FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1988, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: releng/12.0/sys/kern/uipc_mbuf.c 334054 2018-05-22 15:54:25Z fabient $");
36
37 #include "opt_param.h"
38 #include "opt_mbuf_stress_test.h"
39 #include "opt_mbuf_profiling.h"
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
44 #include <sys/limits.h>
45 #include <sys/lock.h>
46 #include <sys/malloc.h>
47 #include <sys/mbuf.h>
48 #include <sys/sysctl.h>
49 #include <sys/domain.h>
50 #include <sys/protosw.h>
51 #include <sys/uio.h>
52 #include <sys/sdt.h>
53
54 SDT_PROBE_DEFINE5_XLATE(sdt, , , m__init,
55 "struct mbuf *", "mbufinfo_t *",
56 "uint32_t", "uint32_t",
57 "uint16_t", "uint16_t",
58 "uint32_t", "uint32_t",
59 "uint32_t", "uint32_t");
60
61 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__gethdr,
62 "uint32_t", "uint32_t",
63 "uint16_t", "uint16_t",
64 "struct mbuf *", "mbufinfo_t *");
65
66 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__get,
67 "uint32_t", "uint32_t",
68 "uint16_t", "uint16_t",
69 "struct mbuf *", "mbufinfo_t *");
70
71 SDT_PROBE_DEFINE4_XLATE(sdt, , , m__getcl,
72 "uint32_t", "uint32_t",
73 "uint16_t", "uint16_t",
74 "uint32_t", "uint32_t",
75 "struct mbuf *", "mbufinfo_t *");
76
77 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__clget,
78 "struct mbuf *", "mbufinfo_t *",
79 "uint32_t", "uint32_t",
80 "uint32_t", "uint32_t");
81
82 SDT_PROBE_DEFINE4_XLATE(sdt, , , m__cljget,
83 "struct mbuf *", "mbufinfo_t *",
84 "uint32_t", "uint32_t",
85 "uint32_t", "uint32_t",
86 "void*", "void*");
87
88 SDT_PROBE_DEFINE(sdt, , , m__cljset);
89
90 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__free,
91 "struct mbuf *", "mbufinfo_t *");
92
93 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__freem,
94 "struct mbuf *", "mbufinfo_t *");
95
96 #include <security/mac/mac_framework.h>
97
98 int max_linkhdr;
99 int max_protohdr;
100 int max_hdr;
101 int max_datalen;
102 #ifdef MBUF_STRESS_TEST
103 int m_defragpackets;
104 int m_defragbytes;
105 int m_defraguseless;
106 int m_defragfailure;
107 int m_defragrandomfailures;
108 #endif
109
110 /*
111 * sysctl(8) exported objects
112 */
113 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD,
114 &max_linkhdr, 0, "Size of largest link layer header");
115 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD,
116 &max_protohdr, 0, "Size of largest protocol layer header");
117 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD,
118 &max_hdr, 0, "Size of largest link plus protocol header");
119 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD,
120 &max_datalen, 0, "Minimum space left in mbuf after max_hdr");
121 #ifdef MBUF_STRESS_TEST
122 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
123 &m_defragpackets, 0, "");
124 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
125 &m_defragbytes, 0, "");
126 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
127 &m_defraguseless, 0, "");
128 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
129 &m_defragfailure, 0, "");
130 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
131 &m_defragrandomfailures, 0, "");
132 #endif
133
134 /*
135 * Ensure the correct size of various mbuf parameters. It could be off due
136 * to compiler-induced padding and alignment artifacts.
137 */
138 CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN);
139 CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN);
140
141 /*
142 * mbuf data storage should be 64-bit aligned regardless of architectural
143 * pointer size; check this is the case with and without a packet header.
144 */
145 CTASSERT(offsetof(struct mbuf, m_dat) % 8 == 0);
146 CTASSERT(offsetof(struct mbuf, m_pktdat) % 8 == 0);
147
148 /*
149 * While the specific values here don't matter too much (i.e., +/- a few
150 * words), we do want to ensure that changes to these values are carefully
151 * reasoned about and properly documented. This is especially the case as
152 * network-protocol and device-driver modules encode these layouts, and must
153 * be recompiled if the structures change. Check these values at compile time
154 * against the ones documented in comments in mbuf.h.
155 *
156 * NB: Possibly they should be documented there via #define's and not just
157 * comments.
158 */
159 #if defined(__LP64__)
160 CTASSERT(offsetof(struct mbuf, m_dat) == 32);
161 CTASSERT(sizeof(struct pkthdr) == 56);
162 CTASSERT(sizeof(struct m_ext) == 48);
163 #else
164 CTASSERT(offsetof(struct mbuf, m_dat) == 24);
165 CTASSERT(sizeof(struct pkthdr) == 48);
166 CTASSERT(sizeof(struct m_ext) == 28);
167 #endif
168
169 /*
170 * Assert that the queue(3) macros produce code of the same size as an old
171 * plain pointer does.
172 */
173 #ifdef INVARIANTS
174 static struct mbuf __used m_assertbuf;
175 CTASSERT(sizeof(m_assertbuf.m_slist) == sizeof(m_assertbuf.m_next));
176 CTASSERT(sizeof(m_assertbuf.m_stailq) == sizeof(m_assertbuf.m_next));
177 CTASSERT(sizeof(m_assertbuf.m_slistpkt) == sizeof(m_assertbuf.m_nextpkt));
178 CTASSERT(sizeof(m_assertbuf.m_stailqpkt) == sizeof(m_assertbuf.m_nextpkt));
179 #endif
180
181 /*
182 * Attach the cluster from *m to *n, set up m_ext in *n
183 * and bump the refcount of the cluster.
184 */
185 void
186 mb_dupcl(struct mbuf *n, struct mbuf *m)
187 {
188 volatile u_int *refcnt;
189
190 KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m));
191 KASSERT(!(n->m_flags & M_EXT), ("%s: M_EXT set on %p", __func__, n));
192
193 /*
194 * Cache access optimization. For most kinds of external
195 * storage we don't need full copy of m_ext, since the
196 * holder of the 'ext_count' is responsible to carry the
197 * free routine and its arguments. Exclusion is EXT_EXTREF,
198 * where 'ext_cnt' doesn't point into mbuf at all.
199 */
200 if (m->m_ext.ext_type == EXT_EXTREF)
201 bcopy(&m->m_ext, &n->m_ext, sizeof(struct m_ext));
202 else
203 bcopy(&m->m_ext, &n->m_ext, m_ext_copylen);
204 n->m_flags |= M_EXT;
205 n->m_flags |= m->m_flags & M_RDONLY;
206
207 /* See if this is the mbuf that holds the embedded refcount. */
208 if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
209 refcnt = n->m_ext.ext_cnt = &m->m_ext.ext_count;
210 n->m_ext.ext_flags &= ~EXT_FLAG_EMBREF;
211 } else {
212 KASSERT(m->m_ext.ext_cnt != NULL,
213 ("%s: no refcounting pointer on %p", __func__, m));
214 refcnt = m->m_ext.ext_cnt;
215 }
216
217 if (*refcnt == 1)
218 *refcnt += 1;
219 else
220 atomic_add_int(refcnt, 1);
221 }
222
223 void
224 m_demote_pkthdr(struct mbuf *m)
225 {
226
227 M_ASSERTPKTHDR(m);
228
229 m_tag_delete_chain(m, NULL);
230 m->m_flags &= ~M_PKTHDR;
231 bzero(&m->m_pkthdr, sizeof(struct pkthdr));
232 }
233
234 /*
235 * Clean up mbuf (chain) from any tags and packet headers.
236 * If "all" is set then the first mbuf in the chain will be
237 * cleaned too.
238 */
239 void
240 m_demote(struct mbuf *m0, int all, int flags)
241 {
242 struct mbuf *m;
243
244 for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
245 KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt in m %p, m0 %p",
246 __func__, m, m0));
247 if (m->m_flags & M_PKTHDR)
248 m_demote_pkthdr(m);
249 m->m_flags = m->m_flags & (M_EXT | M_RDONLY | M_NOFREE | flags);
250 }
251 }
252
253 /*
254 * Sanity checks on mbuf (chain) for use in KASSERT() and general
255 * debugging.
256 * Returns 0 or panics when bad and 1 on all tests passed.
257 * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
258 * blow up later.
259 */
260 int
261 m_sanity(struct mbuf *m0, int sanitize)
262 {
263 struct mbuf *m;
264 caddr_t a, b;
265 int pktlen = 0;
266
267 #ifdef INVARIANTS
268 #define M_SANITY_ACTION(s) panic("mbuf %p: " s, m)
269 #else
270 #define M_SANITY_ACTION(s) printf("mbuf %p: " s, m)
271 #endif
272
273 for (m = m0; m != NULL; m = m->m_next) {
274 /*
275 * Basic pointer checks. If any of these fails then some
276 * unrelated kernel memory before or after us is trashed.
277 * No way to recover from that.
278 */
279 a = M_START(m);
280 b = a + M_SIZE(m);
281 if ((caddr_t)m->m_data < a)
282 M_SANITY_ACTION("m_data outside mbuf data range left");
283 if ((caddr_t)m->m_data > b)
284 M_SANITY_ACTION("m_data outside mbuf data range right");
285 if ((caddr_t)m->m_data + m->m_len > b)
286 M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
287
288 /* m->m_nextpkt may only be set on first mbuf in chain. */
289 if (m != m0 && m->m_nextpkt != NULL) {
290 if (sanitize) {
291 m_freem(m->m_nextpkt);
292 m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
293 } else
294 M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
295 }
296
297 /* packet length (not mbuf length!) calculation */
298 if (m0->m_flags & M_PKTHDR)
299 pktlen += m->m_len;
300
301 /* m_tags may only be attached to first mbuf in chain. */
302 if (m != m0 && m->m_flags & M_PKTHDR &&
303 !SLIST_EMPTY(&m->m_pkthdr.tags)) {
304 if (sanitize) {
305 m_tag_delete_chain(m, NULL);
306 /* put in 0xDEADC0DE perhaps? */
307 } else
308 M_SANITY_ACTION("m_tags on in-chain mbuf");
309 }
310
311 /* M_PKTHDR may only be set on first mbuf in chain */
312 if (m != m0 && m->m_flags & M_PKTHDR) {
313 if (sanitize) {
314 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
315 m->m_flags &= ~M_PKTHDR;
316 /* put in 0xDEADCODE and leave hdr flag in */
317 } else
318 M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
319 }
320 }
321 m = m0;
322 if (pktlen && pktlen != m->m_pkthdr.len) {
323 if (sanitize)
324 m->m_pkthdr.len = 0;
325 else
326 M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
327 }
328 return 1;
329
330 #undef M_SANITY_ACTION
331 }
332
333 /*
334 * Non-inlined part of m_init().
335 */
336 int
337 m_pkthdr_init(struct mbuf *m, int how)
338 {
339 #ifdef MAC
340 int error;
341 #endif
342 m->m_data = m->m_pktdat;
343 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
344 #ifdef MAC
345 /* If the label init fails, fail the alloc */
346 error = mac_mbuf_init(m, how);
347 if (error)
348 return (error);
349 #endif
350
351 return (0);
352 }
353
354 /*
355 * "Move" mbuf pkthdr from "from" to "to".
356 * "from" must have M_PKTHDR set, and "to" must be empty.
357 */
358 void
359 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
360 {
361
362 #if 0
363 /* see below for why these are not enabled */
364 M_ASSERTPKTHDR(to);
365 /* Note: with MAC, this may not be a good assertion. */
366 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
367 ("m_move_pkthdr: to has tags"));
368 #endif
369 #ifdef MAC
370 /*
371 * XXXMAC: It could be this should also occur for non-MAC?
372 */
373 if (to->m_flags & M_PKTHDR)
374 m_tag_delete_chain(to, NULL);
375 #endif
376 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
377 if ((to->m_flags & M_EXT) == 0)
378 to->m_data = to->m_pktdat;
379 to->m_pkthdr = from->m_pkthdr; /* especially tags */
380 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */
381 from->m_flags &= ~M_PKTHDR;
382 }
383
384 /*
385 * Duplicate "from"'s mbuf pkthdr in "to".
386 * "from" must have M_PKTHDR set, and "to" must be empty.
387 * In particular, this does a deep copy of the packet tags.
388 */
389 int
390 m_dup_pkthdr(struct mbuf *to, const struct mbuf *from, int how)
391 {
392
393 #if 0
394 /*
395 * The mbuf allocator only initializes the pkthdr
396 * when the mbuf is allocated with m_gethdr(). Many users
397 * (e.g. m_copy*, m_prepend) use m_get() and then
398 * smash the pkthdr as needed causing these
399 * assertions to trip. For now just disable them.
400 */
401 M_ASSERTPKTHDR(to);
402 /* Note: with MAC, this may not be a good assertion. */
403 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
404 #endif
405 MBUF_CHECKSLEEP(how);
406 #ifdef MAC
407 if (to->m_flags & M_PKTHDR)
408 m_tag_delete_chain(to, NULL);
409 #endif
410 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
411 if ((to->m_flags & M_EXT) == 0)
412 to->m_data = to->m_pktdat;
413 to->m_pkthdr = from->m_pkthdr;
414 SLIST_INIT(&to->m_pkthdr.tags);
415 return (m_tag_copy_chain(to, from, how));
416 }
417
418 /*
419 * Lesser-used path for M_PREPEND:
420 * allocate new mbuf to prepend to chain,
421 * copy junk along.
422 */
423 struct mbuf *
424 m_prepend(struct mbuf *m, int len, int how)
425 {
426 struct mbuf *mn;
427
428 if (m->m_flags & M_PKTHDR)
429 mn = m_gethdr(how, m->m_type);
430 else
431 mn = m_get(how, m->m_type);
432 if (mn == NULL) {
433 m_freem(m);
434 return (NULL);
435 }
436 if (m->m_flags & M_PKTHDR)
437 m_move_pkthdr(mn, m);
438 mn->m_next = m;
439 m = mn;
440 if (len < M_SIZE(m))
441 M_ALIGN(m, len);
442 m->m_len = len;
443 return (m);
444 }
445
446 /*
447 * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
448 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf.
449 * The wait parameter is a choice of M_WAITOK/M_NOWAIT from caller.
450 * Note that the copy is read-only, because clusters are not copied,
451 * only their reference counts are incremented.
452 */
453 struct mbuf *
454 m_copym(struct mbuf *m, int off0, int len, int wait)
455 {
456 struct mbuf *n, **np;
457 int off = off0;
458 struct mbuf *top;
459 int copyhdr = 0;
460
461 KASSERT(off >= 0, ("m_copym, negative off %d", off));
462 KASSERT(len >= 0, ("m_copym, negative len %d", len));
463 MBUF_CHECKSLEEP(wait);
464 if (off == 0 && m->m_flags & M_PKTHDR)
465 copyhdr = 1;
466 while (off > 0) {
467 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
468 if (off < m->m_len)
469 break;
470 off -= m->m_len;
471 m = m->m_next;
472 }
473 np = ⊤
474 top = NULL;
475 while (len > 0) {
476 if (m == NULL) {
477 KASSERT(len == M_COPYALL,
478 ("m_copym, length > size of mbuf chain"));
479 break;
480 }
481 if (copyhdr)
482 n = m_gethdr(wait, m->m_type);
483 else
484 n = m_get(wait, m->m_type);
485 *np = n;
486 if (n == NULL)
487 goto nospace;
488 if (copyhdr) {
489 if (!m_dup_pkthdr(n, m, wait))
490 goto nospace;
491 if (len == M_COPYALL)
492 n->m_pkthdr.len -= off0;
493 else
494 n->m_pkthdr.len = len;
495 copyhdr = 0;
496 }
497 n->m_len = min(len, m->m_len - off);
498 if (m->m_flags & M_EXT) {
499 n->m_data = m->m_data + off;
500 mb_dupcl(n, m);
501 } else
502 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
503 (u_int)n->m_len);
504 if (len != M_COPYALL)
505 len -= n->m_len;
506 off = 0;
507 m = m->m_next;
508 np = &n->m_next;
509 }
510
511 return (top);
512 nospace:
513 m_freem(top);
514 return (NULL);
515 }
516
517 /*
518 * Copy an entire packet, including header (which must be present).
519 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
520 * Note that the copy is read-only, because clusters are not copied,
521 * only their reference counts are incremented.
522 * Preserve alignment of the first mbuf so if the creator has left
523 * some room at the beginning (e.g. for inserting protocol headers)
524 * the copies still have the room available.
525 */
526 struct mbuf *
527 m_copypacket(struct mbuf *m, int how)
528 {
529 struct mbuf *top, *n, *o;
530
531 MBUF_CHECKSLEEP(how);
532 n = m_get(how, m->m_type);
533 top = n;
534 if (n == NULL)
535 goto nospace;
536
537 if (!m_dup_pkthdr(n, m, how))
538 goto nospace;
539 n->m_len = m->m_len;
540 if (m->m_flags & M_EXT) {
541 n->m_data = m->m_data;
542 mb_dupcl(n, m);
543 } else {
544 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
545 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
546 }
547
548 m = m->m_next;
549 while (m) {
550 o = m_get(how, m->m_type);
551 if (o == NULL)
552 goto nospace;
553
554 n->m_next = o;
555 n = n->m_next;
556
557 n->m_len = m->m_len;
558 if (m->m_flags & M_EXT) {
559 n->m_data = m->m_data;
560 mb_dupcl(n, m);
561 } else {
562 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
563 }
564
565 m = m->m_next;
566 }
567 return top;
568 nospace:
569 m_freem(top);
570 return (NULL);
571 }
572
573 /*
574 * Copy data from an mbuf chain starting "off" bytes from the beginning,
575 * continuing for "len" bytes, into the indicated buffer.
576 */
577 void
578 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
579 {
580 u_int count;
581
582 KASSERT(off >= 0, ("m_copydata, negative off %d", off));
583 KASSERT(len >= 0, ("m_copydata, negative len %d", len));
584 while (off > 0) {
585 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
586 if (off < m->m_len)
587 break;
588 off -= m->m_len;
589 m = m->m_next;
590 }
591 while (len > 0) {
592 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
593 count = min(m->m_len - off, len);
594 bcopy(mtod(m, caddr_t) + off, cp, count);
595 len -= count;
596 cp += count;
597 off = 0;
598 m = m->m_next;
599 }
600 }
601
602 /*
603 * Copy a packet header mbuf chain into a completely new chain, including
604 * copying any mbuf clusters. Use this instead of m_copypacket() when
605 * you need a writable copy of an mbuf chain.
606 */
607 struct mbuf *
608 m_dup(const struct mbuf *m, int how)
609 {
610 struct mbuf **p, *top = NULL;
611 int remain, moff, nsize;
612
613 MBUF_CHECKSLEEP(how);
614 /* Sanity check */
615 if (m == NULL)
616 return (NULL);
617 M_ASSERTPKTHDR(m);
618
619 /* While there's more data, get a new mbuf, tack it on, and fill it */
620 remain = m->m_pkthdr.len;
621 moff = 0;
622 p = ⊤
623 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
624 struct mbuf *n;
625
626 /* Get the next new mbuf */
627 if (remain >= MINCLSIZE) {
628 n = m_getcl(how, m->m_type, 0);
629 nsize = MCLBYTES;
630 } else {
631 n = m_get(how, m->m_type);
632 nsize = MLEN;
633 }
634 if (n == NULL)
635 goto nospace;
636
637 if (top == NULL) { /* First one, must be PKTHDR */
638 if (!m_dup_pkthdr(n, m, how)) {
639 m_free(n);
640 goto nospace;
641 }
642 if ((n->m_flags & M_EXT) == 0)
643 nsize = MHLEN;
644 n->m_flags &= ~M_RDONLY;
645 }
646 n->m_len = 0;
647
648 /* Link it into the new chain */
649 *p = n;
650 p = &n->m_next;
651
652 /* Copy data from original mbuf(s) into new mbuf */
653 while (n->m_len < nsize && m != NULL) {
654 int chunk = min(nsize - n->m_len, m->m_len - moff);
655
656 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
657 moff += chunk;
658 n->m_len += chunk;
659 remain -= chunk;
660 if (moff == m->m_len) {
661 m = m->m_next;
662 moff = 0;
663 }
664 }
665
666 /* Check correct total mbuf length */
667 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
668 ("%s: bogus m_pkthdr.len", __func__));
669 }
670 return (top);
671
672 nospace:
673 m_freem(top);
674 return (NULL);
675 }
676
677 /*
678 * Concatenate mbuf chain n to m.
679 * Both chains must be of the same type (e.g. MT_DATA).
680 * Any m_pkthdr is not updated.
681 */
682 void
683 m_cat(struct mbuf *m, struct mbuf *n)
684 {
685 while (m->m_next)
686 m = m->m_next;
687 while (n) {
688 if (!M_WRITABLE(m) ||
689 M_TRAILINGSPACE(m) < n->m_len) {
690 /* just join the two chains */
691 m->m_next = n;
692 return;
693 }
694 /* splat the data from one into the other */
695 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
696 (u_int)n->m_len);
697 m->m_len += n->m_len;
698 n = m_free(n);
699 }
700 }
701
702 /*
703 * Concatenate two pkthdr mbuf chains.
704 */
705 void
706 m_catpkt(struct mbuf *m, struct mbuf *n)
707 {
708
709 M_ASSERTPKTHDR(m);
710 M_ASSERTPKTHDR(n);
711
712 m->m_pkthdr.len += n->m_pkthdr.len;
713 m_demote(n, 1, 0);
714
715 m_cat(m, n);
716 }
717
718 void
719 m_adj(struct mbuf *mp, int req_len)
720 {
721 int len = req_len;
722 struct mbuf *m;
723 int count;
724
725 if ((m = mp) == NULL)
726 return;
727 if (len >= 0) {
728 /*
729 * Trim from head.
730 */
731 while (m != NULL && len > 0) {
732 if (m->m_len <= len) {
733 len -= m->m_len;
734 m->m_len = 0;
735 m = m->m_next;
736 } else {
737 m->m_len -= len;
738 m->m_data += len;
739 len = 0;
740 }
741 }
742 if (mp->m_flags & M_PKTHDR)
743 mp->m_pkthdr.len -= (req_len - len);
744 } else {
745 /*
746 * Trim from tail. Scan the mbuf chain,
747 * calculating its length and finding the last mbuf.
748 * If the adjustment only affects this mbuf, then just
749 * adjust and return. Otherwise, rescan and truncate
750 * after the remaining size.
751 */
752 len = -len;
753 count = 0;
754 for (;;) {
755 count += m->m_len;
756 if (m->m_next == (struct mbuf *)0)
757 break;
758 m = m->m_next;
759 }
760 if (m->m_len >= len) {
761 m->m_len -= len;
762 if (mp->m_flags & M_PKTHDR)
763 mp->m_pkthdr.len -= len;
764 return;
765 }
766 count -= len;
767 if (count < 0)
768 count = 0;
769 /*
770 * Correct length for chain is "count".
771 * Find the mbuf with last data, adjust its length,
772 * and toss data from remaining mbufs on chain.
773 */
774 m = mp;
775 if (m->m_flags & M_PKTHDR)
776 m->m_pkthdr.len = count;
777 for (; m; m = m->m_next) {
778 if (m->m_len >= count) {
779 m->m_len = count;
780 if (m->m_next != NULL) {
781 m_freem(m->m_next);
782 m->m_next = NULL;
783 }
784 break;
785 }
786 count -= m->m_len;
787 }
788 }
789 }
790
791 /*
792 * Rearange an mbuf chain so that len bytes are contiguous
793 * and in the data area of an mbuf (so that mtod will work
794 * for a structure of size len). Returns the resulting
795 * mbuf chain on success, frees it and returns null on failure.
796 * If there is room, it will add up to max_protohdr-len extra bytes to the
797 * contiguous region in an attempt to avoid being called next time.
798 */
799 struct mbuf *
800 m_pullup(struct mbuf *n, int len)
801 {
802 struct mbuf *m;
803 int count;
804 int space;
805
806 /*
807 * If first mbuf has no cluster, and has room for len bytes
808 * without shifting current data, pullup into it,
809 * otherwise allocate a new mbuf to prepend to the chain.
810 */
811 if ((n->m_flags & M_EXT) == 0 &&
812 n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
813 if (n->m_len >= len)
814 return (n);
815 m = n;
816 n = n->m_next;
817 len -= m->m_len;
818 } else {
819 if (len > MHLEN)
820 goto bad;
821 m = m_get(M_NOWAIT, n->m_type);
822 if (m == NULL)
823 goto bad;
824 if (n->m_flags & M_PKTHDR)
825 m_move_pkthdr(m, n);
826 }
827 space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
828 do {
829 count = min(min(max(len, max_protohdr), space), n->m_len);
830 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
831 (u_int)count);
832 len -= count;
833 m->m_len += count;
834 n->m_len -= count;
835 space -= count;
836 if (n->m_len)
837 n->m_data += count;
838 else
839 n = m_free(n);
840 } while (len > 0 && n);
841 if (len > 0) {
842 (void) m_free(m);
843 goto bad;
844 }
845 m->m_next = n;
846 return (m);
847 bad:
848 m_freem(n);
849 return (NULL);
850 }
851
852 /*
853 * Like m_pullup(), except a new mbuf is always allocated, and we allow
854 * the amount of empty space before the data in the new mbuf to be specified
855 * (in the event that the caller expects to prepend later).
856 */
857 struct mbuf *
858 m_copyup(struct mbuf *n, int len, int dstoff)
859 {
860 struct mbuf *m;
861 int count, space;
862
863 if (len > (MHLEN - dstoff))
864 goto bad;
865 m = m_get(M_NOWAIT, n->m_type);
866 if (m == NULL)
867 goto bad;
868 if (n->m_flags & M_PKTHDR)
869 m_move_pkthdr(m, n);
870 m->m_data += dstoff;
871 space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
872 do {
873 count = min(min(max(len, max_protohdr), space), n->m_len);
874 memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
875 (unsigned)count);
876 len -= count;
877 m->m_len += count;
878 n->m_len -= count;
879 space -= count;
880 if (n->m_len)
881 n->m_data += count;
882 else
883 n = m_free(n);
884 } while (len > 0 && n);
885 if (len > 0) {
886 (void) m_free(m);
887 goto bad;
888 }
889 m->m_next = n;
890 return (m);
891 bad:
892 m_freem(n);
893 return (NULL);
894 }
895
896 /*
897 * Partition an mbuf chain in two pieces, returning the tail --
898 * all but the first len0 bytes. In case of failure, it returns NULL and
899 * attempts to restore the chain to its original state.
900 *
901 * Note that the resulting mbufs might be read-only, because the new
902 * mbuf can end up sharing an mbuf cluster with the original mbuf if
903 * the "breaking point" happens to lie within a cluster mbuf. Use the
904 * M_WRITABLE() macro to check for this case.
905 */
906 struct mbuf *
907 m_split(struct mbuf *m0, int len0, int wait)
908 {
909 struct mbuf *m, *n;
910 u_int len = len0, remain;
911
912 MBUF_CHECKSLEEP(wait);
913 for (m = m0; m && len > m->m_len; m = m->m_next)
914 len -= m->m_len;
915 if (m == NULL)
916 return (NULL);
917 remain = m->m_len - len;
918 if (m0->m_flags & M_PKTHDR && remain == 0) {
919 n = m_gethdr(wait, m0->m_type);
920 if (n == NULL)
921 return (NULL);
922 n->m_next = m->m_next;
923 m->m_next = NULL;
924 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
925 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
926 m0->m_pkthdr.len = len0;
927 return (n);
928 } else if (m0->m_flags & M_PKTHDR) {
929 n = m_gethdr(wait, m0->m_type);
930 if (n == NULL)
931 return (NULL);
932 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
933 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
934 m0->m_pkthdr.len = len0;
935 if (m->m_flags & M_EXT)
936 goto extpacket;
937 if (remain > MHLEN) {
938 /* m can't be the lead packet */
939 M_ALIGN(n, 0);
940 n->m_next = m_split(m, len, wait);
941 if (n->m_next == NULL) {
942 (void) m_free(n);
943 return (NULL);
944 } else {
945 n->m_len = 0;
946 return (n);
947 }
948 } else
949 M_ALIGN(n, remain);
950 } else if (remain == 0) {
951 n = m->m_next;
952 m->m_next = NULL;
953 return (n);
954 } else {
955 n = m_get(wait, m->m_type);
956 if (n == NULL)
957 return (NULL);
958 M_ALIGN(n, remain);
959 }
960 extpacket:
961 if (m->m_flags & M_EXT) {
962 n->m_data = m->m_data + len;
963 mb_dupcl(n, m);
964 } else {
965 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
966 }
967 n->m_len = remain;
968 m->m_len = len;
969 n->m_next = m->m_next;
970 m->m_next = NULL;
971 return (n);
972 }
973 /*
974 * Routine to copy from device local memory into mbufs.
975 * Note that `off' argument is offset into first mbuf of target chain from
976 * which to begin copying the data to.
977 */
978 struct mbuf *
979 m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
980 void (*copy)(char *from, caddr_t to, u_int len))
981 {
982 struct mbuf *m;
983 struct mbuf *top = NULL, **mp = ⊤
984 int len;
985
986 if (off < 0 || off > MHLEN)
987 return (NULL);
988
989 while (totlen > 0) {
990 if (top == NULL) { /* First one, must be PKTHDR */
991 if (totlen + off >= MINCLSIZE) {
992 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
993 len = MCLBYTES;
994 } else {
995 m = m_gethdr(M_NOWAIT, MT_DATA);
996 len = MHLEN;
997
998 /* Place initial small packet/header at end of mbuf */
999 if (m && totlen + off + max_linkhdr <= MHLEN) {
1000 m->m_data += max_linkhdr;
1001 len -= max_linkhdr;
1002 }
1003 }
1004 if (m == NULL)
1005 return NULL;
1006 m->m_pkthdr.rcvif = ifp;
1007 m->m_pkthdr.len = totlen;
1008 } else {
1009 if (totlen + off >= MINCLSIZE) {
1010 m = m_getcl(M_NOWAIT, MT_DATA, 0);
1011 len = MCLBYTES;
1012 } else {
1013 m = m_get(M_NOWAIT, MT_DATA);
1014 len = MLEN;
1015 }
1016 if (m == NULL) {
1017 m_freem(top);
1018 return NULL;
1019 }
1020 }
1021 if (off) {
1022 m->m_data += off;
1023 len -= off;
1024 off = 0;
1025 }
1026 m->m_len = len = min(totlen, len);
1027 if (copy)
1028 copy(buf, mtod(m, caddr_t), (u_int)len);
1029 else
1030 bcopy(buf, mtod(m, caddr_t), (u_int)len);
1031 buf += len;
1032 *mp = m;
1033 mp = &m->m_next;
1034 totlen -= len;
1035 }
1036 return (top);
1037 }
1038
1039 /*
1040 * Copy data from a buffer back into the indicated mbuf chain,
1041 * starting "off" bytes from the beginning, extending the mbuf
1042 * chain if necessary.
1043 */
1044 void
1045 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
1046 {
1047 int mlen;
1048 struct mbuf *m = m0, *n;
1049 int totlen = 0;
1050
1051 if (m0 == NULL)
1052 return;
1053 while (off > (mlen = m->m_len)) {
1054 off -= mlen;
1055 totlen += mlen;
1056 if (m->m_next == NULL) {
1057 n = m_get(M_NOWAIT, m->m_type);
1058 if (n == NULL)
1059 goto out;
1060 bzero(mtod(n, caddr_t), MLEN);
1061 n->m_len = min(MLEN, len + off);
1062 m->m_next = n;
1063 }
1064 m = m->m_next;
1065 }
1066 while (len > 0) {
1067 if (m->m_next == NULL && (len > m->m_len - off)) {
1068 m->m_len += min(len - (m->m_len - off),
1069 M_TRAILINGSPACE(m));
1070 }
1071 mlen = min (m->m_len - off, len);
1072 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
1073 cp += mlen;
1074 len -= mlen;
1075 mlen += off;
1076 off = 0;
1077 totlen += mlen;
1078 if (len == 0)
1079 break;
1080 if (m->m_next == NULL) {
1081 n = m_get(M_NOWAIT, m->m_type);
1082 if (n == NULL)
1083 break;
1084 n->m_len = min(MLEN, len);
1085 m->m_next = n;
1086 }
1087 m = m->m_next;
1088 }
1089 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
1090 m->m_pkthdr.len = totlen;
1091 }
1092
1093 /*
1094 * Append the specified data to the indicated mbuf chain,
1095 * Extend the mbuf chain if the new data does not fit in
1096 * existing space.
1097 *
1098 * Return 1 if able to complete the job; otherwise 0.
1099 */
1100 int
1101 m_append(struct mbuf *m0, int len, c_caddr_t cp)
1102 {
1103 struct mbuf *m, *n;
1104 int remainder, space;
1105
1106 for (m = m0; m->m_next != NULL; m = m->m_next)
1107 ;
1108 remainder = len;
1109 space = M_TRAILINGSPACE(m);
1110 if (space > 0) {
1111 /*
1112 * Copy into available space.
1113 */
1114 if (space > remainder)
1115 space = remainder;
1116 bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
1117 m->m_len += space;
1118 cp += space, remainder -= space;
1119 }
1120 while (remainder > 0) {
1121 /*
1122 * Allocate a new mbuf; could check space
1123 * and allocate a cluster instead.
1124 */
1125 n = m_get(M_NOWAIT, m->m_type);
1126 if (n == NULL)
1127 break;
1128 n->m_len = min(MLEN, remainder);
1129 bcopy(cp, mtod(n, caddr_t), n->m_len);
1130 cp += n->m_len, remainder -= n->m_len;
1131 m->m_next = n;
1132 m = n;
1133 }
1134 if (m0->m_flags & M_PKTHDR)
1135 m0->m_pkthdr.len += len - remainder;
1136 return (remainder == 0);
1137 }
1138
1139 /*
1140 * Apply function f to the data in an mbuf chain starting "off" bytes from
1141 * the beginning, continuing for "len" bytes.
1142 */
1143 int
1144 m_apply(struct mbuf *m, int off, int len,
1145 int (*f)(void *, void *, u_int), void *arg)
1146 {
1147 u_int count;
1148 int rval;
1149
1150 KASSERT(off >= 0, ("m_apply, negative off %d", off));
1151 KASSERT(len >= 0, ("m_apply, negative len %d", len));
1152 while (off > 0) {
1153 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1154 if (off < m->m_len)
1155 break;
1156 off -= m->m_len;
1157 m = m->m_next;
1158 }
1159 while (len > 0) {
1160 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1161 count = min(m->m_len - off, len);
1162 rval = (*f)(arg, mtod(m, caddr_t) + off, count);
1163 if (rval)
1164 return (rval);
1165 len -= count;
1166 off = 0;
1167 m = m->m_next;
1168 }
1169 return (0);
1170 }
1171
1172 /*
1173 * Return a pointer to mbuf/offset of location in mbuf chain.
1174 */
1175 struct mbuf *
1176 m_getptr(struct mbuf *m, int loc, int *off)
1177 {
1178
1179 while (loc >= 0) {
1180 /* Normal end of search. */
1181 if (m->m_len > loc) {
1182 *off = loc;
1183 return (m);
1184 } else {
1185 loc -= m->m_len;
1186 if (m->m_next == NULL) {
1187 if (loc == 0) {
1188 /* Point at the end of valid data. */
1189 *off = m->m_len;
1190 return (m);
1191 }
1192 return (NULL);
1193 }
1194 m = m->m_next;
1195 }
1196 }
1197 return (NULL);
1198 }
1199
1200 void
1201 m_print(const struct mbuf *m, int maxlen)
1202 {
1203 int len;
1204 int pdata;
1205 const struct mbuf *m2;
1206
1207 if (m == NULL) {
1208 printf("mbuf: %p\n", m);
1209 return;
1210 }
1211
1212 if (m->m_flags & M_PKTHDR)
1213 len = m->m_pkthdr.len;
1214 else
1215 len = -1;
1216 m2 = m;
1217 while (m2 != NULL && (len == -1 || len)) {
1218 pdata = m2->m_len;
1219 if (maxlen != -1 && pdata > maxlen)
1220 pdata = maxlen;
1221 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
1222 m2->m_next, m2->m_flags, "\2\20freelist\17skipfw"
1223 "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
1224 "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
1225 if (pdata)
1226 printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
1227 if (len != -1)
1228 len -= m2->m_len;
1229 m2 = m2->m_next;
1230 }
1231 if (len > 0)
1232 printf("%d bytes unaccounted for.\n", len);
1233 return;
1234 }
1235
1236 u_int
1237 m_fixhdr(struct mbuf *m0)
1238 {
1239 u_int len;
1240
1241 len = m_length(m0, NULL);
1242 m0->m_pkthdr.len = len;
1243 return (len);
1244 }
1245
1246 u_int
1247 m_length(struct mbuf *m0, struct mbuf **last)
1248 {
1249 struct mbuf *m;
1250 u_int len;
1251
1252 len = 0;
1253 for (m = m0; m != NULL; m = m->m_next) {
1254 len += m->m_len;
1255 if (m->m_next == NULL)
1256 break;
1257 }
1258 if (last != NULL)
1259 *last = m;
1260 return (len);
1261 }
1262
1263 /*
1264 * Defragment a mbuf chain, returning the shortest possible
1265 * chain of mbufs and clusters. If allocation fails and
1266 * this cannot be completed, NULL will be returned, but
1267 * the passed in chain will be unchanged. Upon success,
1268 * the original chain will be freed, and the new chain
1269 * will be returned.
1270 *
1271 * If a non-packet header is passed in, the original
1272 * mbuf (chain?) will be returned unharmed.
1273 */
1274 struct mbuf *
1275 m_defrag(struct mbuf *m0, int how)
1276 {
1277 struct mbuf *m_new = NULL, *m_final = NULL;
1278 int progress = 0, length;
1279
1280 MBUF_CHECKSLEEP(how);
1281 if (!(m0->m_flags & M_PKTHDR))
1282 return (m0);
1283
1284 m_fixhdr(m0); /* Needed sanity check */
1285
1286 #ifdef MBUF_STRESS_TEST
1287 if (m_defragrandomfailures) {
1288 int temp = arc4random() & 0xff;
1289 if (temp == 0xba)
1290 goto nospace;
1291 }
1292 #endif
1293
1294 if (m0->m_pkthdr.len > MHLEN)
1295 m_final = m_getcl(how, MT_DATA, M_PKTHDR);
1296 else
1297 m_final = m_gethdr(how, MT_DATA);
1298
1299 if (m_final == NULL)
1300 goto nospace;
1301
1302 if (m_dup_pkthdr(m_final, m0, how) == 0)
1303 goto nospace;
1304
1305 m_new = m_final;
1306
1307 while (progress < m0->m_pkthdr.len) {
1308 length = m0->m_pkthdr.len - progress;
1309 if (length > MCLBYTES)
1310 length = MCLBYTES;
1311
1312 if (m_new == NULL) {
1313 if (length > MLEN)
1314 m_new = m_getcl(how, MT_DATA, 0);
1315 else
1316 m_new = m_get(how, MT_DATA);
1317 if (m_new == NULL)
1318 goto nospace;
1319 }
1320
1321 m_copydata(m0, progress, length, mtod(m_new, caddr_t));
1322 progress += length;
1323 m_new->m_len = length;
1324 if (m_new != m_final)
1325 m_cat(m_final, m_new);
1326 m_new = NULL;
1327 }
1328 #ifdef MBUF_STRESS_TEST
1329 if (m0->m_next == NULL)
1330 m_defraguseless++;
1331 #endif
1332 m_freem(m0);
1333 m0 = m_final;
1334 #ifdef MBUF_STRESS_TEST
1335 m_defragpackets++;
1336 m_defragbytes += m0->m_pkthdr.len;
1337 #endif
1338 return (m0);
1339 nospace:
1340 #ifdef MBUF_STRESS_TEST
1341 m_defragfailure++;
1342 #endif
1343 if (m_final)
1344 m_freem(m_final);
1345 return (NULL);
1346 }
1347
1348 /*
1349 * Defragment an mbuf chain, returning at most maxfrags separate
1350 * mbufs+clusters. If this is not possible NULL is returned and
1351 * the original mbuf chain is left in its present (potentially
1352 * modified) state. We use two techniques: collapsing consecutive
1353 * mbufs and replacing consecutive mbufs by a cluster.
1354 *
1355 * NB: this should really be named m_defrag but that name is taken
1356 */
1357 struct mbuf *
1358 m_collapse(struct mbuf *m0, int how, int maxfrags)
1359 {
1360 struct mbuf *m, *n, *n2, **prev;
1361 u_int curfrags;
1362
1363 /*
1364 * Calculate the current number of frags.
1365 */
1366 curfrags = 0;
1367 for (m = m0; m != NULL; m = m->m_next)
1368 curfrags++;
1369 /*
1370 * First, try to collapse mbufs. Note that we always collapse
1371 * towards the front so we don't need to deal with moving the
1372 * pkthdr. This may be suboptimal if the first mbuf has much
1373 * less data than the following.
1374 */
1375 m = m0;
1376 again:
1377 for (;;) {
1378 n = m->m_next;
1379 if (n == NULL)
1380 break;
1381 if (M_WRITABLE(m) &&
1382 n->m_len < M_TRAILINGSPACE(m)) {
1383 bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
1384 n->m_len);
1385 m->m_len += n->m_len;
1386 m->m_next = n->m_next;
1387 m_free(n);
1388 if (--curfrags <= maxfrags)
1389 return m0;
1390 } else
1391 m = n;
1392 }
1393 KASSERT(maxfrags > 1,
1394 ("maxfrags %u, but normal collapse failed", maxfrags));
1395 /*
1396 * Collapse consecutive mbufs to a cluster.
1397 */
1398 prev = &m0->m_next; /* NB: not the first mbuf */
1399 while ((n = *prev) != NULL) {
1400 if ((n2 = n->m_next) != NULL &&
1401 n->m_len + n2->m_len < MCLBYTES) {
1402 m = m_getcl(how, MT_DATA, 0);
1403 if (m == NULL)
1404 goto bad;
1405 bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
1406 bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
1407 n2->m_len);
1408 m->m_len = n->m_len + n2->m_len;
1409 m->m_next = n2->m_next;
1410 *prev = m;
1411 m_free(n);
1412 m_free(n2);
1413 if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */
1414 return m0;
1415 /*
1416 * Still not there, try the normal collapse
1417 * again before we allocate another cluster.
1418 */
1419 goto again;
1420 }
1421 prev = &n->m_next;
1422 }
1423 /*
1424 * No place where we can collapse to a cluster; punt.
1425 * This can occur if, for example, you request 2 frags
1426 * but the packet requires that both be clusters (we
1427 * never reallocate the first mbuf to avoid moving the
1428 * packet header).
1429 */
1430 bad:
1431 return NULL;
1432 }
1433
1434 #ifdef MBUF_STRESS_TEST
1435
1436 /*
1437 * Fragment an mbuf chain. There's no reason you'd ever want to do
1438 * this in normal usage, but it's great for stress testing various
1439 * mbuf consumers.
1440 *
1441 * If fragmentation is not possible, the original chain will be
1442 * returned.
1443 *
1444 * Possible length values:
1445 * 0 no fragmentation will occur
1446 * > 0 each fragment will be of the specified length
1447 * -1 each fragment will be the same random value in length
1448 * -2 each fragment's length will be entirely random
1449 * (Random values range from 1 to 256)
1450 */
1451 struct mbuf *
1452 m_fragment(struct mbuf *m0, int how, int length)
1453 {
1454 struct mbuf *m_first, *m_last;
1455 int divisor = 255, progress = 0, fraglen;
1456
1457 if (!(m0->m_flags & M_PKTHDR))
1458 return (m0);
1459
1460 if (length == 0 || length < -2)
1461 return (m0);
1462 if (length > MCLBYTES)
1463 length = MCLBYTES;
1464 if (length < 0 && divisor > MCLBYTES)
1465 divisor = MCLBYTES;
1466 if (length == -1)
1467 length = 1 + (arc4random() % divisor);
1468 if (length > 0)
1469 fraglen = length;
1470
1471 m_fixhdr(m0); /* Needed sanity check */
1472
1473 m_first = m_getcl(how, MT_DATA, M_PKTHDR);
1474 if (m_first == NULL)
1475 goto nospace;
1476
1477 if (m_dup_pkthdr(m_first, m0, how) == 0)
1478 goto nospace;
1479
1480 m_last = m_first;
1481
1482 while (progress < m0->m_pkthdr.len) {
1483 if (length == -2)
1484 fraglen = 1 + (arc4random() % divisor);
1485 if (fraglen > m0->m_pkthdr.len - progress)
1486 fraglen = m0->m_pkthdr.len - progress;
1487
1488 if (progress != 0) {
1489 struct mbuf *m_new = m_getcl(how, MT_DATA, 0);
1490 if (m_new == NULL)
1491 goto nospace;
1492
1493 m_last->m_next = m_new;
1494 m_last = m_new;
1495 }
1496
1497 m_copydata(m0, progress, fraglen, mtod(m_last, caddr_t));
1498 progress += fraglen;
1499 m_last->m_len = fraglen;
1500 }
1501 m_freem(m0);
1502 m0 = m_first;
1503 return (m0);
1504 nospace:
1505 if (m_first)
1506 m_freem(m_first);
1507 /* Return the original chain on failure */
1508 return (m0);
1509 }
1510
1511 #endif
1512
1513 /*
1514 * Copy the contents of uio into a properly sized mbuf chain.
1515 */
1516 struct mbuf *
1517 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
1518 {
1519 struct mbuf *m, *mb;
1520 int error, length;
1521 ssize_t total;
1522 int progress = 0;
1523
1524 /*
1525 * len can be zero or an arbitrary large value bound by
1526 * the total data supplied by the uio.
1527 */
1528 if (len > 0)
1529 total = (uio->uio_resid < len) ? uio->uio_resid : len;
1530 else
1531 total = uio->uio_resid;
1532
1533 /*
1534 * The smallest unit returned by m_getm2() is a single mbuf
1535 * with pkthdr. We can't align past it.
1536 */
1537 if (align >= MHLEN)
1538 return (NULL);
1539
1540 /*
1541 * Give us the full allocation or nothing.
1542 * If len is zero return the smallest empty mbuf.
1543 */
1544 m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
1545 if (m == NULL)
1546 return (NULL);
1547 m->m_data += align;
1548
1549 /* Fill all mbufs with uio data and update header information. */
1550 for (mb = m; mb != NULL; mb = mb->m_next) {
1551 length = min(M_TRAILINGSPACE(mb), total - progress);
1552
1553 error = uiomove(mtod(mb, void *), length, uio);
1554 if (error) {
1555 m_freem(m);
1556 return (NULL);
1557 }
1558
1559 mb->m_len = length;
1560 progress += length;
1561 if (flags & M_PKTHDR)
1562 m->m_pkthdr.len += length;
1563 }
1564 KASSERT(progress == total, ("%s: progress != total", __func__));
1565
1566 return (m);
1567 }
1568
1569 /*
1570 * Copy an mbuf chain into a uio limited by len if set.
1571 */
1572 int
1573 m_mbuftouio(struct uio *uio, const struct mbuf *m, int len)
1574 {
1575 int error, length, total;
1576 int progress = 0;
1577
1578 if (len > 0)
1579 total = min(uio->uio_resid, len);
1580 else
1581 total = uio->uio_resid;
1582
1583 /* Fill the uio with data from the mbufs. */
1584 for (; m != NULL; m = m->m_next) {
1585 length = min(m->m_len, total - progress);
1586
1587 error = uiomove(mtod(m, void *), length, uio);
1588 if (error)
1589 return (error);
1590
1591 progress += length;
1592 }
1593
1594 return (0);
1595 }
1596
1597 /*
1598 * Create a writable copy of the mbuf chain. While doing this
1599 * we compact the chain with a goal of producing a chain with
1600 * at most two mbufs. The second mbuf in this chain is likely
1601 * to be a cluster. The primary purpose of this work is to create
1602 * a writable packet for encryption, compression, etc. The
1603 * secondary goal is to linearize the data so the data can be
1604 * passed to crypto hardware in the most efficient manner possible.
1605 */
1606 struct mbuf *
1607 m_unshare(struct mbuf *m0, int how)
1608 {
1609 struct mbuf *m, *mprev;
1610 struct mbuf *n, *mfirst, *mlast;
1611 int len, off;
1612
1613 mprev = NULL;
1614 for (m = m0; m != NULL; m = mprev->m_next) {
1615 /*
1616 * Regular mbufs are ignored unless there's a cluster
1617 * in front of it that we can use to coalesce. We do
1618 * the latter mainly so later clusters can be coalesced
1619 * also w/o having to handle them specially (i.e. convert
1620 * mbuf+cluster -> cluster). This optimization is heavily
1621 * influenced by the assumption that we're running over
1622 * Ethernet where MCLBYTES is large enough that the max
1623 * packet size will permit lots of coalescing into a
1624 * single cluster. This in turn permits efficient
1625 * crypto operations, especially when using hardware.
1626 */
1627 if ((m->m_flags & M_EXT) == 0) {
1628 if (mprev && (mprev->m_flags & M_EXT) &&
1629 m->m_len <= M_TRAILINGSPACE(mprev)) {
1630 /* XXX: this ignores mbuf types */
1631 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1632 mtod(m, caddr_t), m->m_len);
1633 mprev->m_len += m->m_len;
1634 mprev->m_next = m->m_next; /* unlink from chain */
1635 m_free(m); /* reclaim mbuf */
1636 } else {
1637 mprev = m;
1638 }
1639 continue;
1640 }
1641 /*
1642 * Writable mbufs are left alone (for now).
1643 */
1644 if (M_WRITABLE(m)) {
1645 mprev = m;
1646 continue;
1647 }
1648
1649 /*
1650 * Not writable, replace with a copy or coalesce with
1651 * the previous mbuf if possible (since we have to copy
1652 * it anyway, we try to reduce the number of mbufs and
1653 * clusters so that future work is easier).
1654 */
1655 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
1656 /* NB: we only coalesce into a cluster or larger */
1657 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
1658 m->m_len <= M_TRAILINGSPACE(mprev)) {
1659 /* XXX: this ignores mbuf types */
1660 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1661 mtod(m, caddr_t), m->m_len);
1662 mprev->m_len += m->m_len;
1663 mprev->m_next = m->m_next; /* unlink from chain */
1664 m_free(m); /* reclaim mbuf */
1665 continue;
1666 }
1667
1668 /*
1669 * Allocate new space to hold the copy and copy the data.
1670 * We deal with jumbo mbufs (i.e. m_len > MCLBYTES) by
1671 * splitting them into clusters. We could just malloc a
1672 * buffer and make it external but too many device drivers
1673 * don't know how to break up the non-contiguous memory when
1674 * doing DMA.
1675 */
1676 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
1677 if (n == NULL) {
1678 m_freem(m0);
1679 return (NULL);
1680 }
1681 if (m->m_flags & M_PKTHDR) {
1682 KASSERT(mprev == NULL, ("%s: m0 %p, m %p has M_PKTHDR",
1683 __func__, m0, m));
1684 m_move_pkthdr(n, m);
1685 }
1686 len = m->m_len;
1687 off = 0;
1688 mfirst = n;
1689 mlast = NULL;
1690 for (;;) {
1691 int cc = min(len, MCLBYTES);
1692 memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
1693 n->m_len = cc;
1694 if (mlast != NULL)
1695 mlast->m_next = n;
1696 mlast = n;
1697 #if 0
1698 newipsecstat.ips_clcopied++;
1699 #endif
1700
1701 len -= cc;
1702 if (len <= 0)
1703 break;
1704 off += cc;
1705
1706 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
1707 if (n == NULL) {
1708 m_freem(mfirst);
1709 m_freem(m0);
1710 return (NULL);
1711 }
1712 }
1713 n->m_next = m->m_next;
1714 if (mprev == NULL)
1715 m0 = mfirst; /* new head of chain */
1716 else
1717 mprev->m_next = mfirst; /* replace old mbuf */
1718 m_free(m); /* release old mbuf */
1719 mprev = mfirst;
1720 }
1721 return (m0);
1722 }
1723
1724 #ifdef MBUF_PROFILING
1725
1726 #define MP_BUCKETS 32 /* don't just change this as things may overflow.*/
1727 struct mbufprofile {
1728 uintmax_t wasted[MP_BUCKETS];
1729 uintmax_t used[MP_BUCKETS];
1730 uintmax_t segments[MP_BUCKETS];
1731 } mbprof;
1732
1733 #define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */
1734 #define MP_NUMLINES 6
1735 #define MP_NUMSPERLINE 16
1736 #define MP_EXTRABYTES 64 /* > strlen("used:\nwasted:\nsegments:\n") */
1737 /* work out max space needed and add a bit of spare space too */
1738 #define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
1739 #define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
1740
1741 char mbprofbuf[MP_BUFSIZE];
1742
1743 void
1744 m_profile(struct mbuf *m)
1745 {
1746 int segments = 0;
1747 int used = 0;
1748 int wasted = 0;
1749
1750 while (m) {
1751 segments++;
1752 used += m->m_len;
1753 if (m->m_flags & M_EXT) {
1754 wasted += MHLEN - sizeof(m->m_ext) +
1755 m->m_ext.ext_size - m->m_len;
1756 } else {
1757 if (m->m_flags & M_PKTHDR)
1758 wasted += MHLEN - m->m_len;
1759 else
1760 wasted += MLEN - m->m_len;
1761 }
1762 m = m->m_next;
1763 }
1764 /* be paranoid.. it helps */
1765 if (segments > MP_BUCKETS - 1)
1766 segments = MP_BUCKETS - 1;
1767 if (used > 100000)
1768 used = 100000;
1769 if (wasted > 100000)
1770 wasted = 100000;
1771 /* store in the appropriate bucket */
1772 /* don't bother locking. if it's slightly off, so what? */
1773 mbprof.segments[segments]++;
1774 mbprof.used[fls(used)]++;
1775 mbprof.wasted[fls(wasted)]++;
1776 }
1777
1778 static void
1779 mbprof_textify(void)
1780 {
1781 int offset;
1782 char *c;
1783 uint64_t *p;
1784
1785 p = &mbprof.wasted[0];
1786 c = mbprofbuf;
1787 offset = snprintf(c, MP_MAXLINE + 10,
1788 "wasted:\n"
1789 "%ju %ju %ju %ju %ju %ju %ju %ju "
1790 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1791 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1792 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1793 #ifdef BIG_ARRAY
1794 p = &mbprof.wasted[16];
1795 c += offset;
1796 offset = snprintf(c, MP_MAXLINE,
1797 "%ju %ju %ju %ju %ju %ju %ju %ju "
1798 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1799 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1800 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1801 #endif
1802 p = &mbprof.used[0];
1803 c += offset;
1804 offset = snprintf(c, MP_MAXLINE + 10,
1805 "used:\n"
1806 "%ju %ju %ju %ju %ju %ju %ju %ju "
1807 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1808 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1809 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1810 #ifdef BIG_ARRAY
1811 p = &mbprof.used[16];
1812 c += offset;
1813 offset = snprintf(c, MP_MAXLINE,
1814 "%ju %ju %ju %ju %ju %ju %ju %ju "
1815 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1816 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1817 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1818 #endif
1819 p = &mbprof.segments[0];
1820 c += offset;
1821 offset = snprintf(c, MP_MAXLINE + 10,
1822 "segments:\n"
1823 "%ju %ju %ju %ju %ju %ju %ju %ju "
1824 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1825 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1826 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1827 #ifdef BIG_ARRAY
1828 p = &mbprof.segments[16];
1829 c += offset;
1830 offset = snprintf(c, MP_MAXLINE,
1831 "%ju %ju %ju %ju %ju %ju %ju %ju "
1832 "%ju %ju %ju %ju %ju %ju %ju %jju",
1833 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1834 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1835 #endif
1836 }
1837
1838 static int
1839 mbprof_handler(SYSCTL_HANDLER_ARGS)
1840 {
1841 int error;
1842
1843 mbprof_textify();
1844 error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
1845 return (error);
1846 }
1847
1848 static int
1849 mbprof_clr_handler(SYSCTL_HANDLER_ARGS)
1850 {
1851 int clear, error;
1852
1853 clear = 0;
1854 error = sysctl_handle_int(oidp, &clear, 0, req);
1855 if (error || !req->newptr)
1856 return (error);
1857
1858 if (clear) {
1859 bzero(&mbprof, sizeof(mbprof));
1860 }
1861
1862 return (error);
1863 }
1864
1865
1866 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
1867 NULL, 0, mbprof_handler, "A", "mbuf profiling statistics");
1868
1869 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW,
1870 NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics");
1871 #endif
1872
Cache object: 1160e34c91fe4ec809cc64219bb74c21
|