152          * chop the current mbuf into two pieces, set off to 0.
  153          */
  154         if (len <= n->m_len - off) {
  155                 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
  156                 if (o == NULL) {
  157                         m_freem(m);
  158                         return NULL;    /* ENOBUFS */
  159                 }
  160                 n->m_len = off;
  161                 o->m_next = n->m_next;
  162                 n->m_next = o;
  163                 n = n->m_next;
  164                 off = 0;
  165                 goto ok;
  166         }
  167 
  168         /*
  169          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
  170          * and construct contiguous mbuf with m_len == len.
  171          * note that hlen + tlen == len, and tlen > 0.
  172          */
  173         hlen = n->m_len - off;
  174         tlen = len - hlen;
  175 
  176         /*
  177          * ensure that we have enough trailing data on mbuf chain.
  178          * if not, we can do nothing about the chain.
  179          */
  180         olen = 0;
  181         for (o = n->m_next; o != NULL; o = o->m_next)
  182                 olen += o->m_len;
  183         if (hlen + olen < len) {
  184                 m_freem(m);
  185                 return NULL;    /* mbuf chain too short */
  186         }
  187 
  188         /*
  189          * easy cases first.
  190          * we need to use m_copydata() to get data from <n->m_next, 0>.
  191          */
  192         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
  193             !sharedcluster) {
  194                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
  195                 n->m_len += tlen;
  196                 m_adj(n->m_next, tlen);
  197                 goto ok;
  198         }
  199         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
  200             !sharedcluster) {
  201                 n->m_next->m_data -= hlen;
  202                 n->m_next->m_len += hlen;
  203                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
  204                 n->m_len -= hlen;
  205                 n = n->m_next;
  206                 off = 0;
  207                 goto ok;
  208         }
  209 
  210         /*
  211          * now, we need to do the hard way.  don't m_copy as there's no room
  212          * on both end.
  213          */
  214         MGET(o, M_DONTWAIT, m->m_type);
  215         if (o && len > MLEN) {
  216                 MCLGET(o, M_DONTWAIT);
  217                 if ((o->m_flags & M_EXT) == 0) {
  218                         m_free(o);
  219                         o = NULL;
  220                 }
  221         }
  222         if (!o) {
  223                 m_freem(m);
  224                 return NULL;    /* ENOBUFS */
  225         }
  226         /* get hlen from <n, off> into <o, 0> */
  227         o->m_len = hlen;
  228         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
  229         n->m_len -= hlen;
  230         /* get tlen from <n->m_next, 0> into <o, hlen> */
  231         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
  232         o->m_len += tlen;
  233         m_adj(n->m_next, tlen);
  234         o->m_next = n->m_next;
  235         n->m_next = o;
  236         n = o;
  237         off = 0;
  238 
  239 ok:
  240 #ifdef PULLDOWN_DEBUG
  241     {
  242         struct mbuf *t;
  243         printf("after:");
  244         for (t = m; t; t = t->m_next)
  245                 printf("%c%d", t == n ? '*' : ' ', t->m_len);
  246         printf(" (off=%d)\n", off);
  247     }
  248 #endif
  249         if (offp)
  250                 *offp = off;
  251         return n;
  252 }
  253 
  254 static struct mbuf *
  255 m_dup1(m, off, len, wait)
  256         struct mbuf *m;
  257         int off;
  258         int len;
  259         int wait;
  260 {
  261         struct mbuf *n;
  262         int l;
  263         int copyhdr;
  264 
  265         if (len > MCLBYTES)
  266                 return NULL;
  267         if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
  268                 copyhdr = 1;
  269                 MGETHDR(n, wait, m->m_type);
  270                 l = MHLEN;
  271         } else {
  272                 copyhdr = 0;
  273                 MGET(n, wait, m->m_type);
  274                 l = MLEN;
  275         }
  276         if (n && len > l) {
  277                 MCLGET(n, wait);
  278                 if ((n->m_flags & M_EXT) == 0) {
  279                         m_free(n);
  280                         n = NULL;
  281                 }
  282         }
  283         if (!n)
  284                 return NULL;
  285 
  286         if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
  287                 m_free(n);
  288                 return NULL;
  289         }
  290         m_copydata(m, off, len, mtod(n, caddr_t));
  291         return n;
  292 }
  293 
  294 /* Get a packet tag structure along with specified data following. */
  295 struct m_tag *
  296 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
  297 {
  298         struct m_tag *t;
  299 
  300         if (len < 0)
  301                 return NULL;
  302         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
  303         if (t == NULL)
  304                 return NULL;
  305         t->m_tag_id = type;
  306         t->m_tag_len = len;
  307         t->m_tag_cookie = cookie;
  308         return t;
  309 }
  310 
  311 
  312 /* Free a packet tag. */
  313 void
  314 m_tag_free(struct m_tag *t)
  315 {
  316         free(t, M_PACKET_TAGS);
  317 }
  318 
  319 /* Prepend a packet tag. */
  320 void
  321 m_tag_prepend(struct mbuf *m, struct m_tag *t)
  322 {
  323         KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
  324         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
  325 }
  326 
  327 /* Unlink a packet tag. */
  328 void
  329 m_tag_unlink(struct mbuf *m, struct m_tag *t)
  330 {
  331         KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
  332         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
  333 }
  334 
  335 /* Unlink and free a packet tag. */
  336 void
  337 m_tag_delete(struct mbuf *m, struct m_tag *t)
  338 {
  339         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
  340         m_tag_unlink(m, t);
  341         m_tag_free(t);
  342 }
  343 
  344 /* Unlink and free a packet tag chain, starting from given tag. */
  345 void
  346 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
  347 {
  348         struct m_tag *p, *q;
  349 
  350         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
  351         if (t != NULL)
  352                 p = t;
  353         else
  354                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  355         if (p == NULL)
  356                 return;
  357         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
  358                 m_tag_delete(m, q);
  359         m_tag_delete(m, p);
  360 }
  361 
  362 /* Find a tag, starting from a given position. */
  363 struct m_tag *
  364 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
  365 {
  366         struct m_tag *p;
  367 
  368         KASSERT(m, ("m_tag_find: null mbuf"));
  369         if (t == NULL)
  370                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  371         else
  372                 p = SLIST_NEXT(t, m_tag_link);
  373         while (p != NULL) {
  374                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
  375                         return p;
  376                 p = SLIST_NEXT(p, m_tag_link);
  377         }
  378         return NULL;
  379 }
  380 
  381 /* Copy a single tag. */
  382 struct m_tag *
  383 m_tag_copy(struct m_tag *t, int how)
  384 {
  385         struct m_tag *p;
  386 
  387         KASSERT(t, ("m_tag_copy: null tag"));
  388         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
  389         if (p == NULL)
  390                 return (NULL);
  391         bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
  392         return p;
  393 }
  394 
  395 /*
  396  * Copy two tag chains. The destination mbuf (to) loses any attached
  397  * tags even if the operation fails. This should not be a problem, as
  398  * m_tag_copy_chain() is typically called with a newly-allocated
  399  * destination mbuf.
  400  */
  401 int
  402 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
  403 {
  404         struct m_tag *p, *t, *tprev = NULL;
  405 
  406         KASSERT(to && from,
  407                 ("m_tag_copy: null argument, to %p from %p", to, from));
  408         m_tag_delete_chain(to, NULL);
  409         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
  410                 t = m_tag_copy(p, how);
  411                 if (t == NULL) {
  412                         m_tag_delete_chain(to, NULL);
  413                         return 0;
  414                 }
  415                 if (tprev == NULL)
  416                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
  417                 else {
  418                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
  419                         tprev = t;
  420                 }
  421         }
  422         return 1;
  423 }
  424 
  425 /* Initialize tags on an mbuf. */
  426 void
  427 m_tag_init(struct mbuf *m)
  428 {
  429         SLIST_INIT(&m->m_pkthdr.tags);
  430 }
  431 
  432 /* Get first tag in chain. */
  433 struct m_tag *
  434 m_tag_first(struct mbuf *m)
  435 {
  436         return SLIST_FIRST(&m->m_pkthdr.tags);
  437 }
  438 
  439 /* Get next tag in chain. */
  440 struct m_tag *
  441 m_tag_next(struct mbuf *m, struct m_tag *t)
  442 {
  443         return SLIST_NEXT(t, m_tag_link);
  444 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/uipc_mbuf2.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf2.c
