Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c
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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("$FreeBSD$"); 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_DEFINE5_XLATE(sdt, , , m__getjcl, 78 "uint32_t", "uint32_t", 79 "uint16_t", "uint16_t", 80 "uint32_t", "uint32_t", 81 "uint32_t", "uint32_t", 82 "struct mbuf *", "mbufinfo_t *"); 83 84 SDT_PROBE_DEFINE3_XLATE(sdt, , , m__clget, 85 "struct mbuf *", "mbufinfo_t *", 86 "uint32_t", "uint32_t", 87 "uint32_t", "uint32_t"); 88 89 SDT_PROBE_DEFINE4_XLATE(sdt, , , m__cljget, 90 "struct mbuf *", "mbufinfo_t *", 91 "uint32_t", "uint32_t", 92 "uint32_t", "uint32_t", 93 "void*", "void*"); 94 95 SDT_PROBE_DEFINE(sdt, , , m__cljset); 96 97 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__free, 98 "struct mbuf *", "mbufinfo_t *"); 99 100 SDT_PROBE_DEFINE1_XLATE(sdt, , , m__freem, 101 "struct mbuf *", "mbufinfo_t *"); 102 103 #include <security/mac/mac_framework.h> 104 105 int max_linkhdr; 106 int max_protohdr; 107 int max_hdr; 108 int max_datalen; 109 #ifdef MBUF_STRESS_TEST 110 int m_defragpackets; 111 int m_defragbytes; 112 int m_defraguseless; 113 int m_defragfailure; 114 int m_defragrandomfailures; 115 #endif 116 117 /* 118 * sysctl(8) exported objects 119 */ 120 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD, 121 &max_linkhdr, 0, "Size of largest link layer header"); 122 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD, 123 &max_protohdr, 0, "Size of largest protocol layer header"); 124 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD, 125 &max_hdr, 0, "Size of largest link plus protocol header"); 126 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD, 127 &max_datalen, 0, "Minimum space left in mbuf after max_hdr"); 128 #ifdef MBUF_STRESS_TEST 129 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD, 130 &m_defragpackets, 0, ""); 131 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD, 132 &m_defragbytes, 0, ""); 133 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD, 134 &m_defraguseless, 0, ""); 135 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD, 136 &m_defragfailure, 0, ""); 137 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW, 138 &m_defragrandomfailures, 0, ""); 139 #endif 140 141 /* 142 * Ensure the correct size of various mbuf parameters. It could be off due 143 * to compiler-induced padding and alignment artifacts. 144 */ 145 CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN); 146 CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN); 147 148 /* 149 * mbuf data storage should be 64-bit aligned regardless of architectural 150 * pointer size; check this is the case with and without a packet header. 151 */ 152 CTASSERT(offsetof(struct mbuf, m_dat) % 8 == 0); 153 CTASSERT(offsetof(struct mbuf, m_pktdat) % 8 == 0); 154 155 /* 156 * While the specific values here don't matter too much (i.e., +/- a few 157 * words), we do want to ensure that changes to these values are carefully 158 * reasoned about and properly documented. This is especially the case as 159 * network-protocol and device-driver modules encode these layouts, and must 160 * be recompiled if the structures change. Check these values at compile time 161 * against the ones documented in comments in mbuf.h. 162 * 163 * NB: Possibly they should be documented there via #define's and not just 164 * comments. 165 */ 166 #if defined(__LP64__) 167 CTASSERT(offsetof(struct mbuf, m_dat) == 32); 168 CTASSERT(sizeof(struct pkthdr) == 56); 169 CTASSERT(sizeof(struct m_ext) == 48); 170 #else 171 CTASSERT(offsetof(struct mbuf, m_dat) == 24); 172 CTASSERT(sizeof(struct pkthdr) == 48); 173 CTASSERT(sizeof(struct m_ext) == 28); 174 #endif 175 176 /* 177 * Assert that the queue(3) macros produce code of the same size as an old 178 * plain pointer does. 179 */ 180 #ifdef INVARIANTS 181 static struct mbuf __used m_assertbuf; 182 CTASSERT(sizeof(m_assertbuf.m_slist) == sizeof(m_assertbuf.m_next)); 183 CTASSERT(sizeof(m_assertbuf.m_stailq) == sizeof(m_assertbuf.m_next)); 184 CTASSERT(sizeof(m_assertbuf.m_slistpkt) == sizeof(m_assertbuf.m_nextpkt)); 185 CTASSERT(sizeof(m_assertbuf.m_stailqpkt) == sizeof(m_assertbuf.m_nextpkt)); 186 #endif 187 188 /* 189 * Attach the cluster from *m to *n, set up m_ext in *n 190 * and bump the refcount of the cluster. 191 */ 192 void 193 mb_dupcl(struct mbuf *n, struct mbuf *m) 194 { 195 volatile u_int *refcnt; 196 197 KASSERT(m->m_flags & M_EXT, ("%s: M_EXT not set on %p", __func__, m)); 198 KASSERT(!(n->m_flags & M_EXT), ("%s: M_EXT set on %p", __func__, n)); 199 200 /* 201 * Cache access optimization. For most kinds of external 202 * storage we don't need full copy of m_ext, since the 203 * holder of the 'ext_count' is responsible to carry the 204 * free routine and its arguments. Exclusion is EXT_EXTREF, 205 * where 'ext_cnt' doesn't point into mbuf at all. 206 */ 207 if (m->m_ext.ext_type == EXT_EXTREF) 208 bcopy(&m->m_ext, &n->m_ext, sizeof(struct m_ext)); 209 else 210 bcopy(&m->m_ext, &n->m_ext, m_ext_copylen); 211 n->m_flags |= M_EXT; 212 n->m_flags |= m->m_flags & M_RDONLY; 213 214 /* See if this is the mbuf that holds the embedded refcount. */ 215 if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) { 216 refcnt = n->m_ext.ext_cnt = &m->m_ext.ext_count; 217 n->m_ext.ext_flags &= ~EXT_FLAG_EMBREF; 218 } else { 219 KASSERT(m->m_ext.ext_cnt != NULL, 220 ("%s: no refcounting pointer on %p", __func__, m)); 221 refcnt = m->m_ext.ext_cnt; 222 } 223 224 if (*refcnt == 1) 225 *refcnt += 1; 226 else 227 atomic_add_int(refcnt, 1); 228 } 229 230 void 231 m_demote_pkthdr(struct mbuf *m) 232 { 233 234 M_ASSERTPKTHDR(m); 235 236 m_tag_delete_chain(m, NULL); 237 m->m_flags &= ~M_PKTHDR; 238 bzero(&m->m_pkthdr, sizeof(struct pkthdr)); 239 } 240 241 /* 242 * Clean up mbuf (chain) from any tags and packet headers. 243 * If "all" is set then the first mbuf in the chain will be 244 * cleaned too. 245 */ 246 void 247 m_demote(struct mbuf *m0, int all, int flags) 248 { 249 struct mbuf *m; 250 251 for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) { 252 KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt in m %p, m0 %p", 253 __func__, m, m0)); 254 if (m->m_flags & M_PKTHDR) 255 m_demote_pkthdr(m); 256 m->m_flags = m->m_flags & (M_EXT | M_RDONLY | M_NOFREE | flags); 257 } 258 } 259 260 /* 261 * Sanity checks on mbuf (chain) for use in KASSERT() and general 262 * debugging. 263 * Returns 0 or panics when bad and 1 on all tests passed. 264 * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they 265 * blow up later. 266 */ 267 int 268 m_sanity(struct mbuf *m0, int sanitize) 269 { 270 struct mbuf *m; 271 caddr_t a, b; 272 int pktlen = 0; 273 274 #ifdef INVARIANTS 275 #define M_SANITY_ACTION(s) panic("mbuf %p: " s, m) 276 #else 277 #define M_SANITY_ACTION(s) printf("mbuf %p: " s, m) 278 #endif 279 280 for (m = m0; m != NULL; m = m->m_next) { 281 /* 282 * Basic pointer checks. If any of these fails then some 283 * unrelated kernel memory before or after us is trashed. 284 * No way to recover from that. 285 */ 286 a = M_START(m); 287 b = a + M_SIZE(m); 288 if ((caddr_t)m->m_data < a) 289 M_SANITY_ACTION("m_data outside mbuf data range left"); 290 if ((caddr_t)m->m_data > b) 291 M_SANITY_ACTION("m_data outside mbuf data range right"); 292 if ((caddr_t)m->m_data + m->m_len > b) 293 M_SANITY_ACTION("m_data + m_len exeeds mbuf space"); 294 295 /* m->m_nextpkt may only be set on first mbuf in chain. */ 296 if (m != m0 && m->m_nextpkt != NULL) { 297 if (sanitize) { 298 m_freem(m->m_nextpkt); 299 m->m_nextpkt = (struct mbuf *)0xDEADC0DE; 300 } else 301 M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf"); 302 } 303 304 /* packet length (not mbuf length!) calculation */ 305 if (m0->m_flags & M_PKTHDR) 306 pktlen += m->m_len; 307 308 /* m_tags may only be attached to first mbuf in chain. */ 309 if (m != m0 && m->m_flags & M_PKTHDR && 310 !SLIST_EMPTY(&m->m_pkthdr.tags)) { 311 if (sanitize) { 312 m_tag_delete_chain(m, NULL); 313 /* put in 0xDEADC0DE perhaps? */ 314 } else 315 M_SANITY_ACTION("m_tags on in-chain mbuf"); 316 } 317 318 /* M_PKTHDR may only be set on first mbuf in chain */ 319 if (m != m0 && m->m_flags & M_PKTHDR) { 320 if (sanitize) { 321 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr)); 322 m->m_flags &= ~M_PKTHDR; 323 /* put in 0xDEADCODE and leave hdr flag in */ 324 } else 325 M_SANITY_ACTION("M_PKTHDR on in-chain mbuf"); 326 } 327 } 328 m = m0; 329 if (pktlen && pktlen != m->m_pkthdr.len) { 330 if (sanitize) 331 m->m_pkthdr.len = 0; 332 else 333 M_SANITY_ACTION("m_pkthdr.len != mbuf chain length"); 334 } 335 return 1; 336 337 #undef M_SANITY_ACTION 338 } 339 340 /* 341 * Non-inlined part of m_init(). 342 */ 343 int 344 m_pkthdr_init(struct mbuf *m, int how) 345 { 346 #ifdef MAC 347 int error; 348 #endif 349 m->m_data = m->m_pktdat; 350 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr)); 351 #ifdef MAC 352 /* If the label init fails, fail the alloc */ 353 error = mac_mbuf_init(m, how); 354 if (error) 355 return (error); 356 #endif 357 358 return (0); 359 } 360 361 /* 362 * "Move" mbuf pkthdr from "from" to "to". 363 * "from" must have M_PKTHDR set, and "to" must be empty. 364 */ 365 void 366 m_move_pkthdr(struct mbuf *to, struct mbuf *from) 367 { 368 369 #if 0 370 /* see below for why these are not enabled */ 371 M_ASSERTPKTHDR(to); 372 /* Note: with MAC, this may not be a good assertion. */ 373 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), 374 ("m_move_pkthdr: to has tags")); 375 #endif 376 #ifdef MAC 377 /* 378 * XXXMAC: It could be this should also occur for non-MAC? 379 */ 380 if (to->m_flags & M_PKTHDR) 381 m_tag_delete_chain(to, NULL); 382 #endif 383 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 384 if ((to->m_flags & M_EXT) == 0) 385 to->m_data = to->m_pktdat; 386 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 387 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 388 from->m_flags &= ~M_PKTHDR; 389 } 390 391 /* 392 * Duplicate "from"'s mbuf pkthdr in "to". 393 * "from" must have M_PKTHDR set, and "to" must be empty. 394 * In particular, this does a deep copy of the packet tags. 395 */ 396 int 397 m_dup_pkthdr(struct mbuf *to, const struct mbuf *from, int how) 398 { 399 400 #if 0 401 /* 402 * The mbuf allocator only initializes the pkthdr 403 * when the mbuf is allocated with m_gethdr(). Many users 404 * (e.g. m_copy*, m_prepend) use m_get() and then 405 * smash the pkthdr as needed causing these 406 * assertions to trip. For now just disable them. 407 */ 408 M_ASSERTPKTHDR(to); 409 /* Note: with MAC, this may not be a good assertion. */ 410 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags")); 411 #endif 412 MBUF_CHECKSLEEP(how); 413 #ifdef MAC 414 if (to->m_flags & M_PKTHDR) 415 m_tag_delete_chain(to, NULL); 416 #endif 417 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 418 if ((to->m_flags & M_EXT) == 0) 419 to->m_data = to->m_pktdat; 420 to->m_pkthdr = from->m_pkthdr; 421 SLIST_INIT(&to->m_pkthdr.tags); 422 return (m_tag_copy_chain(to, from, how)); 423 } 424 425 /* 426 * Lesser-used path for M_PREPEND: 427 * allocate new mbuf to prepend to chain, 428 * copy junk along. 429 */ 430 struct mbuf * 431 m_prepend(struct mbuf *m, int len, int how) 432 { 433 struct mbuf *mn; 434 435 if (m->m_flags & M_PKTHDR) 436 mn = m_gethdr(how, m->m_type); 437 else 438 mn = m_get(how, m->m_type); 439 if (mn == NULL) { 440 m_freem(m); 441 return (NULL); 442 } 443 if (m->m_flags & M_PKTHDR) 444 m_move_pkthdr(mn, m); 445 mn->m_next = m; 446 m = mn; 447 if (len < M_SIZE(m)) 448 M_ALIGN(m, len); 449 m->m_len = len; 450 return (m); 451 } 452 453 /* 454 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 455 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 456 * The wait parameter is a choice of M_WAITOK/M_NOWAIT from caller. 457 * Note that the copy is read-only, because clusters are not copied, 458 * only their reference counts are incremented. 459 */ 460 struct mbuf * 461 m_copym(struct mbuf *m, int off0, int len, int wait) 462 { 463 struct mbuf *n, **np; 464 int off = off0; 465 struct mbuf *top; 466 int copyhdr = 0; 467 468 KASSERT(off >= 0, ("m_copym, negative off %d", off)); 469 KASSERT(len >= 0, ("m_copym, negative len %d", len)); 470 MBUF_CHECKSLEEP(wait); 471 if (off == 0 && m->m_flags & M_PKTHDR) 472 copyhdr = 1; 473 while (off > 0) { 474 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); 475 if (off < m->m_len) 476 break; 477 off -= m->m_len; 478 m = m->m_next; 479 } 480 np = ⊤ 481 top = NULL; 482 while (len > 0) { 483 if (m == NULL) { 484 KASSERT(len == M_COPYALL, 485 ("m_copym, length > size of mbuf chain")); 486 break; 487 } 488 if (copyhdr) 489 n = m_gethdr(wait, m->m_type); 490 else 491 n = m_get(wait, m->m_type); 492 *np = n; 493 if (n == NULL) 494 goto nospace; 495 if (copyhdr) { 496 if (!m_dup_pkthdr(n, m, wait)) 497 goto nospace; 498 if (len == M_COPYALL) 499 n->m_pkthdr.len -= off0; 500 else 501 n->m_pkthdr.len = len; 502 copyhdr = 0; 503 } 504 n->m_len = min(len, m->m_len - off); 505 if (m->m_flags & M_EXT) { 506 n->m_data = m->m_data + off; 507 mb_dupcl(n, m); 508 } else 509 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 510 (u_int)n->m_len); 511 if (len != M_COPYALL) 512 len -= n->m_len; 513 off = 0; 514 m = m->m_next; 515 np = &n->m_next; 516 } 517 518 return (top); 519 nospace: 520 m_freem(top); 521 return (NULL); 522 } 523 524 /* 525 * Copy an entire packet, including header (which must be present). 526 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 527 * Note that the copy is read-only, because clusters are not copied, 528 * only their reference counts are incremented. 529 * Preserve alignment of the first mbuf so if the creator has left 530 * some room at the beginning (e.g. for inserting protocol headers) 531 * the copies still have the room available. 532 */ 533 struct mbuf * 534 m_copypacket(struct mbuf *m, int how) 535 { 536 struct mbuf *top, *n, *o; 537 538 MBUF_CHECKSLEEP(how); 539 n = m_get(how, m->m_type); 540 top = n; 541 if (n == NULL) 542 goto nospace; 543 544 if (!m_dup_pkthdr(n, m, how)) 545 goto nospace; 546 n->m_len = m->m_len; 547 if (m->m_flags & M_EXT) { 548 n->m_data = m->m_data; 549 mb_dupcl(n, m); 550 } else { 551 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 552 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 553 } 554 555 m = m->m_next; 556 while (m) { 557 o = m_get(how, m->m_type); 558 if (o == NULL) 559 goto nospace; 560 561 n->m_next = o; 562 n = n->m_next; 563 564 n->m_len = m->m_len; 565 if (m->m_flags & M_EXT) { 566 n->m_data = m->m_data; 567 mb_dupcl(n, m); 568 } else { 569 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 570 } 571 572 m = m->m_next; 573 } 574 return top; 575 nospace: 576 m_freem(top); 577 return (NULL); 578 } 579 580 /* 581 * Copy data from an mbuf chain starting "off" bytes from the beginning, 582 * continuing for "len" bytes, into the indicated buffer. 583 */ 584 void 585 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 586 { 587 u_int count; 588 589 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 590 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 591 while (off > 0) { 592 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 593 if (off < m->m_len) 594 break; 595 off -= m->m_len; 596 m = m->m_next; 597 } 598 while (len > 0) { 599 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 600 count = min(m->m_len - off, len); 601 bcopy(mtod(m, caddr_t) + off, cp, count); 602 len -= count; 603 cp += count; 604 off = 0; 605 m = m->m_next; 606 } 607 } 608 609 /* 610 * Copy a packet header mbuf chain into a completely new chain, including 611 * copying any mbuf clusters. Use this instead of m_copypacket() when 612 * you need a writable copy of an mbuf chain. 613 */ 614 struct mbuf * 615 m_dup(const struct mbuf *m, int how) 616 { 617 struct mbuf **p, *top = NULL; 618 int remain, moff, nsize; 619 620 MBUF_CHECKSLEEP(how); 621 /* Sanity check */ 622 if (m == NULL) 623 return (NULL); 624 M_ASSERTPKTHDR(m); 625 626 /* While there's more data, get a new mbuf, tack it on, and fill it */ 627 remain = m->m_pkthdr.len; 628 moff = 0; 629 p = ⊤ 630 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 631 struct mbuf *n; 632 633 /* Get the next new mbuf */ 634 if (remain >= MINCLSIZE) { 635 n = m_getcl(how, m->m_type, 0); 636 nsize = MCLBYTES; 637 } else { 638 n = m_get(how, m->m_type); 639 nsize = MLEN; 640 } 641 if (n == NULL) 642 goto nospace; 643 644 if (top == NULL) { /* First one, must be PKTHDR */ 645 if (!m_dup_pkthdr(n, m, how)) { 646 m_free(n); 647 goto nospace; 648 } 649 if ((n->m_flags & M_EXT) == 0) 650 nsize = MHLEN; 651 n->m_flags &= ~M_RDONLY; 652 } 653 n->m_len = 0; 654 655 /* Link it into the new chain */ 656 *p = n; 657 p = &n->m_next; 658 659 /* Copy data from original mbuf(s) into new mbuf */ 660 while (n->m_len < nsize && m != NULL) { 661 int chunk = min(nsize - n->m_len, m->m_len - moff); 662 663 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 664 moff += chunk; 665 n->m_len += chunk; 666 remain -= chunk; 667 if (moff == m->m_len) { 668 m = m->m_next; 669 moff = 0; 670 } 671 } 672 673 /* Check correct total mbuf length */ 674 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 675 ("%s: bogus m_pkthdr.len", __func__)); 676 } 677 return (top); 678 679 nospace: 680 m_freem(top); 681 return (NULL); 682 } 683 684 /* 685 * Concatenate mbuf chain n to m. 686 * Both chains must be of the same type (e.g. MT_DATA). 687 * Any m_pkthdr is not updated. 688 */ 689 void 690 m_cat(struct mbuf *m, struct mbuf *n) 691 { 692 while (m->m_next) 693 m = m->m_next; 694 while (n) { 695 if (!M_WRITABLE(m) || 696 M_TRAILINGSPACE(m) < n->m_len) { 697 /* just join the two chains */ 698 m->m_next = n; 699 return; 700 } 701 /* splat the data from one into the other */ 702 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 703 (u_int)n->m_len); 704 m->m_len += n->m_len; 705 n = m_free(n); 706 } 707 } 708 709 /* 710 * Concatenate two pkthdr mbuf chains. 711 */ 712 void 713 m_catpkt(struct mbuf *m, struct mbuf *n) 714 { 715 716 M_ASSERTPKTHDR(m); 717 M_ASSERTPKTHDR(n); 718 719 m->m_pkthdr.len += n->m_pkthdr.len; 720 m_demote(n, 1, 0); 721 722 m_cat(m, n); 723 } 724 725 void 726 m_adj(struct mbuf *mp, int req_len) 727 { 728 int len = req_len; 729 struct mbuf *m; 730 int count; 731 732 if ((m = mp) == NULL) 733 return; 734 if (len >= 0) { 735 /* 736 * Trim from head. 737 */ 738 while (m != NULL && len > 0) { 739 if (m->m_len <= len) { 740 len -= m->m_len; 741 m->m_len = 0; 742 m = m->m_next; 743 } else { 744 m->m_len -= len; 745 m->m_data += len; 746 len = 0; 747 } 748 } 749 if (mp->m_flags & M_PKTHDR) 750 mp->m_pkthdr.len -= (req_len - len); 751 } else { 752 /* 753 * Trim from tail. Scan the mbuf chain, 754 * calculating its length and finding the last mbuf. 755 * If the adjustment only affects this mbuf, then just 756 * adjust and return. Otherwise, rescan and truncate 757 * after the remaining size. 758 */ 759 len = -len; 760 count = 0; 761 for (;;) { 762 count += m->m_len; 763 if (m->m_next == (struct mbuf *)0) 764 break; 765 m = m->m_next; 766 } 767 if (m->m_len >= len) { 768 m->m_len -= len; 769 if (mp->m_flags & M_PKTHDR) 770 mp->m_pkthdr.len -= len; 771 return; 772 } 773 count -= len; 774 if (count < 0) 775 count = 0; 776 /* 777 * Correct length for chain is "count". 778 * Find the mbuf with last data, adjust its length, 779 * and toss data from remaining mbufs on chain. 780 */ 781 m = mp; 782 if (m->m_flags & M_PKTHDR) 783 m->m_pkthdr.len = count; 784 for (; m; m = m->m_next) { 785 if (m->m_len >= count) { 786 m->m_len = count; 787 if (m->m_next != NULL) { 788 m_freem(m->m_next); 789 m->m_next = NULL; 790 } 791 break; 792 } 793 count -= m->m_len; 794 } 795 } 796 } 797 798 void 799 m_adj_decap(struct mbuf *mp, int len) 800 { 801 uint8_t rsstype; 802 803 m_adj(mp, len); 804 if ((mp->m_flags & M_PKTHDR) != 0) { 805 /* 806 * If flowid was calculated by card from the inner 807 * headers, move flowid to the decapsulated mbuf 808 * chain, otherwise clear. This depends on the 809 * internals of m_adj, which keeps pkthdr as is, in 810 * particular not changing rsstype and flowid. 811 */ 812 rsstype = mp->m_pkthdr.rsstype; 813 if ((rsstype & M_HASHTYPE_INNER) != 0) { 814 M_HASHTYPE_SET(mp, rsstype & ~M_HASHTYPE_INNER); 815 } else { 816 M_HASHTYPE_CLEAR(mp); 817 } 818 } 819 } 820 821 /* 822 * Rearange an mbuf chain so that len bytes are contiguous 823 * and in the data area of an mbuf (so that mtod will work 824 * for a structure of size len). Returns the resulting 825 * mbuf chain on success, frees it and returns null on failure. 826 * If there is room, it will add up to max_protohdr-len extra bytes to the 827 * contiguous region in an attempt to avoid being called next time. 828 */ 829 struct mbuf * 830 m_pullup(struct mbuf *n, int len) 831 { 832 struct mbuf *m; 833 int count; 834 int space; 835 836 /* 837 * If first mbuf has no cluster, and has room for len bytes 838 * without shifting current data, pullup into it, 839 * otherwise allocate a new mbuf to prepend to the chain. 840 */ 841 if ((n->m_flags & M_EXT) == 0 && 842 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 843 if (n->m_len >= len) 844 return (n); 845 m = n; 846 n = n->m_next; 847 len -= m->m_len; 848 } else { 849 if (len > MHLEN) 850 goto bad; 851 m = m_get(M_NOWAIT, n->m_type); 852 if (m == NULL) 853 goto bad; 854 if (n->m_flags & M_PKTHDR) 855 m_move_pkthdr(m, n); 856 } 857 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 858 do { 859 count = min(min(max(len, max_protohdr), space), n->m_len); 860 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 861 (u_int)count); 862 len -= count; 863 m->m_len += count; 864 n->m_len -= count; 865 space -= count; 866 if (n->m_len) 867 n->m_data += count; 868 else 869 n = m_free(n); 870 } while (len > 0 && n); 871 if (len > 0) { 872 (void) m_free(m); 873 goto bad; 874 } 875 m->m_next = n; 876 return (m); 877 bad: 878 m_freem(n); 879 return (NULL); 880 } 881 882 /* 883 * Like m_pullup(), except a new mbuf is always allocated, and we allow 884 * the amount of empty space before the data in the new mbuf to be specified 885 * (in the event that the caller expects to prepend later). 886 */ 887 struct mbuf * 888 m_copyup(struct mbuf *n, int len, int dstoff) 889 { 890 struct mbuf *m; 891 int count, space; 892 893 if (len > (MHLEN - dstoff)) 894 goto bad; 895 m = m_get(M_NOWAIT, n->m_type); 896 if (m == NULL) 897 goto bad; 898 if (n->m_flags & M_PKTHDR) 899 m_move_pkthdr(m, n); 900 m->m_data += dstoff; 901 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 902 do { 903 count = min(min(max(len, max_protohdr), space), n->m_len); 904 memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t), 905 (unsigned)count); 906 len -= count; 907 m->m_len += count; 908 n->m_len -= count; 909 space -= count; 910 if (n->m_len) 911 n->m_data += count; 912 else 913 n = m_free(n); 914 } while (len > 0 && n); 915 if (len > 0) { 916 (void) m_free(m); 917 goto bad; 918 } 919 m->m_next = n; 920 return (m); 921 bad: 922 m_freem(n); 923 return (NULL); 924 } 925 926 /* 927 * Partition an mbuf chain in two pieces, returning the tail -- 928 * all but the first len0 bytes. In case of failure, it returns NULL and 929 * attempts to restore the chain to its original state. 930 * 931 * Note that the resulting mbufs might be read-only, because the new 932 * mbuf can end up sharing an mbuf cluster with the original mbuf if 933 * the "breaking point" happens to lie within a cluster mbuf. Use the 934 * M_WRITABLE() macro to check for this case. 935 */ 936 struct mbuf * 937 m_split(struct mbuf *m0, int len0, int wait) 938 { 939 struct mbuf *m, *n; 940 u_int len = len0, remain; 941 942 MBUF_CHECKSLEEP(wait); 943 for (m = m0; m && len > m->m_len; m = m->m_next) 944 len -= m->m_len; 945 if (m == NULL) 946 return (NULL); 947 remain = m->m_len - len; 948 if (m0->m_flags & M_PKTHDR && remain == 0) { 949 n = m_gethdr(wait, m0->m_type); 950 if (n == NULL) 951 return (NULL); 952 n->m_next = m->m_next; 953 m->m_next = NULL; 954 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 955 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 956 m0->m_pkthdr.len = len0; 957 return (n); 958 } else if (m0->m_flags & M_PKTHDR) { 959 n = m_gethdr(wait, m0->m_type); 960 if (n == NULL) 961 return (NULL); 962 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 963 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 964 m0->m_pkthdr.len = len0; 965 if (m->m_flags & M_EXT) 966 goto extpacket; 967 if (remain > MHLEN) { 968 /* m can't be the lead packet */ 969 M_ALIGN(n, 0); 970 n->m_next = m_split(m, len, wait); 971 if (n->m_next == NULL) { 972 (void) m_free(n); 973 return (NULL); 974 } else { 975 n->m_len = 0; 976 return (n); 977 } 978 } else 979 M_ALIGN(n, remain); 980 } else if (remain == 0) { 981 n = m->m_next; 982 m->m_next = NULL; 983 return (n); 984 } else { 985 n = m_get(wait, m->m_type); 986 if (n == NULL) 987 return (NULL); 988 M_ALIGN(n, remain); 989 } 990 extpacket: 991 if (m->m_flags & M_EXT) { 992 n->m_data = m->m_data + len; 993 mb_dupcl(n, m); 994 } else { 995 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 996 } 997 n->m_len = remain; 998 m->m_len = len; 999 n->m_next = m->m_next; 1000 m->m_next = NULL; 1001 return (n); 1002 } 1003 /* 1004 * Routine to copy from device local memory into mbufs. 1005 * Note that `off' argument is offset into first mbuf of target chain from 1006 * which to begin copying the data to. 1007 */ 1008 struct mbuf * 1009 m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 1010 void (*copy)(char *from, caddr_t to, u_int len)) 1011 { 1012 struct mbuf *m; 1013 struct mbuf *top = NULL, **mp = ⊤ 1014 int len; 1015 1016 if (off < 0 || off > MHLEN) 1017 return (NULL); 1018 1019 while (totlen > 0) { 1020 if (top == NULL) { /* First one, must be PKTHDR */ 1021 if (totlen + off >= MINCLSIZE) { 1022 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 1023 len = MCLBYTES; 1024 } else { 1025 m = m_gethdr(M_NOWAIT, MT_DATA); 1026 len = MHLEN; 1027 1028 /* Place initial small packet/header at end of mbuf */ 1029 if (m && totlen + off + max_linkhdr <= MHLEN) { 1030 m->m_data += max_linkhdr; 1031 len -= max_linkhdr; 1032 } 1033 } 1034 if (m == NULL) 1035 return NULL; 1036 m->m_pkthdr.rcvif = ifp; 1037 m->m_pkthdr.len = totlen; 1038 } else { 1039 if (totlen + off >= MINCLSIZE) { 1040 m = m_getcl(M_NOWAIT, MT_DATA, 0); 1041 len = MCLBYTES; 1042 } else { 1043 m = m_get(M_NOWAIT, MT_DATA); 1044 len = MLEN; 1045 } 1046 if (m == NULL) { 1047 m_freem(top); 1048 return NULL; 1049 } 1050 } 1051 if (off) { 1052 m->m_data += off; 1053 len -= off; 1054 off = 0; 1055 } 1056 m->m_len = len = min(totlen, len); 1057 if (copy) 1058 copy(buf, mtod(m, caddr_t), (u_int)len); 1059 else 1060 bcopy(buf, mtod(m, caddr_t), (u_int)len); 1061 buf += len; 1062 *mp = m; 1063 mp = &m->m_next; 1064 totlen -= len; 1065 } 1066 return (top); 1067 } 1068 1069 /* 1070 * Copy data from a buffer back into the indicated mbuf chain, 1071 * starting "off" bytes from the beginning, extending the mbuf 1072 * chain if necessary. 1073 */ 1074 void 1075 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp) 1076 { 1077 int mlen; 1078 struct mbuf *m = m0, *n; 1079 int totlen = 0; 1080 1081 if (m0 == NULL) 1082 return; 1083 while (off > (mlen = m->m_len)) { 1084 off -= mlen; 1085 totlen += mlen; 1086 if (m->m_next == NULL) { 1087 n = m_get(M_NOWAIT, m->m_type); 1088 if (n == NULL) 1089 goto out; 1090 bzero(mtod(n, caddr_t), MLEN); 1091 n->m_len = min(MLEN, len + off); 1092 m->m_next = n; 1093 } 1094 m = m->m_next; 1095 } 1096 while (len > 0) { 1097 if (m->m_next == NULL && (len > m->m_len - off)) { 1098 m->m_len += min(len - (m->m_len - off), 1099 M_TRAILINGSPACE(m)); 1100 } 1101 mlen = min (m->m_len - off, len); 1102 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 1103 cp += mlen; 1104 len -= mlen; 1105 mlen += off; 1106 off = 0; 1107 totlen += mlen; 1108 if (len == 0) 1109 break; 1110 if (m->m_next == NULL) { 1111 n = m_get(M_NOWAIT, m->m_type); 1112 if (n == NULL) 1113 break; 1114 n->m_len = min(MLEN, len); 1115 m->m_next = n; 1116 } 1117 m = m->m_next; 1118 } 1119 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 1120 m->m_pkthdr.len = totlen; 1121 } 1122 1123 /* 1124 * Append the specified data to the indicated mbuf chain, 1125 * Extend the mbuf chain if the new data does not fit in 1126 * existing space. 1127 * 1128 * Return 1 if able to complete the job; otherwise 0. 1129 */ 1130 int 1131 m_append(struct mbuf *m0, int len, c_caddr_t cp) 1132 { 1133 struct mbuf *m, *n; 1134 int remainder, space; 1135 1136 for (m = m0; m->m_next != NULL; m = m->m_next) 1137 ; 1138 remainder = len; 1139 space = M_TRAILINGSPACE(m); 1140 if (space > 0) { 1141 /* 1142 * Copy into available space. 1143 */ 1144 if (space > remainder) 1145 space = remainder; 1146 bcopy(cp, mtod(m, caddr_t) + m->m_len, space); 1147 m->m_len += space; 1148 cp += space, remainder -= space; 1149 } 1150 while (remainder > 0) { 1151 /* 1152 * Allocate a new mbuf; could check space 1153 * and allocate a cluster instead. 1154 */ 1155 n = m_get(M_NOWAIT, m->m_type); 1156 if (n == NULL) 1157 break; 1158 n->m_len = min(MLEN, remainder); 1159 bcopy(cp, mtod(n, caddr_t), n->m_len); 1160 cp += n->m_len, remainder -= n->m_len; 1161 m->m_next = n; 1162 m = n; 1163 } 1164 if (m0->m_flags & M_PKTHDR) 1165 m0->m_pkthdr.len += len - remainder; 1166 return (remainder == 0); 1167 } 1168 1169 /* 1170 * Apply function f to the data in an mbuf chain starting "off" bytes from 1171 * the beginning, continuing for "len" bytes. 1172 */ 1173 int 1174 m_apply(struct mbuf *m, int off, int len, 1175 int (*f)(void *, void *, u_int), void *arg) 1176 { 1177 u_int count; 1178 int rval; 1179 1180 KASSERT(off >= 0, ("m_apply, negative off %d", off)); 1181 KASSERT(len >= 0, ("m_apply, negative len %d", len)); 1182 while (off > 0) { 1183 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain")); 1184 if (off < m->m_len) 1185 break; 1186 off -= m->m_len; 1187 m = m->m_next; 1188 } 1189 while (len > 0) { 1190 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain")); 1191 count = min(m->m_len - off, len); 1192 rval = (*f)(arg, mtod(m, caddr_t) + off, count); 1193 if (rval) 1194 return (rval); 1195 len -= count; 1196 off = 0; 1197 m = m->m_next; 1198 } 1199 return (0); 1200 } 1201 1202 /* 1203 * Return a pointer to mbuf/offset of location in mbuf chain. 1204 */ 1205 struct mbuf * 1206 m_getptr(struct mbuf *m, int loc, int *off) 1207 { 1208 1209 while (loc >= 0) { 1210 /* Normal end of search. */ 1211 if (m->m_len > loc) { 1212 *off = loc; 1213 return (m); 1214 } else { 1215 loc -= m->m_len; 1216 if (m->m_next == NULL) { 1217 if (loc == 0) { 1218 /* Point at the end of valid data. */ 1219 *off = m->m_len; 1220 return (m); 1221 } 1222 return (NULL); 1223 } 1224 m = m->m_next; 1225 } 1226 } 1227 return (NULL); 1228 } 1229 1230 void 1231 m_print(const struct mbuf *m, int maxlen) 1232 { 1233 int len; 1234 int pdata; 1235 const struct mbuf *m2; 1236 1237 if (m == NULL) { 1238 printf("mbuf: %p\n", m); 1239 return; 1240 } 1241 1242 if (m->m_flags & M_PKTHDR) 1243 len = m->m_pkthdr.len; 1244 else 1245 len = -1; 1246 m2 = m; 1247 while (m2 != NULL && (len == -1 || len)) { 1248 pdata = m2->m_len; 1249 if (maxlen != -1 && pdata > maxlen) 1250 pdata = maxlen; 1251 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len, 1252 m2->m_next, m2->m_flags, "\2\20freelist\17skipfw" 1253 "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly" 1254 "\3eor\2pkthdr\1ext", pdata ? "" : "\n"); 1255 if (pdata) 1256 printf(", %*D\n", pdata, (u_char *)m2->m_data, "-"); 1257 if (len != -1) 1258 len -= m2->m_len; 1259 m2 = m2->m_next; 1260 } 1261 if (len > 0) 1262 printf("%d bytes unaccounted for.\n", len); 1263 return; 1264 } 1265 1266 u_int 1267 m_fixhdr(struct mbuf *m0) 1268 { 1269 u_int len; 1270 1271 len = m_length(m0, NULL); 1272 m0->m_pkthdr.len = len; 1273 return (len); 1274 } 1275 1276 u_int 1277 m_length(struct mbuf *m0, struct mbuf **last) 1278 { 1279 struct mbuf *m; 1280 u_int len; 1281 1282 len = 0; 1283 for (m = m0; m != NULL; m = m->m_next) { 1284 len += m->m_len; 1285 if (m->m_next == NULL) 1286 break; 1287 } 1288 if (last != NULL) 1289 *last = m; 1290 return (len); 1291 } 1292 1293 /* 1294 * Defragment a mbuf chain, returning the shortest possible 1295 * chain of mbufs and clusters. If allocation fails and 1296 * this cannot be completed, NULL will be returned, but 1297 * the passed in chain will be unchanged. Upon success, 1298 * the original chain will be freed, and the new chain 1299 * will be returned. 1300 * 1301 * If a non-packet header is passed in, the original 1302 * mbuf (chain?) will be returned unharmed. 1303 */ 1304 struct mbuf * 1305 m_defrag(struct mbuf *m0, int how) 1306 { 1307 struct mbuf *m_new = NULL, *m_final = NULL; 1308 int progress = 0, length; 1309 1310 MBUF_CHECKSLEEP(how); 1311 if (!(m0->m_flags & M_PKTHDR)) 1312 return (m0); 1313 1314 m_fixhdr(m0); /* Needed sanity check */ 1315 1316 #ifdef MBUF_STRESS_TEST 1317 if (m_defragrandomfailures) { 1318 int temp = arc4random() & 0xff; 1319 if (temp == 0xba) 1320 goto nospace; 1321 } 1322 #endif 1323 1324 if (m0->m_pkthdr.len > MHLEN) 1325 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 1326 else 1327 m_final = m_gethdr(how, MT_DATA); 1328 1329 if (m_final == NULL) 1330 goto nospace; 1331 1332 if (m_dup_pkthdr(m_final, m0, how) == 0) 1333 goto nospace; 1334 1335 m_new = m_final; 1336 1337 while (progress < m0->m_pkthdr.len) { 1338 length = m0->m_pkthdr.len - progress; 1339 if (length > MCLBYTES) 1340 length = MCLBYTES; 1341 1342 if (m_new == NULL) { 1343 if (length > MLEN) 1344 m_new = m_getcl(how, MT_DATA, 0); 1345 else 1346 m_new = m_get(how, MT_DATA); 1347 if (m_new == NULL) 1348 goto nospace; 1349 } 1350 1351 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 1352 progress += length; 1353 m_new->m_len = length; 1354 if (m_new != m_final) 1355 m_cat(m_final, m_new); 1356 m_new = NULL; 1357 } 1358 #ifdef MBUF_STRESS_TEST 1359 if (m0->m_next == NULL) 1360 m_defraguseless++; 1361 #endif 1362 m_freem(m0); 1363 m0 = m_final; 1364 #ifdef MBUF_STRESS_TEST 1365 m_defragpackets++; 1366 m_defragbytes += m0->m_pkthdr.len; 1367 #endif 1368 return (m0); 1369 nospace: 1370 #ifdef MBUF_STRESS_TEST 1371 m_defragfailure++; 1372 #endif 1373 if (m_final) 1374 m_freem(m_final); 1375 return (NULL); 1376 } 1377 1378 /* 1379 * Defragment an mbuf chain, returning at most maxfrags separate 1380 * mbufs+clusters. If this is not possible NULL is returned and 1381 * the original mbuf chain is left in its present (potentially 1382 * modified) state. We use two techniques: collapsing consecutive 1383 * mbufs and replacing consecutive mbufs by a cluster. 1384 * 1385 * NB: this should really be named m_defrag but that name is taken 1386 */ 1387 struct mbuf * 1388 m_collapse(struct mbuf *m0, int how, int maxfrags) 1389 { 1390 struct mbuf *m, *n, *n2, **prev; 1391 u_int curfrags; 1392 1393 /* 1394 * Calculate the current number of frags. 1395 */ 1396 curfrags = 0; 1397 for (m = m0; m != NULL; m = m->m_next) 1398 curfrags++; 1399 /* 1400 * First, try to collapse mbufs. Note that we always collapse 1401 * towards the front so we don't need to deal with moving the 1402 * pkthdr. This may be suboptimal if the first mbuf has much 1403 * less data than the following. 1404 */ 1405 m = m0; 1406 again: 1407 for (;;) { 1408 n = m->m_next; 1409 if (n == NULL) 1410 break; 1411 if (M_WRITABLE(m) && 1412 n->m_len < M_TRAILINGSPACE(m)) { 1413 bcopy(mtod(n, void *), mtod(m, char *) + m->m_len, 1414 n->m_len); 1415 m->m_len += n->m_len; 1416 m->m_next = n->m_next; 1417 m_free(n); 1418 if (--curfrags <= maxfrags) 1419 return m0; 1420 } else 1421 m = n; 1422 } 1423 KASSERT(maxfrags > 1, 1424 ("maxfrags %u, but normal collapse failed", maxfrags)); 1425 /* 1426 * Collapse consecutive mbufs to a cluster. 1427 */ 1428 prev = &m0->m_next; /* NB: not the first mbuf */ 1429 while ((n = *prev) != NULL) { 1430 if ((n2 = n->m_next) != NULL && 1431 n->m_len + n2->m_len < MCLBYTES) { 1432 m = m_getcl(how, MT_DATA, 0); 1433 if (m == NULL) 1434 goto bad; 1435 bcopy(mtod(n, void *), mtod(m, void *), n->m_len); 1436 bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len, 1437 n2->m_len); 1438 m->m_len = n->m_len + n2->m_len; 1439 m->m_next = n2->m_next; 1440 *prev = m; 1441 m_free(n); 1442 m_free(n2); 1443 if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */ 1444 return m0; 1445 /* 1446 * Still not there, try the normal collapse 1447 * again before we allocate another cluster. 1448 */ 1449 goto again; 1450 } 1451 prev = &n->m_next; 1452 } 1453 /* 1454 * No place where we can collapse to a cluster; punt. 1455 * This can occur if, for example, you request 2 frags 1456 * but the packet requires that both be clusters (we 1457 * never reallocate the first mbuf to avoid moving the 1458 * packet header). 1459 */ 1460 bad: 1461 return NULL; 1462 } 1463 1464 #ifdef MBUF_STRESS_TEST 1465 1466 /* 1467 * Fragment an mbuf chain. There's no reason you'd ever want to do 1468 * this in normal usage, but it's great for stress testing various 1469 * mbuf consumers. 1470 * 1471 * If fragmentation is not possible, the original chain will be 1472 * returned. 1473 * 1474 * Possible length values: 1475 * 0 no fragmentation will occur 1476 * > 0 each fragment will be of the specified length 1477 * -1 each fragment will be the same random value in length 1478 * -2 each fragment's length will be entirely random 1479 * (Random values range from 1 to 256) 1480 */ 1481 struct mbuf * 1482 m_fragment(struct mbuf *m0, int how, int length) 1483 { 1484 struct mbuf *m_first, *m_last; 1485 int divisor = 255, progress = 0, fraglen; 1486 1487 if (!(m0->m_flags & M_PKTHDR)) 1488 return (m0); 1489 1490 if (length == 0 || length < -2) 1491 return (m0); 1492 if (length > MCLBYTES) 1493 length = MCLBYTES; 1494 if (length < 0 && divisor > MCLBYTES) 1495 divisor = MCLBYTES; 1496 if (length == -1) 1497 length = 1 + (arc4random() % divisor); 1498 if (length > 0) 1499 fraglen = length; 1500 1501 m_fixhdr(m0); /* Needed sanity check */ 1502 1503 m_first = m_getcl(how, MT_DATA, M_PKTHDR); 1504 if (m_first == NULL) 1505 goto nospace; 1506 1507 if (m_dup_pkthdr(m_first, m0, how) == 0) 1508 goto nospace; 1509 1510 m_last = m_first; 1511 1512 while (progress < m0->m_pkthdr.len) { 1513 if (length == -2) 1514 fraglen = 1 + (arc4random() % divisor); 1515 if (fraglen > m0->m_pkthdr.len - progress) 1516 fraglen = m0->m_pkthdr.len - progress; 1517 1518 if (progress != 0) { 1519 struct mbuf *m_new = m_getcl(how, MT_DATA, 0); 1520 if (m_new == NULL) 1521 goto nospace; 1522 1523 m_last->m_next = m_new; 1524 m_last = m_new; 1525 } 1526 1527 m_copydata(m0, progress, fraglen, mtod(m_last, caddr_t)); 1528 progress += fraglen; 1529 m_last->m_len = fraglen; 1530 } 1531 m_freem(m0); 1532 m0 = m_first; 1533 return (m0); 1534 nospace: 1535 if (m_first) 1536 m_freem(m_first); 1537 /* Return the original chain on failure */ 1538 return (m0); 1539 } 1540 1541 #endif 1542 1543 /* 1544 * Copy the contents of uio into a properly sized mbuf chain. 1545 */ 1546 struct mbuf * 1547 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags) 1548 { 1549 struct mbuf *m, *mb; 1550 int error, length; 1551 ssize_t total; 1552 int progress = 0; 1553 1554 /* 1555 * len can be zero or an arbitrary large value bound by 1556 * the total data supplied by the uio. 1557 */ 1558 if (len > 0) 1559 total = (uio->uio_resid < len) ? uio->uio_resid : len; 1560 else 1561 total = uio->uio_resid; 1562 1563 /* 1564 * The smallest unit returned by m_getm2() is a single mbuf 1565 * with pkthdr. We can't align past it. 1566 */ 1567 if (align >= MHLEN) 1568 return (NULL); 1569 1570 /* 1571 * Give us the full allocation or nothing. 1572 * If len is zero return the smallest empty mbuf. 1573 */ 1574 m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags); 1575 if (m == NULL) 1576 return (NULL); 1577 m->m_data += align; 1578 1579 /* Fill all mbufs with uio data and update header information. */ 1580 for (mb = m; mb != NULL; mb = mb->m_next) { 1581 length = min(M_TRAILINGSPACE(mb), total - progress); 1582 1583 error = uiomove(mtod(mb, void *), length, uio); 1584 if (error) { 1585 m_freem(m); 1586 return (NULL); 1587 } 1588 1589 mb->m_len = length; 1590 progress += length; 1591 if (flags & M_PKTHDR) 1592 m->m_pkthdr.len += length; 1593 } 1594 KASSERT(progress == total, ("%s: progress != total", __func__)); 1595 1596 return (m); 1597 } 1598 1599 /* 1600 * Copy an mbuf chain into a uio limited by len if set. 1601 */ 1602 int 1603 m_mbuftouio(struct uio *uio, const struct mbuf *m, int len) 1604 { 1605 int error, length, total; 1606 int progress = 0; 1607 1608 if (len > 0) 1609 total = min(uio->uio_resid, len); 1610 else 1611 total = uio->uio_resid; 1612 1613 /* Fill the uio with data from the mbufs. */ 1614 for (; m != NULL; m = m->m_next) { 1615 length = min(m->m_len, total - progress); 1616 1617 error = uiomove(mtod(m, void *), length, uio); 1618 if (error) 1619 return (error); 1620 1621 progress += length; 1622 } 1623 1624 return (0); 1625 } 1626 1627 /* 1628 * Create a writable copy of the mbuf chain. While doing this 1629 * we compact the chain with a goal of producing a chain with 1630 * at most two mbufs. The second mbuf in this chain is likely 1631 * to be a cluster. The primary purpose of this work is to create 1632 * a writable packet for encryption, compression, etc. The 1633 * secondary goal is to linearize the data so the data can be 1634 * passed to crypto hardware in the most efficient manner possible. 1635 */ 1636 struct mbuf * 1637 m_unshare(struct mbuf *m0, int how) 1638 { 1639 struct mbuf *m, *mprev; 1640 struct mbuf *n, *mfirst, *mlast; 1641 int len, off; 1642 1643 mprev = NULL; 1644 for (m = m0; m != NULL; m = mprev->m_next) { 1645 /* 1646 * Regular mbufs are ignored unless there's a cluster 1647 * in front of it that we can use to coalesce. We do 1648 * the latter mainly so later clusters can be coalesced 1649 * also w/o having to handle them specially (i.e. convert 1650 * mbuf+cluster -> cluster). This optimization is heavily 1651 * influenced by the assumption that we're running over 1652 * Ethernet where MCLBYTES is large enough that the max 1653 * packet size will permit lots of coalescing into a 1654 * single cluster. This in turn permits efficient 1655 * crypto operations, especially when using hardware. 1656 */ 1657 if ((m->m_flags & M_EXT) == 0) { 1658 if (mprev && (mprev->m_flags & M_EXT) && 1659 m->m_len <= M_TRAILINGSPACE(mprev)) { 1660 /* XXX: this ignores mbuf types */ 1661 memcpy(mtod(mprev, caddr_t) + mprev->m_len, 1662 mtod(m, caddr_t), m->m_len); 1663 mprev->m_len += m->m_len; 1664 mprev->m_next = m->m_next; /* unlink from chain */ 1665 m_free(m); /* reclaim mbuf */ 1666 } else { 1667 mprev = m; 1668 } 1669 continue; 1670 } 1671 /* 1672 * Writable mbufs are left alone (for now). 1673 */ 1674 if (M_WRITABLE(m)) { 1675 mprev = m; 1676 continue; 1677 } 1678 1679 /* 1680 * Not writable, replace with a copy or coalesce with 1681 * the previous mbuf if possible (since we have to copy 1682 * it anyway, we try to reduce the number of mbufs and 1683 * clusters so that future work is easier). 1684 */ 1685 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags)); 1686 /* NB: we only coalesce into a cluster or larger */ 1687 if (mprev != NULL && (mprev->m_flags & M_EXT) && 1688 m->m_len <= M_TRAILINGSPACE(mprev)) { 1689 /* XXX: this ignores mbuf types */ 1690 memcpy(mtod(mprev, caddr_t) + mprev->m_len, 1691 mtod(m, caddr_t), m->m_len); 1692 mprev->m_len += m->m_len; 1693 mprev->m_next = m->m_next; /* unlink from chain */ 1694 m_free(m); /* reclaim mbuf */ 1695 continue; 1696 } 1697 1698 /* 1699 * Allocate new space to hold the copy and copy the data. 1700 * We deal with jumbo mbufs (i.e. m_len > MCLBYTES) by 1701 * splitting them into clusters. We could just malloc a 1702 * buffer and make it external but too many device drivers 1703 * don't know how to break up the non-contiguous memory when 1704 * doing DMA. 1705 */ 1706 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS); 1707 if (n == NULL) { 1708 m_freem(m0); 1709 return (NULL); 1710 } 1711 if (m->m_flags & M_PKTHDR) { 1712 KASSERT(mprev == NULL, ("%s: m0 %p, m %p has M_PKTHDR", 1713 __func__, m0, m)); 1714 m_move_pkthdr(n, m); 1715 } 1716 len = m->m_len; 1717 off = 0; 1718 mfirst = n; 1719 mlast = NULL; 1720 for (;;) { 1721 int cc = min(len, MCLBYTES); 1722 memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc); 1723 n->m_len = cc; 1724 if (mlast != NULL) 1725 mlast->m_next = n; 1726 mlast = n; 1727 #if 0 1728 newipsecstat.ips_clcopied++; 1729 #endif 1730 1731 len -= cc; 1732 if (len <= 0) 1733 break; 1734 off += cc; 1735 1736 n = m_getcl(how, m->m_type, m->m_flags & M_COPYFLAGS); 1737 if (n == NULL) { 1738 m_freem(mfirst); 1739 m_freem(m0); 1740 return (NULL); 1741 } 1742 } 1743 n->m_next = m->m_next; 1744 if (mprev == NULL) 1745 m0 = mfirst; /* new head of chain */ 1746 else 1747 mprev->m_next = mfirst; /* replace old mbuf */ 1748 m_free(m); /* release old mbuf */ 1749 mprev = mfirst; 1750 } 1751 return (m0); 1752 } 1753 1754 #ifdef MBUF_PROFILING 1755 1756 #define MP_BUCKETS 32 /* don't just change this as things may overflow.*/ 1757 struct mbufprofile { 1758 uintmax_t wasted[MP_BUCKETS]; 1759 uintmax_t used[MP_BUCKETS]; 1760 uintmax_t segments[MP_BUCKETS]; 1761 } mbprof; 1762 1763 #define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */ 1764 #define MP_NUMLINES 6 1765 #define MP_NUMSPERLINE 16 1766 #define MP_EXTRABYTES 64 /* > strlen("used:\nwasted:\nsegments:\n") */ 1767 /* work out max space needed and add a bit of spare space too */ 1768 #define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE) 1769 #define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES) 1770 1771 char mbprofbuf[MP_BUFSIZE]; 1772 1773 void 1774 m_profile(struct mbuf *m) 1775 { 1776 int segments = 0; 1777 int used = 0; 1778 int wasted = 0; 1779 1780 while (m) { 1781 segments++; 1782 used += m->m_len; 1783 if (m->m_flags & M_EXT) { 1784 wasted += MHLEN - sizeof(m->m_ext) + 1785 m->m_ext.ext_size - m->m_len; 1786 } else { 1787 if (m->m_flags & M_PKTHDR) 1788 wasted += MHLEN - m->m_len; 1789 else 1790 wasted += MLEN - m->m_len; 1791 } 1792 m = m->m_next; 1793 } 1794 /* be paranoid.. it helps */ 1795 if (segments > MP_BUCKETS - 1) 1796 segments = MP_BUCKETS - 1; 1797 if (used > 100000) 1798 used = 100000; 1799 if (wasted > 100000) 1800 wasted = 100000; 1801 /* store in the appropriate bucket */ 1802 /* don't bother locking. if it's slightly off, so what? */ 1803 mbprof.segments[segments]++; 1804 mbprof.used[fls(used)]++; 1805 mbprof.wasted[fls(wasted)]++; 1806 } 1807 1808 static void 1809 mbprof_textify(void) 1810 { 1811 int offset; 1812 char *c; 1813 uint64_t *p; 1814 1815 p = &mbprof.wasted[0]; 1816 c = mbprofbuf; 1817 offset = snprintf(c, MP_MAXLINE + 10, 1818 "wasted:\n" 1819 "%ju %ju %ju %ju %ju %ju %ju %ju " 1820 "%ju %ju %ju %ju %ju %ju %ju %ju\n", 1821 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1822 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1823 #ifdef BIG_ARRAY 1824 p = &mbprof.wasted[16]; 1825 c += offset; 1826 offset = snprintf(c, MP_MAXLINE, 1827 "%ju %ju %ju %ju %ju %ju %ju %ju " 1828 "%ju %ju %ju %ju %ju %ju %ju %ju\n", 1829 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1830 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1831 #endif 1832 p = &mbprof.used[0]; 1833 c += offset; 1834 offset = snprintf(c, MP_MAXLINE + 10, 1835 "used:\n" 1836 "%ju %ju %ju %ju %ju %ju %ju %ju " 1837 "%ju %ju %ju %ju %ju %ju %ju %ju\n", 1838 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1839 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1840 #ifdef BIG_ARRAY 1841 p = &mbprof.used[16]; 1842 c += offset; 1843 offset = snprintf(c, MP_MAXLINE, 1844 "%ju %ju %ju %ju %ju %ju %ju %ju " 1845 "%ju %ju %ju %ju %ju %ju %ju %ju\n", 1846 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1847 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1848 #endif 1849 p = &mbprof.segments[0]; 1850 c += offset; 1851 offset = snprintf(c, MP_MAXLINE + 10, 1852 "segments:\n" 1853 "%ju %ju %ju %ju %ju %ju %ju %ju " 1854 "%ju %ju %ju %ju %ju %ju %ju %ju\n", 1855 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1856 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1857 #ifdef BIG_ARRAY 1858 p = &mbprof.segments[16]; 1859 c += offset; 1860 offset = snprintf(c, MP_MAXLINE, 1861 "%ju %ju %ju %ju %ju %ju %ju %ju " 1862 "%ju %ju %ju %ju %ju %ju %ju %jju", 1863 p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], 1864 p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]); 1865 #endif 1866 } 1867 1868 static int 1869 mbprof_handler(SYSCTL_HANDLER_ARGS) 1870 { 1871 int error; 1872 1873 mbprof_textify(); 1874 error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1); 1875 return (error); 1876 } 1877 1878 static int 1879 mbprof_clr_handler(SYSCTL_HANDLER_ARGS) 1880 { 1881 int clear, error; 1882 1883 clear = 0; 1884 error = sysctl_handle_int(oidp, &clear, 0, req); 1885 if (error || !req->newptr) 1886 return (error); 1887 1888 if (clear) { 1889 bzero(&mbprof, sizeof(mbprof)); 1890 } 1891 1892 return (error); 1893 } 1894 1895 1896 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD, 1897 NULL, 0, mbprof_handler, "A", "mbuf profiling statistics"); 1898 1899 SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofileclr, CTLTYPE_INT|CTLFLAG_RW, 1900 NULL, 0, mbprof_clr_handler, "I", "clear mbuf profiling statistics"); 1901 #endif 1902
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