1 /* 2 * Copyright (c) 1982, 1986, 1988, 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 * @(#)mbuf.h 8.5 (Berkeley) 2/19/95 34 * $FreeBSD$ 35 */ 36 37 #ifndef _SYS_MBUF_H_ 38 #define _SYS_MBUF_H_ 39 40 /* 41 * Mbufs are of a single size, MSIZE (machine/param.h), which 42 * includes overhead. An mbuf may add a single "mbuf cluster" of size 43 * MCLBYTES (also in machine/param.h), which has no additional overhead 44 * and is used instead of the internal data area; this is done when 45 * at least MINCLSIZE of data must be stored. 46 */ 47 48 #define MLEN (MSIZE - sizeof(struct m_hdr)) /* normal data len */ 49 #define MHLEN (MLEN - sizeof(struct pkthdr)) /* data len w/pkthdr */ 50 51 #define MINCLSIZE (MHLEN + 1) /* smallest amount to put in cluster */ 52 #define M_MAXCOMPRESS (MHLEN / 2) /* max amount to copy for compression */ 53 54 /* 55 * Macros for type conversion 56 * mtod(m, t) - convert mbuf pointer to data pointer of correct type 57 * dtom(x) - convert data pointer within mbuf to mbuf pointer (XXX) 58 * mtocl(x) - convert pointer within cluster to cluster index # 59 * cltom(x) - convert cluster # to ptr to beginning of cluster 60 */ 61 #define mtod(m, t) ((t)((m)->m_data)) 62 #define dtom(x) ((struct mbuf *)((intptr_t)(x) & ~(MSIZE-1))) 63 #define mtocl(x) (((uintptr_t)(x) - (uintptr_t)mbutl) >> MCLSHIFT) 64 #define cltom(x) ((caddr_t)((uintptr_t)mbutl + \ 65 ((uintptr_t)(x) << MCLSHIFT))) 66 67 /* header at beginning of each mbuf: */ 68 struct m_hdr { 69 struct mbuf *mh_next; /* next buffer in chain */ 70 struct mbuf *mh_nextpkt; /* next chain in queue/record */ 71 caddr_t mh_data; /* location of data */ 72 int mh_len; /* amount of data in this mbuf */ 73 short mh_type; /* type of data in this mbuf */ 74 short mh_flags; /* flags; see below */ 75 }; 76 77 /* record/packet header in first mbuf of chain; valid if M_PKTHDR set */ 78 struct pkthdr { 79 struct ifnet *rcvif; /* rcv interface */ 80 int len; /* total packet length */ 81 /* variables for ip and tcp reassembly */ 82 caddr_t header; /* pointer to packet header */ 83 /* variables for hardware checksum */ 84 int csum_flags; /* flags regarding checksum */ 85 int csum_data; /* data field used by csum routines */ 86 }; 87 88 /* description of external storage mapped into mbuf, valid if M_EXT set */ 89 struct m_ext { 90 caddr_t ext_buf; /* start of buffer */ 91 void (*ext_free) /* free routine if not the usual */ 92 __P((caddr_t, u_int)); 93 u_int ext_size; /* size of buffer, for ext_free */ 94 void (*ext_ref) /* add a reference to the ext object */ 95 __P((caddr_t, u_int)); 96 }; 97 98 struct mbuf { 99 struct m_hdr m_hdr; 100 union { 101 struct { 102 struct pkthdr MH_pkthdr; /* M_PKTHDR set */ 103 union { 104 struct m_ext MH_ext; /* M_EXT set */ 105 char MH_databuf[MHLEN]; 106 } MH_dat; 107 } MH; 108 char M_databuf[MLEN]; /* !M_PKTHDR, !M_EXT */ 109 } M_dat; 110 }; 111 #define m_next m_hdr.mh_next 112 #define m_len m_hdr.mh_len 113 #define m_data m_hdr.mh_data 114 #define m_type m_hdr.mh_type 115 #define m_flags m_hdr.mh_flags 116 #define m_nextpkt m_hdr.mh_nextpkt 117 #define m_act m_nextpkt 118 #define m_pkthdr M_dat.MH.MH_pkthdr 119 #define m_ext M_dat.MH.MH_dat.MH_ext 120 #define m_pktdat M_dat.MH.MH_dat.MH_databuf 121 #define m_dat M_dat.M_databuf 122 123 /* mbuf flags */ 124 #define M_EXT 0x0001 /* has associated external storage */ 125 #define M_PKTHDR 0x0002 /* start of record */ 126 #define M_EOR 0x0004 /* end of record */ 127 #define M_PROTO1 0x0008 /* protocol-specific */ 128 #define M_PROTO2 0x0010 /* protocol-specific */ 129 #define M_PROTO3 0x0020 /* protocol-specific */ 130 #define M_PROTO4 0x0040 /* protocol-specific */ 131 #define M_PROTO5 0x0080 /* protocol-specific */ 132 133 /* mbuf pkthdr flags, also in m_flags */ 134 #define M_BCAST 0x0100 /* send/received as link-level broadcast */ 135 #define M_MCAST 0x0200 /* send/received as link-level multicast */ 136 #define M_FRAG 0x0400 /* packet is a fragment of a larger packet */ 137 #define M_FIRSTFRAG 0x0800 /* packet is first fragment */ 138 #define M_LASTFRAG 0x1000 /* packet is last fragment */ 139 140 /* flags copied when copying m_pkthdr */ 141 #define M_COPYFLAGS (M_PKTHDR|M_EOR|M_PROTO1|M_PROTO1|M_PROTO2|M_PROTO3 | \ 142 M_PROTO4|M_PROTO5|M_BCAST|M_MCAST|M_FRAG) 143 144 /* flags indicating hw checksum support and sw checksum requirements */ 145 #define CSUM_IP 0x0001 /* will csum IP */ 146 #define CSUM_TCP 0x0002 /* will csum TCP */ 147 #define CSUM_UDP 0x0004 /* will csum UDP */ 148 #define CSUM_IP_FRAGS 0x0008 /* will csum IP fragments */ 149 #define CSUM_FRAGMENT 0x0010 /* will do IP fragmentation */ 150 151 #define CSUM_IP_CHECKED 0x0100 /* did csum IP */ 152 #define CSUM_IP_VALID 0x0200 /* ... the csum is valid */ 153 #define CSUM_DATA_VALID 0x0400 /* csum_data field is valid */ 154 #define CSUM_PSEUDO_HDR 0x0800 /* csum_data has pseudo hdr */ 155 156 #define CSUM_DELAY_DATA (CSUM_TCP | CSUM_UDP) 157 #define CSUM_DELAY_IP (CSUM_IP) /* XXX add ipv6 here too? */ 158 159 /* mbuf types */ 160 #define MT_FREE 0 /* should be on free list */ 161 #define MT_DATA 1 /* dynamic (data) allocation */ 162 #define MT_HEADER 2 /* packet header */ 163 #if 0 164 #define MT_SOCKET 3 /* socket structure */ 165 #define MT_PCB 4 /* protocol control block */ 166 #define MT_RTABLE 5 /* routing tables */ 167 #define MT_HTABLE 6 /* IMP host tables */ 168 #define MT_ATABLE 7 /* address resolution tables */ 169 #endif 170 #define MT_SONAME 8 /* socket name */ 171 #if 0 172 #define MT_SOOPTS 10 /* socket options */ 173 #endif 174 #define MT_FTABLE 11 /* fragment reassembly header */ 175 #if 0 176 #define MT_RIGHTS 12 /* access rights */ 177 #define MT_IFADDR 13 /* interface address */ 178 #endif 179 #define MT_CONTROL 14 /* extra-data protocol message */ 180 #define MT_OOBDATA 15 /* expedited data */ 181 182 /* 183 * mbuf statistics 184 */ 185 struct mbstat { 186 u_long m_mbufs; /* mbufs obtained from page pool */ 187 u_long m_clusters; /* clusters obtained from page pool */ 188 u_long m_spare; /* spare field */ 189 u_long m_clfree; /* free clusters */ 190 u_long m_drops; /* times failed to find space */ 191 u_long m_wait; /* times waited for space */ 192 u_long m_drain; /* times drained protocols for space */ 193 u_short m_mtypes[256]; /* type specific mbuf allocations */ 194 u_long m_mcfail; /* times m_copym failed */ 195 u_long m_mpfail; /* times m_pullup failed */ 196 u_long m_msize; /* length of an mbuf */ 197 u_long m_mclbytes; /* length of an mbuf cluster */ 198 u_long m_minclsize; /* min length of data to allocate a cluster */ 199 u_long m_mlen; /* length of data in an mbuf */ 200 u_long m_mhlen; /* length of data in a header mbuf */ 201 }; 202 203 /* flags to m_get/MGET */ 204 #define M_DONTWAIT 1 205 #define M_WAIT 0 206 207 /* Freelists: 208 * 209 * Normal mbuf clusters are normally treated as character arrays 210 * after allocation, but use the first word of the buffer as a free list 211 * pointer while on the free list. 212 */ 213 union mcluster { 214 union mcluster *mcl_next; 215 char mcl_buf[MCLBYTES]; 216 }; 217 218 219 /* 220 * These are identifying numbers passed to the m_mballoc_wait function, 221 * allowing us to determine whether the call came from an MGETHDR or 222 * an MGET. 223 */ 224 #define MGETHDR_C 1 225 #define MGET_C 2 226 227 /* 228 * Wake up the next instance (if any) of m_mballoc_wait() which is 229 * waiting for an mbuf to be freed. This should be called at splimp(). 230 * 231 * XXX: If there is another free mbuf, this routine will be called [again] 232 * from the m_mballoc_wait routine in order to wake another sleep instance. 233 */ 234 #define MMBWAKEUP() do { \ 235 if (m_mballoc_wid) { \ 236 m_mballoc_wid--; \ 237 wakeup_one(&m_mballoc_wid); \ 238 } \ 239 } while (0) 240 241 /* 242 * Same as above, but for mbuf cluster(s). 243 */ 244 #define MCLWAKEUP() do { \ 245 if (m_clalloc_wid) { \ 246 m_clalloc_wid--; \ 247 wakeup_one(&m_clalloc_wid); \ 248 } \ 249 } while (0) 250 251 /* 252 * mbuf utility macros: 253 * 254 * MBUFLOCK(code) 255 * prevents a section of code from from being interrupted by network 256 * drivers. 257 */ 258 #define MBUFLOCK(code) do { \ 259 int _ms = splimp(); \ 260 \ 261 { code } \ 262 splx(_ms); \ 263 } while (0) 264 265 /* 266 * mbuf allocation/deallocation macros: 267 * 268 * MGET(struct mbuf *m, int how, int type) 269 * allocates an mbuf and initializes it to contain internal data. 270 * 271 * MGETHDR(struct mbuf *m, int how, int type) 272 * allocates an mbuf and initializes it to contain a packet header 273 * and internal data. 274 */ 275 #define MGET(m, how, type) do { \ 276 struct mbuf *_mm; \ 277 int _mhow = (how); \ 278 int _mtype = (type); \ 279 int _ms = splimp(); \ 280 \ 281 if (mmbfree == NULL) \ 282 (void)m_mballoc(1, _mhow); \ 283 _mm = mmbfree; \ 284 if (_mm != NULL) { \ 285 mmbfree = _mm->m_next; \ 286 mbstat.m_mtypes[MT_FREE]--; \ 287 _mm->m_type = _mtype; \ 288 mbstat.m_mtypes[_mtype]++; \ 289 _mm->m_next = NULL; \ 290 _mm->m_nextpkt = NULL; \ 291 _mm->m_data = _mm->m_dat; \ 292 _mm->m_flags = 0; \ 293 (m) = _mm; \ 294 splx(_ms); \ 295 } else { \ 296 splx(_ms); \ 297 _mm = m_retry(_mhow, _mtype); \ 298 if (_mm == NULL && _mhow == M_WAIT) \ 299 (m) = m_mballoc_wait(MGET_C, _mtype); \ 300 else \ 301 (m) = _mm; \ 302 } \ 303 } while (0) 304 305 #define MGETHDR(m, how, type) do { \ 306 struct mbuf *_mm; \ 307 int _mhow = (how); \ 308 int _mtype = (type); \ 309 int _ms = splimp(); \ 310 \ 311 if (mmbfree == NULL) \ 312 (void)m_mballoc(1, _mhow); \ 313 _mm = mmbfree; \ 314 if (_mm != NULL) { \ 315 mmbfree = _mm->m_next; \ 316 mbstat.m_mtypes[MT_FREE]--; \ 317 _mm->m_type = _mtype; \ 318 mbstat.m_mtypes[_mtype]++; \ 319 _mm->m_next = NULL; \ 320 _mm->m_nextpkt = NULL; \ 321 _mm->m_data = _mm->m_pktdat; \ 322 _mm->m_flags = M_PKTHDR; \ 323 _mm->m_pkthdr.rcvif = NULL; \ 324 _mm->m_pkthdr.csum_flags = 0; \ 325 (m) = _mm; \ 326 splx(_ms); \ 327 } else { \ 328 splx(_ms); \ 329 _mm = m_retryhdr(_mhow, _mtype); \ 330 if (_mm == NULL && _mhow == M_WAIT) \ 331 (m) = m_mballoc_wait(MGETHDR_C, _mtype); \ 332 else \ 333 (m) = _mm; \ 334 } \ 335 } while (0) 336 337 /* 338 * Mbuf cluster macros. 339 * MCLALLOC(caddr_t p, int how) allocates an mbuf cluster. 340 * MCLGET adds such clusters to a normal mbuf; 341 * the flag M_EXT is set upon success. 342 * MCLFREE releases a reference to a cluster allocated by MCLALLOC, 343 * freeing the cluster if the reference count has reached 0. 344 */ 345 #define MCLALLOC(p, how) do { \ 346 caddr_t _mp; \ 347 int _mhow = (how); \ 348 int _ms = splimp(); \ 349 \ 350 if (mclfree == NULL) \ 351 (void)m_clalloc(1, _mhow); \ 352 _mp = (caddr_t)mclfree; \ 353 if (_mp != NULL) { \ 354 mclrefcnt[mtocl(_mp)]++; \ 355 mbstat.m_clfree--; \ 356 mclfree = ((union mcluster *)_mp)->mcl_next; \ 357 (p) = _mp; \ 358 splx(_ms); \ 359 } else { \ 360 splx(_ms); \ 361 if (_mhow == M_WAIT) \ 362 (p) = m_clalloc_wait(); \ 363 else \ 364 (p) = NULL; \ 365 } \ 366 } while (0) 367 368 #define MCLGET(m, how) do { \ 369 struct mbuf *_mm = (m); \ 370 \ 371 MCLALLOC(_mm->m_ext.ext_buf, (how)); \ 372 if (_mm->m_ext.ext_buf != NULL) { \ 373 _mm->m_data = _mm->m_ext.ext_buf; \ 374 _mm->m_flags |= M_EXT; \ 375 _mm->m_ext.ext_free = NULL; \ 376 _mm->m_ext.ext_ref = NULL; \ 377 _mm->m_ext.ext_size = MCLBYTES; \ 378 } \ 379 } while (0) 380 381 #define MCLFREE1(p) do { \ 382 union mcluster *_mp = (union mcluster *)(p); \ 383 \ 384 if (--mclrefcnt[mtocl(_mp)] == 0) { \ 385 _mp->mcl_next = mclfree; \ 386 mclfree = _mp; \ 387 mbstat.m_clfree++; \ 388 MCLWAKEUP(); \ 389 } \ 390 } while (0) 391 392 #define MCLFREE(p) MBUFLOCK( \ 393 MCLFREE1(p); \ 394 ) 395 396 #define MEXTFREE1(m) do { \ 397 struct mbuf *_mm = (m); \ 398 \ 399 if (_mm->m_ext.ext_free != NULL) \ 400 (*_mm->m_ext.ext_free)(_mm->m_ext.ext_buf, \ 401 _mm->m_ext.ext_size); \ 402 else \ 403 MCLFREE1(_mm->m_ext.ext_buf); \ 404 } while (0) 405 406 #define MEXTFREE(m) MBUFLOCK( \ 407 MEXTFREE1(m); \ 408 ) 409 410 /* 411 * MFREE(struct mbuf *m, struct mbuf *n) 412 * Free a single mbuf and associated external storage. 413 * Place the successor, if any, in n. 414 */ 415 #define MFREE(m, n) MBUFLOCK( \ 416 struct mbuf *_mm = (m); \ 417 \ 418 mbstat.m_mtypes[_mm->m_type]--; \ 419 if (_mm->m_flags & M_EXT) \ 420 MEXTFREE1(m); \ 421 (n) = _mm->m_next; \ 422 _mm->m_type = MT_FREE; \ 423 mbstat.m_mtypes[MT_FREE]++; \ 424 _mm->m_next = mmbfree; \ 425 mmbfree = _mm; \ 426 MMBWAKEUP(); \ 427 ) 428 429 /* 430 * Copy mbuf pkthdr from "from" to "to". 431 * from must have M_PKTHDR set, and to must be empty. 432 */ 433 #define M_COPY_PKTHDR(to, from) do { \ 434 struct mbuf *_mfrom = (from); \ 435 struct mbuf *_mto = (to); \ 436 \ 437 _mto->m_data = _mto->m_pktdat; \ 438 _mto->m_flags = _mfrom->m_flags & M_COPYFLAGS; \ 439 _mto->m_pkthdr = _mfrom->m_pkthdr; \ 440 } while (0) 441 442 /* 443 * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place 444 * an object of the specified size at the end of the mbuf, longword aligned. 445 */ 446 #define M_ALIGN(m, len) do { \ 447 (m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1); \ 448 } while (0) 449 450 /* 451 * As above, for mbufs allocated with m_gethdr/MGETHDR 452 * or initialized by M_COPY_PKTHDR. 453 */ 454 #define MH_ALIGN(m, len) do { \ 455 (m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1); \ 456 } while (0) 457 458 /* 459 * Compute the amount of space available 460 * before the current start of data in an mbuf. 461 */ 462 #define M_LEADINGSPACE(m) \ 463 ((m)->m_flags & M_EXT ? \ 464 /* (m)->m_data - (m)->m_ext.ext_buf */ 0 : \ 465 (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat : \ 466 (m)->m_data - (m)->m_dat) 467 468 /* 469 * Compute the amount of space available 470 * after the end of data in an mbuf. 471 */ 472 #define M_TRAILINGSPACE(m) \ 473 ((m)->m_flags & M_EXT ? (m)->m_ext.ext_buf + \ 474 (m)->m_ext.ext_size - ((m)->m_data + (m)->m_len) : \ 475 &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len)) 476 477 /* 478 * Arrange to prepend space of size plen to mbuf m. 479 * If a new mbuf must be allocated, how specifies whether to wait. 480 * If how is M_DONTWAIT and allocation fails, the original mbuf chain 481 * is freed and m is set to NULL. 482 */ 483 #define M_PREPEND(m, plen, how) do { \ 484 struct mbuf **_mmp = &(m); \ 485 struct mbuf *_mm = *_mmp; \ 486 int _mplen = (plen); \ 487 int __mhow = (how); \ 488 \ 489 if (M_LEADINGSPACE(_mm) >= _mplen) { \ 490 _mm->m_data -= _mplen; \ 491 _mm->m_len += _mplen; \ 492 } else \ 493 _mm = m_prepend(_mm, _mplen, __mhow); \ 494 if (_mm != NULL && _mm->m_flags & M_PKTHDR) \ 495 _mm->m_pkthdr.len += _mplen; \ 496 *_mmp = _mm; \ 497 } while (0) 498 499 /* change mbuf to new type */ 500 #define MCHTYPE(m, t) do { \ 501 struct mbuf *_mm = (m); \ 502 int _mt = (t); \ 503 int _ms = splimp(); \ 504 \ 505 mbstat.m_mtypes[_mm->m_type]--; \ 506 mbstat.m_mtypes[_mt]++; \ 507 splx(_ms); \ 508 _mm->m_type = (_mt); \ 509 } while (0) 510 511 /* length to m_copy to copy all */ 512 #define M_COPYALL 1000000000 513 514 /* compatibility with 4.3 */ 515 #define m_copy(m, o, l) m_copym((m), (o), (l), M_DONTWAIT) 516 517 #ifdef _KERNEL 518 extern u_int m_clalloc_wid; /* mbuf cluster wait count */ 519 extern u_int m_mballoc_wid; /* mbuf wait count */ 520 extern int max_linkhdr; /* largest link-level header */ 521 extern int max_protohdr; /* largest protocol header */ 522 extern int max_hdr; /* largest link+protocol header */ 523 extern int max_datalen; /* MHLEN - max_hdr */ 524 extern struct mbstat mbstat; 525 extern int mbuf_wait; /* mbuf sleep time */ 526 extern struct mbuf *mbutl; /* virtual address of mclusters */ 527 extern char *mclrefcnt; /* cluster reference counts */ 528 extern union mcluster *mclfree; 529 extern struct mbuf *mmbfree; 530 extern int nmbclusters; 531 extern int nmbufs; 532 extern int nsfbufs; 533 534 void m_adj __P((struct mbuf *, int)); 535 void m_cat __P((struct mbuf *,struct mbuf *)); 536 int m_clalloc __P((int, int)); 537 caddr_t m_clalloc_wait __P((void)); 538 void m_copyback __P((struct mbuf *, int, int, caddr_t)); 539 void m_copydata __P((struct mbuf *,int,int,caddr_t)); 540 struct mbuf *m_copym __P((struct mbuf *, int, int, int)); 541 struct mbuf *m_copypacket __P((struct mbuf *, int)); 542 struct mbuf *m_devget __P((char *, int, int, struct ifnet *, 543 void (*copy)(char *, caddr_t, u_int))); 544 struct mbuf *m_dup __P((struct mbuf *, int)); 545 struct mbuf *m_free __P((struct mbuf *)); 546 void m_freem __P((struct mbuf *)); 547 struct mbuf *m_get __P((int, int)); 548 struct mbuf *m_getclr __P((int, int)); 549 struct mbuf *m_gethdr __P((int, int)); 550 int m_mballoc __P((int, int)); 551 struct mbuf *m_mballoc_wait __P((int, int)); 552 struct mbuf *m_prepend __P((struct mbuf *,int,int)); 553 void m_print __P((const struct mbuf *m)); 554 struct mbuf *m_pullup __P((struct mbuf *, int)); 555 struct mbuf *m_retry __P((int, int)); 556 struct mbuf *m_retryhdr __P((int, int)); 557 struct mbuf *m_split __P((struct mbuf *,int,int)); 558 #endif /* _KERNEL */ 559 560 #endif /* !_SYS_MBUF_H_ */ 561