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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94 34 * $FreeBSD$ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/malloc.h> 40 #include <sys/mbuf.h> 41 #include <sys/kernel.h> 42 #include <sys/sysctl.h> 43 #include <sys/domain.h> 44 #include <sys/protosw.h> 45 46 #include <vm/vm.h> 47 #include <vm/vm_kern.h> 48 #include <vm/vm_extern.h> 49 50 #ifdef INVARIANTS 51 #include <machine/cpu.h> 52 #endif 53 54 static void mbinit __P((void *)); 55 SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL) 56 57 struct mbuf *mbutl; 58 char *mclrefcnt; 59 struct mbstat mbstat; 60 struct mbuf *mmbfree; 61 union mcluster *mclfree; 62 int max_linkhdr; 63 int max_protohdr; 64 int max_hdr; 65 int max_datalen; 66 u_int m_mballoc_wid = 0; 67 u_int m_clalloc_wid = 0; 68 69 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 70 &max_linkhdr, 0, ""); 71 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 72 &max_protohdr, 0, ""); 73 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 74 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 75 &max_datalen, 0, ""); 76 SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW, 77 &mbuf_wait, 0, ""); 78 SYSCTL_STRUCT(_kern_ipc, KIPC_MBSTAT, mbstat, CTLFLAG_RW, &mbstat, mbstat, ""); 79 80 static void m_reclaim __P((void)); 81 82 /* "number of clusters of pages" */ 83 #define NCL_INIT 1 84 85 #define NMB_INIT 16 86 87 /* ARGSUSED*/ 88 static void 89 mbinit(dummy) 90 void *dummy; 91 { 92 int s; 93 94 mmbfree = NULL; mclfree = NULL; 95 mbstat.m_msize = MSIZE; 96 mbstat.m_mclbytes = MCLBYTES; 97 mbstat.m_minclsize = MINCLSIZE; 98 mbstat.m_mlen = MLEN; 99 mbstat.m_mhlen = MHLEN; 100 101 s = splimp(); 102 if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0) 103 goto bad; 104 #if MCLBYTES <= PAGE_SIZE 105 if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0) 106 goto bad; 107 #else 108 /* It's OK to call contigmalloc in this context. */ 109 if (m_clalloc(16, M_WAIT) == 0) 110 goto bad; 111 #endif 112 splx(s); 113 return; 114 bad: 115 panic("mbinit"); 116 } 117 118 /* 119 * Allocate at least nmb mbufs and place on mbuf free list. 120 * Must be called at splimp. 121 */ 122 /* ARGSUSED */ 123 int 124 m_mballoc(nmb, how) 125 register int nmb; 126 int how; 127 { 128 register caddr_t p; 129 register int i; 130 int nbytes; 131 132 /* 133 * If we've hit the mbuf limit, stop allocating from mb_map, 134 * (or trying to) in order to avoid dipping into the section of 135 * mb_map which we've "reserved" for clusters. 136 */ 137 if ((nmb + mbstat.m_mbufs) > nmbufs) 138 return (0); 139 140 /* 141 * Once we run out of map space, it will be impossible to get 142 * any more (nothing is ever freed back to the map) 143 * -- however you are not dead as m_reclaim might 144 * still be able to free a substantial amount of space. 145 * 146 * XXX Furthermore, we can also work with "recycled" mbufs (when 147 * we're calling with M_WAIT the sleep procedure will be woken 148 * up when an mbuf is freed. See m_mballoc_wait()). 149 */ 150 if (mb_map_full) 151 return (0); 152 153 nbytes = round_page(nmb * MSIZE); 154 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT); 155 if (p == 0 && how == M_WAIT) { 156 mbstat.m_wait++; 157 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_WAITOK); 158 } 159 160 /* 161 * Either the map is now full, or `how' is M_NOWAIT and there 162 * are no pages left. 163 */ 164 if (p == NULL) 165 return (0); 166 167 nmb = nbytes / MSIZE; 168 for (i = 0; i < nmb; i++) { 169 ((struct mbuf *)p)->m_next = mmbfree; 170 mmbfree = (struct mbuf *)p; 171 p += MSIZE; 172 } 173 mbstat.m_mbufs += nmb; 174 return (1); 175 } 176 177 /* 178 * Once the mb_map has been exhausted and if the call to the allocation macros 179 * (or, in some cases, functions) is with M_WAIT, then it is necessary to rely 180 * solely on reclaimed mbufs. Here we wait for an mbuf to be freed for a 181 * designated (mbuf_wait) time. 182 */ 183 struct mbuf * 184 m_mballoc_wait(int caller, int type) 185 { 186 struct mbuf *p; 187 int s; 188 189 m_mballoc_wid++; 190 if ((tsleep(&m_mballoc_wid, PVM, "mballc", mbuf_wait)) == EWOULDBLOCK) 191 m_mballoc_wid--; 192 193 /* 194 * Now that we (think) that we've got something, we will redo an 195 * MGET, but avoid getting into another instance of m_mballoc_wait() 196 * XXX: We retry to fetch _even_ if the sleep timed out. This is left 197 * this way, purposely, in the [unlikely] case that an mbuf was 198 * freed but the sleep was not awakened in time. 199 */ 200 p = NULL; 201 switch (caller) { 202 case MGET_C: 203 MGET(p, M_DONTWAIT, type); 204 break; 205 case MGETHDR_C: 206 MGETHDR(p, M_DONTWAIT, type); 207 break; 208 default: 209 panic("m_mballoc_wait: invalid caller (%d)", caller); 210 } 211 212 s = splimp(); 213 if (p != NULL) { /* We waited and got something... */ 214 mbstat.m_wait++; 215 /* Wake up another if we have more free. */ 216 if (mmbfree != NULL) 217 MMBWAKEUP(); 218 } 219 splx(s); 220 return (p); 221 } 222 223 #if MCLBYTES > PAGE_SIZE 224 static int i_want_my_mcl; 225 226 static void 227 kproc_mclalloc(void) 228 { 229 int status; 230 231 while (1) { 232 tsleep(&i_want_my_mcl, PVM, "mclalloc", 0); 233 234 for (; i_want_my_mcl; i_want_my_mcl--) { 235 if (m_clalloc(1, M_WAIT) == 0) 236 printf("m_clalloc failed even in process context!\n"); 237 } 238 } 239 } 240 241 static struct proc *mclallocproc; 242 static struct kproc_desc mclalloc_kp = { 243 "mclalloc", 244 kproc_mclalloc, 245 &mclallocproc 246 }; 247 SYSINIT_KT(mclallocproc, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start, 248 &mclalloc_kp); 249 #endif 250 251 /* 252 * Allocate some number of mbuf clusters 253 * and place on cluster free list. 254 * Must be called at splimp. 255 */ 256 /* ARGSUSED */ 257 int 258 m_clalloc(ncl, how) 259 register int ncl; 260 int how; 261 { 262 register caddr_t p; 263 register int i; 264 int npg; 265 266 /* 267 * If we've hit the mcluster number limit, stop allocating from 268 * mb_map, (or trying to) in order to avoid dipping into the section 269 * of mb_map which we've "reserved" for mbufs. 270 */ 271 if ((ncl + mbstat.m_clusters) > nmbclusters) { 272 mbstat.m_drops++; 273 return (0); 274 } 275 276 /* 277 * Once we run out of map space, it will be impossible 278 * to get any more (nothing is ever freed back to the 279 * map). From this point on, we solely rely on freed 280 * mclusters. 281 */ 282 if (mb_map_full) { 283 mbstat.m_drops++; 284 return (0); 285 } 286 287 #if MCLBYTES > PAGE_SIZE 288 if (how != M_WAIT) { 289 i_want_my_mcl += ncl; 290 wakeup(&i_want_my_mcl); 291 mbstat.m_wait++; 292 p = 0; 293 } else { 294 p = contigmalloc1(MCLBYTES * ncl, M_DEVBUF, M_WAITOK, 0ul, 295 ~0ul, PAGE_SIZE, 0, mb_map); 296 } 297 #else 298 npg = ncl; 299 p = (caddr_t)kmem_malloc(mb_map, ctob(npg), 300 how != M_WAIT ? M_NOWAIT : M_WAITOK); 301 ncl = ncl * PAGE_SIZE / MCLBYTES; 302 #endif 303 /* 304 * Either the map is now full, or `how' is M_NOWAIT and there 305 * are no pages left. 306 */ 307 if (p == NULL) { 308 mbstat.m_drops++; 309 return (0); 310 } 311 312 for (i = 0; i < ncl; i++) { 313 ((union mcluster *)p)->mcl_next = mclfree; 314 mclfree = (union mcluster *)p; 315 p += MCLBYTES; 316 mbstat.m_clfree++; 317 } 318 mbstat.m_clusters += ncl; 319 return (1); 320 } 321 322 /* 323 * Once the mb_map submap has been exhausted and the allocation is called with 324 * M_WAIT, we rely on the mclfree union pointers. If nothing is free, we will 325 * sleep for a designated amount of time (mbuf_wait) or until we're woken up 326 * due to sudden mcluster availability. 327 */ 328 caddr_t 329 m_clalloc_wait(void) 330 { 331 caddr_t p; 332 int s; 333 334 #ifdef __i386__ 335 /* If in interrupt context, and INVARIANTS, maintain sanity and die. */ 336 KASSERT(intr_nesting_level == 0, ("CLALLOC: CANNOT WAIT IN INTERRUPT")); 337 #endif 338 339 /* Sleep until something's available or until we expire. */ 340 m_clalloc_wid++; 341 if ((tsleep(&m_clalloc_wid, PVM, "mclalc", mbuf_wait)) == EWOULDBLOCK) 342 m_clalloc_wid--; 343 344 /* 345 * Now that we (think) that we've got something, we will redo and 346 * MGET, but avoid getting into another instance of m_clalloc_wait() 347 */ 348 p = NULL; 349 MCLALLOC(p, M_DONTWAIT); 350 351 s = splimp(); 352 if (p != NULL) { /* We waited and got something... */ 353 mbstat.m_wait++; 354 /* Wake up another if we have more free. */ 355 if (mclfree != NULL) 356 MCLWAKEUP(); 357 } 358 359 splx(s); 360 return (p); 361 } 362 363 /* 364 * When MGET fails, ask protocols to free space when short of memory, 365 * then re-attempt to allocate an mbuf. 366 */ 367 struct mbuf * 368 m_retry(i, t) 369 int i, t; 370 { 371 register struct mbuf *m; 372 373 /* 374 * Must only do the reclaim if not in an interrupt context. 375 */ 376 if (i == M_WAIT) { 377 #ifdef __i386__ 378 KASSERT(intr_nesting_level == 0, 379 ("MBALLOC: CANNOT WAIT IN INTERRUPT")); 380 #endif 381 m_reclaim(); 382 } 383 384 /* 385 * Both m_mballoc_wait and m_retry must be nulled because 386 * when the MGET macro is run from here, we deffinately do _not_ 387 * want to enter an instance of m_mballoc_wait() or m_retry() (again!) 388 */ 389 #define m_mballoc_wait(caller,type) (struct mbuf *)0 390 #define m_retry(i, t) (struct mbuf *)0 391 MGET(m, i, t); 392 #undef m_retry 393 #undef m_mballoc_wait 394 395 if (m != NULL) 396 mbstat.m_wait++; 397 else 398 mbstat.m_drops++; 399 400 return (m); 401 } 402 403 /* 404 * As above; retry an MGETHDR. 405 */ 406 struct mbuf * 407 m_retryhdr(i, t) 408 int i, t; 409 { 410 register struct mbuf *m; 411 412 /* 413 * Must only do the reclaim if not in an interrupt context. 414 */ 415 if (i == M_WAIT) { 416 #ifdef __i386__ 417 KASSERT(intr_nesting_level == 0, 418 ("MBALLOC: CANNOT WAIT IN INTERRUPT")); 419 #endif 420 m_reclaim(); 421 } 422 423 #define m_mballoc_wait(caller,type) (struct mbuf *)0 424 #define m_retryhdr(i, t) (struct mbuf *)0 425 MGETHDR(m, i, t); 426 #undef m_retryhdr 427 #undef m_mballoc_wait 428 429 if (m != NULL) 430 mbstat.m_wait++; 431 else 432 mbstat.m_drops++; 433 434 return (m); 435 } 436 437 static void 438 m_reclaim() 439 { 440 register struct domain *dp; 441 register struct protosw *pr; 442 int s = splimp(); 443 444 for (dp = domains; dp; dp = dp->dom_next) 445 for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++) 446 if (pr->pr_drain) 447 (*pr->pr_drain)(); 448 splx(s); 449 mbstat.m_drain++; 450 } 451 452 /* 453 * Space allocation routines. 454 * These are also available as macros 455 * for critical paths. 456 */ 457 struct mbuf * 458 m_get(how, type) 459 int how, type; 460 { 461 register struct mbuf *m; 462 463 MGET(m, how, type); 464 return (m); 465 } 466 467 struct mbuf * 468 m_gethdr(how, type) 469 int how, type; 470 { 471 register struct mbuf *m; 472 473 MGETHDR(m, how, type); 474 return (m); 475 } 476 477 struct mbuf * 478 m_getclr(how, type) 479 int how, type; 480 { 481 register struct mbuf *m; 482 483 MGET(m, how, type); 484 if (m == 0) 485 return (0); 486 bzero(mtod(m, caddr_t), MLEN); 487 return (m); 488 } 489 490 struct mbuf * 491 m_free(m) 492 struct mbuf *m; 493 { 494 register struct mbuf *n; 495 496 MFREE(m, n); 497 return (n); 498 } 499 500 void 501 m_freem(m) 502 register struct mbuf *m; 503 { 504 register struct mbuf *n; 505 506 if (m == NULL) 507 return; 508 do { 509 MFREE(m, n); 510 m = n; 511 } while (m); 512 } 513 514 /* 515 * Mbuffer utility routines. 516 */ 517 518 /* 519 * Lesser-used path for M_PREPEND: 520 * allocate new mbuf to prepend to chain, 521 * copy junk along. 522 */ 523 struct mbuf * 524 m_prepend(m, len, how) 525 register struct mbuf *m; 526 int len, how; 527 { 528 struct mbuf *mn; 529 530 MGET(mn, how, m->m_type); 531 if (mn == (struct mbuf *)NULL) { 532 m_freem(m); 533 return ((struct mbuf *)NULL); 534 } 535 if (m->m_flags & M_PKTHDR) { 536 M_COPY_PKTHDR(mn, m); 537 m->m_flags &= ~M_PKTHDR; 538 } 539 mn->m_next = m; 540 m = mn; 541 if (len < MHLEN) 542 MH_ALIGN(m, len); 543 m->m_len = len; 544 return (m); 545 } 546 547 /* 548 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 549 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 550 * The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller. 551 * Note that the copy is read-only, because clusters are not copied, 552 * only their reference counts are incremented. 553 */ 554 #define MCFail (mbstat.m_mcfail) 555 556 struct mbuf * 557 m_copym(m, off0, len, wait) 558 register struct mbuf *m; 559 int off0, wait; 560 register int len; 561 { 562 register struct mbuf *n, **np; 563 register int off = off0; 564 struct mbuf *top; 565 int copyhdr = 0; 566 567 if (off < 0 || len < 0) 568 panic("m_copym"); 569 if (off == 0 && m->m_flags & M_PKTHDR) 570 copyhdr = 1; 571 while (off > 0) { 572 if (m == 0) 573 panic("m_copym"); 574 if (off < m->m_len) 575 break; 576 off -= m->m_len; 577 m = m->m_next; 578 } 579 np = ⊤ 580 top = 0; 581 while (len > 0) { 582 if (m == 0) { 583 if (len != M_COPYALL) 584 panic("m_copym"); 585 break; 586 } 587 MGET(n, wait, m->m_type); 588 *np = n; 589 if (n == 0) 590 goto nospace; 591 if (copyhdr) { 592 M_COPY_PKTHDR(n, m); 593 if (len == M_COPYALL) 594 n->m_pkthdr.len -= off0; 595 else 596 n->m_pkthdr.len = len; 597 copyhdr = 0; 598 } 599 n->m_len = min(len, m->m_len - off); 600 if (m->m_flags & M_EXT) { 601 n->m_data = m->m_data + off; 602 if(!m->m_ext.ext_ref) 603 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 604 else 605 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 606 m->m_ext.ext_size); 607 n->m_ext = m->m_ext; 608 n->m_flags |= M_EXT; 609 } else 610 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 611 (unsigned)n->m_len); 612 if (len != M_COPYALL) 613 len -= n->m_len; 614 off = 0; 615 m = m->m_next; 616 np = &n->m_next; 617 } 618 if (top == 0) 619 MCFail++; 620 return (top); 621 nospace: 622 m_freem(top); 623 MCFail++; 624 return (0); 625 } 626 627 /* 628 * Copy an entire packet, including header (which must be present). 629 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 630 * Note that the copy is read-only, because clusters are not copied, 631 * only their reference counts are incremented. 632 */ 633 struct mbuf * 634 m_copypacket(m, how) 635 struct mbuf *m; 636 int how; 637 { 638 struct mbuf *top, *n, *o; 639 640 MGET(n, how, m->m_type); 641 top = n; 642 if (!n) 643 goto nospace; 644 645 M_COPY_PKTHDR(n, m); 646 n->m_len = m->m_len; 647 if (m->m_flags & M_EXT) { 648 n->m_data = m->m_data; 649 if(!m->m_ext.ext_ref) 650 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 651 else 652 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 653 m->m_ext.ext_size); 654 n->m_ext = m->m_ext; 655 n->m_flags |= M_EXT; 656 } else { 657 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 658 } 659 660 m = m->m_next; 661 while (m) { 662 MGET(o, how, m->m_type); 663 if (!o) 664 goto nospace; 665 666 n->m_next = o; 667 n = n->m_next; 668 669 n->m_len = m->m_len; 670 if (m->m_flags & M_EXT) { 671 n->m_data = m->m_data; 672 if(!m->m_ext.ext_ref) 673 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 674 else 675 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 676 m->m_ext.ext_size); 677 n->m_ext = m->m_ext; 678 n->m_flags |= M_EXT; 679 } else { 680 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 681 } 682 683 m = m->m_next; 684 } 685 return top; 686 nospace: 687 m_freem(top); 688 MCFail++; 689 return 0; 690 } 691 692 /* 693 * Copy data from an mbuf chain starting "off" bytes from the beginning, 694 * continuing for "len" bytes, into the indicated buffer. 695 */ 696 void 697 m_copydata(m, off, len, cp) 698 register struct mbuf *m; 699 register int off; 700 register int len; 701 caddr_t cp; 702 { 703 register unsigned count; 704 705 if (off < 0 || len < 0) 706 panic("m_copydata"); 707 while (off > 0) { 708 if (m == 0) 709 panic("m_copydata"); 710 if (off < m->m_len) 711 break; 712 off -= m->m_len; 713 m = m->m_next; 714 } 715 while (len > 0) { 716 if (m == 0) 717 panic("m_copydata"); 718 count = min(m->m_len - off, len); 719 bcopy(mtod(m, caddr_t) + off, cp, count); 720 len -= count; 721 cp += count; 722 off = 0; 723 m = m->m_next; 724 } 725 } 726 727 /* 728 * Copy a packet header mbuf chain into a completely new chain, including 729 * copying any mbuf clusters. Use this instead of m_copypacket() when 730 * you need a writable copy of an mbuf chain. 731 */ 732 struct mbuf * 733 m_dup(m, how) 734 struct mbuf *m; 735 int how; 736 { 737 struct mbuf **p, *top = NULL; 738 int remain, moff, nsize; 739 740 /* Sanity check */ 741 if (m == NULL) 742 return (0); 743 KASSERT((m->m_flags & M_PKTHDR) != 0, ("%s: !PKTHDR", __FUNCTION__)); 744 745 /* While there's more data, get a new mbuf, tack it on, and fill it */ 746 remain = m->m_pkthdr.len; 747 moff = 0; 748 p = ⊤ 749 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 750 struct mbuf *n; 751 752 /* Get the next new mbuf */ 753 MGET(n, how, m->m_type); 754 if (n == NULL) 755 goto nospace; 756 if (top == NULL) { /* first one, must be PKTHDR */ 757 M_COPY_PKTHDR(n, m); 758 nsize = MHLEN; 759 } else /* not the first one */ 760 nsize = MLEN; 761 if (remain >= MINCLSIZE) { 762 MCLGET(n, how); 763 if ((n->m_flags & M_EXT) == 0) { 764 (void)m_free(n); 765 goto nospace; 766 } 767 nsize = MCLBYTES; 768 } 769 n->m_len = 0; 770 771 /* Link it into the new chain */ 772 *p = n; 773 p = &n->m_next; 774 775 /* Copy data from original mbuf(s) into new mbuf */ 776 while (n->m_len < nsize && m != NULL) { 777 int chunk = min(nsize - n->m_len, m->m_len - moff); 778 779 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 780 moff += chunk; 781 n->m_len += chunk; 782 remain -= chunk; 783 if (moff == m->m_len) { 784 m = m->m_next; 785 moff = 0; 786 } 787 } 788 789 /* Check correct total mbuf length */ 790 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 791 ("%s: bogus m_pkthdr.len", __FUNCTION__)); 792 } 793 return (top); 794 795 nospace: 796 m_freem(top); 797 MCFail++; 798 return (0); 799 } 800 801 /* 802 * Concatenate mbuf chain n to m. 803 * Both chains must be of the same type (e.g. MT_DATA). 804 * Any m_pkthdr is not updated. 805 */ 806 void 807 m_cat(m, n) 808 register struct mbuf *m, *n; 809 { 810 while (m->m_next) 811 m = m->m_next; 812 while (n) { 813 if (m->m_flags & M_EXT || 814 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 815 /* just join the two chains */ 816 m->m_next = n; 817 return; 818 } 819 /* splat the data from one into the other */ 820 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 821 (u_int)n->m_len); 822 m->m_len += n->m_len; 823 n = m_free(n); 824 } 825 } 826 827 void 828 m_adj(mp, req_len) 829 struct mbuf *mp; 830 int req_len; 831 { 832 register int len = req_len; 833 register struct mbuf *m; 834 register int count; 835 836 if ((m = mp) == NULL) 837 return; 838 if (len >= 0) { 839 /* 840 * Trim from head. 841 */ 842 while (m != NULL && len > 0) { 843 if (m->m_len <= len) { 844 len -= m->m_len; 845 m->m_len = 0; 846 m = m->m_next; 847 } else { 848 m->m_len -= len; 849 m->m_data += len; 850 len = 0; 851 } 852 } 853 m = mp; 854 if (mp->m_flags & M_PKTHDR) 855 m->m_pkthdr.len -= (req_len - len); 856 } else { 857 /* 858 * Trim from tail. Scan the mbuf chain, 859 * calculating its length and finding the last mbuf. 860 * If the adjustment only affects this mbuf, then just 861 * adjust and return. Otherwise, rescan and truncate 862 * after the remaining size. 863 */ 864 len = -len; 865 count = 0; 866 for (;;) { 867 count += m->m_len; 868 if (m->m_next == (struct mbuf *)0) 869 break; 870 m = m->m_next; 871 } 872 if (m->m_len >= len) { 873 m->m_len -= len; 874 if (mp->m_flags & M_PKTHDR) 875 mp->m_pkthdr.len -= len; 876 return; 877 } 878 count -= len; 879 if (count < 0) 880 count = 0; 881 /* 882 * Correct length for chain is "count". 883 * Find the mbuf with last data, adjust its length, 884 * and toss data from remaining mbufs on chain. 885 */ 886 m = mp; 887 if (m->m_flags & M_PKTHDR) 888 m->m_pkthdr.len = count; 889 for (; m; m = m->m_next) { 890 if (m->m_len >= count) { 891 m->m_len = count; 892 break; 893 } 894 count -= m->m_len; 895 } 896 while (m->m_next) 897 (m = m->m_next) ->m_len = 0; 898 } 899 } 900 901 /* 902 * Rearange an mbuf chain so that len bytes are contiguous 903 * and in the data area of an mbuf (so that mtod and dtom 904 * will work for a structure of size len). Returns the resulting 905 * mbuf chain on success, frees it and returns null on failure. 906 * If there is room, it will add up to max_protohdr-len extra bytes to the 907 * contiguous region in an attempt to avoid being called next time. 908 */ 909 #define MPFail (mbstat.m_mpfail) 910 911 struct mbuf * 912 m_pullup(n, len) 913 register struct mbuf *n; 914 int len; 915 { 916 register struct mbuf *m; 917 register int count; 918 int space; 919 920 /* 921 * If first mbuf has no cluster, and has room for len bytes 922 * without shifting current data, pullup into it, 923 * otherwise allocate a new mbuf to prepend to the chain. 924 */ 925 if ((n->m_flags & M_EXT) == 0 && 926 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 927 if (n->m_len >= len) 928 return (n); 929 m = n; 930 n = n->m_next; 931 len -= m->m_len; 932 } else { 933 if (len > MHLEN) 934 goto bad; 935 MGET(m, M_DONTWAIT, n->m_type); 936 if (m == 0) 937 goto bad; 938 m->m_len = 0; 939 if (n->m_flags & M_PKTHDR) { 940 M_COPY_PKTHDR(m, n); 941 n->m_flags &= ~M_PKTHDR; 942 } 943 } 944 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 945 do { 946 count = min(min(max(len, max_protohdr), space), n->m_len); 947 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 948 (unsigned)count); 949 len -= count; 950 m->m_len += count; 951 n->m_len -= count; 952 space -= count; 953 if (n->m_len) 954 n->m_data += count; 955 else 956 n = m_free(n); 957 } while (len > 0 && n); 958 if (len > 0) { 959 (void) m_free(m); 960 goto bad; 961 } 962 m->m_next = n; 963 return (m); 964 bad: 965 m_freem(n); 966 MPFail++; 967 return (0); 968 } 969 970 /* 971 * Partition an mbuf chain in two pieces, returning the tail -- 972 * all but the first len0 bytes. In case of failure, it returns NULL and 973 * attempts to restore the chain to its original state. 974 */ 975 struct mbuf * 976 m_split(m0, len0, wait) 977 register struct mbuf *m0; 978 int len0, wait; 979 { 980 register struct mbuf *m, *n; 981 unsigned len = len0, remain; 982 983 for (m = m0; m && len > m->m_len; m = m->m_next) 984 len -= m->m_len; 985 if (m == 0) 986 return (0); 987 remain = m->m_len - len; 988 if (m0->m_flags & M_PKTHDR) { 989 MGETHDR(n, wait, m0->m_type); 990 if (n == 0) 991 return (0); 992 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 993 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 994 m0->m_pkthdr.len = len0; 995 if (m->m_flags & M_EXT) 996 goto extpacket; 997 if (remain > MHLEN) { 998 /* m can't be the lead packet */ 999 MH_ALIGN(n, 0); 1000 n->m_next = m_split(m, len, wait); 1001 if (n->m_next == 0) { 1002 (void) m_free(n); 1003 return (0); 1004 } else 1005 return (n); 1006 } else 1007 MH_ALIGN(n, remain); 1008 } else if (remain == 0) { 1009 n = m->m_next; 1010 m->m_next = 0; 1011 return (n); 1012 } else { 1013 MGET(n, wait, m->m_type); 1014 if (n == 0) 1015 return (0); 1016 M_ALIGN(n, remain); 1017 } 1018 extpacket: 1019 if (m->m_flags & M_EXT) { 1020 n->m_flags |= M_EXT; 1021 n->m_ext = m->m_ext; 1022 if(!m->m_ext.ext_ref) 1023 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 1024 else 1025 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 1026 m->m_ext.ext_size); 1027 m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */ 1028 n->m_data = m->m_data + len; 1029 } else { 1030 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 1031 } 1032 n->m_len = remain; 1033 m->m_len = len; 1034 n->m_next = m->m_next; 1035 m->m_next = 0; 1036 return (n); 1037 } 1038 /* 1039 * Routine to copy from device local memory into mbufs. 1040 */ 1041 struct mbuf * 1042 m_devget(buf, totlen, off0, ifp, copy) 1043 char *buf; 1044 int totlen, off0; 1045 struct ifnet *ifp; 1046 void (*copy) __P((char *from, caddr_t to, u_int len)); 1047 { 1048 register struct mbuf *m; 1049 struct mbuf *top = 0, **mp = ⊤ 1050 register int off = off0, len; 1051 register char *cp; 1052 char *epkt; 1053 1054 cp = buf; 1055 epkt = cp + totlen; 1056 if (off) { 1057 cp += off + 2 * sizeof(u_short); 1058 totlen -= 2 * sizeof(u_short); 1059 } 1060 MGETHDR(m, M_DONTWAIT, MT_DATA); 1061 if (m == 0) 1062 return (0); 1063 m->m_pkthdr.rcvif = ifp; 1064 m->m_pkthdr.len = totlen; 1065 m->m_len = MHLEN; 1066 1067 while (totlen > 0) { 1068 if (top) { 1069 MGET(m, M_DONTWAIT, MT_DATA); 1070 if (m == 0) { 1071 m_freem(top); 1072 return (0); 1073 } 1074 m->m_len = MLEN; 1075 } 1076 len = min(totlen, epkt - cp); 1077 if (len >= MINCLSIZE) { 1078 MCLGET(m, M_DONTWAIT); 1079 if (m->m_flags & M_EXT) 1080 m->m_len = len = min(len, MCLBYTES); 1081 else 1082 len = m->m_len; 1083 } else { 1084 /* 1085 * Place initial small packet/header at end of mbuf. 1086 */ 1087 if (len < m->m_len) { 1088 if (top == 0 && len + max_linkhdr <= m->m_len) 1089 m->m_data += max_linkhdr; 1090 m->m_len = len; 1091 } else 1092 len = m->m_len; 1093 } 1094 if (copy) 1095 copy(cp, mtod(m, caddr_t), (unsigned)len); 1096 else 1097 bcopy(cp, mtod(m, caddr_t), (unsigned)len); 1098 cp += len; 1099 *mp = m; 1100 mp = &m->m_next; 1101 totlen -= len; 1102 if (cp == epkt) 1103 cp = buf; 1104 } 1105 return (top); 1106 } 1107 1108 /* 1109 * Copy data from a buffer back into the indicated mbuf chain, 1110 * starting "off" bytes from the beginning, extending the mbuf 1111 * chain if necessary. 1112 */ 1113 void 1114 m_copyback(m0, off, len, cp) 1115 struct mbuf *m0; 1116 register int off; 1117 register int len; 1118 caddr_t cp; 1119 { 1120 register int mlen; 1121 register struct mbuf *m = m0, *n; 1122 int totlen = 0; 1123 1124 if (m0 == 0) 1125 return; 1126 while (off > (mlen = m->m_len)) { 1127 off -= mlen; 1128 totlen += mlen; 1129 if (m->m_next == 0) { 1130 n = m_getclr(M_DONTWAIT, m->m_type); 1131 if (n == 0) 1132 goto out; 1133 n->m_len = min(MLEN, len + off); 1134 m->m_next = n; 1135 } 1136 m = m->m_next; 1137 } 1138 while (len > 0) { 1139 mlen = min (m->m_len - off, len); 1140 bcopy(cp, off + mtod(m, caddr_t), (unsigned)mlen); 1141 cp += mlen; 1142 len -= mlen; 1143 mlen += off; 1144 off = 0; 1145 totlen += mlen; 1146 if (len == 0) 1147 break; 1148 if (m->m_next == 0) { 1149 n = m_get(M_DONTWAIT, m->m_type); 1150 if (n == 0) 1151 break; 1152 n->m_len = min(MLEN, len); 1153 m->m_next = n; 1154 } 1155 m = m->m_next; 1156 } 1157 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 1158 m->m_pkthdr.len = totlen; 1159 }
Cache object: 89605f036febb9043a040f522775ea90
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