format cleanup for readability. Tab out back-slashes.
[dragonfly.git] / sys / kern / uipc_mbuf.c
CommitLineData
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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 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
34 * $FreeBSD: src/sys/kern/uipc_mbuf.c,v 1.51.2.24 2003/04/15 06:59:29 silby Exp $
bc6dffab 35 * $DragonFly: src/sys/kern/uipc_mbuf.c,v 1.3 2003/06/22 17:39:42 dillon Exp $
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36 */
37
38#include "opt_param.h"
39#include "opt_mbuf_stress_test.h"
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/malloc.h>
43#include <sys/mbuf.h>
44#include <sys/kernel.h>
45#include <sys/sysctl.h>
46#include <sys/domain.h>
47#include <sys/protosw.h>
48
49#include <vm/vm.h>
50#include <vm/vm_kern.h>
51#include <vm/vm_extern.h>
52
53#ifdef INVARIANTS
54#include <machine/cpu.h>
55#endif
56
57static void mbinit __P((void *));
58SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL)
59
60struct mbuf *mbutl;
61char *mclrefcnt;
62struct mbstat mbstat;
63u_long mbtypes[MT_NTYPES];
64struct mbuf *mmbfree;
65union mcluster *mclfree;
66int max_linkhdr;
67int max_protohdr;
68int max_hdr;
69int max_datalen;
70int m_defragpackets;
71int m_defragbytes;
72int m_defraguseless;
73int m_defragfailure;
74#ifdef MBUF_STRESS_TEST
75int m_defragrandomfailures;
76#endif
77
78int nmbclusters;
79int nmbufs;
80u_int m_mballoc_wid = 0;
81u_int m_clalloc_wid = 0;
82
83SYSCTL_DECL(_kern_ipc);
84SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW,
85 &max_linkhdr, 0, "");
86SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW,
87 &max_protohdr, 0, "");
88SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, "");
89SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW,
90 &max_datalen, 0, "");
91SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW,
92 &mbuf_wait, 0, "");
93SYSCTL_STRUCT(_kern_ipc, KIPC_MBSTAT, mbstat, CTLFLAG_RW, &mbstat, mbstat, "");
94SYSCTL_OPAQUE(_kern_ipc, OID_AUTO, mbtypes, CTLFLAG_RD, mbtypes,
95 sizeof(mbtypes), "LU", "");
96SYSCTL_INT(_kern_ipc, KIPC_NMBCLUSTERS, nmbclusters, CTLFLAG_RD,
97 &nmbclusters, 0, "Maximum number of mbuf clusters available");
98SYSCTL_INT(_kern_ipc, OID_AUTO, nmbufs, CTLFLAG_RD, &nmbufs, 0,
99 "Maximum number of mbufs available");
100SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
101 &m_defragpackets, 0, "");
102SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
103 &m_defragbytes, 0, "");
104SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
105 &m_defraguseless, 0, "");
106SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
107 &m_defragfailure, 0, "");
108#ifdef MBUF_STRESS_TEST
109SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
110 &m_defragrandomfailures, 0, "");
111#endif
112
113static void m_reclaim __P((void));
114
115#ifndef NMBCLUSTERS
116#define NMBCLUSTERS (512 + maxusers * 16)
117#endif
118#ifndef NMBUFS
119#define NMBUFS (nmbclusters * 4)
120#endif
121
122/*
123 * Perform sanity checks of tunables declared above.
124 */
125static void
126tunable_mbinit(void *dummy)
127{
128
129 /*
130 * This has to be done before VM init.
131 */
132 nmbclusters = NMBCLUSTERS;
133 TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
134 nmbufs = NMBUFS;
135 TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs);
136 /* Sanity checks */
137 if (nmbufs < nmbclusters * 2)
138 nmbufs = nmbclusters * 2;
139
140 return;
141}
142SYSINIT(tunable_mbinit, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_mbinit, NULL);
143
144/* "number of clusters of pages" */
145#define NCL_INIT 1
146
147#define NMB_INIT 16
148
149/* ARGSUSED*/
150static void
151mbinit(dummy)
152 void *dummy;
153{
154 int s;
155
156 mmbfree = NULL; mclfree = NULL;
157 mbstat.m_msize = MSIZE;
158 mbstat.m_mclbytes = MCLBYTES;
159 mbstat.m_minclsize = MINCLSIZE;
160 mbstat.m_mlen = MLEN;
161 mbstat.m_mhlen = MHLEN;
162
163 s = splimp();
164 if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0)
165 goto bad;
166#if MCLBYTES <= PAGE_SIZE
167 if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0)
168 goto bad;
169#else
170 /* It's OK to call contigmalloc in this context. */
171 if (m_clalloc(16, M_WAIT) == 0)
172 goto bad;
173#endif
174 splx(s);
175 return;
176bad:
177 panic("mbinit");
178}
179
180/*
181 * Allocate at least nmb mbufs and place on mbuf free list.
182 * Must be called at splimp.
183 */
184/* ARGSUSED */
185int
186m_mballoc(nmb, how)
187 register int nmb;
188 int how;
189{
190 register caddr_t p;
191 register int i;
192 int nbytes;
193
194 /*
195 * If we've hit the mbuf limit, stop allocating from mb_map,
196 * (or trying to) in order to avoid dipping into the section of
197 * mb_map which we've "reserved" for clusters.
198 */
199 if ((nmb + mbstat.m_mbufs) > nmbufs)
200 return (0);
201
202 /*
203 * Once we run out of map space, it will be impossible to get
204 * any more (nothing is ever freed back to the map)
205 * -- however you are not dead as m_reclaim might
206 * still be able to free a substantial amount of space.
207 *
208 * XXX Furthermore, we can also work with "recycled" mbufs (when
209 * we're calling with M_WAIT the sleep procedure will be woken
210 * up when an mbuf is freed. See m_mballoc_wait()).
211 */
212 if (mb_map_full)
213 return (0);
214
215 nbytes = round_page(nmb * MSIZE);
216 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT);
217 if (p == 0 && how == M_WAIT) {
218 mbstat.m_wait++;
219 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_WAITOK);
220 }
221
222 /*
223 * Either the map is now full, or `how' is M_NOWAIT and there
224 * are no pages left.
225 */
226 if (p == NULL)
227 return (0);
228
229 nmb = nbytes / MSIZE;
230 for (i = 0; i < nmb; i++) {
231 ((struct mbuf *)p)->m_next = mmbfree;
232 mmbfree = (struct mbuf *)p;
233 p += MSIZE;
234 }
235 mbstat.m_mbufs += nmb;
236 mbtypes[MT_FREE] += nmb;
237 return (1);
238}
239
240/*
241 * Once the mb_map has been exhausted and if the call to the allocation macros
242 * (or, in some cases, functions) is with M_WAIT, then it is necessary to rely
243 * solely on reclaimed mbufs. Here we wait for an mbuf to be freed for a
244 * designated (mbuf_wait) time.
245 */
246struct mbuf *
247m_mballoc_wait(int caller, int type)
248{
249 struct mbuf *p;
250 int s;
251
252 s = splimp();
253 m_mballoc_wid++;
254 if ((tsleep(&m_mballoc_wid, PVM, "mballc", mbuf_wait)) == EWOULDBLOCK)
255 m_mballoc_wid--;
256 splx(s);
257
258 /*
259 * Now that we (think) that we've got something, we will redo an
260 * MGET, but avoid getting into another instance of m_mballoc_wait()
261 * XXX: We retry to fetch _even_ if the sleep timed out. This is left
262 * this way, purposely, in the [unlikely] case that an mbuf was
263 * freed but the sleep was not awakened in time.
264 */
265 p = NULL;
266 switch (caller) {
267 case MGET_C:
268 MGET(p, M_DONTWAIT, type);
269 break;
270 case MGETHDR_C:
271 MGETHDR(p, M_DONTWAIT, type);
272 break;
273 default:
274 panic("m_mballoc_wait: invalid caller (%d)", caller);
275 }
276
277 s = splimp();
278 if (p != NULL) { /* We waited and got something... */
279 mbstat.m_wait++;
280 /* Wake up another if we have more free. */
281 if (mmbfree != NULL)
282 MMBWAKEUP();
283 }
284 splx(s);
285 return (p);
286}
287
288#if MCLBYTES > PAGE_SIZE
289static int i_want_my_mcl;
290
291static void
292kproc_mclalloc(void)
293{
294 int status;
295
296 while (1) {
297 tsleep(&i_want_my_mcl, PVM, "mclalloc", 0);
298
299 for (; i_want_my_mcl; i_want_my_mcl--) {
300 if (m_clalloc(1, M_WAIT) == 0)
301 printf("m_clalloc failed even in process context!\n");
302 }
303 }
304}
305
bc6dffab 306static struct thread *mclallocthread;
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307static struct kproc_desc mclalloc_kp = {
308 "mclalloc",
309 kproc_mclalloc,
bc6dffab 310 &mclallocthread
984263bc 311};
bc6dffab 312SYSINIT(mclallocthread, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start,
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313 &mclalloc_kp);
314#endif
315
316/*
317 * Allocate some number of mbuf clusters
318 * and place on cluster free list.
319 * Must be called at splimp.
320 */
321/* ARGSUSED */
322int
323m_clalloc(ncl, how)
324 register int ncl;
325 int how;
326{
327 register caddr_t p;
328 register int i;
329 int npg;
330
331 /*
332 * If we've hit the mcluster number limit, stop allocating from
333 * mb_map, (or trying to) in order to avoid dipping into the section
334 * of mb_map which we've "reserved" for mbufs.
335 */
336 if ((ncl + mbstat.m_clusters) > nmbclusters)
337 goto m_clalloc_fail;
338
339 /*
340 * Once we run out of map space, it will be impossible
341 * to get any more (nothing is ever freed back to the
342 * map). From this point on, we solely rely on freed
343 * mclusters.
344 */
345 if (mb_map_full)
346 goto m_clalloc_fail;
347
348#if MCLBYTES > PAGE_SIZE
349 if (how != M_WAIT) {
350 i_want_my_mcl += ncl;
351 wakeup(&i_want_my_mcl);
352 mbstat.m_wait++;
353 p = 0;
354 } else {
355 p = contigmalloc1(MCLBYTES * ncl, M_DEVBUF, M_WAITOK, 0ul,
356 ~0ul, PAGE_SIZE, 0, mb_map);
357 }
358#else
359 npg = ncl;
360 p = (caddr_t)kmem_malloc(mb_map, ctob(npg),
361 how != M_WAIT ? M_NOWAIT : M_WAITOK);
362 ncl = ncl * PAGE_SIZE / MCLBYTES;
363#endif
364 /*
365 * Either the map is now full, or `how' is M_NOWAIT and there
366 * are no pages left.
367 */
368 if (p == NULL) {
369 static int last_report ; /* when we did that (in ticks) */
370m_clalloc_fail:
371 mbstat.m_drops++;
372 if (ticks < last_report || (ticks - last_report) >= hz) {
373 last_report = ticks;
374 printf("All mbuf clusters exhausted, please see tuning(7).\n");
375 }
376 return (0);
377 }
378
379 for (i = 0; i < ncl; i++) {
380 ((union mcluster *)p)->mcl_next = mclfree;
381 mclfree = (union mcluster *)p;
382 p += MCLBYTES;
383 mbstat.m_clfree++;
384 }
385 mbstat.m_clusters += ncl;
386 return (1);
387}
388
389/*
390 * Once the mb_map submap has been exhausted and the allocation is called with
391 * M_WAIT, we rely on the mclfree union pointers. If nothing is free, we will
392 * sleep for a designated amount of time (mbuf_wait) or until we're woken up
393 * due to sudden mcluster availability.
394 */
395caddr_t
396m_clalloc_wait(void)
397{
398 caddr_t p;
399 int s;
400
401#ifdef __i386__
402 /* If in interrupt context, and INVARIANTS, maintain sanity and die. */
403 KASSERT(intr_nesting_level == 0, ("CLALLOC: CANNOT WAIT IN INTERRUPT"));
404#endif
405
406 /* Sleep until something's available or until we expire. */
407 m_clalloc_wid++;
408 if ((tsleep(&m_clalloc_wid, PVM, "mclalc", mbuf_wait)) == EWOULDBLOCK)
409 m_clalloc_wid--;
410
411 /*
412 * Now that we (think) that we've got something, we will redo and
413 * MGET, but avoid getting into another instance of m_clalloc_wait()
414 */
415 p = NULL;
416 MCLALLOC(p, M_DONTWAIT);
417
418 s = splimp();
419 if (p != NULL) { /* We waited and got something... */
420 mbstat.m_wait++;
421 /* Wake up another if we have more free. */
422 if (mclfree != NULL)
423 MCLWAKEUP();
424 }
425
426 splx(s);
427 return (p);
428}
429
430/*
431 * When MGET fails, ask protocols to free space when short of memory,
432 * then re-attempt to allocate an mbuf.
433 */
434struct mbuf *
435m_retry(i, t)
436 int i, t;
437{
438 register struct mbuf *m;
439
440 /*
441 * Must only do the reclaim if not in an interrupt context.
442 */
443 if (i == M_WAIT) {
444#ifdef __i386__
445 KASSERT(intr_nesting_level == 0,
446 ("MBALLOC: CANNOT WAIT IN INTERRUPT"));
447#endif
448 m_reclaim();
449 }
450
451 /*
452 * Both m_mballoc_wait and m_retry must be nulled because
453 * when the MGET macro is run from here, we deffinately do _not_
454 * want to enter an instance of m_mballoc_wait() or m_retry() (again!)
455 */
456#define m_mballoc_wait(caller,type) (struct mbuf *)0
457#define m_retry(i, t) (struct mbuf *)0
458 MGET(m, i, t);
459#undef m_retry
460#undef m_mballoc_wait
461
462 if (m != NULL)
463 mbstat.m_wait++;
464 else {
465 static int last_report ; /* when we did that (in ticks) */
466 mbstat.m_drops++;
467 if (ticks < last_report || (ticks - last_report) >= hz) {
468 last_report = ticks;
469 printf("All mbufs exhausted, please see tuning(7).\n");
470 }
471 }
472
473 return (m);
474}
475
476/*
477 * As above; retry an MGETHDR.
478 */
479struct mbuf *
480m_retryhdr(i, t)
481 int i, t;
482{
483 register struct mbuf *m;
484
485 /*
486 * Must only do the reclaim if not in an interrupt context.
487 */
488 if (i == M_WAIT) {
489#ifdef __i386__
490 KASSERT(intr_nesting_level == 0,
491 ("MBALLOC: CANNOT WAIT IN INTERRUPT"));
492#endif
493 m_reclaim();
494 }
495
496#define m_mballoc_wait(caller,type) (struct mbuf *)0
497#define m_retryhdr(i, t) (struct mbuf *)0
498 MGETHDR(m, i, t);
499#undef m_retryhdr
500#undef m_mballoc_wait
501
502 if (m != NULL)
503 mbstat.m_wait++;
504 else {
505 static int last_report ; /* when we did that (in ticks) */
506 mbstat.m_drops++;
507 if (ticks < last_report || (ticks - last_report) >= hz) {
508 last_report = ticks;
509 printf("All mbufs exhausted, please see tuning(7).\n");
510 }
511 }
512
513 return (m);
514}
515
516static void
517m_reclaim()
518{
519 register struct domain *dp;
520 register struct protosw *pr;
521 int s = splimp();
522
523 for (dp = domains; dp; dp = dp->dom_next)
524 for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
525 if (pr->pr_drain)
526 (*pr->pr_drain)();
527 splx(s);
528 mbstat.m_drain++;
529}
530
531/*
532 * Space allocation routines.
533 * These are also available as macros
534 * for critical paths.
535 */
536struct mbuf *
537m_get(how, type)
538 int how, type;
539{
540 register struct mbuf *m;
541
542 MGET(m, how, type);
543 return (m);
544}
545
546struct mbuf *
547m_gethdr(how, type)
548 int how, type;
549{
550 register struct mbuf *m;
551
552 MGETHDR(m, how, type);
553 return (m);
554}
555
556struct mbuf *
557m_getclr(how, type)
558 int how, type;
559{
560 register struct mbuf *m;
561
562 MGET(m, how, type);
563 if (m == 0)
564 return (0);
565 bzero(mtod(m, caddr_t), MLEN);
566 return (m);
567}
568
569/*
570 * m_getcl() returns an mbuf with an attached cluster.
571 * Because many network drivers use this kind of buffers a lot, it is
572 * convenient to keep a small pool of free buffers of this kind.
573 * Even a small size such as 10 gives about 10% improvement in the
574 * forwarding rate in a bridge or router.
575 * The size of this free list is controlled by the sysctl variable
576 * mcl_pool_max. The list is populated on m_freem(), and used in
577 * m_getcl() if elements are available.
578 */
579static struct mbuf *mcl_pool;
580static int mcl_pool_now;
581static int mcl_pool_max = 0;
582
583SYSCTL_INT(_kern_ipc, OID_AUTO, mcl_pool_max, CTLFLAG_RW, &mcl_pool_max, 0,
584 "Maximum number of mbufs+cluster in free list");
585SYSCTL_INT(_kern_ipc, OID_AUTO, mcl_pool_now, CTLFLAG_RD, &mcl_pool_now, 0,
586 "Current number of mbufs+cluster in free list");
587
588struct mbuf *
589m_getcl(int how, short type, int flags)
590{
591 int s = splimp();
592 struct mbuf *mp;
593
594 if (flags & M_PKTHDR) {
595 if (type == MT_DATA && mcl_pool) {
596 mp = mcl_pool;
597 mcl_pool = mp->m_nextpkt;
598 mcl_pool_now--;
599 splx(s);
600 mp->m_nextpkt = NULL;
601 mp->m_data = mp->m_ext.ext_buf;
602 mp->m_flags = M_PKTHDR|M_EXT;
603 mp->m_pkthdr.rcvif = NULL;
604 mp->m_pkthdr.csum_flags = 0;
605 return mp;
606 } else
607 MGETHDR(mp, how, type);
608 } else
609 MGET(mp, how, type);
610 if (mp) {
611 MCLGET(mp, how);
612 if ( (mp->m_flags & M_EXT) == 0) {
613 m_free(mp);
614 mp = NULL;
615 }
616 }
617 splx(s);
618 return mp;
619}
620
621/*
622 * struct mbuf *
623 * m_getm(m, len, how, type)
624 *
625 * This will allocate len-worth of mbufs and/or mbuf clusters (whatever fits
626 * best) and return a pointer to the top of the allocated chain. If m is
627 * non-null, then we assume that it is a single mbuf or an mbuf chain to
628 * which we want len bytes worth of mbufs and/or clusters attached, and so
629 * if we succeed in allocating it, we will just return a pointer to m.
630 *
631 * If we happen to fail at any point during the allocation, we will free
632 * up everything we have already allocated and return NULL.
633 *
634 */
635struct mbuf *
636m_getm(struct mbuf *m, int len, int how, int type)
637{
638 struct mbuf *top, *tail, *mp, *mtail = NULL;
639
640 KASSERT(len >= 0, ("len is < 0 in m_getm"));
641
642 MGET(mp, how, type);
643 if (mp == NULL)
644 return (NULL);
645 else if (len > MINCLSIZE) {
646 MCLGET(mp, how);
647 if ((mp->m_flags & M_EXT) == 0) {
648 m_free(mp);
649 return (NULL);
650 }
651 }
652 mp->m_len = 0;
653 len -= M_TRAILINGSPACE(mp);
654
655 if (m != NULL)
656 for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next);
657 else
658 m = mp;
659
660 top = tail = mp;
661 while (len > 0) {
662 MGET(mp, how, type);
663 if (mp == NULL)
664 goto failed;
665
666 tail->m_next = mp;
667 tail = mp;
668 if (len > MINCLSIZE) {
669 MCLGET(mp, how);
670 if ((mp->m_flags & M_EXT) == 0)
671 goto failed;
672 }
673
674 mp->m_len = 0;
675 len -= M_TRAILINGSPACE(mp);
676 }
677
678 if (mtail != NULL)
679 mtail->m_next = top;
680 return (m);
681
682failed:
683 m_freem(top);
684 return (NULL);
685}
686
687/*
688 * MFREE(struct mbuf *m, struct mbuf *n)
689 * Free a single mbuf and associated external storage.
690 * Place the successor, if any, in n.
691 *
692 * we do need to check non-first mbuf for m_aux, since some of existing
693 * code does not call M_PREPEND properly.
694 * (example: call to bpf_mtap from drivers)
695 */
696#define MFREE(m, n) MBUFLOCK( \
697 struct mbuf *_mm = (m); \
698 \
699 KASSERT(_mm->m_type != MT_FREE, ("freeing free mbuf")); \
700 mbtypes[_mm->m_type]--; \
701 if ((_mm->m_flags & M_PKTHDR) != 0) \
702 m_tag_delete_chain(_mm, NULL); \
703 if (_mm->m_flags & M_EXT) \
704 MEXTFREE1(m); \
705 (n) = _mm->m_next; \
706 _mm->m_type = MT_FREE; \
707 mbtypes[MT_FREE]++; \
708 _mm->m_next = mmbfree; \
709 mmbfree = _mm; \
710 MMBWAKEUP(); \
711)
712
713struct mbuf *
714m_free(m)
715 struct mbuf *m;
716{
717 register struct mbuf *n;
718
719 MFREE(m, n);
720 return (n);
721}
722
723void
724m_freem(m)
725 struct mbuf *m;
726{
727 int s = splimp();
728
729 /*
730 * Try to keep a small pool of mbuf+cluster for quick use in
731 * device drivers. A good candidate is a M_PKTHDR buffer with
732 * only one cluster attached. Other mbufs, or those exceeding
733 * the pool size, are just m_free'd in the usual way.
734 * The following code makes sure that m_next, m_type,
735 * m_pkthdr.aux and m_ext.* are properly initialized.
736 * Other fields in the mbuf are initialized in m_getcl()
737 * upon allocation.
738 */
739 if (mcl_pool_now < mcl_pool_max && m && m->m_next == NULL &&
740 (m->m_flags & (M_PKTHDR|M_EXT)) == (M_PKTHDR|M_EXT) &&
741 m->m_type == MT_DATA && M_EXT_WRITABLE(m) ) {
742 m_tag_delete_chain(m, NULL);
743 m->m_nextpkt = mcl_pool;
744 mcl_pool = m;
745 mcl_pool_now++;
746 } else {
747 while (m)
748 m = m_free(m);
749 }
750 splx(s);
751}
752
753/*
754 * Mbuffer utility routines.
755 */
756
757/*
758 * Lesser-used path for M_PREPEND:
759 * allocate new mbuf to prepend to chain,
760 * copy junk along.
761 */
762struct mbuf *
763m_prepend(m, len, how)
764 register struct mbuf *m;
765 int len, how;
766{
767 struct mbuf *mn;
768
769 MGET(mn, how, m->m_type);
770 if (mn == (struct mbuf *)NULL) {
771 m_freem(m);
772 return ((struct mbuf *)NULL);
773 }
774 if (m->m_flags & M_PKTHDR)
775 M_MOVE_PKTHDR(mn, m);
776 mn->m_next = m;
777 m = mn;
778 if (len < MHLEN)
779 MH_ALIGN(m, len);
780 m->m_len = len;
781 return (m);
782}
783
784/*
785 * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
786 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf.
787 * The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller.
788 * Note that the copy is read-only, because clusters are not copied,
789 * only their reference counts are incremented.
790 */
791#define MCFail (mbstat.m_mcfail)
792
793struct mbuf *
794m_copym(m, off0, len, wait)
795 register struct mbuf *m;
796 int off0, wait;
797 register int len;
798{
799 register struct mbuf *n, **np;
800 register int off = off0;
801 struct mbuf *top;
802 int copyhdr = 0;
803
804 KASSERT(off >= 0, ("m_copym, negative off %d", off));
805 KASSERT(len >= 0, ("m_copym, negative len %d", len));
806 if (off == 0 && m->m_flags & M_PKTHDR)
807 copyhdr = 1;
808 while (off > 0) {
809 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
810 if (off < m->m_len)
811 break;
812 off -= m->m_len;
813 m = m->m_next;
814 }
815 np = &top;
816 top = 0;
817 while (len > 0) {
818 if (m == 0) {
819 KASSERT(len == M_COPYALL,
820 ("m_copym, length > size of mbuf chain"));
821 break;
822 }
823 MGET(n, wait, m->m_type);
824 *np = n;
825 if (n == 0)
826 goto nospace;
827 if (copyhdr) {
828 if (!m_dup_pkthdr(n, m, wait))
829 goto nospace;
830 if (len == M_COPYALL)
831 n->m_pkthdr.len -= off0;
832 else
833 n->m_pkthdr.len = len;
834 copyhdr = 0;
835 }
836 n->m_len = min(len, m->m_len - off);
837 if (m->m_flags & M_EXT) {
838 n->m_data = m->m_data + off;
839 if (m->m_ext.ext_ref == NULL) {
840 atomic_add_char(
841 &mclrefcnt[mtocl(m->m_ext.ext_buf)], 1);
842 } else {
843 int s = splimp();
844
845 (*m->m_ext.ext_ref)(m->m_ext.ext_buf,
846 m->m_ext.ext_size);
847 splx(s);
848 }
849 n->m_ext = m->m_ext;
850 n->m_flags |= M_EXT;
851 } else
852 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
853 (unsigned)n->m_len);
854 if (len != M_COPYALL)
855 len -= n->m_len;
856 off = 0;
857 m = m->m_next;
858 np = &n->m_next;
859 }
860 if (top == 0)
861 MCFail++;
862 return (top);
863nospace:
864 m_freem(top);
865 MCFail++;
866 return (0);
867}
868
869/*
870 * Copy an entire packet, including header (which must be present).
871 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
872 * Note that the copy is read-only, because clusters are not copied,
873 * only their reference counts are incremented.
874 * Preserve alignment of the first mbuf so if the creator has left
875 * some room at the beginning (e.g. for inserting protocol headers)
876 * the copies also have the room available.
877 */
878struct mbuf *
879m_copypacket(m, how)
880 struct mbuf *m;
881 int how;
882{
883 struct mbuf *top, *n, *o;
884
885 MGET(n, how, m->m_type);
886 top = n;
887 if (!n)
888 goto nospace;
889
890 if (!m_dup_pkthdr(n, m, how))
891 goto nospace;
892 n->m_len = m->m_len;
893 if (m->m_flags & M_EXT) {
894 n->m_data = m->m_data;
895 if (m->m_ext.ext_ref == NULL)
896 atomic_add_char(&mclrefcnt[mtocl(m->m_ext.ext_buf)], 1);
897 else {
898 int s = splimp();
899
900 (*m->m_ext.ext_ref)(m->m_ext.ext_buf,
901 m->m_ext.ext_size);
902 splx(s);
903 }
904 n->m_ext = m->m_ext;
905 n->m_flags |= M_EXT;
906 } else {
907 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
908 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
909 }
910
911 m = m->m_next;
912 while (m) {
913 MGET(o, how, m->m_type);
914 if (!o)
915 goto nospace;
916
917 n->m_next = o;
918 n = n->m_next;
919
920 n->m_len = m->m_len;
921 if (m->m_flags & M_EXT) {
922 n->m_data = m->m_data;
923 if (m->m_ext.ext_ref == NULL) {
924 atomic_add_char(
925 &mclrefcnt[mtocl(m->m_ext.ext_buf)], 1);
926 } else {
927 int s = splimp();
928
929 (*m->m_ext.ext_ref)(m->m_ext.ext_buf,
930 m->m_ext.ext_size);
931 splx(s);
932 }
933 n->m_ext = m->m_ext;
934 n->m_flags |= M_EXT;
935 } else {
936 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
937 }
938
939 m = m->m_next;
940 }
941 return top;
942nospace:
943 m_freem(top);
944 MCFail++;
945 return 0;
946}
947
948/*
949 * Copy data from an mbuf chain starting "off" bytes from the beginning,
950 * continuing for "len" bytes, into the indicated buffer.
951 */
952void
953m_copydata(m, off, len, cp)
954 register struct mbuf *m;
955 register int off;
956 register int len;
957 caddr_t cp;
958{
959 register unsigned count;
960
961 KASSERT(off >= 0, ("m_copydata, negative off %d", off));
962 KASSERT(len >= 0, ("m_copydata, negative len %d", len));
963 while (off > 0) {
964 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
965 if (off < m->m_len)
966 break;
967 off -= m->m_len;
968 m = m->m_next;
969 }
970 while (len > 0) {
971 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
972 count = min(m->m_len - off, len);
973 bcopy(mtod(m, caddr_t) + off, cp, count);
974 len -= count;
975 cp += count;
976 off = 0;
977 m = m->m_next;
978 }
979}
980
981/*
982 * Copy a packet header mbuf chain into a completely new chain, including
983 * copying any mbuf clusters. Use this instead of m_copypacket() when
984 * you need a writable copy of an mbuf chain.
985 */
986struct mbuf *
987m_dup(m, how)
988 struct mbuf *m;
989 int how;
990{
991 struct mbuf **p, *top = NULL;
992 int remain, moff, nsize;
993
994 /* Sanity check */
995 if (m == NULL)
996 return (0);
997 KASSERT((m->m_flags & M_PKTHDR) != 0, ("%s: !PKTHDR", __FUNCTION__));
998
999 /* While there's more data, get a new mbuf, tack it on, and fill it */
1000 remain = m->m_pkthdr.len;
1001 moff = 0;
1002 p = &top;
1003 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
1004 struct mbuf *n;
1005
1006 /* Get the next new mbuf */
1007 MGET(n, how, m->m_type);
1008 if (n == NULL)
1009 goto nospace;
1010 if (top == NULL) { /* first one, must be PKTHDR */
1011 if (!m_dup_pkthdr(n, m, how))
1012 goto nospace;
1013 nsize = MHLEN;
1014 } else /* not the first one */
1015 nsize = MLEN;
1016 if (remain >= MINCLSIZE) {
1017 MCLGET(n, how);
1018 if ((n->m_flags & M_EXT) == 0) {
1019 (void)m_free(n);
1020 goto nospace;
1021 }
1022 nsize = MCLBYTES;
1023 }
1024 n->m_len = 0;
1025
1026 /* Link it into the new chain */
1027 *p = n;
1028 p = &n->m_next;
1029
1030 /* Copy data from original mbuf(s) into new mbuf */
1031 while (n->m_len < nsize && m != NULL) {
1032 int chunk = min(nsize - n->m_len, m->m_len - moff);
1033
1034 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
1035 moff += chunk;
1036 n->m_len += chunk;
1037 remain -= chunk;
1038 if (moff == m->m_len) {
1039 m = m->m_next;
1040 moff = 0;
1041 }
1042 }
1043
1044 /* Check correct total mbuf length */
1045 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
1046 ("%s: bogus m_pkthdr.len", __FUNCTION__));
1047 }
1048 return (top);
1049
1050nospace:
1051 m_freem(top);
1052 MCFail++;
1053 return (0);
1054}
1055
1056/*
1057 * Concatenate mbuf chain n to m.
1058 * Both chains must be of the same type (e.g. MT_DATA).
1059 * Any m_pkthdr is not updated.
1060 */
1061void
1062m_cat(m, n)
1063 register struct mbuf *m, *n;
1064{
1065 while (m->m_next)
1066 m = m->m_next;
1067 while (n) {
1068 if (m->m_flags & M_EXT ||
1069 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
1070 /* just join the two chains */
1071 m->m_next = n;
1072 return;
1073 }
1074 /* splat the data from one into the other */
1075 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
1076 (u_int)n->m_len);
1077 m->m_len += n->m_len;
1078 n = m_free(n);
1079 }
1080}
1081
1082void
1083m_adj(mp, req_len)
1084 struct mbuf *mp;
1085 int req_len;
1086{
1087 register int len = req_len;
1088 register struct mbuf *m;
1089 register int count;
1090
1091 if ((m = mp) == NULL)
1092 return;
1093 if (len >= 0) {
1094 /*
1095 * Trim from head.
1096 */
1097 while (m != NULL && len > 0) {
1098 if (m->m_len <= len) {
1099 len -= m->m_len;
1100 m->m_len = 0;
1101 m = m->m_next;
1102 } else {
1103 m->m_len -= len;
1104 m->m_data += len;
1105 len = 0;
1106 }
1107 }
1108 m = mp;
1109 if (mp->m_flags & M_PKTHDR)
1110 m->m_pkthdr.len -= (req_len - len);
1111 } else {
1112 /*
1113 * Trim from tail. Scan the mbuf chain,
1114 * calculating its length and finding the last mbuf.
1115 * If the adjustment only affects this mbuf, then just
1116 * adjust and return. Otherwise, rescan and truncate
1117 * after the remaining size.
1118 */
1119 len = -len;
1120 count = 0;
1121 for (;;) {
1122 count += m->m_len;
1123 if (m->m_next == (struct mbuf *)0)
1124 break;
1125 m = m->m_next;
1126 }
1127 if (m->m_len >= len) {
1128 m->m_len -= len;
1129 if (mp->m_flags & M_PKTHDR)
1130 mp->m_pkthdr.len -= len;
1131 return;
1132 }
1133 count -= len;
1134 if (count < 0)
1135 count = 0;
1136 /*
1137 * Correct length for chain is "count".
1138 * Find the mbuf with last data, adjust its length,
1139 * and toss data from remaining mbufs on chain.
1140 */
1141 m = mp;
1142 if (m->m_flags & M_PKTHDR)
1143 m->m_pkthdr.len = count;
1144 for (; m; m = m->m_next) {
1145 if (m->m_len >= count) {
1146 m->m_len = count;
1147 break;
1148 }
1149 count -= m->m_len;
1150 }
1151 while (m->m_next)
1152 (m = m->m_next) ->m_len = 0;
1153 }
1154}
1155
1156/*
1157 * Rearange an mbuf chain so that len bytes are contiguous
1158 * and in the data area of an mbuf (so that mtod and dtom
1159 * will work for a structure of size len). Returns the resulting
1160 * mbuf chain on success, frees it and returns null on failure.
1161 * If there is room, it will add up to max_protohdr-len extra bytes to the
1162 * contiguous region in an attempt to avoid being called next time.
1163 */
1164#define MPFail (mbstat.m_mpfail)
1165
1166struct mbuf *
1167m_pullup(n, len)
1168 register struct mbuf *n;
1169 int len;
1170{
1171 register struct mbuf *m;
1172 register int count;
1173 int space;
1174
1175 /*
1176 * If first mbuf has no cluster, and has room for len bytes
1177 * without shifting current data, pullup into it,
1178 * otherwise allocate a new mbuf to prepend to the chain.
1179 */
1180 if ((n->m_flags & M_EXT) == 0 &&
1181 n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
1182 if (n->m_len >= len)
1183 return (n);
1184 m = n;
1185 n = n->m_next;
1186 len -= m->m_len;
1187 } else {
1188 if (len > MHLEN)
1189 goto bad;
1190 MGET(m, M_DONTWAIT, n->m_type);
1191 if (m == 0)
1192 goto bad;
1193 m->m_len = 0;
1194 if (n->m_flags & M_PKTHDR)
1195 M_MOVE_PKTHDR(m, n);
1196 }
1197 space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
1198 do {
1199 count = min(min(max(len, max_protohdr), space), n->m_len);
1200 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
1201 (unsigned)count);
1202 len -= count;
1203 m->m_len += count;
1204 n->m_len -= count;
1205 space -= count;
1206 if (n->m_len)
1207 n->m_data += count;
1208 else
1209 n = m_free(n);
1210 } while (len > 0 && n);
1211 if (len > 0) {
1212 (void) m_free(m);
1213 goto bad;
1214 }
1215 m->m_next = n;
1216 return (m);
1217bad:
1218 m_freem(n);
1219 MPFail++;
1220 return (0);
1221}
1222
1223/*
1224 * Partition an mbuf chain in two pieces, returning the tail --
1225 * all but the first len0 bytes. In case of failure, it returns NULL and
1226 * attempts to restore the chain to its original state.
1227 *
1228 * Note that the resulting mbufs might be read-only, because the new
1229 * mbuf can end up sharing an mbuf cluster with the original mbuf if
1230 * the "breaking point" happens to lie within a cluster mbuf. Use the
1231 * M_WRITABLE() macro to check for this case.
1232 */
1233struct mbuf *
1234m_split(m0, len0, wait)
1235 register struct mbuf *m0;
1236 int len0, wait;
1237{
1238 register struct mbuf *m, *n;
1239 unsigned len = len0, remain;
1240
1241 for (m = m0; m && len > m->m_len; m = m->m_next)
1242 len -= m->m_len;
1243 if (m == 0)
1244 return (0);
1245 remain = m->m_len - len;
1246 if (m0->m_flags & M_PKTHDR) {
1247 MGETHDR(n, wait, m0->m_type);
1248 if (n == 0)
1249 return (0);
1250 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
1251 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
1252 m0->m_pkthdr.len = len0;
1253 if (m->m_flags & M_EXT)
1254 goto extpacket;
1255 if (remain > MHLEN) {
1256 /* m can't be the lead packet */
1257 MH_ALIGN(n, 0);
1258 n->m_next = m_split(m, len, wait);
1259 if (n->m_next == 0) {
1260 (void) m_free(n);
1261 return (0);
1262 } else {
1263 n->m_len = 0;
1264 return (n);
1265 }
1266 } else
1267 MH_ALIGN(n, remain);
1268 } else if (remain == 0) {
1269 n = m->m_next;
1270 m->m_next = 0;
1271 return (n);
1272 } else {
1273 MGET(n, wait, m->m_type);
1274 if (n == 0)
1275 return (0);
1276 M_ALIGN(n, remain);
1277 }
1278extpacket:
1279 if (m->m_flags & M_EXT) {
1280 n->m_flags |= M_EXT;
1281 n->m_ext = m->m_ext;
1282 if (m->m_ext.ext_ref == NULL)
1283 atomic_add_char(&mclrefcnt[mtocl(m->m_ext.ext_buf)], 1);
1284 else {
1285 int s = splimp();
1286
1287 (*m->m_ext.ext_ref)(m->m_ext.ext_buf,
1288 m->m_ext.ext_size);
1289 splx(s);
1290 }
1291 n->m_data = m->m_data + len;
1292 } else {
1293 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
1294 }
1295 n->m_len = remain;
1296 m->m_len = len;
1297 n->m_next = m->m_next;
1298 m->m_next = 0;
1299 return (n);
1300}
1301/*
1302 * Routine to copy from device local memory into mbufs.
1303 */
1304struct mbuf *
1305m_devget(buf, totlen, off0, ifp, copy)
1306 char *buf;
1307 int totlen, off0;
1308 struct ifnet *ifp;
1309 void (*copy) __P((char *from, caddr_t to, u_int len));
1310{
1311 register struct mbuf *m;
1312 struct mbuf *top = 0, **mp = &top;
1313 register int off = off0, len;
1314 register char *cp;
1315 char *epkt;
1316
1317 cp = buf;
1318 epkt = cp + totlen;
1319 if (off) {
1320 cp += off + 2 * sizeof(u_short);
1321 totlen -= 2 * sizeof(u_short);
1322 }
1323 MGETHDR(m, M_DONTWAIT, MT_DATA);
1324 if (m == 0)
1325 return (0);
1326 m->m_pkthdr.rcvif = ifp;
1327 m->m_pkthdr.len = totlen;
1328 m->m_len = MHLEN;
1329
1330 while (totlen > 0) {
1331 if (top) {
1332 MGET(m, M_DONTWAIT, MT_DATA);
1333 if (m == 0) {
1334 m_freem(top);
1335 return (0);
1336 }
1337 m->m_len = MLEN;
1338 }
1339 len = min(totlen, epkt - cp);
1340 if (len >= MINCLSIZE) {
1341 MCLGET(m, M_DONTWAIT);
1342 if (m->m_flags & M_EXT)
1343 m->m_len = len = min(len, MCLBYTES);
1344 else
1345 len = m->m_len;
1346 } else {
1347 /*
1348 * Place initial small packet/header at end of mbuf.
1349 */
1350 if (len < m->m_len) {
1351 if (top == 0 && len + max_linkhdr <= m->m_len)
1352 m->m_data += max_linkhdr;
1353 m->m_len = len;
1354 } else
1355 len = m->m_len;
1356 }
1357 if (copy)
1358 copy(cp, mtod(m, caddr_t), (unsigned)len);
1359 else
1360 bcopy(cp, mtod(m, caddr_t), (unsigned)len);
1361 cp += len;
1362 *mp = m;
1363 mp = &m->m_next;
1364 totlen -= len;
1365 if (cp == epkt)
1366 cp = buf;
1367 }
1368 return (top);
1369}
1370
1371/*
1372 * Copy data from a buffer back into the indicated mbuf chain,
1373 * starting "off" bytes from the beginning, extending the mbuf
1374 * chain if necessary.
1375 */
1376void
1377m_copyback(m0, off, len, cp)
1378 struct mbuf *m0;
1379 register int off;
1380 register int len;
1381 caddr_t cp;
1382{
1383 register int mlen;
1384 register struct mbuf *m = m0, *n;
1385 int totlen = 0;
1386
1387 if (m0 == 0)
1388 return;
1389 while (off > (mlen = m->m_len)) {
1390 off -= mlen;
1391 totlen += mlen;
1392 if (m->m_next == 0) {
1393 n = m_getclr(M_DONTWAIT, m->m_type);
1394 if (n == 0)
1395 goto out;
1396 n->m_len = min(MLEN, len + off);
1397 m->m_next = n;
1398 }
1399 m = m->m_next;
1400 }
1401 while (len > 0) {
1402 mlen = min (m->m_len - off, len);
1403 bcopy(cp, off + mtod(m, caddr_t), (unsigned)mlen);
1404 cp += mlen;
1405 len -= mlen;
1406 mlen += off;
1407 off = 0;
1408 totlen += mlen;
1409 if (len == 0)
1410 break;
1411 if (m->m_next == 0) {
1412 n = m_get(M_DONTWAIT, m->m_type);
1413 if (n == 0)
1414 break;
1415 n->m_len = min(MLEN, len);
1416 m->m_next = n;
1417 }
1418 m = m->m_next;
1419 }
1420out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
1421 m->m_pkthdr.len = totlen;
1422}
1423
1424void
1425m_print(const struct mbuf *m)
1426{
1427 int len;
1428 const struct mbuf *m2;
1429
1430 len = m->m_pkthdr.len;
1431 m2 = m;
1432 while (len) {
1433 printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-");
1434 len -= m2->m_len;
1435 m2 = m2->m_next;
1436 }
1437 return;
1438}
1439
1440/*
1441 * "Move" mbuf pkthdr from "from" to "to".
1442 * "from" must have M_PKTHDR set, and "to" must be empty.
1443 */
1444void
1445m_move_pkthdr(struct mbuf *to, struct mbuf *from)
1446{
1447 KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster"));
1448
1449 to->m_flags = from->m_flags & M_COPYFLAGS;
1450 to->m_data = to->m_pktdat;
1451 to->m_pkthdr = from->m_pkthdr; /* especially tags */
1452 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */
1453 from->m_flags &= ~M_PKTHDR;
1454}
1455
1456/*
1457 * Duplicate "from"'s mbuf pkthdr in "to".
1458 * "from" must have M_PKTHDR set, and "to" must be empty.
1459 * In particular, this does a deep copy of the packet tags.
1460 */
1461int
1462m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
1463{
1464 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
1465 if ((to->m_flags & M_EXT) == 0)
1466 to->m_data = to->m_pktdat;
1467 to->m_pkthdr = from->m_pkthdr;
1468 SLIST_INIT(&to->m_pkthdr.tags);
1469 return (m_tag_copy_chain(to, from, how));
1470}
1471
1472/*
1473 * Defragment a mbuf chain, returning the shortest possible
1474 * chain of mbufs and clusters. If allocation fails and
1475 * this cannot be completed, NULL will be returned, but
1476 * the passed in chain will be unchanged. Upon success,
1477 * the original chain will be freed, and the new chain
1478 * will be returned.
1479 *
1480 * If a non-packet header is passed in, the original
1481 * mbuf (chain?) will be returned unharmed.
1482 */
1483struct mbuf *
1484m_defrag(struct mbuf *m0, int how)
1485{
1486 struct mbuf *m_new = NULL, *m_final = NULL;
1487 int progress = 0, length;
1488
1489 if (!(m0->m_flags & M_PKTHDR))
1490 return (m0);
1491
1492#ifdef MBUF_STRESS_TEST
1493 if (m_defragrandomfailures) {
1494 int temp = arc4random() & 0xff;
1495 if (temp == 0xba)
1496 goto nospace;
1497 }
1498#endif
1499
1500 if (m0->m_pkthdr.len > MHLEN)
1501 m_final = m_getcl(how, MT_DATA, M_PKTHDR);
1502 else
1503 m_final = m_gethdr(how, MT_DATA);
1504
1505 if (m_final == NULL)
1506 goto nospace;
1507
1508 if (m_dup_pkthdr(m_final, m0, how) == NULL)
1509 goto nospace;
1510
1511 m_new = m_final;
1512
1513 while (progress < m0->m_pkthdr.len) {
1514 length = m0->m_pkthdr.len - progress;
1515 if (length > MCLBYTES)
1516 length = MCLBYTES;
1517
1518 if (m_new == NULL) {
1519 if (length > MLEN)
1520 m_new = m_getcl(how, MT_DATA, 0);
1521 else
1522 m_new = m_get(how, MT_DATA);
1523 if (m_new == NULL)
1524 goto nospace;
1525 }
1526
1527 m_copydata(m0, progress, length, mtod(m_new, caddr_t));
1528 progress += length;
1529 m_new->m_len = length;
1530 if (m_new != m_final)
1531 m_cat(m_final, m_new);
1532 m_new = NULL;
1533 }
1534 if (m0->m_next == NULL)
1535 m_defraguseless++;
1536 m_freem(m0);
1537 m0 = m_final;
1538 m_defragpackets++;
1539 m_defragbytes += m0->m_pkthdr.len;
1540 return (m0);
1541nospace:
1542 m_defragfailure++;
1543 if (m_new)
1544 m_free(m_new);
1545 if (m_final)
1546 m_freem(m_final);
1547 return (NULL);
1548}