FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c
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 #include <sys/sdt.h>
51
52 SDT_PROBE_DEFINE5_XLATE(sdt, , , m__init,
53 "struct mbuf *", "mbufinfo_t *",
54 "uint32_t", "uint32_t",
55 "uint16_t", "uint16_t",
56 "uint32_t", "uint32_t",
57 "uint32_t", "uint32_t");
58
59 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__gethdr,
60 "uint32_t", "uint32_t",
61 "uint16_t", "uint16_t",
62 "struct mbuf *", "mbufinfo_t *");
63
64 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__get,
65 "uint32_t", "uint32_t",
66 "uint16_t", "uint16_t",
67 "struct mbuf *", "mbufinfo_t *");
68
69 SDT_PROBE_DEFINE4_XLATE(sdt, , , m__getcl,
70 "uint32_t", "uint32_t",
71 "uint16_t", "uint16_t",
72 "uint32_t", "uint32_t",
73 "struct mbuf *", "mbufinfo_t *");
74
75 SDT_PROBE_DEFINE5_XLATE(sdt, , , m__getjcl,
76 "uint32_t", "uint32_t",
77 "uint16_t", "uint16_t",
78 "uint32_t", "uint32_t",
79 "uint32_t", "uint32_t",
80 "struct mbuf *", "mbufinfo_t *");
81
82 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__clget,
83 "struct mbuf *", "mbufinfo_t *",
84 "uint32_t", "uint32_t",
85 "uint32_t", "uint32_t");
86
87 SDT_PROBE_DEFINE4_XLATE(sdt, , , m__cljget,
88 "struct mbuf *", "mbufinfo_t *",
89 "uint32_t", "uint32_t",
90 "uint32_t", "uint32_t",
91 "void*", "void*");
92
93 SDT_PROBE_DEFINE(sdt, , , m__cljset);
94
95 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__free,
96 "struct mbuf *", "mbufinfo_t *");
97
98 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__freem,
99 "struct mbuf *", "mbufinfo_t *");
100
101 #include <security/mac/mac_framework.h>
102
103 int max_linkhdr;
104 int max_protohdr;
105 int max_hdr;
106 int max_datalen;
107 #ifdef MBUF_STRESS_TEST
108 int m_defragpackets;
109 int m_defragbytes;
110 int m_defraguseless;
111 int m_defragfailure;
112 int m_defragrandomfailures;
113 #endif
114
115 /*
116 * sysctl(8) exported objects
117 */
118 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD,
119 &max_linkhdr, 0, "Size of largest link layer header");
120 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD,
121 &max_protohdr, 0, "Size of largest protocol layer header");
122 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD,
123 &max_hdr, 0, "Size of largest link plus protocol header");
124 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD,
125 &max_datalen, 0, "Minimum space left in mbuf after max_hdr");
126 #ifdef MBUF_STRESS_TEST
127 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
128 &m_defragpackets, 0, "");
129 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
130 &m_defragbytes, 0, "");
131 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
132 &m_defraguseless, 0, "");
133 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
134 &m_defragfailure, 0, "");
135 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
136 &m_defragrandomfailures, 0, "");
137 #endif
138
139 /*
140 * Ensure the correct size of various mbuf parameters. It could be off due
141 * to compiler-induced padding and alignment artifacts.
142 */
143 CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN);
144 CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN);
145
146 /*
147 * mbuf data storage should be 64-bit aligned regardless of architectural
148 * pointer size; check this is the case with and without a packet header.
149 */
150 CTASSERT(offsetof(struct mbuf, m_dat) % 8 == 0);
151 CTASSERT(offsetof(struct mbuf, m_pktdat) % 8 == 0);
152
153 /*
154 * While the specific values here don't matter too much (i.e., +/- a few
155 * words), we do want to ensure that changes to these values are carefully
156 * reasoned about and properly documented. This is especially the case as
157 * network-protocol and device-driver modules encode these layouts, and must
158 * be recompiled if the structures change. Check these values at compile time
159 * against the ones documented in comments in mbuf.h.
160 *
161 * NB: Possibly they should be documented there via #define's and not just
162 * comments.
163 */
164 #if defined(__LP64__)
165 CTASSERT(offsetof(struct mbuf, m_dat) == 32);
166 CTASSERT(sizeof(struct pkthdr) == 56);
167 CTASSERT(sizeof(struct m_ext) == 48);
168 #else
169 CTASSERT(offsetof(struct mbuf, m_dat) == 24);
170 CTASSERT(sizeof(struct pkthdr) == 48);
171 CTASSERT(sizeof(struct m_ext) == 28);
172 #endif
173
174 /*
175 * Assert that the queue(3) macros produce code of the same size as an old
176 * plain pointer does.
177 */
178 #ifdef INVARIANTS
179 static struct mbuf __used m_assertbuf;
180 CTASSERT(sizeof(m_assertbuf.m_slist) == sizeof(m_assertbuf.m_next));
181 CTASSERT(sizeof(m_assertbuf.m_stailq) == sizeof(m_assertbuf.m_next));
182 CTASSERT(sizeof(m_assertbuf.m_slistpkt) == sizeof(m_assertbuf.m_nextpkt));
183 CTASSERT(sizeof(m_assertbuf.m_stailqpkt) == sizeof(m_assertbuf.m_nextpkt));
184 #endif
185
186 /*
187 * Attach the cluster from *m to *n, set up m_ext in *n
188 * and bump the refcount of the cluster.
189 */
190 void
191 mb_dupcl(struct mbuf *n, struct mbuf *m)
192 {
193 volatile u_int *refcnt;
194
195 KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m));
196 KASSERT(!(n->m_flags & M_EXT), ("%s: M_EXT set on %p", __func__, n));
197
198 n->m_ext = m->m_ext;
199 n->m_flags |= M_EXT;
200 n->m_flags |= m->m_flags & M_RDONLY;
201
202 /* See if this is the mbuf that holds the embedded refcount. */
203 if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) {
204 refcnt = n->m_ext.ext_cnt = &m->m_ext.ext_count;
205 n->m_ext.ext_flags &= ~EXT_FLAG_EMBREF;
206 } else {
207 KASSERT(m->m_ext.ext_cnt != NULL,
208 ("%s: no refcounting pointer on %p", __func__, m));
209 refcnt = m->m_ext.ext_cnt;
210 }
211
212 if (*refcnt == 1)
213 *refcnt += 1;
214 else
215 atomic_add_int(refcnt, 1);
216 }
217
218 void
219 m_demote_pkthdr(struct mbuf *m)
220 {
221
222 M_ASSERTPKTHDR(m);
223
224 m_tag_delete_chain(m, NULL);
225 m->m_flags &= ~M_PKTHDR;
226 bzero(&m->m_pkthdr, sizeof(struct pkthdr));
227 }
228
229 /*
230 * Clean up mbuf (chain) from any tags and packet headers.
231 * If "all" is set then the first mbuf in the chain will be
232 * cleaned too.
233 */
234 void
235 m_demote(struct mbuf *m0, int all, int flags)
236 {
237 struct mbuf *m;
238
239 for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
240 KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt in m %p, m0 %p",
241 __func__, m, m0));
242 if (m->m_flags & M_PKTHDR)
243 m_demote_pkthdr(m);
244 m->m_flags = m->m_flags & (M_EXT | M_RDONLY | M_NOFREE | flags);
245 }
246 }
247
248 /*
249 * Sanity checks on mbuf (chain) for use in KASSERT() and general
250 * debugging.
251 * Returns 0 or panics when bad and 1 on all tests passed.
252 * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
253 * blow up later.
254 */
255 int
256 m_sanity(struct mbuf *m0, int sanitize)
257 {
258 struct mbuf *m;
259 caddr_t a, b;
260 int pktlen = 0;
261
262 #ifdef INVARIANTS
263 #define M_SANITY_ACTION(s) panic("mbuf %p: " s, m)
264 #else
265 #define M_SANITY_ACTION(s) printf("mbuf %p: " s, m)
266 #endif
267
268 for (m = m0; m != NULL; m = m->m_next) {
269 /*
270 * Basic pointer checks. If any of these fails then some
271 * unrelated kernel memory before or after us is trashed.
272 * No way to recover from that.
273 */
274 a = M_START(m);
275 b = a + M_SIZE(m);
276 if ((caddr_t)m->m_data < a)
277 M_SANITY_ACTION("m_data outside mbuf data range left");
278 if ((caddr_t)m->m_data > b)
279 M_SANITY_ACTION("m_data outside mbuf data range right");
280 if ((caddr_t)m->m_data + m->m_len > b)
281 M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
282
283 /* m->m_nextpkt may only be set on first mbuf in chain. */
284 if (m != m0 && m->m_nextpkt != NULL) {
285 if (sanitize) {
286 m_freem(m->m_nextpkt);
287 m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
288 } else
289 M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
290 }
291
292 /* packet length (not mbuf length!) calculation */
293 if (m0->m_flags & M_PKTHDR)
294 pktlen += m->m_len;
295
296 /* m_tags may only be attached to first mbuf in chain. */
297 if (m != m0 && m->m_flags & M_PKTHDR &&
298 !SLIST_EMPTY(&m->m_pkthdr.tags)) {
299 if (sanitize) {
300 m_tag_delete_chain(m, NULL);
301 /* put in 0xDEADC0DE perhaps? */
302 } else
303 M_SANITY_ACTION("m_tags on in-chain mbuf");
304 }
305
306 /* M_PKTHDR may only be set on first mbuf in chain */
307 if (m != m0 && m->m_flags & M_PKTHDR) {
308 if (sanitize) {
309 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
310 m->m_flags &= ~M_PKTHDR;
311 /* put in 0xDEADCODE and leave hdr flag in */
312 } else
313 M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
314 }
315 }
316 m = m0;
317 if (pktlen && pktlen != m->m_pkthdr.len) {
318 if (sanitize)
319 m->m_pkthdr.len = 0;
320 else
321 M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
322 }
323 return 1;
324
325 #undef M_SANITY_ACTION
326 }
327
328 /*
329 * Non-inlined part of m_init().
330 */
331 int
332 m_pkthdr_init(struct mbuf *m, int how)
333 {
334 #ifdef MAC
335 int error;
336 #endif
337 m->m_data = m->m_pktdat;
338 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
339 #ifdef MAC
340 /* If the label init fails, fail the alloc */
341 error = mac_mbuf_init(m, how);
342 if (error)
343 return (error);
344 #endif
345
346 return (0);
347 }
348
349 /*
350 * "Move" mbuf pkthdr from "from" to "to".
351 * "from" must have M_PKTHDR set, and "to" must be empty.
352 */
353 void
354 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
355 {
356
357 #if 0
358 /* see below for why these are not enabled */
359 M_ASSERTPKTHDR(to);
360 /* Note: with MAC, this may not be a good assertion. */
361 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
362 ("m_move_pkthdr: to has tags"));
363 #endif
364 #ifdef MAC
365 /*
366 * XXXMAC: It could be this should also occur for non-MAC?
367 */
368 if (to->m_flags & M_PKTHDR)
369 m_tag_delete_chain(to, NULL);
370 #endif
371 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
372 if ((to->m_flags & M_EXT) == 0)
373 to->m_data = to->m_pktdat;
374 to->m_pkthdr = from->m_pkthdr; /* especially tags */
375 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */
376 from->m_flags &= ~M_PKTHDR;
377 }
378
379 /*
380 * Duplicate "from"'s mbuf pkthdr in "to".
381 * "from" must have M_PKTHDR set, and "to" must be empty.
382 * In particular, this does a deep copy of the packet tags.
383 */
384 int
385 m_dup_pkthdr(struct mbuf *to, const struct mbuf *from, int how)
386 {
387
388 #if 0
389 /*
390 * The mbuf allocator only initializes the pkthdr
391 * when the mbuf is allocated with m_gethdr(). Many users
392 * (e.g. m_copy*, m_prepend) use m_get() and then
393 * smash the pkthdr as needed causing these
394 * assertions to trip. For now just disable them.
395 */
396 M_ASSERTPKTHDR(to);
397 /* Note: with MAC, this may not be a good assertion. */
398 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
399 #endif
400 MBUF_CHECKSLEEP(how);
401 #ifdef MAC
402 if (to->m_flags & M_PKTHDR)
403 m_tag_delete_chain(to, NULL);
404 #endif
405 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
406 if ((to->m_flags & M_EXT) == 0)
407 to->m_data = to->m_pktdat;
408 to->m_pkthdr = from->m_pkthdr;
409 SLIST_INIT(&to->m_pkthdr.tags);
410 return (m_tag_copy_chain(to, from, how));
411 }
412
413 /*
414 * Lesser-used path for M_PREPEND:
415 * allocate new mbuf to prepend to chain,
416 * copy junk along.
417 */
418 struct mbuf *
419 m_prepend(struct mbuf *m, int len, int how)
420 {
421 struct mbuf *mn;
422
423 if (m->m_flags & M_PKTHDR)
424 mn = m_gethdr(how, m->m_type);
425 else
426 mn = m_get(how, m->m_type);
427 if (mn == NULL) {
428 m_freem(m);
429 return (NULL);
430 }
431 if (m->m_flags & M_PKTHDR)
432 m_move_pkthdr(mn, m);
433 mn->m_next = m;
434 m = mn;
435 if (len < M_SIZE(m))
436 M_ALIGN(m, len);
437 m->m_len = len;
438 return (m);
439 }
440
441 /*
442 * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
443 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf.
444 * The wait parameter is a choice of M_WAITOK/M_NOWAIT from caller.
445 * Note that the copy is read-only, because clusters are not copied,
446 * only their reference counts are incremented.
447 */
448 struct mbuf *
449 m_copym(struct mbuf *m, int off0, int len, int wait)
450 {
451 struct mbuf *n, **np;
452 int off = off0;
453 struct mbuf *top;
454 int copyhdr = 0;
455
456 KASSERT(off >= 0, ("m_copym, negative off %d", off));
457 KASSERT(len >= 0, ("m_copym, negative len %d", len));
458 MBUF_CHECKSLEEP(wait);
459 if (off == 0 && m->m_flags & M_PKTHDR)
460 copyhdr = 1;
461 while (off > 0) {
462 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
463 if (off < m->m_len)
464 break;
465 off -= m->m_len;
466 m = m->m_next;
467 }
468 np = ⊤
469 top = NULL;
470 while (len > 0) {
471 if (m == NULL) {
472 KASSERT(len == M_COPYALL,
473 ("m_copym, length > size of mbuf chain"));
474 break;
475 }
476 if (copyhdr)
477 n = m_gethdr(wait, m->m_type);
478 else
479 n = m_get(wait, m->m_type);
480 *np = n;
481 if (n == NULL)
482 goto nospace;
483 if (copyhdr) {
484 if (!m_dup_pkthdr(n, m, wait))
485 goto nospace;
486 if (len == M_COPYALL)
487 n->m_pkthdr.len -= off0;
488 else
489 n->m_pkthdr.len = len;
490 copyhdr = 0;
491 }
492 n->m_len = min(len, m->m_len - off);
493 if (m->m_flags & M_EXT) {
494 n->m_data = m->m_data + off;
495 mb_dupcl(n, m);
496 } else
497 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
498 (u_int)n->m_len);
499 if (len != M_COPYALL)
500 len -= n->m_len;
501 off = 0;
502 m = m->m_next;
503 np = &n->m_next;
504 }
505
506 return (top);
507 nospace:
508 m_freem(top);
509 return (NULL);
510 }
511
512 /*
513 * Copy an entire packet, including header (which must be present).
514 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
515 * Note that the copy is read-only, because clusters are not copied,
516 * only their reference counts are incremented.
517 * Preserve alignment of the first mbuf so if the creator has left
518 * some room at the beginning (e.g. for inserting protocol headers)
519 * the copies still have the room available.
520 */
521 struct mbuf *
522 m_copypacket(struct mbuf *m, int how)
523 {
524 struct mbuf *top, *n, *o;
525
526 MBUF_CHECKSLEEP(how);
527 n = m_get(how, m->m_type);
528 top = n;
529 if (n == NULL)
530 goto nospace;
531
532 if (!m_dup_pkthdr(n, m, how))
533 goto nospace;
534 n->m_len = m->m_len;
535 if (m->m_flags & M_EXT) {
536 n->m_data = m->m_data;
537 mb_dupcl(n, m);
538 } else {
539 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
540 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
541 }
542
543 m = m->m_next;
544 while (m) {
545 o = m_get(how, m->m_type);
546 if (o == NULL)
547 goto nospace;
548
549 n->m_next = o;
550 n = n->m_next;
551
552 n->m_len = m->m_len;
553 if (m->m_flags & M_EXT) {
554 n->m_data = m->m_data;
555 mb_dupcl(n, m);
556 } else {
557 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
558 }
559
560 m = m->m_next;
561 }
562 return top;
563 nospace:
564 m_freem(top);
565 return (NULL);
566 }
567
568 /*
569 * Copy data from an mbuf chain starting "off" bytes from the beginning,
570 * continuing for "len" bytes, into the indicated buffer.
571 */
572 void
573 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
574 {
575 u_int count;
576
577 KASSERT(off >= 0, ("m_copydata, negative off %d", off));
578 KASSERT(len >= 0, ("m_copydata, negative len %d", len));
579 while (off > 0) {
580 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
581 if (off < m->m_len)
582 break;
583 off -= m->m_len;
584 m = m->m_next;
585 }
586 while (len > 0) {
587 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
588 count = min(m->m_len - off, len);
589 bcopy(mtod(m, caddr_t) + off, cp, count);
590 len -= count;
591 cp += count;
592 off = 0;
593 m = m->m_next;
594 }
595 }
596
597 /*
598 * Copy a packet header mbuf chain into a completely new chain, including
599 * copying any mbuf clusters. Use this instead of m_copypacket() when
600 * you need a writable copy of an mbuf chain.
601 */
602 struct mbuf *
603 m_dup(const struct mbuf *m, int how)
604 {
605 struct mbuf **p, *top = NULL;
606 int remain, moff, nsize;
607
608 MBUF_CHECKSLEEP(how);
609 /* Sanity check */
610 if (m == NULL)
611 return (NULL);
612 M_ASSERTPKTHDR(m);
613
614 /* While there's more data, get a new mbuf, tack it on, and fill it */
615 remain = m->m_pkthdr.len;
616 moff = 0;
617 p = ⊤
618 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
619 struct mbuf *n;
620
621 /* Get the next new mbuf */
622 if (remain >= MINCLSIZE) {
623 n = m_getcl(how, m->m_type, 0);
624 nsize = MCLBYTES;
625 } else {
626 n = m_get(how, m->m_type);
627 nsize = MLEN;
628 }
629 if (n == NULL)
630 goto nospace;
631
632 if (top == NULL) { /* First one, must be PKTHDR */
633 if (!m_dup_pkthdr(n, m, how)) {
634 m_free(n);
635 goto nospace;
636 }
637 if ((n->m_flags & M_EXT) == 0)
638 nsize = MHLEN;
639 n->m_flags &= ~M_RDONLY;
640 }
641 n->m_len = 0;
642
643 /* Link it into the new chain */
644 *p = n;
645 p = &n->m_next;
646
647 /* Copy data from original mbuf(s) into new mbuf */
648 while (n->m_len < nsize && m != NULL) {
649 int chunk = min(nsize - n->m_len, m->m_len - moff);
650
651 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
652 moff += chunk;
653 n->m_len += chunk;
654 remain -= chunk;
655 if (moff == m->m_len) {
656 m = m->m_next;
657 moff = 0;
658 }
659 }
660
661 /* Check correct total mbuf length */
662 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
663 ("%s: bogus m_pkthdr.len", __func__));
664 }
665 return (top);
666
667 nospace:
668 m_freem(top);
669 return (NULL);
670 }
671
672 /*
673 * Concatenate mbuf chain n to m.
674 * Both chains must be of the same type (e.g. MT_DATA).
675 * Any m_pkthdr is not updated.
676 */
677 void
678 m_cat(struct mbuf *m, struct mbuf *n)
679 {
680 while (m->m_next)
681 m = m->m_next;
682 while (n) {
683 if (!M_WRITABLE(m) ||
684 M_TRAILINGSPACE(m) < n->m_len) {
685 /* just join the two chains */
686 m->m_next = n;
687 return;
688 }
689 /* splat the data from one into the other */
690 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
691 (u_int)n->m_len);
692 m->m_len += n->m_len;
693 n = m_free(n);
694 }
695 }
696
697 /*
698 * Concatenate two pkthdr mbuf chains.
699 */
700 void
701 m_catpkt(struct mbuf *m, struct mbuf *n)
702 {
703
704 M_ASSERTPKTHDR(m);
705 M_ASSERTPKTHDR(n);
706
707 m->m_pkthdr.len += n->m_pkthdr.len;
708 m_demote(n, 1, 0);
709
710 m_cat(m, n);
711 }
712
713 void
714 m_adj(struct mbuf *mp, int req_len)
715 {
716 int len = req_len;
717 struct mbuf *m;
718 int count;
719
720 if ((m = mp) == NULL)
721 return;
722 if (len >= 0) {
723 /*
724 * Trim from head.
725 */
726 while (m != NULL && len > 0) {
727 if (m->m_len <= len) {
728 len -= m->m_len;
729 m->m_len = 0;
730 m = m->m_next;
731 } else {
732 m->m_len -= len;
733 m->m_data += len;
734 len = 0;
735 }
736 }
737 if (mp->m_flags & M_PKTHDR)
738 mp->m_pkthdr.len -= (req_len - len);
739 } else {
740 /*
741 * Trim from tail. Scan the mbuf chain,
742 * calculating its length and finding the last mbuf.
743 * If the adjustment only affects this mbuf, then just
744 * adjust and return. Otherwise, rescan and truncate
745 * after the remaining size.
746 */
747 len = -len;
748 count = 0;
749 for (;;) {
750 count += m->m_len;
751 if (m->m_next == (struct mbuf *)0)
752 break;
753 m = m->m_next;
754 }
755 if (m->m_len >= len) {
756 m->m_len -= len;
757 if (mp->m_flags & M_PKTHDR)
758 mp->m_pkthdr.len -= len;
759 return;
760 }
761 count -= len;
762 if (count < 0)
763 count = 0;
764 /*
765 * Correct length for chain is "count".
766 * Find the mbuf with last data, adjust its length,
767 * and toss data from remaining mbufs on chain.
768 */
769 m = mp;
770 if (m->m_flags & M_PKTHDR)
771 m->m_pkthdr.len = count;
772 for (; m; m = m->m_next) {
773 if (m->m_len >= count) {
774 m->m_len = count;
775 if (m->m_next != NULL) {
776 m_freem(m->m_next);
777 m->m_next = NULL;
778 }
779 break;
780 }
781 count -= m->m_len;
782 }
783 }
784 }
785
786 /*
787 * Rearange an mbuf chain so that len bytes are contiguous
788 * and in the data area of an mbuf (so that mtod will work
789 * for a structure of size len). Returns the resulting
790 * mbuf chain on success, frees it and returns null on failure.
791 * If there is room, it will add up to max_protohdr-len extra bytes to the
792 * contiguous region in an attempt to avoid being called next time.
793 */
794 struct mbuf *
795 m_pullup(struct mbuf *n, int len)
796 {
797 struct mbuf *m;
798 int count;
799 int space;
800
801 /*
802 * If first mbuf has no cluster, and has room for len bytes
803 * without shifting current data, pullup into it,
804 * otherwise allocate a new mbuf to prepend to the chain.
805 */
806 if ((n->m_flags & M_EXT) == 0 &&
807 n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
808 if (n->m_len >= len)
809 return (n);
810 m = n;
811 n = n->m_next;
812 len -= m->m_len;
813 } else {
814 if (len > MHLEN)
815 goto bad;
816 m = m_get(M_NOWAIT, n->m_type);
817 if (m == NULL)
818 goto bad;
819 if (n->m_flags & M_PKTHDR)
820 m_move_pkthdr(m, n);
821 }
822 space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
823 do {
824 count = min(min(max(len, max_protohdr), space), n->m_len);
825 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
826 (u_int)count);
827 len -= count;
828 m->m_len += count;
829 n->m_len -= count;
830 space -= count;
831 if (n->m_len)
832 n->m_data += count;
833 else
834 n = m_free(n);
835 } while (len > 0 && n);
836 if (len > 0) {
837 (void) m_free(m);
838 goto bad;
839 }
840 m->m_next = n;
841 return (m);
842 bad:
843 m_freem(n);
844 return (NULL);
845 }
846
847 /*
848 * Like m_pullup(), except a new mbuf is always allocated, and we allow
849 * the amount of empty space before the data in the new mbuf to be specified
850 * (in the event that the caller expects to prepend later).
851 */
852 struct mbuf *
853 m_copyup(struct mbuf *n, int len, int dstoff)
854 {
855 struct mbuf *m;
856 int count, space;
857
858 if (len > (MHLEN - dstoff))
859 goto bad;
860 m = m_get(M_NOWAIT, n->m_type);
861 if (m == NULL)
862 goto bad;
863 if (n->m_flags & M_PKTHDR)
864 m_move_pkthdr(m, n);
865 m->m_data += dstoff;
866 space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
867 do {
868 count = min(min(max(len, max_protohdr), space), n->m_len);
869 memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
870 (unsigned)count);
871 len -= count;
872 m->m_len += count;
873 n->m_len -= count;
874 space -= count;
875 if (n->m_len)
876 n->m_data += count;
877 else
878 n = m_free(n);
879 } while (len > 0 && n);
880 if (len > 0) {
881 (void) m_free(m);
882 goto bad;
883 }
884 m->m_next = n;
885 return (m);
886 bad:
887 m_freem(n);
888 return (NULL);
889 }
890
891 /*
892 * Partition an mbuf chain in two pieces, returning the tail --
893 * all but the first len0 bytes. In case of failure, it returns NULL and
894 * attempts to restore the chain to its original state.
895 *
896 * Note that the resulting mbufs might be read-only, because the new
897 * mbuf can end up sharing an mbuf cluster with the original mbuf if
898 * the "breaking point" happens to lie within a cluster mbuf. Use the
899 * M_WRITABLE() macro to check for this case.
900 */
901 struct mbuf *
902 m_split(struct mbuf *m0, int len0, int wait)
903 {
904 struct mbuf *m, *n;
905 u_int len = len0, remain;
906
907 MBUF_CHECKSLEEP(wait);
908 for (m = m0; m && len > m->m_len; m = m->m_next)
909 len -= m->m_len;
910 if (m == NULL)
911 return (NULL);
912 remain = m->m_len - len;
913 if (m0->m_flags & M_PKTHDR && remain == 0) {
914 n = m_gethdr(wait, m0->m_type);
915 if (n == NULL)
916 return (NULL);
917 n->m_next = m->m_next;
918 m->m_next = NULL;
919 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
920 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
921 m0->m_pkthdr.len = len0;
922 return (n);
923 } else if (m0->m_flags & M_PKTHDR) {
924 n = m_gethdr(wait, m0->m_type);
925 if (n == NULL)
926 return (NULL);
927 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
928 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
929 m0->m_pkthdr.len = len0;
930 if (m->m_flags & M_EXT)
931 goto extpacket;
932 if (remain > MHLEN) {
933 /* m can't be the lead packet */
934 M_ALIGN(n, 0);
935 n->m_next = m_split(m, len, wait);
936 if (n->m_next == NULL) {
937 (void) m_free(n);
938 return (NULL);
939 } else {
940 n->m_len = 0;
941 return (n);
942 }
943 } else
944 M_ALIGN(n, remain);
945 } else if (remain == 0) {
946 n = m->m_next;
947 m->m_next = NULL;
948 return (n);
949 } else {
950 n = m_get(wait, m->m_type);
951 if (n == NULL)
952 return (NULL);
953 M_ALIGN(n, remain);
954 }
955 extpacket:
956 if (m->m_flags & M_EXT) {
957 n->m_data = m->m_data + len;
958 mb_dupcl(n, m);
959 } else {
960 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
961 }
962 n->m_len = remain;
963 m->m_len = len;
964 n->m_next = m->m_next;
965 m->m_next = NULL;
966 return (n);
967 }
968 /*
969 * Routine to copy from device local memory into mbufs.
970 * Note that `off' argument is offset into first mbuf of target chain from
971 * which to begin copying the data to.
972 */
973 struct mbuf *
974 m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
975 void (*copy)(char *from, caddr_t to, u_int len))
976 {
977 struct mbuf *m;
978 struct mbuf *top = NULL, **mp = ⊤
979 int len;
980
981 if (off < 0 || off > MHLEN)
982 return (NULL);
983
984 while (totlen > 0) {
985 if (top == NULL) { /* First one, must be PKTHDR */
986 if (totlen + off >= MINCLSIZE) {
987 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
988 len = MCLBYTES;
989 } else {
990 m = m_gethdr(M_NOWAIT, MT_DATA);
991 len = MHLEN;
992
993 /* Place initial small packet/header at end of mbuf */
994 if (m && totlen + off + max_linkhdr <= MHLEN) {
995 m->m_data += max_linkhdr;
996 len -= max_linkhdr;
997 }
998 }
999 if (m == NULL)
1000 return NULL;
1001 m->m_pkthdr.rcvif = ifp;
1002 m->m_pkthdr.len = totlen;
1003 } else {
1004 if (totlen + off >= MINCLSIZE) {
1005 m = m_getcl(M_NOWAIT, MT_DATA, 0);
1006 len = MCLBYTES;
1007 } else {
1008 m = m_get(M_NOWAIT, MT_DATA);
1009 len = MLEN;
1010 }
1011 if (m == NULL) {
1012 m_freem(top);
1013 return NULL;
1014 }
1015 }
1016 if (off) {
1017 m->m_data += off;
1018 len -= off;
1019 off = 0;
1020 }
1021 m->m_len = len = min(totlen, len);
1022 if (copy)
1023 copy(buf, mtod(m, caddr_t), (u_int)len);
1024 else
1025 bcopy(buf, mtod(m, caddr_t), (u_int)len);
1026 buf += len;
1027 *mp = m;
1028 mp = &m->m_next;
1029 totlen -= len;
1030 }
1031 return (top);
1032 }
1033
1034 /*
1035 * Copy data from a buffer back into the indicated mbuf chain,
1036 * starting "off" bytes from the beginning, extending the mbuf
1037 * chain if necessary.
1038 */
1039 void
1040 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
1041 {
1042 int mlen;
1043 struct mbuf *m = m0, *n;
1044 int totlen = 0;
1045
1046 if (m0 == NULL)
1047 return;
1048 while (off > (mlen = m->m_len)) {
1049 off -= mlen;
1050 totlen += mlen;
1051 if (m->m_next == NULL) {
1052 n = m_get(M_NOWAIT, m->m_type);
1053 if (n == NULL)
1054 goto out;
1055 bzero(mtod(n, caddr_t), MLEN);
1056 n->m_len = min(MLEN, len + off);
1057 m->m_next = n;
1058 }
1059 m = m->m_next;
1060 }
1061 while (len > 0) {
1062 if (m->m_next == NULL && (len > m->m_len - off)) {
1063 m->m_len += min(len - (m->m_len - off),
1064 M_TRAILINGSPACE(m));
1065 }
1066 mlen = min (m->m_len - off, len);
1067 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
1068 cp += mlen;
1069 len -= mlen;
1070 mlen += off;
1071 off = 0;
1072 totlen += mlen;
1073 if (len == 0)
1074 break;
1075 if (m->m_next == NULL) {
1076 n = m_get(M_NOWAIT, m->m_type);
1077 if (n == NULL)
1078 break;
1079 n->m_len = min(MLEN, len);
1080 m->m_next = n;
1081 }
1082 m = m->m_next;
1083 }
1084 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
1085 m->m_pkthdr.len = totlen;
1086 }
1087
1088 /*
1089 * Append the specified data to the indicated mbuf chain,
1090 * Extend the mbuf chain if the new data does not fit in
1091 * existing space.
1092 *
1093 * Return 1 if able to complete the job; otherwise 0.
1094 */
1095 int
1096 m_append(struct mbuf *m0, int len, c_caddr_t cp)
1097 {
1098 struct mbuf *m, *n;
1099 int remainder, space;
1100
1101 for (m = m0; m->m_next != NULL; m = m->m_next)
1102 ;
1103 remainder = len;
1104 space = M_TRAILINGSPACE(m);
1105 if (space > 0) {
1106 /*
1107 * Copy into available space.
1108 */
1109 if (space > remainder)
1110 space = remainder;
1111 bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
1112 m->m_len += space;
1113 cp += space, remainder -= space;
1114 }
1115 while (remainder > 0) {
1116 /*
1117 * Allocate a new mbuf; could check space
1118 * and allocate a cluster instead.
1119 */
1120 n = m_get(M_NOWAIT, m->m_type);
1121 if (n == NULL)
1122 break;
1123 n->m_len = min(MLEN, remainder);
1124 bcopy(cp, mtod(n, caddr_t), n->m_len);
1125 cp += n->m_len, remainder -= n->m_len;
1126 m->m_next = n;
1127 m = n;
1128 }
1129 if (m0->m_flags & M_PKTHDR)
1130 m0->m_pkthdr.len += len - remainder;
1131 return (remainder == 0);
1132 }
1133
1134 /*
1135 * Apply function f to the data in an mbuf chain starting "off" bytes from
1136 * the beginning, continuing for "len" bytes.
1137 */
1138 int
1139 m_apply(struct mbuf *m, int off, int len,
1140 int (*f)(void *, void *, u_int), void *arg)
1141 {
1142 u_int count;
1143 int rval;
1144
1145 KASSERT(off >= 0, ("m_apply, negative off %d", off));
1146 KASSERT(len >= 0, ("m_apply, negative len %d", len));
1147 while (off > 0) {
1148 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1149 if (off < m->m_len)
1150 break;
1151 off -= m->m_len;
1152 m = m->m_next;
1153 }
1154 while (len > 0) {
1155 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
1156 count = min(m->m_len - off, len);
1157 rval = (*f)(arg, mtod(m, caddr_t) + off, count);
1158 if (rval)
1159 return (rval);
1160 len -= count;
1161 off = 0;
1162 m = m->m_next;
1163 }
1164 return (0);
1165 }
1166
1167 /*
1168 * Return a pointer to mbuf/offset of location in mbuf chain.
1169 */
1170 struct mbuf *
1171 m_getptr(struct mbuf *m, int loc, int *off)
1172 {
1173
1174 while (loc >= 0) {
1175 /* Normal end of search. */
1176 if (m->m_len > loc) {
1177 *off = loc;
1178 return (m);
1179 } else {
1180 loc -= m->m_len;
1181 if (m->m_next == NULL) {
1182 if (loc == 0) {
1183 /* Point at the end of valid data. */
1184 *off = m->m_len;
1185 return (m);
1186 }
1187 return (NULL);
1188 }
1189 m = m->m_next;
1190 }
1191 }
1192 return (NULL);
1193 }
1194
1195 void
1196 m_print(const struct mbuf *m, int maxlen)
1197 {
1198 int len;
1199 int pdata;
1200 const struct mbuf *m2;
1201
1202 if (m == NULL) {
1203 printf("mbuf: %p\n", m);
1204 return;
1205 }
1206
1207 if (m->m_flags & M_PKTHDR)
1208 len = m->m_pkthdr.len;
1209 else
1210 len = -1;
1211 m2 = m;
1212 while (m2 != NULL && (len == -1 || len)) {
1213 pdata = m2->m_len;
1214 if (maxlen != -1 && pdata > maxlen)
1215 pdata = maxlen;
1216 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
1217 m2->m_next, m2->m_flags, "\2\20freelist\17skipfw"
1218 "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
1219 "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
1220 if (pdata)
1221 printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
1222 if (len != -1)
1223 len -= m2->m_len;
1224 m2 = m2->m_next;
1225 }
1226 if (len > 0)
1227 printf("%d bytes unaccounted for.\n", len);
1228 return;
1229 }
1230
1231 u_int
1232 m_fixhdr(struct mbuf *m0)
1233 {
1234 u_int len;
1235
1236 len = m_length(m0, NULL);
1237 m0->m_pkthdr.len = len;
1238 return (len);
1239 }
1240
1241 u_int
1242 m_length(struct mbuf *m0, struct mbuf **last)
1243 {
1244 struct mbuf *m;
1245 u_int len;
1246
1247 len = 0;
1248 for (m = m0; m != NULL; m = m->m_next) {
1249 len += m->m_len;
1250 if (m->m_next == NULL)
1251 break;
1252 }
1253 if (last != NULL)
1254 *last = m;
1255 return (len);
1256 }
1257
1258 /*
1259 * Defragment a mbuf chain, returning the shortest possible
1260 * chain of mbufs and clusters. If allocation fails and
1261 * this cannot be completed, NULL will be returned, but
1262 * the passed in chain will be unchanged. Upon success,
1263 * the original chain will be freed, and the new chain
1264 * will be returned.
1265 *
1266 * If a non-packet header is passed in, the original
1267 * mbuf (chain?) will be returned unharmed.
1268 */
1269 struct mbuf *
1270 m_defrag(struct mbuf *m0, int how)
1271 {
1272 struct mbuf *m_new = NULL, *m_final = NULL;
1273 int progress = 0, length;
1274
1275 MBUF_CHECKSLEEP(how);
1276 if (!(m0->m_flags & M_PKTHDR))
1277 return (m0);
1278
1279 m_fixhdr(m0); /* Needed sanity check */
1280
1281 #ifdef MBUF_STRESS_TEST
1282 if (m_defragrandomfailures) {
1283 int temp = arc4random() & 0xff;
1284 if (temp == 0xba)
1285 goto nospace;
1286 }
1287 #endif
1288
1289 if (m0->m_pkthdr.len > MHLEN)
1290 m_final = m_getcl(how, MT_DATA, M_PKTHDR);
1291 else
1292 m_final = m_gethdr(how, MT_DATA);
1293
1294 if (m_final == NULL)
1295 goto nospace;
1296
1297 if (m_dup_pkthdr(m_final, m0, how) == 0)
1298 goto nospace;
1299
1300 m_new = m_final;
1301
1302 while (progress < m0->m_pkthdr.len) {
1303 length = m0->m_pkthdr.len - progress;
1304 if (length > MCLBYTES)
1305 length = MCLBYTES;
1306
1307 if (m_new == NULL) {
1308 if (length > MLEN)
1309 m_new = m_getcl(how, MT_DATA, 0);
1310 else
1311 m_new = m_get(how, MT_DATA);
1312 if (m_new == NULL)
1313 goto nospace;
1314 }
1315
1316 m_copydata(m0, progress, length, mtod(m_new, caddr_t));
1317 progress += length;
1318 m_new->m_len = length;
1319 if (m_new != m_final)
1320 m_cat(m_final, m_new);
1321 m_new = NULL;
1322 }
1323 #ifdef MBUF_STRESS_TEST
1324 if (m0->m_next == NULL)
1325 m_defraguseless++;
1326 #endif
1327 m_freem(m0);
1328 m0 = m_final;
1329 #ifdef MBUF_STRESS_TEST
1330 m_defragpackets++;
1331 m_defragbytes += m0->m_pkthdr.len;
1332 #endif
1333 return (m0);
1334 nospace:
1335 #ifdef MBUF_STRESS_TEST
1336 m_defragfailure++;
1337 #endif
1338 if (m_final)
1339 m_freem(m_final);
1340 return (NULL);
1341 }
1342
1343 /*
1344 * Defragment an mbuf chain, returning at most maxfrags separate
1345 * mbufs+clusters. If this is not possible NULL is returned and
1346 * the original mbuf chain is left in it's present (potentially
1347 * modified) state. We use two techniques: collapsing consecutive
1348 * mbufs and replacing consecutive mbufs by a cluster.
1349 *
1350 * NB: this should really be named m_defrag but that name is taken
1351 */
1352 struct mbuf *
1353 m_collapse(struct mbuf *m0, int how, int maxfrags)
1354 {
1355 struct mbuf *m, *n, *n2, **prev;
1356 u_int curfrags;
1357
1358 /*
1359 * Calculate the current number of frags.
1360 */
1361 curfrags = 0;
1362 for (m = m0; m != NULL; m = m->m_next)
1363 curfrags++;
1364 /*
1365 * First, try to collapse mbufs. Note that we always collapse
1366 * towards the front so we don't need to deal with moving the
1367 * pkthdr. This may be suboptimal if the first mbuf has much
1368 * less data than the following.
1369 */
1370 m = m0;
1371 again:
1372 for (;;) {
1373 n = m->m_next;
1374 if (n == NULL)
1375 break;
1376 if (M_WRITABLE(m) &&
1377 n->m_len < M_TRAILINGSPACE(m)) {
1378 bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
1379 n->m_len);
1380 m->m_len += n->m_len;
1381 m->m_next = n->m_next;
1382 m_free(n);
1383 if (--curfrags <= maxfrags)
1384 return m0;
1385 } else
1386 m = n;
1387 }
1388 KASSERT(maxfrags > 1,
1389 ("maxfrags %u, but normal collapse failed", maxfrags));
1390 /*
1391 * Collapse consecutive mbufs to a cluster.
1392 */
1393 prev = &m0->m_next; /* NB: not the first mbuf */
1394 while ((n = *prev) != NULL) {
1395 if ((n2 = n->m_next) != NULL &&
1396 n->m_len + n2->m_len < MCLBYTES) {
1397 m = m_getcl(how, MT_DATA, 0);
1398 if (m == NULL)
1399 goto bad;
1400 bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
1401 bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
1402 n2->m_len);
1403 m->m_len = n->m_len + n2->m_len;
1404 m->m_next = n2->m_next;
1405 *prev = m;
1406 m_free(n);
1407 m_free(n2);
1408 if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */
1409 return m0;
1410 /*
1411 * Still not there, try the normal collapse
1412 * again before we allocate another cluster.
1413 */
1414 goto again;
1415 }
1416 prev = &n->m_next;
1417 }
1418 /*
1419 * No place where we can collapse to a cluster; punt.
1420 * This can occur if, for example, you request 2 frags
1421 * but the packet requires that both be clusters (we
1422 * never reallocate the first mbuf to avoid moving the
1423 * packet header).
1424 */
1425 bad:
1426 return NULL;
1427 }
1428
1429 #ifdef MBUF_STRESS_TEST
1430
1431 /*
1432 * Fragment an mbuf chain. There's no reason you'd ever want to do
1433 * this in normal usage, but it's great for stress testing various
1434 * mbuf consumers.
1435 *
1436 * If fragmentation is not possible, the original chain will be
1437 * returned.
1438 *
1439 * Possible length values:
1440 * 0 no fragmentation will occur
1441 * > 0 each fragment will be of the specified length
1442 * -1 each fragment will be the same random value in length
1443 * -2 each fragment's length will be entirely random
1444 * (Random values range from 1 to 256)
1445 */
1446 struct mbuf *
1447 m_fragment(struct mbuf *m0, int how, int length)
1448 {
1449 struct mbuf *m_first, *m_last;
1450 int divisor = 255, progress = 0, fraglen;
1451
1452 if (!(m0->m_flags & M_PKTHDR))
1453 return (m0);
1454
1455 if (length == 0 || length < -2)
1456 return (m0);
1457 if (length > MCLBYTES)
1458 length = MCLBYTES;
1459 if (length < 0 && divisor > MCLBYTES)
1460 divisor = MCLBYTES;
1461 if (length == -1)
1462 length = 1 + (arc4random() % divisor);
1463 if (length > 0)
1464 fraglen = length;
1465
1466 m_fixhdr(m0); /* Needed sanity check */
1467
1468 m_first = m_getcl(how, MT_DATA, M_PKTHDR);
1469 if (m_first == NULL)
1470 goto nospace;
1471
1472 if (m_dup_pkthdr(m_first, m0, how) == 0)
1473 goto nospace;
1474
1475 m_last = m_first;
1476
1477 while (progress < m0->m_pkthdr.len) {
1478 if (length == -2)
1479 fraglen = 1 + (arc4random() % divisor);
1480 if (fraglen > m0->m_pkthdr.len - progress)
1481 fraglen = m0->m_pkthdr.len - progress;
1482
1483 if (progress != 0) {
1484 struct mbuf *m_new = m_getcl(how, MT_DATA, 0);
1485 if (m_new == NULL)
1486 goto nospace;
1487
1488 m_last->m_next = m_new;
1489 m_last = m_new;
1490 }
1491
1492 m_copydata(m0, progress, fraglen, mtod(m_last, caddr_t));
1493 progress += fraglen;
1494 m_last->m_len = fraglen;
1495 }
1496 m_freem(m0);
1497 m0 = m_first;
1498 return (m0);
1499 nospace:
1500 if (m_first)
1501 m_freem(m_first);
1502 /* Return the original chain on failure */
1503 return (m0);
1504 }
1505
1506 #endif
1507
1508 /*
1509 * Copy the contents of uio into a properly sized mbuf chain.
1510 */
1511 struct mbuf *
1512 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
1513 {
1514 struct mbuf *m, *mb;
1515 int error, length;
1516 ssize_t total;
1517 int progress = 0;
1518
1519 /*
1520 * len can be zero or an arbitrary large value bound by
1521 * the total data supplied by the uio.
1522 */
1523 if (len > 0)
1524 total = min(uio->uio_resid, len);
1525 else
1526 total = uio->uio_resid;
1527
1528 /*
1529 * The smallest unit returned by m_getm2() is a single mbuf
1530 * with pkthdr. We can't align past it.
1531 */
1532 if (align >= MHLEN)
1533 return (NULL);
1534
1535 /*
1536 * Give us the full allocation or nothing.
1537 * If len is zero return the smallest empty mbuf.
1538 */
1539 m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
1540 if (m == NULL)
1541 return (NULL);
1542 m->m_data += align;
1543
1544 /* Fill all mbufs with uio data and update header information. */
1545 for (mb = m; mb != NULL; mb = mb->m_next) {
1546 length = min(M_TRAILINGSPACE(mb), total - progress);
1547
1548 error = uiomove(mtod(mb, void *), length, uio);
1549 if (error) {
1550 m_freem(m);
1551 return (NULL);
1552 }
1553
1554 mb->m_len = length;
1555 progress += length;
1556 if (flags & M_PKTHDR)
1557 m->m_pkthdr.len += length;
1558 }
1559 KASSERT(progress == total, ("%s: progress != total", __func__));
1560
1561 return (m);
1562 }
1563
1564 /*
1565 * Copy an mbuf chain into a uio limited by len if set.
1566 */
1567 int
1568 m_mbuftouio(struct uio *uio, struct mbuf *m, int len)
1569 {
1570 int error, length, total;
1571 int progress = 0;
1572
1573 if (len > 0)
1574 total = min(uio->uio_resid, len);
1575 else
1576 total = uio->uio_resid;
1577
1578 /* Fill the uio with data from the mbufs. */
1579 for (; m != NULL; m = m->m_next) {
1580 length = min(m->m_len, total - progress);
1581
1582 error = uiomove(mtod(m, void *), length, uio);
1583 if (error)
1584 return (error);
1585
1586 progress += length;
1587 }
1588
1589 return (0);
1590 }
1591
1592 /*
1593 * Create a writable copy of the mbuf chain. While doing this
1594 * we compact the chain with a goal of producing a chain with
1595 * at most two mbufs. The second mbuf in this chain is likely
1596 * to be a cluster. The primary purpose of this work is to create
1597 * a writable packet for encryption, compression, etc. The
1598 * secondary goal is to linearize the data so the data can be
1599 * passed to crypto hardware in the most efficient manner possible.
1600 */
1601 struct mbuf *
1602 m_unshare(struct mbuf *m0, int how)
1603 {
1604 struct mbuf *m, *mprev;
1605 struct mbuf *n, *mfirst, *mlast;
1606 int len, off;
1607
1608 mprev = NULL;
1609 for (m = m0; m != NULL; m = mprev->m_next) {
1610 /*
1611 * Regular mbufs are ignored unless there's a cluster
1612 * in front of it that we can use to coalesce. We do
1613 * the latter mainly so later clusters can be coalesced
1614 * also w/o having to handle them specially (i.e. convert
1615 * mbuf+cluster -> cluster). This optimization is heavily
1616 * influenced by the assumption that we're running over
1617 * Ethernet where MCLBYTES is large enough that the max
1618 * packet size will permit lots of coalescing into a
1619 * single cluster. This in turn permits efficient
1620 * crypto operations, especially when using hardware.
1621 */
1622 if ((m->m_flags & M_EXT) == 0) {
1623 if (mprev && (mprev->m_flags & M_EXT) &&
1624 m->m_len <= M_TRAILINGSPACE(mprev)) {
1625 /* XXX: this ignores mbuf types */
1626 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1627 mtod(m, caddr_t), m->m_len);
1628 mprev->m_len += m->m_len;
1629 mprev->m_next = m->m_next; /* unlink from chain */
1630 m_free(m); /* reclaim mbuf */
1631 #if 0
1632 newipsecstat.ips_mbcoalesced++;
1633 #endif
1634 } else {
1635 mprev = m;
1636 }
1637 continue;
1638 }
1639 /*
1640 * Writable mbufs are left alone (for now).
1641 */
1642 if (M_WRITABLE(m)) {
1643 mprev = m;
1644 continue;
1645 }
1646
1647 /*
1648 * Not writable, replace with a copy or coalesce with
1649 * the previous mbuf if possible (since we have to copy
1650 * it anyway, we try to reduce the number of mbufs and
1651 * clusters so that future work is easier).
1652 */
1653 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
1654 /* NB: we only coalesce into a cluster or larger */
1655 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
1656 m->m_len <= M_TRAILINGSPACE(mprev)) {
1657 /* XXX: this ignores mbuf types */
1658 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
1659 mtod(m, caddr_t), m->m_len);
1660 mprev->m_len += m->m_len;
1661 mprev->m_next = m->m_next; /* unlink from chain */
1662 m_free(m); /* reclaim mbuf */
1663 #if 0
1664 newipsecstat.ips_clcoalesced++;
1665 #endif
1666 continue;
1667 }
1668
1669 /*
1670 * Allocate new space to hold the copy and copy the data.
1671 * We deal with jumbo mbufs (i.e. m_len > MCLBYTES) by
1672 * splitting them into clusters. We could just malloc a
1673 * buffer and make it external but too many device drivers
1674 * don't know how to break up the non-contiguous memory when
1675 * doing DMA.
1676 */
1677 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
1678 if (n == NULL) {
1679 m_freem(m0);
1680 return (NULL);
1681 }
1682 if (m->m_flags & M_PKTHDR) {
1683 KASSERT(mprev == NULL, ("%s: m0 %p, m %p has M_PKTHDR",
1684 __func__, m0, m));
1685 m_move_pkthdr(n, m);
1686 }
1687 len = m->m_len;
1688 off = 0;
1689 mfirst = n;
1690 mlast = NULL;
1691 for (;;) {
1692 int cc = min(len, MCLBYTES);
1693 memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
1694 n->m_len = cc;
1695 if (mlast != NULL)
1696 mlast->m_next = n;
1697 mlast = n;
1698 #if 0
1699 newipsecstat.ips_clcopied++;
1700 #endif
1701
1702 len -= cc;
1703 if (len <= 0)
1704 break;
1705 off += cc;
1706
1707 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS);
1708 if (n == NULL) {
1709 m_freem(mfirst);
1710 m_freem(m0);
1711 return (NULL);
1712 }
1713 }
1714 n->m_next = m->m_next;
1715 if (mprev == NULL)
1716 m0 = mfirst; /* new head of chain */
1717 else
1718 mprev->m_next = mfirst; /* replace old mbuf */
1719 m_free(m); /* release old mbuf */
1720 mprev = mfirst;
1721 }
1722 return (m0);
1723 }
1724
1725 #ifdef MBUF_PROFILING
1726
1727 #define MP_BUCKETS 32 /* don't just change this as things may overflow.*/
1728 struct mbufprofile {
1729 uintmax_t wasted[MP_BUCKETS];
1730 uintmax_t used[MP_BUCKETS];
1731 uintmax_t segments[MP_BUCKETS];
1732 } mbprof;
1733
1734 #define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */
1735 #define MP_NUMLINES 6
1736 #define MP_NUMSPERLINE 16
1737 #define MP_EXTRABYTES 64 /* > strlen("used:\nwasted:\nsegments:\n") */
1738 /* work out max space needed and add a bit of spare space too */
1739 #define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
1740 #define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
1741
1742 char mbprofbuf[MP_BUFSIZE];
1743
1744 void
1745 m_profile(struct mbuf *m)
1746 {
1747 int segments = 0;
1748 int used = 0;
1749 int wasted = 0;
1750
1751 while (m) {
1752 segments++;
1753 used += m->m_len;
1754 if (m->m_flags & M_EXT) {
1755 wasted += MHLEN - sizeof(m->m_ext) +
1756 m->m_ext.ext_size - m->m_len;
1757 } else {
1758 if (m->m_flags & M_PKTHDR)
1759 wasted += MHLEN - m->m_len;
1760 else
1761 wasted += MLEN - m->m_len;
1762 }
1763 m = m->m_next;
1764 }
1765 /* be paranoid.. it helps */
1766 if (segments > MP_BUCKETS - 1)
1767 segments = MP_BUCKETS - 1;
1768 if (used > 100000)
1769 used = 100000;
1770 if (wasted > 100000)
1771 wasted = 100000;
1772 /* store in the appropriate bucket */
1773 /* don't bother locking. if it's slightly off, so what? */
1774 mbprof.segments[segments]++;
1775 mbprof.used[fls(used)]++;
1776 mbprof.wasted[fls(wasted)]++;
1777 }
1778
1779 static void
1780 mbprof_textify(void)
1781 {
1782 int offset;
1783 char *c;
1784 uint64_t *p;
1785
1786 p = &mbprof.wasted[0];
1787 c = mbprofbuf;
1788 offset = snprintf(c, MP_MAXLINE + 10,
1789 "wasted:\n"
1790 "%ju %ju %ju %ju %ju %ju %ju %ju "
1791 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1792 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1793 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1794 #ifdef BIG_ARRAY
1795 p = &mbprof.wasted[16];
1796 c += offset;
1797 offset = snprintf(c, MP_MAXLINE,
1798 "%ju %ju %ju %ju %ju %ju %ju %ju "
1799 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1800 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1801 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1802 #endif
1803 p = &mbprof.used[0];
1804 c += offset;
1805 offset = snprintf(c, MP_MAXLINE + 10,
1806 "used:\n"
1807 "%ju %ju %ju %ju %ju %ju %ju %ju "
1808 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1809 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1810 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1811 #ifdef BIG_ARRAY
1812 p = &mbprof.used[16];
1813 c += offset;
1814 offset = snprintf(c, MP_MAXLINE,
1815 "%ju %ju %ju %ju %ju %ju %ju %ju "
1816 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1817 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1818 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1819 #endif
1820 p = &mbprof.segments[0];
1821 c += offset;
1822 offset = snprintf(c, MP_MAXLINE + 10,
1823 "segments:\n"
1824 "%ju %ju %ju %ju %ju %ju %ju %ju "
1825 "%ju %ju %ju %ju %ju %ju %ju %ju\n",
1826 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1827 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1828 #ifdef BIG_ARRAY
1829 p = &mbprof.segments[16];
1830 c += offset;
1831 offset = snprintf(c, MP_MAXLINE,
1832 "%ju %ju %ju %ju %ju %ju %ju %ju "
1833 "%ju %ju %ju %ju %ju %ju %ju %jju",
1834 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
1835 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
1836 #endif
1837 }
1838
1839 static int
1840 mbprof_handler(SYSCTL_HANDLER_ARGS)
1841 {
1842 int error;
1843
1844 mbprof_textify();
1845 error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
1846 return (error);
1847 }
1848
1849 static int
1850 mbprof_clr_handler(SYSCTL_HANDLER_ARGS)
1851 {
1852 int clear, error;
1853
1854 clear = 0;
1855 error = sysctl_handle_int(oidp, &clear, 0, req);
1856 if (error || !req->newptr)
1857 return (error);
1858
1859 if (clear) {
1860 bzero(&mbprof, sizeof(mbprof));
1861 }
1862
1863 return (error);
1864 }
1865
1866
1867 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
1868 NULL, 0, mbprof_handler, "A", "mbuf profiling statistics");
1869
1870 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW,
1871 NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics");
1872 #endif
1873
Cache object: 0ea41b878b10309f648a887d28284754
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