xref: /freebsd/sys/kern/uipc_mbuf.c (revision 298cf604ccf133b101c6fad42d1a078a1fac58ca)
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("$FreeBSD$");
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  * Allocate a given length worth of mbufs and/or clusters (whatever fits
89  * best) and return a pointer to the top of the allocated chain.  If an
90  * existing mbuf chain is provided, then we will append the new chain
91  * to the existing one but still return the top of the newly allocated
92  * chain.
93  */
94 struct mbuf *
95 m_getm2(struct mbuf *m, int len, int how, short type, int flags)
96 {
97 	struct mbuf *mb, *nm = NULL, *mtail = NULL;
98 
99 	KASSERT(len >= 0, ("%s: len is < 0", __func__));
100 
101 	/* Validate flags. */
102 	flags &= (M_PKTHDR | M_EOR);
103 
104 	/* Packet header mbuf must be first in chain. */
105 	if ((flags & M_PKTHDR) && m != NULL)
106 		flags &= ~M_PKTHDR;
107 
108 	/* Loop and append maximum sized mbufs to the chain tail. */
109 	while (len > 0) {
110 		if (len > MCLBYTES)
111 			mb = m_getjcl(how, type, (flags & M_PKTHDR),
112 			    MJUMPAGESIZE);
113 		else if (len >= MINCLSIZE)
114 			mb = m_getcl(how, type, (flags & M_PKTHDR));
115 		else if (flags & M_PKTHDR)
116 			mb = m_gethdr(how, type);
117 		else
118 			mb = m_get(how, type);
119 
120 		/* Fail the whole operation if one mbuf can't be allocated. */
121 		if (mb == NULL) {
122 			if (nm != NULL)
123 				m_freem(nm);
124 			return (NULL);
125 		}
126 
127 		/* Book keeping. */
128 		len -= (mb->m_flags & M_EXT) ? mb->m_ext.ext_size :
129 			((mb->m_flags & M_PKTHDR) ? MHLEN : MLEN);
130 		if (mtail != NULL)
131 			mtail->m_next = mb;
132 		else
133 			nm = mb;
134 		mtail = mb;
135 		flags &= ~M_PKTHDR;	/* Only valid on the first mbuf. */
136 	}
137 	if (flags & M_EOR)
138 		mtail->m_flags |= M_EOR;  /* Only valid on the last mbuf. */
139 
140 	/* If mbuf was supplied, append new chain to the end of it. */
141 	if (m != NULL) {
142 		for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next)
143 			;
144 		mtail->m_next = nm;
145 		mtail->m_flags &= ~M_EOR;
146 	} else
147 		m = nm;
148 
149 	return (m);
150 }
151 
152 /*
153  * Free an entire chain of mbufs and associated external buffers, if
154  * applicable.
155  */
156 void
157 m_freem(struct mbuf *mb)
158 {
159 
160 	while (mb != NULL)
161 		mb = m_free(mb);
162 }
163 
164 /*-
165  * Configure a provided mbuf to refer to the provided external storage
166  * buffer and setup a reference count for said buffer.  If the setting
167  * up of the reference count fails, the M_EXT bit will not be set.  If
168  * successfull, the M_EXT bit is set in the mbuf's flags.
169  *
170  * Arguments:
171  *    mb     The existing mbuf to which to attach the provided buffer.
172  *    buf    The address of the provided external storage buffer.
173  *    size   The size of the provided buffer.
174  *    freef  A pointer to a routine that is responsible for freeing the
175  *           provided external storage buffer.
176  *    args   A pointer to an argument structure (of any type) to be passed
177  *           to the provided freef routine (may be NULL).
178  *    flags  Any other flags to be passed to the provided mbuf.
179  *    type   The type that the external storage buffer should be
180  *           labeled with.
181  *
182  * Returns:
183  *    Nothing.
184  */
185 void
186 m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
187     void (*freef)(void *, void *), void *arg1, void *arg2, int flags, int type)
188 {
189 	KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
190 
191 	if (type != EXT_EXTREF)
192 		mb->m_ext.ref_cnt = (u_int *)uma_zalloc(zone_ext_refcnt, M_NOWAIT);
193 	if (mb->m_ext.ref_cnt != NULL) {
194 		*(mb->m_ext.ref_cnt) = 1;
195 		mb->m_flags |= (M_EXT | flags);
196 		mb->m_ext.ext_buf = buf;
197 		mb->m_data = mb->m_ext.ext_buf;
198 		mb->m_ext.ext_size = size;
199 		mb->m_ext.ext_free = freef;
200 		mb->m_ext.ext_arg1 = arg1;
201 		mb->m_ext.ext_arg2 = arg2;
202 		mb->m_ext.ext_type = type;
203         }
204 }
205 
206 /*
207  * Non-directly-exported function to clean up after mbufs with M_EXT
208  * storage attached to them if the reference count hits 1.
209  */
210 void
211 mb_free_ext(struct mbuf *m)
212 {
213 	int skipmbuf;
214 
215 	KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
216 	KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
217 
218 
219 	/*
220 	 * check if the header is embedded in the cluster
221 	 */
222 	skipmbuf = (m->m_flags & M_NOFREE);
223 
224 	/* Free attached storage if this mbuf is the only reference to it. */
225 	if (*(m->m_ext.ref_cnt) == 1 ||
226 	    atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 1) {
227 		switch (m->m_ext.ext_type) {
228 		case EXT_PACKET:	/* The packet zone is special. */
229 			if (*(m->m_ext.ref_cnt) == 0)
230 				*(m->m_ext.ref_cnt) = 1;
231 			uma_zfree(zone_pack, m);
232 			return;		/* Job done. */
233 		case EXT_CLUSTER:
234 			uma_zfree(zone_clust, m->m_ext.ext_buf);
235 			break;
236 		case EXT_JUMBOP:
237 			uma_zfree(zone_jumbop, m->m_ext.ext_buf);
238 			break;
239 		case EXT_JUMBO9:
240 			uma_zfree(zone_jumbo9, m->m_ext.ext_buf);
241 			break;
242 		case EXT_JUMBO16:
243 			uma_zfree(zone_jumbo16, m->m_ext.ext_buf);
244 			break;
245 		case EXT_SFBUF:
246 		case EXT_NET_DRV:
247 		case EXT_MOD_TYPE:
248 		case EXT_DISPOSABLE:
249 			*(m->m_ext.ref_cnt) = 0;
250 			uma_zfree(zone_ext_refcnt, __DEVOLATILE(u_int *,
251 				m->m_ext.ref_cnt));
252 			/* FALLTHROUGH */
253 		case EXT_EXTREF:
254 			KASSERT(m->m_ext.ext_free != NULL,
255 				("%s: ext_free not set", __func__));
256 			(*(m->m_ext.ext_free))(m->m_ext.ext_arg1,
257 			    m->m_ext.ext_arg2);
258 			break;
259 		default:
260 			KASSERT(m->m_ext.ext_type == 0,
261 				("%s: unknown ext_type", __func__));
262 		}
263 	}
264 	if (skipmbuf)
265 		return;
266 
267 	/*
268 	 * Free this mbuf back to the mbuf zone with all m_ext
269 	 * information purged.
270 	 */
271 	m->m_ext.ext_buf = NULL;
272 	m->m_ext.ext_free = NULL;
273 	m->m_ext.ext_arg1 = NULL;
274 	m->m_ext.ext_arg2 = NULL;
275 	m->m_ext.ref_cnt = NULL;
276 	m->m_ext.ext_size = 0;
277 	m->m_ext.ext_type = 0;
278 	m->m_flags &= ~M_EXT;
279 	uma_zfree(zone_mbuf, m);
280 }
281 
282 /*
283  * Attach the cluster from *m to *n, set up m_ext in *n
284  * and bump the refcount of the cluster.
285  */
286 static void
287 mb_dupcl(struct mbuf *n, struct mbuf *m)
288 {
289 	KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
290 	KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
291 	KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
292 
293 	if (*(m->m_ext.ref_cnt) == 1)
294 		*(m->m_ext.ref_cnt) += 1;
295 	else
296 		atomic_add_int(m->m_ext.ref_cnt, 1);
297 	n->m_ext.ext_buf = m->m_ext.ext_buf;
298 	n->m_ext.ext_free = m->m_ext.ext_free;
299 	n->m_ext.ext_arg1 = m->m_ext.ext_arg1;
300 	n->m_ext.ext_arg2 = m->m_ext.ext_arg2;
301 	n->m_ext.ext_size = m->m_ext.ext_size;
302 	n->m_ext.ref_cnt = m->m_ext.ref_cnt;
303 	n->m_ext.ext_type = m->m_ext.ext_type;
304 	n->m_flags |= M_EXT;
305 	n->m_flags |= m->m_flags & M_RDONLY;
306 }
307 
308 /*
309  * Clean up mbuf (chain) from any tags and packet headers.
310  * If "all" is set then the first mbuf in the chain will be
311  * cleaned too.
312  */
313 void
314 m_demote(struct mbuf *m0, int all)
315 {
316 	struct mbuf *m;
317 
318 	for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
319 		if (m->m_flags & M_PKTHDR) {
320 			m_tag_delete_chain(m, NULL);
321 			m->m_flags &= ~M_PKTHDR;
322 			bzero(&m->m_pkthdr, sizeof(struct pkthdr));
323 		}
324 		if (m != m0 && m->m_nextpkt != NULL) {
325 			KASSERT(m->m_nextpkt == NULL,
326 			    ("%s: m_nextpkt not NULL", __func__));
327 			m_freem(m->m_nextpkt);
328 			m->m_nextpkt = NULL;
329 		}
330 		m->m_flags = m->m_flags & (M_EXT|M_RDONLY|M_FREELIST|M_NOFREE);
331 	}
332 }
333 
334 /*
335  * Sanity checks on mbuf (chain) for use in KASSERT() and general
336  * debugging.
337  * Returns 0 or panics when bad and 1 on all tests passed.
338  * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
339  * blow up later.
340  */
341 int
342 m_sanity(struct mbuf *m0, int sanitize)
343 {
344 	struct mbuf *m;
345 	caddr_t a, b;
346 	int pktlen = 0;
347 
348 #ifdef INVARIANTS
349 #define	M_SANITY_ACTION(s)	panic("mbuf %p: " s, m)
350 #else
351 #define	M_SANITY_ACTION(s)	printf("mbuf %p: " s, m)
352 #endif
353 
354 	for (m = m0; m != NULL; m = m->m_next) {
355 		/*
356 		 * Basic pointer checks.  If any of these fails then some
357 		 * unrelated kernel memory before or after us is trashed.
358 		 * No way to recover from that.
359 		 */
360 		a = ((m->m_flags & M_EXT) ? m->m_ext.ext_buf :
361 			((m->m_flags & M_PKTHDR) ? (caddr_t)(&m->m_pktdat) :
362 			 (caddr_t)(&m->m_dat)) );
363 		b = (caddr_t)(a + (m->m_flags & M_EXT ? m->m_ext.ext_size :
364 			((m->m_flags & M_PKTHDR) ? MHLEN : MLEN)));
365 		if ((caddr_t)m->m_data < a)
366 			M_SANITY_ACTION("m_data outside mbuf data range left");
367 		if ((caddr_t)m->m_data > b)
368 			M_SANITY_ACTION("m_data outside mbuf data range right");
369 		if ((caddr_t)m->m_data + m->m_len > b)
370 			M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
371 		if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.header) {
372 			if ((caddr_t)m->m_pkthdr.header < a ||
373 			    (caddr_t)m->m_pkthdr.header > b)
374 				M_SANITY_ACTION("m_pkthdr.header outside mbuf data range");
375 		}
376 
377 		/* m->m_nextpkt may only be set on first mbuf in chain. */
378 		if (m != m0 && m->m_nextpkt != NULL) {
379 			if (sanitize) {
380 				m_freem(m->m_nextpkt);
381 				m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
382 			} else
383 				M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
384 		}
385 
386 		/* packet length (not mbuf length!) calculation */
387 		if (m0->m_flags & M_PKTHDR)
388 			pktlen += m->m_len;
389 
390 		/* m_tags may only be attached to first mbuf in chain. */
391 		if (m != m0 && m->m_flags & M_PKTHDR &&
392 		    !SLIST_EMPTY(&m->m_pkthdr.tags)) {
393 			if (sanitize) {
394 				m_tag_delete_chain(m, NULL);
395 				/* put in 0xDEADC0DE perhaps? */
396 			} else
397 				M_SANITY_ACTION("m_tags on in-chain mbuf");
398 		}
399 
400 		/* M_PKTHDR may only be set on first mbuf in chain */
401 		if (m != m0 && m->m_flags & M_PKTHDR) {
402 			if (sanitize) {
403 				bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
404 				m->m_flags &= ~M_PKTHDR;
405 				/* put in 0xDEADCODE and leave hdr flag in */
406 			} else
407 				M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
408 		}
409 	}
410 	m = m0;
411 	if (pktlen && pktlen != m->m_pkthdr.len) {
412 		if (sanitize)
413 			m->m_pkthdr.len = 0;
414 		else
415 			M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
416 	}
417 	return 1;
418 
419 #undef	M_SANITY_ACTION
420 }
421 
422 
423 /*
424  * "Move" mbuf pkthdr from "from" to "to".
425  * "from" must have M_PKTHDR set, and "to" must be empty.
426  */
427 void
428 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
429 {
430 
431 #if 0
432 	/* see below for why these are not enabled */
433 	M_ASSERTPKTHDR(to);
434 	/* Note: with MAC, this may not be a good assertion. */
435 	KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
436 	    ("m_move_pkthdr: to has tags"));
437 #endif
438 #ifdef MAC
439 	/*
440 	 * XXXMAC: It could be this should also occur for non-MAC?
441 	 */
442 	if (to->m_flags & M_PKTHDR)
443 		m_tag_delete_chain(to, NULL);
444 #endif
445 	to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
446 	if ((to->m_flags & M_EXT) == 0)
447 		to->m_data = to->m_pktdat;
448 	to->m_pkthdr = from->m_pkthdr;		/* especially tags */
449 	SLIST_INIT(&from->m_pkthdr.tags);	/* purge tags from src */
450 	from->m_flags &= ~M_PKTHDR;
451 }
452 
453 /*
454  * Duplicate "from"'s mbuf pkthdr in "to".
455  * "from" must have M_PKTHDR set, and "to" must be empty.
456  * In particular, this does a deep copy of the packet tags.
457  */
458 int
459 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
460 {
461 
462 #if 0
463 	/*
464 	 * The mbuf allocator only initializes the pkthdr
465 	 * when the mbuf is allocated with MGETHDR. Many users
466 	 * (e.g. m_copy*, m_prepend) use MGET and then
467 	 * smash the pkthdr as needed causing these
468 	 * assertions to trip.  For now just disable them.
469 	 */
470 	M_ASSERTPKTHDR(to);
471 	/* Note: with MAC, this may not be a good assertion. */
472 	KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
473 #endif
474 	MBUF_CHECKSLEEP(how);
475 #ifdef MAC
476 	if (to->m_flags & M_PKTHDR)
477 		m_tag_delete_chain(to, NULL);
478 #endif
479 	to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
480 	if ((to->m_flags & M_EXT) == 0)
481 		to->m_data = to->m_pktdat;
482 	to->m_pkthdr = from->m_pkthdr;
483 	SLIST_INIT(&to->m_pkthdr.tags);
484 	return (m_tag_copy_chain(to, from, MBTOM(how)));
485 }
486 
487 /*
488  * Lesser-used path for M_PREPEND:
489  * allocate new mbuf to prepend to chain,
490  * copy junk along.
491  */
492 struct mbuf *
493 m_prepend(struct mbuf *m, int len, int how)
494 {
495 	struct mbuf *mn;
496 
497 	if (m->m_flags & M_PKTHDR)
498 		MGETHDR(mn, how, m->m_type);
499 	else
500 		MGET(mn, how, m->m_type);
501 	if (mn == NULL) {
502 		m_freem(m);
503 		return (NULL);
504 	}
505 	if (m->m_flags & M_PKTHDR)
506 		M_MOVE_PKTHDR(mn, m);
507 	mn->m_next = m;
508 	m = mn;
509 	if(m->m_flags & M_PKTHDR) {
510 		if (len < MHLEN)
511 			MH_ALIGN(m, len);
512 	} else {
513 		if (len < MLEN)
514 			M_ALIGN(m, len);
515 	}
516 	m->m_len = len;
517 	return (m);
518 }
519 
520 /*
521  * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
522  * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
523  * The wait parameter is a choice of M_WAITOK/M_NOWAIT from caller.
524  * Note that the copy is read-only, because clusters are not copied,
525  * only their reference counts are incremented.
526  */
527 struct mbuf *
528 m_copym(struct mbuf *m, int off0, int len, int wait)
529 {
530 	struct mbuf *n, **np;
531 	int off = off0;
532 	struct mbuf *top;
533 	int copyhdr = 0;
534 
535 	KASSERT(off >= 0, ("m_copym, negative off %d", off));
536 	KASSERT(len >= 0, ("m_copym, negative len %d", len));
537 	MBUF_CHECKSLEEP(wait);
538 	if (off == 0 && m->m_flags & M_PKTHDR)
539 		copyhdr = 1;
540 	while (off > 0) {
541 		KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
542 		if (off < m->m_len)
543 			break;
544 		off -= m->m_len;
545 		m = m->m_next;
546 	}
547 	np = &top;
548 	top = 0;
549 	while (len > 0) {
550 		if (m == NULL) {
551 			KASSERT(len == M_COPYALL,
552 			    ("m_copym, length > size of mbuf chain"));
553 			break;
554 		}
555 		if (copyhdr)
556 			MGETHDR(n, wait, m->m_type);
557 		else
558 			MGET(n, wait, m->m_type);
559 		*np = n;
560 		if (n == NULL)
561 			goto nospace;
562 		if (copyhdr) {
563 			if (!m_dup_pkthdr(n, m, wait))
564 				goto nospace;
565 			if (len == M_COPYALL)
566 				n->m_pkthdr.len -= off0;
567 			else
568 				n->m_pkthdr.len = len;
569 			copyhdr = 0;
570 		}
571 		n->m_len = min(len, m->m_len - off);
572 		if (m->m_flags & M_EXT) {
573 			n->m_data = m->m_data + off;
574 			mb_dupcl(n, m);
575 		} else
576 			bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
577 			    (u_int)n->m_len);
578 		if (len != M_COPYALL)
579 			len -= n->m_len;
580 		off = 0;
581 		m = m->m_next;
582 		np = &n->m_next;
583 	}
584 	if (top == NULL)
585 		mbstat.m_mcfail++;	/* XXX: No consistency. */
586 
587 	return (top);
588 nospace:
589 	m_freem(top);
590 	mbstat.m_mcfail++;	/* XXX: No consistency. */
591 	return (NULL);
592 }
593 
594 /*
595  * Returns mbuf chain with new head for the prepending case.
596  * Copies from mbuf (chain) n from off for len to mbuf (chain) m
597  * either prepending or appending the data.
598  * The resulting mbuf (chain) m is fully writeable.
599  * m is destination (is made writeable)
600  * n is source, off is offset in source, len is len from offset
601  * dir, 0 append, 1 prepend
602  * how, wait or nowait
603  */
604 
605 static int
606 m_bcopyxxx(void *s, void *t, u_int len)
607 {
608 	bcopy(s, t, (size_t)len);
609 	return 0;
610 }
611 
612 struct mbuf *
613 m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len,
614     int prep, int how)
615 {
616 	struct mbuf *mm, *x, *z, *prev = NULL;
617 	caddr_t p;
618 	int i, nlen = 0;
619 	caddr_t buf[MLEN];
620 
621 	KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source"));
622 	KASSERT(off >= 0, ("m_copymdata, negative off %d", off));
623 	KASSERT(len >= 0, ("m_copymdata, negative len %d", len));
624 	KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep));
625 
626 	mm = m;
627 	if (!prep) {
628 		while(mm->m_next) {
629 			prev = mm;
630 			mm = mm->m_next;
631 		}
632 	}
633 	for (z = n; z != NULL; z = z->m_next)
634 		nlen += z->m_len;
635 	if (len == M_COPYALL)
636 		len = nlen - off;
637 	if (off + len > nlen || len < 1)
638 		return NULL;
639 
640 	if (!M_WRITABLE(mm)) {
641 		/* XXX: Use proper m_xxx function instead. */
642 		x = m_getcl(how, MT_DATA, mm->m_flags);
643 		if (x == NULL)
644 			return NULL;
645 		bcopy(mm->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size);
646 		p = x->m_ext.ext_buf + (mm->m_data - mm->m_ext.ext_buf);
647 		x->m_data = p;
648 		mm->m_next = NULL;
649 		if (mm != m)
650 			prev->m_next = x;
651 		m_free(mm);
652 		mm = x;
653 	}
654 
655 	/*
656 	 * Append/prepend the data.  Allocating mbufs as necessary.
657 	 */
658 	/* Shortcut if enough free space in first/last mbuf. */
659 	if (!prep && M_TRAILINGSPACE(mm) >= len) {
660 		m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) +
661 			 mm->m_len);
662 		mm->m_len += len;
663 		mm->m_pkthdr.len += len;
664 		return m;
665 	}
666 	if (prep && M_LEADINGSPACE(mm) >= len) {
667 		mm->m_data = mtod(mm, caddr_t) - len;
668 		m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t));
669 		mm->m_len += len;
670 		mm->m_pkthdr.len += len;
671 		return mm;
672 	}
673 
674 	/* Expand first/last mbuf to cluster if possible. */
675 	if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) {
676 		bcopy(mm->m_data, &buf, mm->m_len);
677 		m_clget(mm, how);
678 		if (!(mm->m_flags & M_EXT))
679 			return NULL;
680 		bcopy(&buf, mm->m_ext.ext_buf, mm->m_len);
681 		mm->m_data = mm->m_ext.ext_buf;
682 		mm->m_pkthdr.header = NULL;
683 	}
684 	if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) {
685 		bcopy(mm->m_data, &buf, mm->m_len);
686 		m_clget(mm, how);
687 		if (!(mm->m_flags & M_EXT))
688 			return NULL;
689 		bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf +
690 		       mm->m_ext.ext_size - mm->m_len, mm->m_len);
691 		mm->m_data = (caddr_t)mm->m_ext.ext_buf +
692 			      mm->m_ext.ext_size - mm->m_len;
693 		mm->m_pkthdr.header = NULL;
694 	}
695 
696 	/* Append/prepend as many mbuf (clusters) as necessary to fit len. */
697 	if (!prep && len > M_TRAILINGSPACE(mm)) {
698 		if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA))
699 			return NULL;
700 	}
701 	if (prep && len > M_LEADINGSPACE(mm)) {
702 		if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA)))
703 			return NULL;
704 		i = 0;
705 		for (x = z; x != NULL; x = x->m_next) {
706 			i += x->m_flags & M_EXT ? x->m_ext.ext_size :
707 			      (x->m_flags & M_PKTHDR ? MHLEN : MLEN);
708 			if (!x->m_next)
709 				break;
710 		}
711 		z->m_data += i - len;
712 		m_move_pkthdr(mm, z);
713 		x->m_next = mm;
714 		mm = z;
715 	}
716 
717 	/* Seek to start position in source mbuf. Optimization for long chains. */
718 	while (off > 0) {
719 		if (off < n->m_len)
720 			break;
721 		off -= n->m_len;
722 		n = n->m_next;
723 	}
724 
725 	/* Copy data into target mbuf. */
726 	z = mm;
727 	while (len > 0) {
728 		KASSERT(z != NULL, ("m_copymdata, falling off target edge"));
729 		i = M_TRAILINGSPACE(z);
730 		m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len);
731 		z->m_len += i;
732 		/* fixup pkthdr.len if necessary */
733 		if ((prep ? mm : m)->m_flags & M_PKTHDR)
734 			(prep ? mm : m)->m_pkthdr.len += i;
735 		off += i;
736 		len -= i;
737 		z = z->m_next;
738 	}
739 	return (prep ? mm : m);
740 }
741 
742 /*
743  * Copy an entire packet, including header (which must be present).
744  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
745  * Note that the copy is read-only, because clusters are not copied,
746  * only their reference counts are incremented.
747  * Preserve alignment of the first mbuf so if the creator has left
748  * some room at the beginning (e.g. for inserting protocol headers)
749  * the copies still have the room available.
750  */
751 struct mbuf *
752 m_copypacket(struct mbuf *m, int how)
753 {
754 	struct mbuf *top, *n, *o;
755 
756 	MBUF_CHECKSLEEP(how);
757 	MGET(n, how, m->m_type);
758 	top = n;
759 	if (n == NULL)
760 		goto nospace;
761 
762 	if (!m_dup_pkthdr(n, m, how))
763 		goto nospace;
764 	n->m_len = m->m_len;
765 	if (m->m_flags & M_EXT) {
766 		n->m_data = m->m_data;
767 		mb_dupcl(n, m);
768 	} else {
769 		n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
770 		bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
771 	}
772 
773 	m = m->m_next;
774 	while (m) {
775 		MGET(o, how, m->m_type);
776 		if (o == NULL)
777 			goto nospace;
778 
779 		n->m_next = o;
780 		n = n->m_next;
781 
782 		n->m_len = m->m_len;
783 		if (m->m_flags & M_EXT) {
784 			n->m_data = m->m_data;
785 			mb_dupcl(n, m);
786 		} else {
787 			bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
788 		}
789 
790 		m = m->m_next;
791 	}
792 	return top;
793 nospace:
794 	m_freem(top);
795 	mbstat.m_mcfail++;	/* XXX: No consistency. */
796 	return (NULL);
797 }
798 
799 /*
800  * Copy data from an mbuf chain starting "off" bytes from the beginning,
801  * continuing for "len" bytes, into the indicated buffer.
802  */
803 void
804 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
805 {
806 	u_int count;
807 
808 	KASSERT(off >= 0, ("m_copydata, negative off %d", off));
809 	KASSERT(len >= 0, ("m_copydata, negative len %d", len));
810 	while (off > 0) {
811 		KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
812 		if (off < m->m_len)
813 			break;
814 		off -= m->m_len;
815 		m = m->m_next;
816 	}
817 	while (len > 0) {
818 		KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
819 		count = min(m->m_len - off, len);
820 		bcopy(mtod(m, caddr_t) + off, cp, count);
821 		len -= count;
822 		cp += count;
823 		off = 0;
824 		m = m->m_next;
825 	}
826 }
827 
828 /*
829  * Copy a packet header mbuf chain into a completely new chain, including
830  * copying any mbuf clusters.  Use this instead of m_copypacket() when
831  * you need a writable copy of an mbuf chain.
832  */
833 struct mbuf *
834 m_dup(struct mbuf *m, int how)
835 {
836 	struct mbuf **p, *top = NULL;
837 	int remain, moff, nsize;
838 
839 	MBUF_CHECKSLEEP(how);
840 	/* Sanity check */
841 	if (m == NULL)
842 		return (NULL);
843 	M_ASSERTPKTHDR(m);
844 
845 	/* While there's more data, get a new mbuf, tack it on, and fill it */
846 	remain = m->m_pkthdr.len;
847 	moff = 0;
848 	p = &top;
849 	while (remain > 0 || top == NULL) {	/* allow m->m_pkthdr.len == 0 */
850 		struct mbuf *n;
851 
852 		/* Get the next new mbuf */
853 		if (remain >= MINCLSIZE) {
854 			n = m_getcl(how, m->m_type, 0);
855 			nsize = MCLBYTES;
856 		} else {
857 			n = m_get(how, m->m_type);
858 			nsize = MLEN;
859 		}
860 		if (n == NULL)
861 			goto nospace;
862 
863 		if (top == NULL) {		/* First one, must be PKTHDR */
864 			if (!m_dup_pkthdr(n, m, how)) {
865 				m_free(n);
866 				goto nospace;
867 			}
868 			if ((n->m_flags & M_EXT) == 0)
869 				nsize = MHLEN;
870 		}
871 		n->m_len = 0;
872 
873 		/* Link it into the new chain */
874 		*p = n;
875 		p = &n->m_next;
876 
877 		/* Copy data from original mbuf(s) into new mbuf */
878 		while (n->m_len < nsize && m != NULL) {
879 			int chunk = min(nsize - n->m_len, m->m_len - moff);
880 
881 			bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
882 			moff += chunk;
883 			n->m_len += chunk;
884 			remain -= chunk;
885 			if (moff == m->m_len) {
886 				m = m->m_next;
887 				moff = 0;
888 			}
889 		}
890 
891 		/* Check correct total mbuf length */
892 		KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
893 		    	("%s: bogus m_pkthdr.len", __func__));
894 	}
895 	return (top);
896 
897 nospace:
898 	m_freem(top);
899 	mbstat.m_mcfail++;	/* XXX: No consistency. */
900 	return (NULL);
901 }
902 
903 /*
904  * Concatenate mbuf chain n to m.
905  * Both chains must be of the same type (e.g. MT_DATA).
906  * Any m_pkthdr is not updated.
907  */
908 void
909 m_cat(struct mbuf *m, struct mbuf *n)
910 {
911 	while (m->m_next)
912 		m = m->m_next;
913 	while (n) {
914 		if (!M_WRITABLE(m) ||
915 		    M_TRAILINGSPACE(m) < n->m_len) {
916 			/* just join the two chains */
917 			m->m_next = n;
918 			return;
919 		}
920 		/* splat the data from one into the other */
921 		bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
922 		    (u_int)n->m_len);
923 		m->m_len += n->m_len;
924 		n = m_free(n);
925 	}
926 }
927 
928 void
929 m_adj(struct mbuf *mp, int req_len)
930 {
931 	int len = req_len;
932 	struct mbuf *m;
933 	int count;
934 
935 	if ((m = mp) == NULL)
936 		return;
937 	if (len >= 0) {
938 		/*
939 		 * Trim from head.
940 		 */
941 		while (m != NULL && len > 0) {
942 			if (m->m_len <= len) {
943 				len -= m->m_len;
944 				m->m_len = 0;
945 				m = m->m_next;
946 			} else {
947 				m->m_len -= len;
948 				m->m_data += len;
949 				len = 0;
950 			}
951 		}
952 		if (mp->m_flags & M_PKTHDR)
953 			mp->m_pkthdr.len -= (req_len - len);
954 	} else {
955 		/*
956 		 * Trim from tail.  Scan the mbuf chain,
957 		 * calculating its length and finding the last mbuf.
958 		 * If the adjustment only affects this mbuf, then just
959 		 * adjust and return.  Otherwise, rescan and truncate
960 		 * after the remaining size.
961 		 */
962 		len = -len;
963 		count = 0;
964 		for (;;) {
965 			count += m->m_len;
966 			if (m->m_next == (struct mbuf *)0)
967 				break;
968 			m = m->m_next;
969 		}
970 		if (m->m_len >= len) {
971 			m->m_len -= len;
972 			if (mp->m_flags & M_PKTHDR)
973 				mp->m_pkthdr.len -= len;
974 			return;
975 		}
976 		count -= len;
977 		if (count < 0)
978 			count = 0;
979 		/*
980 		 * Correct length for chain is "count".
981 		 * Find the mbuf with last data, adjust its length,
982 		 * and toss data from remaining mbufs on chain.
983 		 */
984 		m = mp;
985 		if (m->m_flags & M_PKTHDR)
986 			m->m_pkthdr.len = count;
987 		for (; m; m = m->m_next) {
988 			if (m->m_len >= count) {
989 				m->m_len = count;
990 				if (m->m_next != NULL) {
991 					m_freem(m->m_next);
992 					m->m_next = NULL;
993 				}
994 				break;
995 			}
996 			count -= m->m_len;
997 		}
998 	}
999 }
1000 
1001 /*
1002  * Rearange an mbuf chain so that len bytes are contiguous
1003  * and in the data area of an mbuf (so that mtod will work
1004  * for a structure of size len).  Returns the resulting
1005  * mbuf chain on success, frees it and returns null on failure.
1006  * If there is room, it will add up to max_protohdr-len extra bytes to the
1007  * contiguous region in an attempt to avoid being called next time.
1008  */
1009 struct mbuf *
1010 m_pullup(struct mbuf *n, int len)
1011 {
1012 	struct mbuf *m;
1013 	int count;
1014 	int space;
1015 
1016 	/*
1017 	 * If first mbuf has no cluster, and has room for len bytes
1018 	 * without shifting current data, pullup into it,
1019 	 * otherwise allocate a new mbuf to prepend to the chain.
1020 	 */
1021 	if ((n->m_flags & M_EXT) == 0 &&
1022 	    n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
1023 		if (n->m_len >= len)
1024 			return (n);
1025 		m = n;
1026 		n = n->m_next;
1027 		len -= m->m_len;
1028 	} else {
1029 		if (len > MHLEN)
1030 			goto bad;
1031 		MGET(m, M_NOWAIT, n->m_type);
1032 		if (m == NULL)
1033 			goto bad;
1034 		m->m_len = 0;
1035 		if (n->m_flags & M_PKTHDR)
1036 			M_MOVE_PKTHDR(m, n);
1037 	}
1038 	space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
1039 	do {
1040 		count = min(min(max(len, max_protohdr), space), n->m_len);
1041 		bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
1042 		  (u_int)count);
1043 		len -= count;
1044 		m->m_len += count;
1045 		n->m_len -= count;
1046 		space -= count;
1047 		if (n->m_len)
1048 			n->m_data += count;
1049 		else
1050 			n = m_free(n);
1051 	} while (len > 0 && n);
1052 	if (len > 0) {
1053 		(void) m_free(m);
1054 		goto bad;
1055 	}
1056 	m->m_next = n;
1057 	return (m);
1058 bad:
1059 	m_freem(n);
1060 	mbstat.m_mpfail++;	/* XXX: No consistency. */
1061 	return (NULL);
1062 }
1063 
1064 /*
1065  * Like m_pullup(), except a new mbuf is always allocated, and we allow
1066  * the amount of empty space before the data in the new mbuf to be specified
1067  * (in the event that the caller expects to prepend later).
1068  */
1069 int MSFail;
1070 
1071 struct mbuf *
1072 m_copyup(struct mbuf *n, int len, int dstoff)
1073 {
1074 	struct mbuf *m;
1075 	int count, space;
1076 
1077 	if (len > (MHLEN - dstoff))
1078 		goto bad;
1079 	MGET(m, M_NOWAIT, n->m_type);
1080 	if (m == NULL)
1081 		goto bad;
1082 	m->m_len = 0;
1083 	if (n->m_flags & M_PKTHDR)
1084 		M_MOVE_PKTHDR(m, n);
1085 	m->m_data += dstoff;
1086 	space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
1087 	do {
1088 		count = min(min(max(len, max_protohdr), space), n->m_len);
1089 		memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
1090 		    (unsigned)count);
1091 		len -= count;
1092 		m->m_len += count;
1093 		n->m_len -= count;
1094 		space -= count;
1095 		if (n->m_len)
1096 			n->m_data += count;
1097 		else
1098 			n = m_free(n);
1099 	} while (len > 0 && n);
1100 	if (len > 0) {
1101 		(void) m_free(m);
1102 		goto bad;
1103 	}
1104 	m->m_next = n;
1105 	return (m);
1106  bad:
1107 	m_freem(n);
1108 	MSFail++;
1109 	return (NULL);
1110 }
1111 
1112 /*
1113  * Partition an mbuf chain in two pieces, returning the tail --
1114  * all but the first len0 bytes.  In case of failure, it returns NULL and
1115  * attempts to restore the chain to its original state.
1116  *
1117  * Note that the resulting mbufs might be read-only, because the new
1118  * mbuf can end up sharing an mbuf cluster with the original mbuf if
1119  * the "breaking point" happens to lie within a cluster mbuf. Use the
1120  * M_WRITABLE() macro to check for this case.
1121  */
1122 struct mbuf *
1123 m_split(struct mbuf *m0, int len0, int wait)
1124 {
1125 	struct mbuf *m, *n;
1126 	u_int len = len0, remain;
1127 
1128 	MBUF_CHECKSLEEP(wait);
1129 	for (m = m0; m && len > m->m_len; m = m->m_next)
1130 		len -= m->m_len;
1131 	if (m == NULL)
1132 		return (NULL);
1133 	remain = m->m_len - len;
1134 	if (m0->m_flags & M_PKTHDR) {
1135 		MGETHDR(n, wait, m0->m_type);
1136 		if (n == NULL)
1137 			return (NULL);
1138 		n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
1139 		n->m_pkthdr.len = m0->m_pkthdr.len - len0;
1140 		m0->m_pkthdr.len = len0;
1141 		if (m->m_flags & M_EXT)
1142 			goto extpacket;
1143 		if (remain > MHLEN) {
1144 			/* m can't be the lead packet */
1145 			MH_ALIGN(n, 0);
1146 			n->m_next = m_split(m, len, wait);
1147 			if (n->m_next == NULL) {
1148 				(void) m_free(n);
1149 				return (NULL);
1150 			} else {
1151 				n->m_len = 0;
1152 				return (n);
1153 			}
1154 		} else
1155 			MH_ALIGN(n, remain);
1156 	} else if (remain == 0) {
1157 		n = m->m_next;
1158 		m->m_next = NULL;
1159 		return (n);
1160 	} else {
1161 		MGET(n, wait, m->m_type);
1162 		if (n == NULL)
1163 			return (NULL);
1164 		M_ALIGN(n, remain);
1165 	}
1166 extpacket:
1167 	if (m->m_flags & M_EXT) {
1168 		n->m_data = m->m_data + len;
1169 		mb_dupcl(n, m);
1170 	} else {
1171 		bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
1172 	}
1173 	n->m_len = remain;
1174 	m->m_len = len;
1175 	n->m_next = m->m_next;
1176 	m->m_next = NULL;
1177 	return (n);
1178 }
1179 /*
1180  * Routine to copy from device local memory into mbufs.
1181  * Note that `off' argument is offset into first mbuf of target chain from
1182  * which to begin copying the data to.
1183  */
1184 struct mbuf *
1185 m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
1186     void (*copy)(char *from, caddr_t to, u_int len))
1187 {
1188 	struct mbuf *m;
1189 	struct mbuf *top = NULL, **mp = &top;
1190 	int len;
1191 
1192 	if (off < 0 || off > MHLEN)
1193 		return (NULL);
1194 
1195 	while (totlen > 0) {
1196 		if (top == NULL) {	/* First one, must be PKTHDR */
1197 			if (totlen + off >= MINCLSIZE) {
1198 				m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
1199 				len = MCLBYTES;
1200 			} else {
1201 				m = m_gethdr(M_NOWAIT, MT_DATA);
1202 				len = MHLEN;
1203 
1204 				/* Place initial small packet/header at end of mbuf */
1205 				if (m && totlen + off + max_linkhdr <= MLEN) {
1206 					m->m_data += max_linkhdr;
1207 					len -= max_linkhdr;
1208 				}
1209 			}
1210 			if (m == NULL)
1211 				return NULL;
1212 			m->m_pkthdr.rcvif = ifp;
1213 			m->m_pkthdr.len = totlen;
1214 		} else {
1215 			if (totlen + off >= MINCLSIZE) {
1216 				m = m_getcl(M_NOWAIT, MT_DATA, 0);
1217 				len = MCLBYTES;
1218 			} else {
1219 				m = m_get(M_NOWAIT, MT_DATA);
1220 				len = MLEN;
1221 			}
1222 			if (m == NULL) {
1223 				m_freem(top);
1224 				return NULL;
1225 			}
1226 		}
1227 		if (off) {
1228 			m->m_data += off;
1229 			len -= off;
1230 			off = 0;
1231 		}
1232 		m->m_len = len = min(totlen, len);
1233 		if (copy)
1234 			copy(buf, mtod(m, caddr_t), (u_int)len);
1235 		else
1236 			bcopy(buf, mtod(m, caddr_t), (u_int)len);
1237 		buf += len;
1238 		*mp = m;
1239 		mp = &m->m_next;
1240 		totlen -= len;
1241 	}
1242 	return (top);
1243 }
1244 
1245 /*
1246  * Copy data from a buffer back into the indicated mbuf chain,
1247  * starting "off" bytes from the beginning, extending the mbuf
1248  * chain if necessary.
1249  */
1250 void
1251 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
1252 {
1253 	int mlen;
1254 	struct mbuf *m = m0, *n;
1255 	int totlen = 0;
1256 
1257 	if (m0 == NULL)
1258 		return;
1259 	while (off > (mlen = m->m_len)) {
1260 		off -= mlen;
1261 		totlen += mlen;
1262 		if (m->m_next == NULL) {
1263 			n = m_get(M_NOWAIT, m->m_type);
1264 			if (n == NULL)
1265 				goto out;
1266 			bzero(mtod(n, caddr_t), MLEN);
1267 			n->m_len = min(MLEN, len + off);
1268 			m->m_next = n;
1269 		}
1270 		m = m->m_next;
1271 	}
1272 	while (len > 0) {
1273 		if (m->m_next == NULL && (len > m->m_len - off)) {
1274 			m->m_len += min(len - (m->m_len - off),
1275 			    M_TRAILINGSPACE(m));
1276 		}
1277 		mlen = min (m->m_len - off, len);
1278 		bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
1279 		cp += mlen;
1280 		len -= mlen;
1281 		mlen += off;
1282 		off = 0;
1283 		totlen += mlen;
1284 		if (len == 0)
1285 			break;
1286 		if (m->m_next == NULL) {
1287 			n = m_get(M_NOWAIT, m->m_type);
1288 			if (n == NULL)
1289 				break;
1290 			n->m_len = min(MLEN, len);
1291 			m->m_next = n;
1292 		}
1293 		m = m->m_next;
1294 	}
1295 out:	if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
1296 		m->m_pkthdr.len = totlen;
1297 }
1298 
1299 /*
1300  * Append the specified data to the indicated mbuf chain,
1301  * Extend the mbuf chain if the new data does not fit in
1302  * existing space.
1303  *
1304  * Return 1 if able to complete the job; otherwise 0.
1305  */
1306 int
1307 m_append(struct mbuf *m0, int len, c_caddr_t cp)
1308 {
1309 	struct mbuf *m, *n;
1310 	int remainder, space;
1311 
1312 	for (m = m0; m->m_next != NULL; m = m->m_next)
1313 		;
1314 	remainder = len;
1315 	space = M_TRAILINGSPACE(m);
1316 	if (space > 0) {
1317 		/*
1318 		 * Copy into available space.
1319 		 */
1320 		if (space > remainder)
1321 			space = remainder;
1322 		bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
1323 		m->m_len += space;
1324 		cp += space, remainder -= space;
1325 	}
1326 	while (remainder > 0) {
1327 		/*
1328 		 * Allocate a new mbuf; could check space
1329 		 * and allocate a cluster instead.
1330 		 */
1331 		n = m_get(M_NOWAIT, m->m_type);
1332 		if (n == NULL)
1333 			break;
1334 		n->m_len = min(MLEN, remainder);
1335 		bcopy(cp, mtod(n, caddr_t), n->m_len);
1336 		cp += n->m_len, remainder -= n->m_len;
1337 		m->m_next = n;
1338 		m = n;
1339 	}
1340 	if (m0->m_flags & M_PKTHDR)
1341 		m0->m_pkthdr.len += len - remainder;
1342 	return (remainder == 0);
1343 }
1344 
1345 /*
1346  * Apply function f to the data in an mbuf chain starting "off" bytes from
1347  * the beginning, continuing for "len" bytes.
1348  */
1349 int
1350 m_apply(struct mbuf *m, int off, int len,
1351     int (*f)(void *, void *, u_int), void *arg)
1352 {
1353 	u_int count;
1354 	int rval;
1355 
1356 	KASSERT(off >= 0, ("m_apply, negative off %d", off));
1357 	KASSERT(len >= 0, ("m_apply, negative len %d", len));
1358 	while (off > 0) {
1359 		KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1360 		if (off < m->m_len)
1361 			break;
1362 		off -= m->m_len;
1363 		m = m->m_next;
1364 	}
1365 	while (len > 0) {
1366 		KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1367 		count = min(m->m_len - off, len);
1368 		rval = (*f)(arg, mtod(m, caddr_t) + off, count);
1369 		if (rval)
1370 			return (rval);
1371 		len -= count;
1372 		off = 0;
1373 		m = m->m_next;
1374 	}
1375 	return (0);
1376 }
1377 
1378 /*
1379  * Return a pointer to mbuf/offset of location in mbuf chain.
1380  */
1381 struct mbuf *
1382 m_getptr(struct mbuf *m, int loc, int *off)
1383 {
1384 
1385 	while (loc >= 0) {
1386 		/* Normal end of search. */
1387 		if (m->m_len > loc) {
1388 			*off = loc;
1389 			return (m);
1390 		} else {
1391 			loc -= m->m_len;
1392 			if (m->m_next == NULL) {
1393 				if (loc == 0) {
1394 					/* Point at the end of valid data. */
1395 					*off = m->m_len;
1396 					return (m);
1397 				}
1398 				return (NULL);
1399 			}
1400 			m = m->m_next;
1401 		}
1402 	}
1403 	return (NULL);
1404 }
1405 
1406 void
1407 m_print(const struct mbuf *m, int maxlen)
1408 {
1409 	int len;
1410 	int pdata;
1411 	const struct mbuf *m2;
1412 
1413 	if (m == NULL) {
1414 		printf("mbuf: %p\n", m);
1415 		return;
1416 	}
1417 
1418 	if (m->m_flags & M_PKTHDR)
1419 		len = m->m_pkthdr.len;
1420 	else
1421 		len = -1;
1422 	m2 = m;
1423 	while (m2 != NULL && (len == -1 || len)) {
1424 		pdata = m2->m_len;
1425 		if (maxlen != -1 && pdata > maxlen)
1426 			pdata = maxlen;
1427 		printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
1428 		    m2->m_next, m2->m_flags, "\20\20freelist\17skipfw"
1429 		    "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
1430 		    "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
1431 		if (pdata)
1432 			printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
1433 		if (len != -1)
1434 			len -= m2->m_len;
1435 		m2 = m2->m_next;
1436 	}
1437 	if (len > 0)
1438 		printf("%d bytes unaccounted for.\n", len);
1439 	return;
1440 }
1441 
1442 u_int
1443 m_fixhdr(struct mbuf *m0)
1444 {
1445 	u_int len;
1446 
1447 	len = m_length(m0, NULL);
1448 	m0->m_pkthdr.len = len;
1449 	return (len);
1450 }
1451 
1452 u_int
1453 m_length(struct mbuf *m0, struct mbuf **last)
1454 {
1455 	struct mbuf *m;
1456 	u_int len;
1457 
1458 	len = 0;
1459 	for (m = m0; m != NULL; m = m->m_next) {
1460 		len += m->m_len;
1461 		if (m->m_next == NULL)
1462 			break;
1463 	}
1464 	if (last != NULL)
1465 		*last = m;
1466 	return (len);
1467 }
1468 
1469 /*
1470  * Defragment a mbuf chain, returning the shortest possible
1471  * chain of mbufs and clusters.  If allocation fails and
1472  * this cannot be completed, NULL will be returned, but
1473  * the passed in chain will be unchanged.  Upon success,
1474  * the original chain will be freed, and the new chain
1475  * will be returned.
1476  *
1477  * If a non-packet header is passed in, the original
1478  * mbuf (chain?) will be returned unharmed.
1479  */
1480 struct mbuf *
1481 m_defrag(struct mbuf *m0, int how)
1482 {
1483 	struct mbuf *m_new = NULL, *m_final = NULL;
1484 	int progress = 0, length;
1485 
1486 	MBUF_CHECKSLEEP(how);
1487 	if (!(m0->m_flags & M_PKTHDR))
1488 		return (m0);
1489 
1490 	m_fixhdr(m0); /* Needed sanity check */
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) == 0)
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 #ifdef MBUF_STRESS_TEST
1535 	if (m0->m_next == NULL)
1536 		m_defraguseless++;
1537 #endif
1538 	m_freem(m0);
1539 	m0 = m_final;
1540 #ifdef MBUF_STRESS_TEST
1541 	m_defragpackets++;
1542 	m_defragbytes += m0->m_pkthdr.len;
1543 #endif
1544 	return (m0);
1545 nospace:
1546 #ifdef MBUF_STRESS_TEST
1547 	m_defragfailure++;
1548 #endif
1549 	if (m_final)
1550 		m_freem(m_final);
1551 	return (NULL);
1552 }
1553 
1554 /*
1555  * Defragment an mbuf chain, returning at most maxfrags separate
1556  * mbufs+clusters.  If this is not possible NULL is returned and
1557  * the original mbuf chain is left in it's present (potentially
1558  * modified) state.  We use two techniques: collapsing consecutive
1559  * mbufs and replacing consecutive mbufs by a cluster.
1560  *
1561  * NB: this should really be named m_defrag but that name is taken
1562  */
1563 struct mbuf *
1564 m_collapse(struct mbuf *m0, int how, int maxfrags)
1565 {
1566 	struct mbuf *m, *n, *n2, **prev;
1567 	u_int curfrags;
1568 
1569 	/*
1570 	 * Calculate the current number of frags.
1571 	 */
1572 	curfrags = 0;
1573 	for (m = m0; m != NULL; m = m->m_next)
1574 		curfrags++;
1575 	/*
1576 	 * First, try to collapse mbufs.  Note that we always collapse
1577 	 * towards the front so we don't need to deal with moving the
1578 	 * pkthdr.  This may be suboptimal if the first mbuf has much
1579 	 * less data than the following.
1580 	 */
1581 	m = m0;
1582 again:
1583 	for (;;) {
1584 		n = m->m_next;
1585 		if (n == NULL)
1586 			break;
1587 		if (M_WRITABLE(m) &&
1588 		    n->m_len < M_TRAILINGSPACE(m)) {
1589 			bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
1590 				n->m_len);
1591 			m->m_len += n->m_len;
1592 			m->m_next = n->m_next;
1593 			m_free(n);
1594 			if (--curfrags <= maxfrags)
1595 				return m0;
1596 		} else
1597 			m = n;
1598 	}
1599 	KASSERT(maxfrags > 1,
1600 		("maxfrags %u, but normal collapse failed", maxfrags));
1601 	/*
1602 	 * Collapse consecutive mbufs to a cluster.
1603 	 */
1604 	prev = &m0->m_next;		/* NB: not the first mbuf */
1605 	while ((n = *prev) != NULL) {
1606 		if ((n2 = n->m_next) != NULL &&
1607 		    n->m_len + n2->m_len < MCLBYTES) {
1608 			m = m_getcl(how, MT_DATA, 0);
1609 			if (m == NULL)
1610 				goto bad;
1611 			bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
1612 			bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
1613 				n2->m_len);
1614 			m->m_len = n->m_len + n2->m_len;
1615 			m->m_next = n2->m_next;
1616 			*prev = m;
1617 			m_free(n);
1618 			m_free(n2);
1619 			if (--curfrags <= maxfrags)	/* +1 cl -2 mbufs */
1620 				return m0;
1621 			/*
1622 			 * Still not there, try the normal collapse
1623 			 * again before we allocate another cluster.
1624 			 */
1625 			goto again;
1626 		}
1627 		prev = &n->m_next;
1628 	}
1629 	/*
1630 	 * No place where we can collapse to a cluster; punt.
1631 	 * This can occur if, for example, you request 2 frags
1632 	 * but the packet requires that both be clusters (we
1633 	 * never reallocate the first mbuf to avoid moving the
1634 	 * packet header).
1635 	 */
1636 bad:
1637 	return NULL;
1638 }
1639 
1640 #ifdef MBUF_STRESS_TEST
1641 
1642 /*
1643  * Fragment an mbuf chain.  There's no reason you'd ever want to do
1644  * this in normal usage, but it's great for stress testing various
1645  * mbuf consumers.
1646  *
1647  * If fragmentation is not possible, the original chain will be
1648  * returned.
1649  *
1650  * Possible length values:
1651  * 0	 no fragmentation will occur
1652  * > 0	each fragment will be of the specified length
1653  * -1	each fragment will be the same random value in length
1654  * -2	each fragment's length will be entirely random
1655  * (Random values range from 1 to 256)
1656  */
1657 struct mbuf *
1658 m_fragment(struct mbuf *m0, int how, int length)
1659 {
1660 	struct mbuf *m_new = NULL, *m_final = NULL;
1661 	int progress = 0;
1662 
1663 	if (!(m0->m_flags & M_PKTHDR))
1664 		return (m0);
1665 
1666 	if ((length == 0) || (length < -2))
1667 		return (m0);
1668 
1669 	m_fixhdr(m0); /* Needed sanity check */
1670 
1671 	m_final = m_getcl(how, MT_DATA, M_PKTHDR);
1672 
1673 	if (m_final == NULL)
1674 		goto nospace;
1675 
1676 	if (m_dup_pkthdr(m_final, m0, how) == 0)
1677 		goto nospace;
1678 
1679 	m_new = m_final;
1680 
1681 	if (length == -1)
1682 		length = 1 + (arc4random() & 255);
1683 
1684 	while (progress < m0->m_pkthdr.len) {
1685 		int fraglen;
1686 
1687 		if (length > 0)
1688 			fraglen = length;
1689 		else
1690 			fraglen = 1 + (arc4random() & 255);
1691 		if (fraglen > m0->m_pkthdr.len - progress)
1692 			fraglen = m0->m_pkthdr.len - progress;
1693 
1694 		if (fraglen > MCLBYTES)
1695 			fraglen = MCLBYTES;
1696 
1697 		if (m_new == NULL) {
1698 			m_new = m_getcl(how, MT_DATA, 0);
1699 			if (m_new == NULL)
1700 				goto nospace;
1701 		}
1702 
1703 		m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
1704 		progress += fraglen;
1705 		m_new->m_len = fraglen;
1706 		if (m_new != m_final)
1707 			m_cat(m_final, m_new);
1708 		m_new = NULL;
1709 	}
1710 	m_freem(m0);
1711 	m0 = m_final;
1712 	return (m0);
1713 nospace:
1714 	if (m_final)
1715 		m_freem(m_final);
1716 	/* Return the original chain on failure */
1717 	return (m0);
1718 }
1719 
1720 #endif
1721 
1722 /*
1723  * Copy the contents of uio into a properly sized mbuf chain.
1724  */
1725 struct mbuf *
1726 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
1727 {
1728 	struct mbuf *m, *mb;
1729 	int error, length;
1730 	ssize_t total;
1731 	int progress = 0;
1732 
1733 	/*
1734 	 * len can be zero or an arbitrary large value bound by
1735 	 * the total data supplied by the uio.
1736 	 */
1737 	if (len > 0)
1738 		total = min(uio->uio_resid, len);
1739 	else
1740 		total = uio->uio_resid;
1741 
1742 	/*
1743 	 * The smallest unit returned by m_getm2() is a single mbuf
1744 	 * with pkthdr.  We can't align past it.
1745 	 */
1746 	if (align >= MHLEN)
1747 		return (NULL);
1748 
1749 	/*
1750 	 * Give us the full allocation or nothing.
1751 	 * If len is zero return the smallest empty mbuf.
1752 	 */
1753 	m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
1754 	if (m == NULL)
1755 		return (NULL);
1756 	m->m_data += align;
1757 
1758 	/* Fill all mbufs with uio data and update header information. */
1759 	for (mb = m; mb != NULL; mb = mb->m_next) {
1760 		length = min(M_TRAILINGSPACE(mb), total - progress);
1761 
1762 		error = uiomove(mtod(mb, void *), length, uio);
1763 		if (error) {
1764 			m_freem(m);
1765 			return (NULL);
1766 		}
1767 
1768 		mb->m_len = length;
1769 		progress += length;
1770 		if (flags & M_PKTHDR)
1771 			m->m_pkthdr.len += length;
1772 	}
1773 	KASSERT(progress == total, ("%s: progress != total", __func__));
1774 
1775 	return (m);
1776 }
1777 
1778 /*
1779  * Copy an mbuf chain into a uio limited by len if set.
1780  */
1781 int
1782 m_mbuftouio(struct uio *uio, struct mbuf *m, int len)
1783 {
1784 	int error, length, total;
1785 	int progress = 0;
1786 
1787 	if (len > 0)
1788 		total = min(uio->uio_resid, len);
1789 	else
1790 		total = uio->uio_resid;
1791 
1792 	/* Fill the uio with data from the mbufs. */
1793 	for (; m != NULL; m = m->m_next) {
1794 		length = min(m->m_len, total - progress);
1795 
1796 		error = uiomove(mtod(m, void *), length, uio);
1797 		if (error)
1798 			return (error);
1799 
1800 		progress += length;
1801 	}
1802 
1803 	return (0);
1804 }
1805 
1806 /*
1807  * Set the m_data pointer of a newly-allocated mbuf
1808  * to place an object of the specified size at the
1809  * end of the mbuf, longword aligned.
1810  */
1811 void
1812 m_align(struct mbuf *m, int len)
1813 {
1814 	int adjust;
1815 
1816 	if (m->m_flags & M_EXT)
1817 		adjust = m->m_ext.ext_size - len;
1818 	else if (m->m_flags & M_PKTHDR)
1819 		adjust = MHLEN - len;
1820 	else
1821 		adjust = MLEN - len;
1822 	m->m_data += adjust &~ (sizeof(long)-1);
1823 }
1824 
1825 /*
1826  * Create a writable copy of the mbuf chain.  While doing this
1827  * we compact the chain with a goal of producing a chain with
1828  * at most two mbufs.  The second mbuf in this chain is likely
1829  * to be a cluster.  The primary purpose of this work is to create
1830  * a writable packet for encryption, compression, etc.  The
1831  * secondary goal is to linearize the data so the data can be
1832  * passed to crypto hardware in the most efficient manner possible.
1833  */
1834 struct mbuf *
1835 m_unshare(struct mbuf *m0, int how)
1836 {
1837 	struct mbuf *m, *mprev;
1838 	struct mbuf *n, *mfirst, *mlast;
1839 	int len, off;
1840 
1841 	mprev = NULL;
1842 	for (m = m0; m != NULL; m = mprev->m_next) {
1843 		/*
1844 		 * Regular mbufs are ignored unless there's a cluster
1845 		 * in front of it that we can use to coalesce.  We do
1846 		 * the latter mainly so later clusters can be coalesced
1847 		 * also w/o having to handle them specially (i.e. convert
1848 		 * mbuf+cluster -> cluster).  This optimization is heavily
1849 		 * influenced by the assumption that we're running over
1850 		 * Ethernet where MCLBYTES is large enough that the max
1851 		 * packet size will permit lots of coalescing into a
1852 		 * single cluster.  This in turn permits efficient
1853 		 * crypto operations, especially when using hardware.
1854 		 */
1855 		if ((m->m_flags & M_EXT) == 0) {
1856 			if (mprev && (mprev->m_flags & M_EXT) &&
1857 			    m->m_len <= M_TRAILINGSPACE(mprev)) {
1858 				/* XXX: this ignores mbuf types */
1859 				memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1860 				       mtod(m, caddr_t), m->m_len);
1861 				mprev->m_len += m->m_len;
1862 				mprev->m_next = m->m_next;	/* unlink from chain */
1863 				m_free(m);			/* reclaim mbuf */
1864 #if 0
1865 				newipsecstat.ips_mbcoalesced++;
1866 #endif
1867 			} else {
1868 				mprev = m;
1869 			}
1870 			continue;
1871 		}
1872 		/*
1873 		 * Writable mbufs are left alone (for now).
1874 		 */
1875 		if (M_WRITABLE(m)) {
1876 			mprev = m;
1877 			continue;
1878 		}
1879 
1880 		/*
1881 		 * Not writable, replace with a copy or coalesce with
1882 		 * the previous mbuf if possible (since we have to copy
1883 		 * it anyway, we try to reduce the number of mbufs and
1884 		 * clusters so that future work is easier).
1885 		 */
1886 		KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
1887 		/* NB: we only coalesce into a cluster or larger */
1888 		if (mprev != NULL && (mprev->m_flags & M_EXT) &&
1889 		    m->m_len <= M_TRAILINGSPACE(mprev)) {
1890 			/* XXX: this ignores mbuf types */
1891 			memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1892 			       mtod(m, caddr_t), m->m_len);
1893 			mprev->m_len += m->m_len;
1894 			mprev->m_next = m->m_next;	/* unlink from chain */
1895 			m_free(m);			/* reclaim mbuf */
1896 #if 0
1897 			newipsecstat.ips_clcoalesced++;
1898 #endif
1899 			continue;
1900 		}
1901 
1902 		/*
1903 		 * Allocate new space to hold the copy...
1904 		 */
1905 		/* XXX why can M_PKTHDR be set past the first mbuf? */
1906 		if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
1907 			/*
1908 			 * NB: if a packet header is present we must
1909 			 * allocate the mbuf separately from any cluster
1910 			 * because M_MOVE_PKTHDR will smash the data
1911 			 * pointer and drop the M_EXT marker.
1912 			 */
1913 			MGETHDR(n, how, m->m_type);
1914 			if (n == NULL) {
1915 				m_freem(m0);
1916 				return (NULL);
1917 			}
1918 			M_MOVE_PKTHDR(n, m);
1919 			MCLGET(n, how);
1920 			if ((n->m_flags & M_EXT) == 0) {
1921 				m_free(n);
1922 				m_freem(m0);
1923 				return (NULL);
1924 			}
1925 		} else {
1926 			n = m_getcl(how, m->m_type, m->m_flags);
1927 			if (n == NULL) {
1928 				m_freem(m0);
1929 				return (NULL);
1930 			}
1931 		}
1932 		/*
1933 		 * ... and copy the data.  We deal with jumbo mbufs
1934 		 * (i.e. m_len > MCLBYTES) by splitting them into
1935 		 * clusters.  We could just malloc a buffer and make
1936 		 * it external but too many device drivers don't know
1937 		 * how to break up the non-contiguous memory when
1938 		 * doing DMA.
1939 		 */
1940 		len = m->m_len;
1941 		off = 0;
1942 		mfirst = n;
1943 		mlast = NULL;
1944 		for (;;) {
1945 			int cc = min(len, MCLBYTES);
1946 			memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
1947 			n->m_len = cc;
1948 			if (mlast != NULL)
1949 				mlast->m_next = n;
1950 			mlast = n;
1951 #if 0
1952 			newipsecstat.ips_clcopied++;
1953 #endif
1954 
1955 			len -= cc;
1956 			if (len <= 0)
1957 				break;
1958 			off += cc;
1959 
1960 			n = m_getcl(how, m->m_type, m->m_flags);
1961 			if (n == NULL) {
1962 				m_freem(mfirst);
1963 				m_freem(m0);
1964 				return (NULL);
1965 			}
1966 		}
1967 		n->m_next = m->m_next;
1968 		if (mprev == NULL)
1969 			m0 = mfirst;		/* new head of chain */
1970 		else
1971 			mprev->m_next = mfirst;	/* replace old mbuf */
1972 		m_free(m);			/* release old mbuf */
1973 		mprev = mfirst;
1974 	}
1975 	return (m0);
1976 }
1977 
1978 #ifdef MBUF_PROFILING
1979 
1980 #define MP_BUCKETS 32 /* don't just change this as things may overflow.*/
1981 struct mbufprofile {
1982 	uintmax_t wasted[MP_BUCKETS];
1983 	uintmax_t used[MP_BUCKETS];
1984 	uintmax_t segments[MP_BUCKETS];
1985 } mbprof;
1986 
1987 #define MP_MAXDIGITS 21	/* strlen("16,000,000,000,000,000,000") == 21 */
1988 #define MP_NUMLINES 6
1989 #define MP_NUMSPERLINE 16
1990 #define MP_EXTRABYTES 64	/* > strlen("used:\nwasted:\nsegments:\n") */
1991 /* work out max space needed and add a bit of spare space too */
1992 #define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
1993 #define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
1994 
1995 char mbprofbuf[MP_BUFSIZE];
1996 
1997 void
1998 m_profile(struct mbuf *m)
1999 {
2000 	int segments = 0;
2001 	int used = 0;
2002 	int wasted = 0;
2003 
2004 	while (m) {
2005 		segments++;
2006 		used += m->m_len;
2007 		if (m->m_flags & M_EXT) {
2008 			wasted += MHLEN - sizeof(m->m_ext) +
2009 			    m->m_ext.ext_size - m->m_len;
2010 		} else {
2011 			if (m->m_flags & M_PKTHDR)
2012 				wasted += MHLEN - m->m_len;
2013 			else
2014 				wasted += MLEN - m->m_len;
2015 		}
2016 		m = m->m_next;
2017 	}
2018 	/* be paranoid.. it helps */
2019 	if (segments > MP_BUCKETS - 1)
2020 		segments = MP_BUCKETS - 1;
2021 	if (used > 100000)
2022 		used = 100000;
2023 	if (wasted > 100000)
2024 		wasted = 100000;
2025 	/* store in the appropriate bucket */
2026 	/* don't bother locking. if it's slightly off, so what? */
2027 	mbprof.segments[segments]++;
2028 	mbprof.used[fls(used)]++;
2029 	mbprof.wasted[fls(wasted)]++;
2030 }
2031 
2032 static void
2033 mbprof_textify(void)
2034 {
2035 	int offset;
2036 	char *c;
2037 	uint64_t *p;
2038 
2039 
2040 	p = &mbprof.wasted[0];
2041 	c = mbprofbuf;
2042 	offset = snprintf(c, MP_MAXLINE + 10,
2043 	    "wasted:\n"
2044 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2045 	    "%ju %ju %ju %ju %ju %ju %ju %ju\n",
2046 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2047 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2048 #ifdef BIG_ARRAY
2049 	p = &mbprof.wasted[16];
2050 	c += offset;
2051 	offset = snprintf(c, MP_MAXLINE,
2052 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2053 	    "%ju %ju %ju %ju %ju %ju %ju %ju\n",
2054 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2055 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2056 #endif
2057 	p = &mbprof.used[0];
2058 	c += offset;
2059 	offset = snprintf(c, MP_MAXLINE + 10,
2060 	    "used:\n"
2061 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2062 	    "%ju %ju %ju %ju %ju %ju %ju %ju\n",
2063 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2064 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2065 #ifdef BIG_ARRAY
2066 	p = &mbprof.used[16];
2067 	c += offset;
2068 	offset = snprintf(c, MP_MAXLINE,
2069 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2070 	    "%ju %ju %ju %ju %ju %ju %ju %ju\n",
2071 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2072 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2073 #endif
2074 	p = &mbprof.segments[0];
2075 	c += offset;
2076 	offset = snprintf(c, MP_MAXLINE + 10,
2077 	    "segments:\n"
2078 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2079 	    "%ju %ju %ju %ju %ju %ju %ju %ju\n",
2080 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2081 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2082 #ifdef BIG_ARRAY
2083 	p = &mbprof.segments[16];
2084 	c += offset;
2085 	offset = snprintf(c, MP_MAXLINE,
2086 	    "%ju %ju %ju %ju %ju %ju %ju %ju "
2087 	    "%ju %ju %ju %ju %ju %ju %ju %jju",
2088 	    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
2089 	    p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
2090 #endif
2091 }
2092 
2093 static int
2094 mbprof_handler(SYSCTL_HANDLER_ARGS)
2095 {
2096 	int error;
2097 
2098 	mbprof_textify();
2099 	error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
2100 	return (error);
2101 }
2102 
2103 static int
2104 mbprof_clr_handler(SYSCTL_HANDLER_ARGS)
2105 {
2106 	int clear, error;
2107 
2108 	clear = 0;
2109 	error = sysctl_handle_int(oidp, &clear, 0, req);
2110 	if (error || !req->newptr)
2111 		return (error);
2112 
2113 	if (clear) {
2114 		bzero(&mbprof, sizeof(mbprof));
2115 	}
2116 
2117 	return (error);
2118 }
2119 
2120 
2121 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
2122 	    NULL, 0, mbprof_handler, "A", "mbuf profiling statistics");
2123 
2124 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW,
2125 	    NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics");
2126 #endif
2127 
2128