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 * $Id: uipc_mbuf.c,v 1.39 1999/04/12 10:07:15 des Exp $ 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 static void mbinit __P((void *)); 51 SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL) 52 53 struct mbuf *mbutl; 54 char *mclrefcnt; 55 struct mbstat mbstat; 56 struct mbuf *mmbfree; 57 union mcluster *mclfree; 58 int max_linkhdr; 59 int max_protohdr; 60 int max_hdr; 61 int max_datalen; 62 63 SYSCTL_DECL(_kern_ipc); 64 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 65 &max_linkhdr, 0, ""); 66 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 67 &max_protohdr, 0, ""); 68 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 69 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 70 &max_datalen, 0, ""); 71 SYSCTL_STRUCT(_kern_ipc, KIPC_MBSTAT, mbstat, CTLFLAG_RW, &mbstat, mbstat, ""); 72 73 static void m_reclaim __P((void)); 74 75 /* "number of clusters of pages" */ 76 #define NCL_INIT 1 77 78 #define NMB_INIT 16 79 80 /* ARGSUSED*/ 81 static void 82 mbinit(dummy) 83 void *dummy; 84 { 85 int s; 86 87 mmbfree = NULL; mclfree = NULL; 88 mbstat.m_msize = MSIZE; 89 mbstat.m_mclbytes = MCLBYTES; 90 mbstat.m_minclsize = MINCLSIZE; 91 mbstat.m_mlen = MLEN; 92 mbstat.m_mhlen = MHLEN; 93 94 s = splimp(); 95 if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0) 96 goto bad; 97 #if MCLBYTES <= PAGE_SIZE 98 if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0) 99 goto bad; 100 #else 101 /* It's OK to call contigmalloc in this context. */ 102 if (m_clalloc(16, M_WAIT) == 0) 103 goto bad; 104 #endif 105 splx(s); 106 return; 107 bad: 108 panic("mbinit"); 109 } 110 111 /* 112 * Allocate at least nmb mbufs and place on mbuf free list. 113 * Must be called at splimp. 114 */ 115 /* ARGSUSED */ 116 int 117 m_mballoc(nmb, how) 118 register int nmb; 119 int how; 120 { 121 register caddr_t p; 122 register int i; 123 int nbytes; 124 125 /* Once we run out of map space, it will be impossible to get 126 * any more (nothing is ever freed back to the map) (XXX which 127 * is dumb). (however you are not dead as m_reclaim might 128 * still be able to free a substantial amount of space). 129 */ 130 if (mb_map_full) 131 return (0); 132 133 nbytes = round_page(nmb * MSIZE); 134 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT); 135 if (p == 0 && how == M_WAIT) { 136 mbstat.m_wait++; 137 p = (caddr_t)kmem_malloc(mb_map, nbytes, M_WAITOK); 138 } 139 140 /* 141 * Either the map is now full, or `how' is M_NOWAIT and there 142 * are no pages left. 143 */ 144 if (p == NULL) 145 return (0); 146 147 nmb = nbytes / MSIZE; 148 for (i = 0; i < nmb; i++) { 149 ((struct mbuf *)p)->m_next = mmbfree; 150 mmbfree = (struct mbuf *)p; 151 p += MSIZE; 152 } 153 mbstat.m_mbufs += nmb; 154 return (1); 155 } 156 157 #if MCLBYTES > PAGE_SIZE 158 static int i_want_my_mcl; 159 160 static void 161 kproc_mclalloc(void) 162 { 163 int status; 164 165 while (1) { 166 tsleep(&i_want_my_mcl, PVM, "mclalloc", 0); 167 168 for (; i_want_my_mcl; i_want_my_mcl--) { 169 if (m_clalloc(1, M_WAIT) == 0) 170 printf("m_clalloc failed even in process context!\n"); 171 } 172 } 173 } 174 175 static struct proc *mclallocproc; 176 static struct kproc_desc mclalloc_kp = { 177 "mclalloc", 178 kproc_mclalloc, 179 &mclallocproc 180 }; 181 SYSINIT(mclallocproc, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start, 182 &mclalloc_kp); 183 #endif 184 185 /* 186 * Allocate some number of mbuf clusters 187 * and place on cluster free list. 188 * Must be called at splimp. 189 */ 190 /* ARGSUSED */ 191 int 192 m_clalloc(ncl, how) 193 register int ncl; 194 int how; 195 { 196 register caddr_t p; 197 register int i; 198 int npg; 199 200 /* 201 * Once we run out of map space, it will be impossible 202 * to get any more (nothing is ever freed back to the 203 * map). 204 */ 205 if (mb_map_full) { 206 mbstat.m_drops++; 207 return (0); 208 } 209 210 #if MCLBYTES > PAGE_SIZE 211 if (how != M_WAIT) { 212 i_want_my_mcl += ncl; 213 wakeup(&i_want_my_mcl); 214 mbstat.m_wait++; 215 p = 0; 216 } else { 217 p = contigmalloc1(MCLBYTES * ncl, M_DEVBUF, M_WAITOK, 0ul, 218 ~0ul, PAGE_SIZE, 0, mb_map); 219 } 220 #else 221 npg = ncl; 222 p = (caddr_t)kmem_malloc(mb_map, ctob(npg), 223 how != M_WAIT ? M_NOWAIT : M_WAITOK); 224 ncl = ncl * PAGE_SIZE / MCLBYTES; 225 #endif 226 /* 227 * Either the map is now full, or `how' is M_NOWAIT and there 228 * are no pages left. 229 */ 230 if (p == NULL) { 231 mbstat.m_drops++; 232 return (0); 233 } 234 235 for (i = 0; i < ncl; i++) { 236 ((union mcluster *)p)->mcl_next = mclfree; 237 mclfree = (union mcluster *)p; 238 p += MCLBYTES; 239 mbstat.m_clfree++; 240 } 241 mbstat.m_clusters += ncl; 242 return (1); 243 } 244 245 /* 246 * When MGET fails, ask protocols to free space when short of memory, 247 * then re-attempt to allocate an mbuf. 248 */ 249 struct mbuf * 250 m_retry(i, t) 251 int i, t; 252 { 253 register struct mbuf *m; 254 255 /* 256 * Must only do the reclaim if not in an interrupt context. 257 */ 258 if (i == M_WAIT) 259 m_reclaim(); 260 #define m_retry(i, t) (struct mbuf *)0 261 MGET(m, i, t); 262 #undef m_retry 263 if (m != NULL) { 264 mbstat.m_wait++; 265 } else { 266 if (i == M_DONTWAIT) 267 mbstat.m_drops++; 268 else 269 panic("Out of mbuf clusters"); 270 } 271 return (m); 272 } 273 274 /* 275 * As above; retry an MGETHDR. 276 */ 277 struct mbuf * 278 m_retryhdr(i, t) 279 int i, t; 280 { 281 register struct mbuf *m; 282 283 /* 284 * Must only do the reclaim if not in an interrupt context. 285 */ 286 if (i == M_WAIT) 287 m_reclaim(); 288 #define m_retryhdr(i, t) (struct mbuf *)0 289 MGETHDR(m, i, t); 290 #undef m_retryhdr 291 if (m != NULL) { 292 mbstat.m_wait++; 293 } else { 294 if (i == M_DONTWAIT) 295 mbstat.m_drops++; 296 else 297 panic("Out of mbuf clusters"); 298 } 299 return (m); 300 } 301 302 static void 303 m_reclaim() 304 { 305 register struct domain *dp; 306 register struct protosw *pr; 307 int s = splimp(); 308 309 for (dp = domains; dp; dp = dp->dom_next) 310 for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++) 311 if (pr->pr_drain) 312 (*pr->pr_drain)(); 313 splx(s); 314 mbstat.m_drain++; 315 } 316 317 /* 318 * Space allocation routines. 319 * These are also available as macros 320 * for critical paths. 321 */ 322 struct mbuf * 323 m_get(how, type) 324 int how, type; 325 { 326 register struct mbuf *m; 327 328 MGET(m, how, type); 329 return (m); 330 } 331 332 struct mbuf * 333 m_gethdr(how, type) 334 int how, type; 335 { 336 register struct mbuf *m; 337 338 MGETHDR(m, how, type); 339 return (m); 340 } 341 342 struct mbuf * 343 m_getclr(how, type) 344 int how, type; 345 { 346 register struct mbuf *m; 347 348 MGET(m, how, type); 349 if (m == 0) 350 return (0); 351 bzero(mtod(m, caddr_t), MLEN); 352 return (m); 353 } 354 355 struct mbuf * 356 m_free(m) 357 struct mbuf *m; 358 { 359 register struct mbuf *n; 360 361 MFREE(m, n); 362 return (n); 363 } 364 365 void 366 m_freem(m) 367 register struct mbuf *m; 368 { 369 register struct mbuf *n; 370 371 if (m == NULL) 372 return; 373 do { 374 MFREE(m, n); 375 m = n; 376 } while (m); 377 } 378 379 /* 380 * Mbuffer utility routines. 381 */ 382 383 /* 384 * Lesser-used path for M_PREPEND: 385 * allocate new mbuf to prepend to chain, 386 * copy junk along. 387 */ 388 struct mbuf * 389 m_prepend(m, len, how) 390 register struct mbuf *m; 391 int len, how; 392 { 393 struct mbuf *mn; 394 395 MGET(mn, how, m->m_type); 396 if (mn == (struct mbuf *)NULL) { 397 m_freem(m); 398 return ((struct mbuf *)NULL); 399 } 400 if (m->m_flags & M_PKTHDR) { 401 M_COPY_PKTHDR(mn, m); 402 m->m_flags &= ~M_PKTHDR; 403 } 404 mn->m_next = m; 405 m = mn; 406 if (len < MHLEN) 407 MH_ALIGN(m, len); 408 m->m_len = len; 409 return (m); 410 } 411 412 /* 413 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 414 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 415 * The wait parameter is a choice of M_WAIT/M_DONTWAIT from caller. 416 */ 417 #define MCFail (mbstat.m_mcfail) 418 419 struct mbuf * 420 m_copym(m, off0, len, wait) 421 register struct mbuf *m; 422 int off0, wait; 423 register int len; 424 { 425 register struct mbuf *n, **np; 426 register int off = off0; 427 struct mbuf *top; 428 int copyhdr = 0; 429 430 if (off < 0 || len < 0) 431 panic("m_copym"); 432 if (off == 0 && m->m_flags & M_PKTHDR) 433 copyhdr = 1; 434 while (off > 0) { 435 if (m == 0) 436 panic("m_copym"); 437 if (off < m->m_len) 438 break; 439 off -= m->m_len; 440 m = m->m_next; 441 } 442 np = ⊤ 443 top = 0; 444 while (len > 0) { 445 if (m == 0) { 446 if (len != M_COPYALL) 447 panic("m_copym"); 448 break; 449 } 450 MGET(n, wait, m->m_type); 451 *np = n; 452 if (n == 0) 453 goto nospace; 454 if (copyhdr) { 455 M_COPY_PKTHDR(n, m); 456 if (len == M_COPYALL) 457 n->m_pkthdr.len -= off0; 458 else 459 n->m_pkthdr.len = len; 460 copyhdr = 0; 461 } 462 n->m_len = min(len, m->m_len - off); 463 if (m->m_flags & M_EXT) { 464 n->m_data = m->m_data + off; 465 if(!m->m_ext.ext_ref) 466 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 467 else 468 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 469 m->m_ext.ext_size); 470 n->m_ext = m->m_ext; 471 n->m_flags |= M_EXT; 472 } else 473 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 474 (unsigned)n->m_len); 475 if (len != M_COPYALL) 476 len -= n->m_len; 477 off = 0; 478 m = m->m_next; 479 np = &n->m_next; 480 } 481 if (top == 0) 482 MCFail++; 483 return (top); 484 nospace: 485 m_freem(top); 486 MCFail++; 487 return (0); 488 } 489 490 /* 491 * Copy an entire packet, including header (which must be present). 492 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 493 */ 494 struct mbuf * 495 m_copypacket(m, how) 496 struct mbuf *m; 497 int how; 498 { 499 struct mbuf *top, *n, *o; 500 501 MGET(n, how, m->m_type); 502 top = n; 503 if (!n) 504 goto nospace; 505 506 M_COPY_PKTHDR(n, m); 507 n->m_len = m->m_len; 508 if (m->m_flags & M_EXT) { 509 n->m_data = m->m_data; 510 if(!m->m_ext.ext_ref) 511 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 512 else 513 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 514 m->m_ext.ext_size); 515 n->m_ext = m->m_ext; 516 n->m_flags |= M_EXT; 517 } else { 518 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 519 } 520 521 m = m->m_next; 522 while (m) { 523 MGET(o, how, m->m_type); 524 if (!o) 525 goto nospace; 526 527 n->m_next = o; 528 n = n->m_next; 529 530 n->m_len = m->m_len; 531 if (m->m_flags & M_EXT) { 532 n->m_data = m->m_data; 533 if(!m->m_ext.ext_ref) 534 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 535 else 536 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 537 m->m_ext.ext_size); 538 n->m_ext = m->m_ext; 539 n->m_flags |= M_EXT; 540 } else { 541 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 542 } 543 544 m = m->m_next; 545 } 546 return top; 547 nospace: 548 m_freem(top); 549 MCFail++; 550 return 0; 551 } 552 553 /* 554 * Copy data from an mbuf chain starting "off" bytes from the beginning, 555 * continuing for "len" bytes, into the indicated buffer. 556 */ 557 void 558 m_copydata(m, off, len, cp) 559 register struct mbuf *m; 560 register int off; 561 register int len; 562 caddr_t cp; 563 { 564 register unsigned count; 565 566 if (off < 0 || len < 0) 567 panic("m_copydata"); 568 while (off > 0) { 569 if (m == 0) 570 panic("m_copydata"); 571 if (off < m->m_len) 572 break; 573 off -= m->m_len; 574 m = m->m_next; 575 } 576 while (len > 0) { 577 if (m == 0) 578 panic("m_copydata"); 579 count = min(m->m_len - off, len); 580 bcopy(mtod(m, caddr_t) + off, cp, count); 581 len -= count; 582 cp += count; 583 off = 0; 584 m = m->m_next; 585 } 586 } 587 588 /* 589 * Concatenate mbuf chain n to m. 590 * Both chains must be of the same type (e.g. MT_DATA). 591 * Any m_pkthdr is not updated. 592 */ 593 void 594 m_cat(m, n) 595 register struct mbuf *m, *n; 596 { 597 while (m->m_next) 598 m = m->m_next; 599 while (n) { 600 if (m->m_flags & M_EXT || 601 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 602 /* just join the two chains */ 603 m->m_next = n; 604 return; 605 } 606 /* splat the data from one into the other */ 607 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 608 (u_int)n->m_len); 609 m->m_len += n->m_len; 610 n = m_free(n); 611 } 612 } 613 614 void 615 m_adj(mp, req_len) 616 struct mbuf *mp; 617 int req_len; 618 { 619 register int len = req_len; 620 register struct mbuf *m; 621 register 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 #define MPFail (mbstat.m_mpfail) 697 698 struct mbuf * 699 m_pullup(n, len) 700 register struct mbuf *n; 701 int len; 702 { 703 register struct mbuf *m; 704 register int count; 705 int space; 706 707 /* 708 * If first mbuf has no cluster, and has room for len bytes 709 * without shifting current data, pullup into it, 710 * otherwise allocate a new mbuf to prepend to the chain. 711 */ 712 if ((n->m_flags & M_EXT) == 0 && 713 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 714 if (n->m_len >= len) 715 return (n); 716 m = n; 717 n = n->m_next; 718 len -= m->m_len; 719 } else { 720 if (len > MHLEN) 721 goto bad; 722 MGET(m, M_DONTWAIT, n->m_type); 723 if (m == 0) 724 goto bad; 725 m->m_len = 0; 726 if (n->m_flags & M_PKTHDR) { 727 M_COPY_PKTHDR(m, n); 728 n->m_flags &= ~M_PKTHDR; 729 } 730 } 731 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 732 do { 733 count = min(min(max(len, max_protohdr), space), n->m_len); 734 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 735 (unsigned)count); 736 len -= count; 737 m->m_len += count; 738 n->m_len -= count; 739 space -= count; 740 if (n->m_len) 741 n->m_data += count; 742 else 743 n = m_free(n); 744 } while (len > 0 && n); 745 if (len > 0) { 746 (void) m_free(m); 747 goto bad; 748 } 749 m->m_next = n; 750 return (m); 751 bad: 752 m_freem(n); 753 MPFail++; 754 return (0); 755 } 756 757 /* 758 * Partition an mbuf chain in two pieces, returning the tail -- 759 * all but the first len0 bytes. In case of failure, it returns NULL and 760 * attempts to restore the chain to its original state. 761 */ 762 struct mbuf * 763 m_split(m0, len0, wait) 764 register struct mbuf *m0; 765 int len0, wait; 766 { 767 register struct mbuf *m, *n; 768 unsigned len = len0, remain; 769 770 for (m = m0; m && len > m->m_len; m = m->m_next) 771 len -= m->m_len; 772 if (m == 0) 773 return (0); 774 remain = m->m_len - len; 775 if (m0->m_flags & M_PKTHDR) { 776 MGETHDR(n, wait, m0->m_type); 777 if (n == 0) 778 return (0); 779 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 780 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 781 m0->m_pkthdr.len = len0; 782 if (m->m_flags & M_EXT) 783 goto extpacket; 784 if (remain > MHLEN) { 785 /* m can't be the lead packet */ 786 MH_ALIGN(n, 0); 787 n->m_next = m_split(m, len, wait); 788 if (n->m_next == 0) { 789 (void) m_free(n); 790 return (0); 791 } else 792 return (n); 793 } else 794 MH_ALIGN(n, remain); 795 } else if (remain == 0) { 796 n = m->m_next; 797 m->m_next = 0; 798 return (n); 799 } else { 800 MGET(n, wait, m->m_type); 801 if (n == 0) 802 return (0); 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 if(!m->m_ext.ext_ref) 810 mclrefcnt[mtocl(m->m_ext.ext_buf)]++; 811 else 812 (*(m->m_ext.ext_ref))(m->m_ext.ext_buf, 813 m->m_ext.ext_size); 814 m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */ 815 n->m_data = m->m_data + len; 816 } else { 817 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 818 } 819 n->m_len = remain; 820 m->m_len = len; 821 n->m_next = m->m_next; 822 m->m_next = 0; 823 return (n); 824 } 825 /* 826 * Routine to copy from device local memory into mbufs. 827 */ 828 struct mbuf * 829 m_devget(buf, totlen, off0, ifp, copy) 830 char *buf; 831 int totlen, off0; 832 struct ifnet *ifp; 833 void (*copy) __P((char *from, caddr_t to, u_int len)); 834 { 835 register struct mbuf *m; 836 struct mbuf *top = 0, **mp = ⊤ 837 register int off = off0, len; 838 register char *cp; 839 char *epkt; 840 841 cp = buf; 842 epkt = cp + totlen; 843 if (off) { 844 cp += off + 2 * sizeof(u_short); 845 totlen -= 2 * sizeof(u_short); 846 } 847 MGETHDR(m, M_DONTWAIT, MT_DATA); 848 if (m == 0) 849 return (0); 850 m->m_pkthdr.rcvif = ifp; 851 m->m_pkthdr.len = totlen; 852 m->m_len = MHLEN; 853 854 while (totlen > 0) { 855 if (top) { 856 MGET(m, M_DONTWAIT, MT_DATA); 857 if (m == 0) { 858 m_freem(top); 859 return (0); 860 } 861 m->m_len = MLEN; 862 } 863 len = min(totlen, epkt - cp); 864 if (len >= MINCLSIZE) { 865 MCLGET(m, M_DONTWAIT); 866 if (m->m_flags & M_EXT) 867 m->m_len = len = min(len, MCLBYTES); 868 else 869 len = m->m_len; 870 } else { 871 /* 872 * Place initial small packet/header at end of mbuf. 873 */ 874 if (len < m->m_len) { 875 if (top == 0 && len + max_linkhdr <= m->m_len) 876 m->m_data += max_linkhdr; 877 m->m_len = len; 878 } else 879 len = m->m_len; 880 } 881 if (copy) 882 copy(cp, mtod(m, caddr_t), (unsigned)len); 883 else 884 bcopy(cp, mtod(m, caddr_t), (unsigned)len); 885 cp += len; 886 *mp = m; 887 mp = &m->m_next; 888 totlen -= len; 889 if (cp == epkt) 890 cp = buf; 891 } 892 return (top); 893 } 894 895 /* 896 * Copy data from a buffer back into the indicated mbuf chain, 897 * starting "off" bytes from the beginning, extending the mbuf 898 * chain if necessary. 899 */ 900 void 901 m_copyback(m0, off, len, cp) 902 struct mbuf *m0; 903 register int off; 904 register int len; 905 caddr_t cp; 906 { 907 register int mlen; 908 register struct mbuf *m = m0, *n; 909 int totlen = 0; 910 911 if (m0 == 0) 912 return; 913 while (off > (mlen = m->m_len)) { 914 off -= mlen; 915 totlen += mlen; 916 if (m->m_next == 0) { 917 n = m_getclr(M_DONTWAIT, m->m_type); 918 if (n == 0) 919 goto out; 920 n->m_len = min(MLEN, len + off); 921 m->m_next = n; 922 } 923 m = m->m_next; 924 } 925 while (len > 0) { 926 mlen = min (m->m_len - off, len); 927 bcopy(cp, off + mtod(m, caddr_t), (unsigned)mlen); 928 cp += mlen; 929 len -= mlen; 930 mlen += off; 931 off = 0; 932 totlen += mlen; 933 if (len == 0) 934 break; 935 if (m->m_next == 0) { 936 n = m_get(M_DONTWAIT, m->m_type); 937 if (n == 0) 938 break; 939 n->m_len = min(MLEN, len); 940 m->m_next = n; 941 } 942 m = m->m_next; 943 } 944 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 945 m->m_pkthdr.len = totlen; 946 } 947