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 * 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: releng/5.3/sys/kern/uipc_mbuf.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 34 35 #include "opt_mac.h" 36 #include "opt_param.h" 37 #include "opt_mbuf_stress_test.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/mac.h> 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/sysctl.h> 48 #include <sys/domain.h> 49 #include <sys/protosw.h> 50 #include <sys/uio.h> 51 52 int max_linkhdr; 53 int max_protohdr; 54 int max_hdr; 55 int max_datalen; 56 #ifdef MBUF_STRESS_TEST 57 int m_defragpackets; 58 int m_defragbytes; 59 int m_defraguseless; 60 int m_defragfailure; 61 int m_defragrandomfailures; 62 #endif 63 64 /* 65 * sysctl(8) exported objects 66 */ 67 SYSCTL_DECL(_kern_ipc); 68 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 69 &max_linkhdr, 0, ""); 70 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 71 &max_protohdr, 0, ""); 72 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 73 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 74 &max_datalen, 0, ""); 75 #ifdef MBUF_STRESS_TEST 76 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD, 77 &m_defragpackets, 0, ""); 78 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD, 79 &m_defragbytes, 0, ""); 80 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD, 81 &m_defraguseless, 0, ""); 82 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD, 83 &m_defragfailure, 0, ""); 84 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW, 85 &m_defragrandomfailures, 0, ""); 86 #endif 87 88 /* 89 * Malloc-type for external ext_buf ref counts. 90 */ 91 MALLOC_DEFINE(M_MBUF, "mbextcnt", "mbuf external ref counts"); 92 93 /* 94 * Allocate a given length worth of mbufs and/or clusters (whatever fits 95 * best) and return a pointer to the top of the allocated chain. If an 96 * existing mbuf chain is provided, then we will append the new chain 97 * to the existing one but still return the top of the newly allocated 98 * chain. 99 */ 100 struct mbuf * 101 m_getm(struct mbuf *m, int len, int how, short type) 102 { 103 struct mbuf *mb, *top, *cur, *mtail; 104 int num, rem; 105 int i; 106 107 KASSERT(len >= 0, ("m_getm(): len is < 0")); 108 109 /* If m != NULL, we will append to the end of that chain. */ 110 if (m != NULL) 111 for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next); 112 else 113 mtail = NULL; 114 115 /* 116 * Calculate how many mbufs+clusters ("packets") we need and how much 117 * leftover there is after that and allocate the first mbuf+cluster 118 * if required. 119 */ 120 num = len / MCLBYTES; 121 rem = len % MCLBYTES; 122 top = cur = NULL; 123 if (num > 0) { 124 if ((top = cur = m_getcl(how, type, 0)) == NULL) 125 goto failed; 126 top->m_len = 0; 127 } 128 num--; 129 130 for (i = 0; i < num; i++) { 131 mb = m_getcl(how, type, 0); 132 if (mb == NULL) 133 goto failed; 134 mb->m_len = 0; 135 cur = (cur->m_next = mb); 136 } 137 if (rem > 0) { 138 mb = (rem > MINCLSIZE) ? 139 m_getcl(how, type, 0) : m_get(how, type); 140 if (mb == NULL) 141 goto failed; 142 mb->m_len = 0; 143 if (cur == NULL) 144 top = mb; 145 else 146 cur->m_next = mb; 147 } 148 149 if (mtail != NULL) 150 mtail->m_next = top; 151 return top; 152 failed: 153 if (top != NULL) 154 m_freem(top); 155 return NULL; 156 } 157 158 /* 159 * Free an entire chain of mbufs and associated external buffers, if 160 * applicable. 161 */ 162 void 163 m_freem(struct mbuf *mb) 164 { 165 166 while (mb != NULL) 167 mb = m_free(mb); 168 } 169 170 /*- 171 * Configure a provided mbuf to refer to the provided external storage 172 * buffer and setup a reference count for said buffer. If the setting 173 * up of the reference count fails, the M_EXT bit will not be set. If 174 * successfull, the M_EXT bit is set in the mbuf's flags. 175 * 176 * Arguments: 177 * mb The existing mbuf to which to attach the provided buffer. 178 * buf The address of the provided external storage buffer. 179 * size The size of the provided buffer. 180 * freef A pointer to a routine that is responsible for freeing the 181 * provided external storage buffer. 182 * args A pointer to an argument structure (of any type) to be passed 183 * to the provided freef routine (may be NULL). 184 * flags Any other flags to be passed to the provided mbuf. 185 * type The type that the external storage buffer should be 186 * labeled with. 187 * 188 * Returns: 189 * Nothing. 190 */ 191 void 192 m_extadd(struct mbuf *mb, caddr_t buf, u_int size, 193 void (*freef)(void *, void *), void *args, int flags, int type) 194 { 195 u_int *ref_cnt = NULL; 196 197 /* XXX Shouldn't be adding EXT_CLUSTER with this API */ 198 if (type == EXT_CLUSTER) 199 ref_cnt = (u_int *)uma_find_refcnt(zone_clust, 200 mb->m_ext.ext_buf); 201 else if (type == EXT_EXTREF) 202 ref_cnt = mb->m_ext.ref_cnt; 203 mb->m_ext.ref_cnt = (ref_cnt == NULL) ? 204 malloc(sizeof(u_int), M_MBUF, M_NOWAIT) : (u_int *)ref_cnt; 205 if (mb->m_ext.ref_cnt != NULL) { 206 *(mb->m_ext.ref_cnt) = 1; 207 mb->m_flags |= (M_EXT | flags); 208 mb->m_ext.ext_buf = buf; 209 mb->m_data = mb->m_ext.ext_buf; 210 mb->m_ext.ext_size = size; 211 mb->m_ext.ext_free = freef; 212 mb->m_ext.ext_args = args; 213 mb->m_ext.ext_type = type; 214 } 215 } 216 217 /* 218 * Non-directly-exported function to clean up after mbufs with M_EXT 219 * storage attached to them if the reference count hits 0. 220 */ 221 void 222 mb_free_ext(struct mbuf *m) 223 { 224 u_int cnt; 225 226 /* 227 * This is tricky. We need to make sure to decrement the 228 * refcount in a safe way but to also clean up if we're the 229 * last reference. This method seems to do it without race. 230 */ 231 do { 232 cnt = *(m->m_ext.ref_cnt); 233 if (atomic_cmpset_int(m->m_ext.ref_cnt, cnt, cnt - 1)) { 234 if (cnt == 1) { 235 /* 236 * Do the free, should be safe. 237 */ 238 if (m->m_ext.ext_type == EXT_PACKET) { 239 uma_zfree(zone_pack, m); 240 return; 241 } else if (m->m_ext.ext_type == EXT_CLUSTER) { 242 uma_zfree(zone_clust, m->m_ext.ext_buf); 243 m->m_ext.ext_buf = NULL; 244 } else { 245 (*(m->m_ext.ext_free))(m->m_ext.ext_buf, 246 m->m_ext.ext_args); 247 if (m->m_ext.ext_type != EXT_EXTREF) 248 free(m->m_ext.ref_cnt, M_MBUF); 249 m->m_ext.ext_buf = NULL; 250 } 251 } 252 /* Decrement (and potentially free) done, safely. */ 253 break; 254 } 255 } while (1); 256 uma_zfree(zone_mbuf, m); 257 } 258 259 /* 260 * "Move" mbuf pkthdr from "from" to "to". 261 * "from" must have M_PKTHDR set, and "to" must be empty. 262 */ 263 void 264 m_move_pkthdr(struct mbuf *to, struct mbuf *from) 265 { 266 267 #if 0 268 /* see below for why these are not enabled */ 269 M_ASSERTPKTHDR(to); 270 /* Note: with MAC, this may not be a good assertion. */ 271 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), 272 ("m_move_pkthdr: to has tags")); 273 #endif 274 KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster")); 275 #ifdef MAC 276 /* 277 * XXXMAC: It could be this should also occur for non-MAC? 278 */ 279 if (to->m_flags & M_PKTHDR) 280 m_tag_delete_chain(to, NULL); 281 #endif 282 to->m_flags = from->m_flags & M_COPYFLAGS; 283 to->m_data = to->m_pktdat; 284 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 285 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 286 from->m_flags &= ~M_PKTHDR; 287 } 288 289 /* 290 * Duplicate "from"'s mbuf pkthdr in "to". 291 * "from" must have M_PKTHDR set, and "to" must be empty. 292 * In particular, this does a deep copy of the packet tags. 293 */ 294 int 295 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how) 296 { 297 298 #if 0 299 /* 300 * The mbuf allocator only initializes the pkthdr 301 * when the mbuf is allocated with MGETHDR. Many users 302 * (e.g. m_copy*, m_prepend) use MGET and then 303 * smash the pkthdr as needed causing these 304 * assertions to trip. For now just disable them. 305 */ 306 M_ASSERTPKTHDR(to); 307 /* Note: with MAC, this may not be a good assertion. */ 308 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags")); 309 #endif 310 MBUF_CHECKSLEEP(how); 311 #ifdef MAC 312 if (to->m_flags & M_PKTHDR) 313 m_tag_delete_chain(to, NULL); 314 #endif 315 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 316 if ((to->m_flags & M_EXT) == 0) 317 to->m_data = to->m_pktdat; 318 to->m_pkthdr = from->m_pkthdr; 319 SLIST_INIT(&to->m_pkthdr.tags); 320 return (m_tag_copy_chain(to, from, MBTOM(how))); 321 } 322 323 /* 324 * Lesser-used path for M_PREPEND: 325 * allocate new mbuf to prepend to chain, 326 * copy junk along. 327 */ 328 struct mbuf * 329 m_prepend(struct mbuf *m, int len, int how) 330 { 331 struct mbuf *mn; 332 333 if (m->m_flags & M_PKTHDR) 334 MGETHDR(mn, how, m->m_type); 335 else 336 MGET(mn, how, m->m_type); 337 if (mn == NULL) { 338 m_freem(m); 339 return (NULL); 340 } 341 if (m->m_flags & M_PKTHDR) 342 M_MOVE_PKTHDR(mn, m); 343 mn->m_next = m; 344 m = mn; 345 if (len < MHLEN) 346 MH_ALIGN(m, len); 347 m->m_len = len; 348 return (m); 349 } 350 351 /* 352 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 353 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 354 * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller. 355 * Note that the copy is read-only, because clusters are not copied, 356 * only their reference counts are incremented. 357 */ 358 struct mbuf * 359 m_copym(struct mbuf *m, int off0, int len, int wait) 360 { 361 struct mbuf *n, **np; 362 int off = off0; 363 struct mbuf *top; 364 int copyhdr = 0; 365 366 KASSERT(off >= 0, ("m_copym, negative off %d", off)); 367 KASSERT(len >= 0, ("m_copym, negative len %d", len)); 368 MBUF_CHECKSLEEP(wait); 369 if (off == 0 && m->m_flags & M_PKTHDR) 370 copyhdr = 1; 371 while (off > 0) { 372 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); 373 if (off < m->m_len) 374 break; 375 off -= m->m_len; 376 m = m->m_next; 377 } 378 np = ⊤ 379 top = 0; 380 while (len > 0) { 381 if (m == NULL) { 382 KASSERT(len == M_COPYALL, 383 ("m_copym, length > size of mbuf chain")); 384 break; 385 } 386 if (copyhdr) 387 MGETHDR(n, wait, m->m_type); 388 else 389 MGET(n, wait, m->m_type); 390 *np = n; 391 if (n == NULL) 392 goto nospace; 393 if (copyhdr) { 394 if (!m_dup_pkthdr(n, m, wait)) 395 goto nospace; 396 if (len == M_COPYALL) 397 n->m_pkthdr.len -= off0; 398 else 399 n->m_pkthdr.len = len; 400 copyhdr = 0; 401 } 402 n->m_len = min(len, m->m_len - off); 403 if (m->m_flags & M_EXT) { 404 n->m_data = m->m_data + off; 405 n->m_ext = m->m_ext; 406 n->m_flags |= M_EXT; 407 MEXT_ADD_REF(m); 408 } else 409 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 410 (u_int)n->m_len); 411 if (len != M_COPYALL) 412 len -= n->m_len; 413 off = 0; 414 m = m->m_next; 415 np = &n->m_next; 416 } 417 if (top == NULL) 418 mbstat.m_mcfail++; /* XXX: No consistency. */ 419 420 return (top); 421 nospace: 422 m_freem(top); 423 mbstat.m_mcfail++; /* XXX: No consistency. */ 424 return (NULL); 425 } 426 427 /* 428 * Copy an entire packet, including header (which must be present). 429 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 430 * Note that the copy is read-only, because clusters are not copied, 431 * only their reference counts are incremented. 432 * Preserve alignment of the first mbuf so if the creator has left 433 * some room at the beginning (e.g. for inserting protocol headers) 434 * the copies still have the room available. 435 */ 436 struct mbuf * 437 m_copypacket(struct mbuf *m, int how) 438 { 439 struct mbuf *top, *n, *o; 440 441 MBUF_CHECKSLEEP(how); 442 MGET(n, how, m->m_type); 443 top = n; 444 if (n == NULL) 445 goto nospace; 446 447 if (!m_dup_pkthdr(n, m, how)) 448 goto nospace; 449 n->m_len = m->m_len; 450 if (m->m_flags & M_EXT) { 451 n->m_data = m->m_data; 452 n->m_ext = m->m_ext; 453 n->m_flags |= M_EXT; 454 MEXT_ADD_REF(m); 455 } else { 456 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 457 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 458 } 459 460 m = m->m_next; 461 while (m) { 462 MGET(o, how, m->m_type); 463 if (o == NULL) 464 goto nospace; 465 466 n->m_next = o; 467 n = n->m_next; 468 469 n->m_len = m->m_len; 470 if (m->m_flags & M_EXT) { 471 n->m_data = m->m_data; 472 n->m_ext = m->m_ext; 473 n->m_flags |= M_EXT; 474 MEXT_ADD_REF(m); 475 } else { 476 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 477 } 478 479 m = m->m_next; 480 } 481 return top; 482 nospace: 483 m_freem(top); 484 mbstat.m_mcfail++; /* XXX: No consistency. */ 485 return (NULL); 486 } 487 488 /* 489 * Copy data from an mbuf chain starting "off" bytes from the beginning, 490 * continuing for "len" bytes, into the indicated buffer. 491 */ 492 void 493 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 494 { 495 u_int count; 496 497 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 498 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 499 while (off > 0) { 500 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 501 if (off < m->m_len) 502 break; 503 off -= m->m_len; 504 m = m->m_next; 505 } 506 while (len > 0) { 507 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 508 count = min(m->m_len - off, len); 509 bcopy(mtod(m, caddr_t) + off, cp, count); 510 len -= count; 511 cp += count; 512 off = 0; 513 m = m->m_next; 514 } 515 } 516 517 /* 518 * Copy a packet header mbuf chain into a completely new chain, including 519 * copying any mbuf clusters. Use this instead of m_copypacket() when 520 * you need a writable copy of an mbuf chain. 521 */ 522 struct mbuf * 523 m_dup(struct mbuf *m, int how) 524 { 525 struct mbuf **p, *top = NULL; 526 int remain, moff, nsize; 527 528 MBUF_CHECKSLEEP(how); 529 /* Sanity check */ 530 if (m == NULL) 531 return (NULL); 532 M_ASSERTPKTHDR(m); 533 534 /* While there's more data, get a new mbuf, tack it on, and fill it */ 535 remain = m->m_pkthdr.len; 536 moff = 0; 537 p = ⊤ 538 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 539 struct mbuf *n; 540 541 /* Get the next new mbuf */ 542 if (remain >= MINCLSIZE) { 543 n = m_getcl(how, m->m_type, 0); 544 nsize = MCLBYTES; 545 } else { 546 n = m_get(how, m->m_type); 547 nsize = MLEN; 548 } 549 if (n == NULL) 550 goto nospace; 551 552 if (top == NULL) { /* First one, must be PKTHDR */ 553 if (!m_dup_pkthdr(n, m, how)) { 554 m_free(n); 555 goto nospace; 556 } 557 nsize = MHLEN; 558 } 559 n->m_len = 0; 560 561 /* Link it into the new chain */ 562 *p = n; 563 p = &n->m_next; 564 565 /* Copy data from original mbuf(s) into new mbuf */ 566 while (n->m_len < nsize && m != NULL) { 567 int chunk = min(nsize - n->m_len, m->m_len - moff); 568 569 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 570 moff += chunk; 571 n->m_len += chunk; 572 remain -= chunk; 573 if (moff == m->m_len) { 574 m = m->m_next; 575 moff = 0; 576 } 577 } 578 579 /* Check correct total mbuf length */ 580 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 581 ("%s: bogus m_pkthdr.len", __func__)); 582 } 583 return (top); 584 585 nospace: 586 m_freem(top); 587 mbstat.m_mcfail++; /* XXX: No consistency. */ 588 return (NULL); 589 } 590 591 /* 592 * Concatenate mbuf chain n to m. 593 * Both chains must be of the same type (e.g. MT_DATA). 594 * Any m_pkthdr is not updated. 595 */ 596 void 597 m_cat(struct mbuf *m, struct mbuf *n) 598 { 599 while (m->m_next) 600 m = m->m_next; 601 while (n) { 602 if (m->m_flags & M_EXT || 603 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 604 /* just join the two chains */ 605 m->m_next = n; 606 return; 607 } 608 /* splat the data from one into the other */ 609 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 610 (u_int)n->m_len); 611 m->m_len += n->m_len; 612 n = m_free(n); 613 } 614 } 615 616 void 617 m_adj(struct mbuf *mp, int req_len) 618 { 619 int len = req_len; 620 struct mbuf *m; 621 int count; 622 623 if ((m = mp) == NULL) 624 return; 625 if (len >= 0) { 626 /* 627 * Trim from head. 628 */ 629 while (m != NULL && len > 0) { 630 if (m->m_len <= len) { 631 len -= m->m_len; 632 m->m_len = 0; 633 m = m->m_next; 634 } else { 635 m->m_len -= len; 636 m->m_data += len; 637 len = 0; 638 } 639 } 640 m = mp; 641 if (mp->m_flags & M_PKTHDR) 642 m->m_pkthdr.len -= (req_len - len); 643 } else { 644 /* 645 * Trim from tail. Scan the mbuf chain, 646 * calculating its length and finding the last mbuf. 647 * If the adjustment only affects this mbuf, then just 648 * adjust and return. Otherwise, rescan and truncate 649 * after the remaining size. 650 */ 651 len = -len; 652 count = 0; 653 for (;;) { 654 count += m->m_len; 655 if (m->m_next == (struct mbuf *)0) 656 break; 657 m = m->m_next; 658 } 659 if (m->m_len >= len) { 660 m->m_len -= len; 661 if (mp->m_flags & M_PKTHDR) 662 mp->m_pkthdr.len -= len; 663 return; 664 } 665 count -= len; 666 if (count < 0) 667 count = 0; 668 /* 669 * Correct length for chain is "count". 670 * Find the mbuf with last data, adjust its length, 671 * and toss data from remaining mbufs on chain. 672 */ 673 m = mp; 674 if (m->m_flags & M_PKTHDR) 675 m->m_pkthdr.len = count; 676 for (; m; m = m->m_next) { 677 if (m->m_len >= count) { 678 m->m_len = count; 679 break; 680 } 681 count -= m->m_len; 682 } 683 while (m->m_next) 684 (m = m->m_next) ->m_len = 0; 685 } 686 } 687 688 /* 689 * Rearange an mbuf chain so that len bytes are contiguous 690 * and in the data area of an mbuf (so that mtod and dtom 691 * will work for a structure of size len). Returns the resulting 692 * mbuf chain on success, frees it and returns null on failure. 693 * If there is room, it will add up to max_protohdr-len extra bytes to the 694 * contiguous region in an attempt to avoid being called next time. 695 */ 696 struct mbuf * 697 m_pullup(struct mbuf *n, int len) 698 { 699 struct mbuf *m; 700 int count; 701 int space; 702 703 /* 704 * If first mbuf has no cluster, and has room for len bytes 705 * without shifting current data, pullup into it, 706 * otherwise allocate a new mbuf to prepend to the chain. 707 */ 708 if ((n->m_flags & M_EXT) == 0 && 709 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 710 if (n->m_len >= len) 711 return (n); 712 m = n; 713 n = n->m_next; 714 len -= m->m_len; 715 } else { 716 if (len > MHLEN) 717 goto bad; 718 MGET(m, M_DONTWAIT, n->m_type); 719 if (m == NULL) 720 goto bad; 721 m->m_len = 0; 722 if (n->m_flags & M_PKTHDR) 723 M_MOVE_PKTHDR(m, n); 724 } 725 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 726 do { 727 count = min(min(max(len, max_protohdr), space), n->m_len); 728 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 729 (u_int)count); 730 len -= count; 731 m->m_len += count; 732 n->m_len -= count; 733 space -= count; 734 if (n->m_len) 735 n->m_data += count; 736 else 737 n = m_free(n); 738 } while (len > 0 && n); 739 if (len > 0) { 740 (void) m_free(m); 741 goto bad; 742 } 743 m->m_next = n; 744 return (m); 745 bad: 746 m_freem(n); 747 mbstat.m_mpfail++; /* XXX: No consistency. */ 748 return (NULL); 749 } 750 751 /* 752 * Partition an mbuf chain in two pieces, returning the tail -- 753 * all but the first len0 bytes. In case of failure, it returns NULL and 754 * attempts to restore the chain to its original state. 755 * 756 * Note that the resulting mbufs might be read-only, because the new 757 * mbuf can end up sharing an mbuf cluster with the original mbuf if 758 * the "breaking point" happens to lie within a cluster mbuf. Use the 759 * M_WRITABLE() macro to check for this case. 760 */ 761 struct mbuf * 762 m_split(struct mbuf *m0, int len0, int wait) 763 { 764 struct mbuf *m, *n; 765 u_int len = len0, remain; 766 767 MBUF_CHECKSLEEP(wait); 768 for (m = m0; m && len > m->m_len; m = m->m_next) 769 len -= m->m_len; 770 if (m == NULL) 771 return (NULL); 772 remain = m->m_len - len; 773 if (m0->m_flags & M_PKTHDR) { 774 MGETHDR(n, wait, m0->m_type); 775 if (n == NULL) 776 return (NULL); 777 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 778 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 779 m0->m_pkthdr.len = len0; 780 if (m->m_flags & M_EXT) 781 goto extpacket; 782 if (remain > MHLEN) { 783 /* m can't be the lead packet */ 784 MH_ALIGN(n, 0); 785 n->m_next = m_split(m, len, wait); 786 if (n->m_next == NULL) { 787 (void) m_free(n); 788 return (NULL); 789 } else { 790 n->m_len = 0; 791 return (n); 792 } 793 } else 794 MH_ALIGN(n, remain); 795 } else if (remain == 0) { 796 n = m->m_next; 797 m->m_next = NULL; 798 return (n); 799 } else { 800 MGET(n, wait, m->m_type); 801 if (n == NULL) 802 return (NULL); 803 M_ALIGN(n, remain); 804 } 805 extpacket: 806 if (m->m_flags & M_EXT) { 807 n->m_flags |= M_EXT; 808 n->m_ext = m->m_ext; 809 MEXT_ADD_REF(m); 810 n->m_data = m->m_data + len; 811 } else { 812 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 813 } 814 n->m_len = remain; 815 m->m_len = len; 816 n->m_next = m->m_next; 817 m->m_next = NULL; 818 return (n); 819 } 820 /* 821 * Routine to copy from device local memory into mbufs. 822 * Note that `off' argument is offset into first mbuf of target chain from 823 * which to begin copying the data to. 824 */ 825 struct mbuf * 826 m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 827 void (*copy)(char *from, caddr_t to, u_int len)) 828 { 829 struct mbuf *m; 830 struct mbuf *top = NULL, **mp = ⊤ 831 int len; 832 833 if (off < 0 || off > MHLEN) 834 return (NULL); 835 836 while (totlen > 0) { 837 if (top == NULL) { /* First one, must be PKTHDR */ 838 if (totlen + off >= MINCLSIZE) { 839 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); 840 len = MCLBYTES; 841 } else { 842 m = m_gethdr(M_DONTWAIT, MT_DATA); 843 len = MHLEN; 844 845 /* Place initial small packet/header at end of mbuf */ 846 if (m && totlen + off + max_linkhdr <= MLEN) { 847 m->m_data += max_linkhdr; 848 len -= max_linkhdr; 849 } 850 } 851 if (m == NULL) 852 return NULL; 853 m->m_pkthdr.rcvif = ifp; 854 m->m_pkthdr.len = totlen; 855 } else { 856 if (totlen + off >= MINCLSIZE) { 857 m = m_getcl(M_DONTWAIT, MT_DATA, 0); 858 len = MCLBYTES; 859 } else { 860 m = m_get(M_DONTWAIT, MT_DATA); 861 len = MLEN; 862 } 863 if (m == NULL) { 864 m_freem(top); 865 return NULL; 866 } 867 } 868 if (off) { 869 m->m_data += off; 870 len -= off; 871 off = 0; 872 } 873 m->m_len = len = min(totlen, len); 874 if (copy) 875 copy(buf, mtod(m, caddr_t), (u_int)len); 876 else 877 bcopy(buf, mtod(m, caddr_t), (u_int)len); 878 buf += len; 879 *mp = m; 880 mp = &m->m_next; 881 totlen -= len; 882 } 883 return (top); 884 } 885 886 /* 887 * Copy data from a buffer back into the indicated mbuf chain, 888 * starting "off" bytes from the beginning, extending the mbuf 889 * chain if necessary. 890 */ 891 void 892 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp) 893 { 894 int mlen; 895 struct mbuf *m = m0, *n; 896 int totlen = 0; 897 898 if (m0 == NULL) 899 return; 900 while (off > (mlen = m->m_len)) { 901 off -= mlen; 902 totlen += mlen; 903 if (m->m_next == NULL) { 904 n = m_get(M_DONTWAIT, m->m_type); 905 if (n == NULL) 906 goto out; 907 bzero(mtod(n, caddr_t), MLEN); 908 n->m_len = min(MLEN, len + off); 909 m->m_next = n; 910 } 911 m = m->m_next; 912 } 913 while (len > 0) { 914 mlen = min (m->m_len - off, len); 915 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 916 cp += mlen; 917 len -= mlen; 918 mlen += off; 919 off = 0; 920 totlen += mlen; 921 if (len == 0) 922 break; 923 if (m->m_next == NULL) { 924 n = m_get(M_DONTWAIT, m->m_type); 925 if (n == NULL) 926 break; 927 n->m_len = min(MLEN, len); 928 m->m_next = n; 929 } 930 m = m->m_next; 931 } 932 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 933 m->m_pkthdr.len = totlen; 934 } 935 936 /* 937 * Apply function f to the data in an mbuf chain starting "off" bytes from 938 * the beginning, continuing for "len" bytes. 939 */ 940 int 941 m_apply(struct mbuf *m, int off, int len, 942 int (*f)(void *, void *, u_int), void *arg) 943 { 944 u_int count; 945 int rval; 946 947 KASSERT(off >= 0, ("m_apply, negative off %d", off)); 948 KASSERT(len >= 0, ("m_apply, negative len %d", len)); 949 while (off > 0) { 950 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain")); 951 if (off < m->m_len) 952 break; 953 off -= m->m_len; 954 m = m->m_next; 955 } 956 while (len > 0) { 957 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain")); 958 count = min(m->m_len - off, len); 959 rval = (*f)(arg, mtod(m, caddr_t) + off, count); 960 if (rval) 961 return (rval); 962 len -= count; 963 off = 0; 964 m = m->m_next; 965 } 966 return (0); 967 } 968 969 /* 970 * Return a pointer to mbuf/offset of location in mbuf chain. 971 */ 972 struct mbuf * 973 m_getptr(struct mbuf *m, int loc, int *off) 974 { 975 976 while (loc >= 0) { 977 /* Normal end of search. */ 978 if (m->m_len > loc) { 979 *off = loc; 980 return (m); 981 } else { 982 loc -= m->m_len; 983 if (m->m_next == NULL) { 984 if (loc == 0) { 985 /* Point at the end of valid data. */ 986 *off = m->m_len; 987 return (m); 988 } 989 return (NULL); 990 } 991 m = m->m_next; 992 } 993 } 994 return (NULL); 995 } 996 997 void 998 m_print(const struct mbuf *m, int maxlen) 999 { 1000 int len; 1001 int pdata; 1002 const struct mbuf *m2; 1003 1004 if (m->m_flags & M_PKTHDR) 1005 len = m->m_pkthdr.len; 1006 else 1007 len = -1; 1008 m2 = m; 1009 while (m2 != NULL && (len == -1 || len)) { 1010 pdata = m2->m_len; 1011 if (maxlen != -1 && pdata > maxlen) 1012 pdata = maxlen; 1013 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len, 1014 m2->m_next, m2->m_flags, "\2\20freelist\17skipfw" 1015 "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly" 1016 "\3eor\2pkthdr\1ext", pdata ? "" : "\n"); 1017 if (pdata) 1018 printf(", %*D\n", m2->m_len, (u_char *)m2->m_data, "-"); 1019 if (len != -1) 1020 len -= m2->m_len; 1021 m2 = m2->m_next; 1022 } 1023 if (len > 0) 1024 printf("%d bytes unaccounted for.\n", len); 1025 return; 1026 } 1027 1028 u_int 1029 m_fixhdr(struct mbuf *m0) 1030 { 1031 u_int len; 1032 1033 len = m_length(m0, NULL); 1034 m0->m_pkthdr.len = len; 1035 return (len); 1036 } 1037 1038 u_int 1039 m_length(struct mbuf *m0, struct mbuf **last) 1040 { 1041 struct mbuf *m; 1042 u_int len; 1043 1044 len = 0; 1045 for (m = m0; m != NULL; m = m->m_next) { 1046 len += m->m_len; 1047 if (m->m_next == NULL) 1048 break; 1049 } 1050 if (last != NULL) 1051 *last = m; 1052 return (len); 1053 } 1054 1055 /* 1056 * Defragment a mbuf chain, returning the shortest possible 1057 * chain of mbufs and clusters. If allocation fails and 1058 * this cannot be completed, NULL will be returned, but 1059 * the passed in chain will be unchanged. Upon success, 1060 * the original chain will be freed, and the new chain 1061 * will be returned. 1062 * 1063 * If a non-packet header is passed in, the original 1064 * mbuf (chain?) will be returned unharmed. 1065 */ 1066 struct mbuf * 1067 m_defrag(struct mbuf *m0, int how) 1068 { 1069 struct mbuf *m_new = NULL, *m_final = NULL; 1070 int progress = 0, length; 1071 1072 MBUF_CHECKSLEEP(how); 1073 if (!(m0->m_flags & M_PKTHDR)) 1074 return (m0); 1075 1076 m_fixhdr(m0); /* Needed sanity check */ 1077 1078 #ifdef MBUF_STRESS_TEST 1079 if (m_defragrandomfailures) { 1080 int temp = arc4random() & 0xff; 1081 if (temp == 0xba) 1082 goto nospace; 1083 } 1084 #endif 1085 1086 if (m0->m_pkthdr.len > MHLEN) 1087 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 1088 else 1089 m_final = m_gethdr(how, MT_DATA); 1090 1091 if (m_final == NULL) 1092 goto nospace; 1093 1094 if (m_dup_pkthdr(m_final, m0, how) == 0) 1095 goto nospace; 1096 1097 m_new = m_final; 1098 1099 while (progress < m0->m_pkthdr.len) { 1100 length = m0->m_pkthdr.len - progress; 1101 if (length > MCLBYTES) 1102 length = MCLBYTES; 1103 1104 if (m_new == NULL) { 1105 if (length > MLEN) 1106 m_new = m_getcl(how, MT_DATA, 0); 1107 else 1108 m_new = m_get(how, MT_DATA); 1109 if (m_new == NULL) 1110 goto nospace; 1111 } 1112 1113 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 1114 progress += length; 1115 m_new->m_len = length; 1116 if (m_new != m_final) 1117 m_cat(m_final, m_new); 1118 m_new = NULL; 1119 } 1120 #ifdef MBUF_STRESS_TEST 1121 if (m0->m_next == NULL) 1122 m_defraguseless++; 1123 #endif 1124 m_freem(m0); 1125 m0 = m_final; 1126 #ifdef MBUF_STRESS_TEST 1127 m_defragpackets++; 1128 m_defragbytes += m0->m_pkthdr.len; 1129 #endif 1130 return (m0); 1131 nospace: 1132 #ifdef MBUF_STRESS_TEST 1133 m_defragfailure++; 1134 #endif 1135 if (m_new) 1136 m_free(m_new); 1137 if (m_final) 1138 m_freem(m_final); 1139 return (NULL); 1140 } 1141 1142 #ifdef MBUF_STRESS_TEST 1143 1144 /* 1145 * Fragment an mbuf chain. There's no reason you'd ever want to do 1146 * this in normal usage, but it's great for stress testing various 1147 * mbuf consumers. 1148 * 1149 * If fragmentation is not possible, the original chain will be 1150 * returned. 1151 * 1152 * Possible length values: 1153 * 0 no fragmentation will occur 1154 * > 0 each fragment will be of the specified length 1155 * -1 each fragment will be the same random value in length 1156 * -2 each fragment's length will be entirely random 1157 * (Random values range from 1 to 256) 1158 */ 1159 struct mbuf * 1160 m_fragment(struct mbuf *m0, int how, int length) 1161 { 1162 struct mbuf *m_new = NULL, *m_final = NULL; 1163 int progress = 0; 1164 1165 if (!(m0->m_flags & M_PKTHDR)) 1166 return (m0); 1167 1168 if ((length == 0) || (length < -2)) 1169 return (m0); 1170 1171 m_fixhdr(m0); /* Needed sanity check */ 1172 1173 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 1174 1175 if (m_final == NULL) 1176 goto nospace; 1177 1178 if (m_dup_pkthdr(m_final, m0, how) == 0) 1179 goto nospace; 1180 1181 m_new = m_final; 1182 1183 if (length == -1) 1184 length = 1 + (arc4random() & 255); 1185 1186 while (progress < m0->m_pkthdr.len) { 1187 int fraglen; 1188 1189 if (length > 0) 1190 fraglen = length; 1191 else 1192 fraglen = 1 + (arc4random() & 255); 1193 if (fraglen > m0->m_pkthdr.len - progress) 1194 fraglen = m0->m_pkthdr.len - progress; 1195 1196 if (fraglen > MCLBYTES) 1197 fraglen = MCLBYTES; 1198 1199 if (m_new == NULL) { 1200 m_new = m_getcl(how, MT_DATA, 0); 1201 if (m_new == NULL) 1202 goto nospace; 1203 } 1204 1205 m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t)); 1206 progress += fraglen; 1207 m_new->m_len = fraglen; 1208 if (m_new != m_final) 1209 m_cat(m_final, m_new); 1210 m_new = NULL; 1211 } 1212 m_freem(m0); 1213 m0 = m_final; 1214 return (m0); 1215 nospace: 1216 if (m_new) 1217 m_free(m_new); 1218 if (m_final) 1219 m_freem(m_final); 1220 /* Return the original chain on failure */ 1221 return (m0); 1222 } 1223 1224 #endif 1225 1226 struct mbuf * 1227 m_uiotombuf(struct uio *uio, int how, int len) 1228 { 1229 struct mbuf *m_new = NULL, *m_final = NULL; 1230 int progress = 0, error = 0, length, total; 1231 1232 if (len > 0) 1233 total = min(uio->uio_resid, len); 1234 else 1235 total = uio->uio_resid; 1236 if (total > MHLEN) 1237 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 1238 else 1239 m_final = m_gethdr(how, MT_DATA); 1240 if (m_final == NULL) 1241 goto nospace; 1242 m_new = m_final; 1243 while (progress < total) { 1244 length = total - progress; 1245 if (length > MCLBYTES) 1246 length = MCLBYTES; 1247 if (m_new == NULL) { 1248 if (length > MLEN) 1249 m_new = m_getcl(how, MT_DATA, 0); 1250 else 1251 m_new = m_get(how, MT_DATA); 1252 if (m_new == NULL) 1253 goto nospace; 1254 } 1255 error = uiomove(mtod(m_new, void *), length, uio); 1256 if (error) 1257 goto nospace; 1258 progress += length; 1259 m_new->m_len = length; 1260 if (m_new != m_final) 1261 m_cat(m_final, m_new); 1262 m_new = NULL; 1263 } 1264 m_fixhdr(m_final); 1265 return (m_final); 1266 nospace: 1267 if (m_new) 1268 m_free(m_new); 1269 if (m_final) 1270 m_freem(m_final); 1271 return (NULL); 1272 }
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