1 /* $FreeBSD$ */ 2 /* $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $ */ 3 /* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */ 4 5 /* 6 * Copyright (C) 1999 WIDE Project. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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 34 /* 35 * Copyright (c) 1982, 1986, 1988, 1991, 1993 36 * The Regents of the University of California. All rights reserved. 37 * 38 * Redistribution and use in source and binary forms, with or without 39 * modification, are permitted provided that the following conditions 40 * are met: 41 * 1. Redistributions of source code must retain the above copyright 42 * notice, this list of conditions and the following disclaimer. 43 * 2. Redistributions in binary form must reproduce the above copyright 44 * notice, this list of conditions and the following disclaimer in the 45 * documentation and/or other materials provided with the distribution. 46 * 3. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgement: 48 * This product includes software developed by the University of 49 * California, Berkeley and its contributors. 50 * 4. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 67 */ 68 69 /*#define PULLDOWN_DEBUG*/ 70 71 #include <sys/param.h> 72 #include <sys/systm.h> 73 #include <sys/kernel.h> 74 #include <sys/lock.h> 75 #include <sys/malloc.h> 76 #include <sys/mbuf.h> 77 #include <sys/mutex.h> 78 79 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information"); 80 81 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 82 static struct mbuf *m_dup1(struct mbuf *, int, int, int); 83 84 /* 85 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 86 * packet chain before "off" is kept untouched. 87 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 88 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 89 * 90 * on error return (NULL return value), original "m" will be freed. 91 * 92 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 93 */ 94 struct mbuf * 95 m_pulldown(struct mbuf *m, int off, int len, int *offp) 96 { 97 struct mbuf *n, *o; 98 int hlen, tlen, olen; 99 int writable; 100 101 /* check invalid arguments. */ 102 if (m == NULL) 103 panic("m == NULL in m_pulldown()"); 104 if (len > MCLBYTES) { 105 m_freem(m); 106 return NULL; /* impossible */ 107 } 108 109 #ifdef PULLDOWN_DEBUG 110 { 111 struct mbuf *t; 112 printf("before:"); 113 for (t = m; t; t = t->m_next) 114 printf(" %d", t->m_len); 115 printf("\n"); 116 } 117 #endif 118 n = m; 119 while (n != NULL && off > 0) { 120 if (n->m_len > off) 121 break; 122 off -= n->m_len; 123 n = n->m_next; 124 } 125 /* be sure to point non-empty mbuf */ 126 while (n != NULL && n->m_len == 0) 127 n = n->m_next; 128 if (!n) { 129 m_freem(m); 130 return NULL; /* mbuf chain too short */ 131 } 132 133 /* 134 * XXX: This code is flawed because it considers a "writable" mbuf 135 * data region to require all of the following: 136 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 137 * mbuf, it is still not considered "writable." 138 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 139 * EXT_CLUSTER. Anything else makes it non-writable. 140 * (iii) M_WRITABLE() must evaluate true. 141 * Ideally, the requirement should only be (iii). 142 * 143 * If we're writable, we're sure we're writable, because the ref. count 144 * cannot increase from 1, as that would require posession of mbuf 145 * n by someone else (which is impossible). However, if we're _not_ 146 * writable, we may eventually become writable )if the ref. count drops 147 * to 1), but we'll fail to notice it unless we re-evaluate 148 * M_WRITABLE(). For now, we only evaluate once at the beginning and 149 * live with this. 150 */ 151 /* 152 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 153 * then we're not "writable," according to this code. 154 */ 155 writable = 0; 156 if ((n->m_flags & M_EXT) == 0 || 157 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 158 writable = 1; 159 160 /* 161 * the target data is on <n, off>. 162 * if we got enough data on the mbuf "n", we're done. 163 */ 164 if ((off == 0 || offp) && len <= n->m_len - off && writable) 165 goto ok; 166 167 /* 168 * when len <= n->m_len - off and off != 0, it is a special case. 169 * len bytes from <n, off> sits in single mbuf, but the caller does 170 * not like the starting position (off). 171 * chop the current mbuf into two pieces, set off to 0. 172 */ 173 if (len <= n->m_len - off) { 174 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT); 175 if (o == NULL) { 176 m_freem(m); 177 return NULL; /* ENOBUFS */ 178 } 179 n->m_len = off; 180 o->m_next = n->m_next; 181 n->m_next = o; 182 n = n->m_next; 183 off = 0; 184 goto ok; 185 } 186 187 /* 188 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 189 * and construct contiguous mbuf with m_len == len. 190 * note that hlen + tlen == len, and tlen > 0. 191 */ 192 hlen = n->m_len - off; 193 tlen = len - hlen; 194 195 /* 196 * ensure that we have enough trailing data on mbuf chain. 197 * if not, we can do nothing about the chain. 198 */ 199 olen = 0; 200 for (o = n->m_next; o != NULL; o = o->m_next) 201 olen += o->m_len; 202 if (hlen + olen < len) { 203 m_freem(m); 204 return NULL; /* mbuf chain too short */ 205 } 206 207 /* 208 * easy cases first. 209 * we need to use m_copydata() to get data from <n->m_next, 0>. 210 */ 211 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 212 && writable) { 213 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 214 n->m_len += tlen; 215 m_adj(n->m_next, tlen); 216 goto ok; 217 } 218 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 219 && writable) { 220 n->m_next->m_data -= hlen; 221 n->m_next->m_len += hlen; 222 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 223 n->m_len -= hlen; 224 n = n->m_next; 225 off = 0; 226 goto ok; 227 } 228 229 /* 230 * now, we need to do the hard way. don't m_copy as there's no room 231 * on both end. 232 */ 233 MGET(o, M_DONTWAIT, m->m_type); 234 if (o && len > MLEN) { 235 MCLGET(o, M_DONTWAIT); 236 if ((o->m_flags & M_EXT) == 0) { 237 m_free(o); 238 o = NULL; 239 } 240 } 241 if (!o) { 242 m_freem(m); 243 return NULL; /* ENOBUFS */ 244 } 245 /* get hlen from <n, off> into <o, 0> */ 246 o->m_len = hlen; 247 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 248 n->m_len -= hlen; 249 /* get tlen from <n->m_next, 0> into <o, hlen> */ 250 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 251 o->m_len += tlen; 252 m_adj(n->m_next, tlen); 253 o->m_next = n->m_next; 254 n->m_next = o; 255 n = o; 256 off = 0; 257 258 ok: 259 #ifdef PULLDOWN_DEBUG 260 { 261 struct mbuf *t; 262 printf("after:"); 263 for (t = m; t; t = t->m_next) 264 printf("%c%d", t == n ? '*' : ' ', t->m_len); 265 printf(" (off=%d)\n", off); 266 } 267 #endif 268 if (offp) 269 *offp = off; 270 return n; 271 } 272 273 static struct mbuf * 274 m_dup1(struct mbuf *m, int off, int len, int wait) 275 { 276 struct mbuf *n; 277 int l; 278 int copyhdr; 279 280 if (len > MCLBYTES) 281 return NULL; 282 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) { 283 copyhdr = 1; 284 MGETHDR(n, wait, m->m_type); 285 l = MHLEN; 286 } else { 287 copyhdr = 0; 288 MGET(n, wait, m->m_type); 289 l = MLEN; 290 } 291 if (n && len > l) { 292 MCLGET(n, wait); 293 if ((n->m_flags & M_EXT) == 0) { 294 m_free(n); 295 n = NULL; 296 } 297 } 298 if (!n) 299 return NULL; 300 301 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 302 m_free(n); 303 return NULL; 304 } 305 m_copydata(m, off, len, mtod(n, caddr_t)); 306 return n; 307 } 308 309 /* Get a packet tag structure along with specified data following. */ 310 struct m_tag * 311 m_tag_alloc(u_int32_t cookie, int type, int len, int wait) 312 { 313 struct m_tag *t; 314 315 if (len < 0) 316 return NULL; 317 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); 318 if (t == NULL) 319 return NULL; 320 t->m_tag_id = type; 321 t->m_tag_len = len; 322 t->m_tag_cookie = cookie; 323 return t; 324 } 325 326 /* Free a packet tag. */ 327 void 328 m_tag_free(struct m_tag *t) 329 { 330 free(t, M_PACKET_TAGS); 331 } 332 333 /* Prepend a packet tag. */ 334 void 335 m_tag_prepend(struct mbuf *m, struct m_tag *t) 336 { 337 KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t)); 338 SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link); 339 } 340 341 /* Unlink a packet tag. */ 342 void 343 m_tag_unlink(struct mbuf *m, struct m_tag *t) 344 { 345 KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t)); 346 SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link); 347 } 348 349 /* Unlink and free a packet tag. */ 350 void 351 m_tag_delete(struct mbuf *m, struct m_tag *t) 352 { 353 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 354 m_tag_unlink(m, t); 355 m_tag_free(t); 356 } 357 358 /* Unlink and free a packet tag chain, starting from given tag. */ 359 void 360 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 361 { 362 struct m_tag *p, *q; 363 364 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 365 if (t != NULL) 366 p = t; 367 else 368 p = SLIST_FIRST(&m->m_pkthdr.tags); 369 if (p == NULL) 370 return; 371 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 372 m_tag_delete(m, q); 373 m_tag_delete(m, p); 374 } 375 376 /* Find a tag, starting from a given position. */ 377 struct m_tag * 378 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t) 379 { 380 struct m_tag *p; 381 382 KASSERT(m, ("m_tag_locate: null mbuf")); 383 if (t == NULL) 384 p = SLIST_FIRST(&m->m_pkthdr.tags); 385 else 386 p = SLIST_NEXT(t, m_tag_link); 387 while (p != NULL) { 388 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 389 return p; 390 p = SLIST_NEXT(p, m_tag_link); 391 } 392 return NULL; 393 } 394 395 /* Copy a single tag. */ 396 struct m_tag * 397 m_tag_copy(struct m_tag *t, int how) 398 { 399 struct m_tag *p; 400 401 KASSERT(t, ("m_tag_copy: null tag")); 402 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 403 if (p == NULL) 404 return (NULL); 405 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 406 return p; 407 } 408 409 /* 410 * Copy two tag chains. The destination mbuf (to) loses any attached 411 * tags even if the operation fails. This should not be a problem, as 412 * m_tag_copy_chain() is typically called with a newly-allocated 413 * destination mbuf. 414 */ 415 int 416 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how) 417 { 418 struct m_tag *p, *t, *tprev = NULL; 419 420 KASSERT(to && from, 421 ("m_tag_copy_chain: null argument, to %p from %p", to, from)); 422 m_tag_delete_chain(to, NULL); 423 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { 424 t = m_tag_copy(p, how); 425 if (t == NULL) { 426 m_tag_delete_chain(to, NULL); 427 return 0; 428 } 429 if (tprev == NULL) 430 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); 431 else 432 SLIST_INSERT_AFTER(tprev, t, m_tag_link); 433 tprev = t; 434 } 435 return 1; 436 } 437 438 /* Initialize tags on an mbuf. */ 439 void 440 m_tag_init(struct mbuf *m) 441 { 442 SLIST_INIT(&m->m_pkthdr.tags); 443 } 444 445 /* Get first tag in chain. */ 446 struct m_tag * 447 m_tag_first(struct mbuf *m) 448 { 449 return SLIST_FIRST(&m->m_pkthdr.tags); 450 } 451 452 /* Get next tag in chain. */ 453 struct m_tag * 454 m_tag_next(struct mbuf *m, struct m_tag *t) 455 { 456 return SLIST_NEXT(t, m_tag_link); 457 } 458