1 /* $FreeBSD$ */ 2 /* $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 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/lock.h> 74 #include <sys/malloc.h> 75 #include <sys/mbuf.h> 76 #include <sys/mutex.h> 77 78 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 79 static struct mbuf *m_dup1 __P((struct mbuf *, int, int, int)); 80 81 /* 82 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 83 * packet chain before "off" is kept untouched. 84 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 85 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 86 * 87 * on error return (NULL return value), original "m" will be freed. 88 * 89 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 90 */ 91 struct mbuf * 92 m_pulldown(struct mbuf *m, int off, int len, int *offp) 93 { 94 struct mbuf *n, *o; 95 int hlen, tlen, olen; 96 int writable; 97 98 /* check invalid arguments. */ 99 if (m == NULL) 100 panic("m == NULL in m_pulldown()"); 101 if (len > MCLBYTES) { 102 m_freem(m); 103 return NULL; /* impossible */ 104 } 105 106 #ifdef PULLDOWN_DEBUG 107 { 108 struct mbuf *t; 109 printf("before:"); 110 for (t = m; t; t = t->m_next) 111 printf(" %d", t->m_len); 112 printf("\n"); 113 } 114 #endif 115 n = m; 116 while (n != NULL && off > 0) { 117 if (n->m_len > off) 118 break; 119 off -= n->m_len; 120 n = n->m_next; 121 } 122 /* be sure to point non-empty mbuf */ 123 while (n != NULL && n->m_len == 0) 124 n = n->m_next; 125 if (!n) { 126 m_freem(m); 127 return NULL; /* mbuf chain too short */ 128 } 129 130 /* 131 * XXX: This code is flawed because it considers a "writable" mbuf 132 * data region to require all of the following: 133 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 134 * mbuf, it is still not considered "writable." 135 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 136 * EXT_CLUSTER. Anything else makes it non-writable. 137 * (iii) M_WRITABLE() must evaluate true. 138 * Ideally, the requirement should only be (iii). 139 * 140 * If we're writable, we're sure we're writable, because the ref. count 141 * cannot increase from 1, as that would require posession of mbuf 142 * n by someone else (which is impossible). However, if we're _not_ 143 * writable, we may eventually become writable )if the ref. count drops 144 * to 1), but we'll fail to notice it unless we re-evaluate 145 * M_WRITABLE(). For now, we only evaluate once at the beginning and 146 * live with this. 147 */ 148 /* 149 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 150 * then we're not "writable," according to this code. 151 */ 152 writable = 0; 153 if ((n->m_flags & M_EXT) == 0 || 154 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 155 writable = 1; 156 157 /* 158 * the target data is on <n, off>. 159 * if we got enough data on the mbuf "n", we're done. 160 */ 161 if ((off == 0 || offp) && len <= n->m_len - off && writable) 162 goto ok; 163 164 /* 165 * when len <= n->m_len - off and off != 0, it is a special case. 166 * len bytes from <n, off> sits in single mbuf, but the caller does 167 * not like the starting position (off). 168 * chop the current mbuf into two pieces, set off to 0. 169 */ 170 if (len <= n->m_len - off) { 171 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT); 172 if (o == NULL) { 173 m_freem(m); 174 return NULL; /* ENOBUFS */ 175 } 176 n->m_len = off; 177 o->m_next = n->m_next; 178 n->m_next = o; 179 n = n->m_next; 180 off = 0; 181 goto ok; 182 } 183 184 /* 185 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 186 * and construct contiguous mbuf with m_len == len. 187 * note that hlen + tlen == len, and tlen > 0. 188 */ 189 hlen = n->m_len - off; 190 tlen = len - hlen; 191 192 /* 193 * ensure that we have enough trailing data on mbuf chain. 194 * if not, we can do nothing about the chain. 195 */ 196 olen = 0; 197 for (o = n->m_next; o != NULL; o = o->m_next) 198 olen += o->m_len; 199 if (hlen + olen < len) { 200 m_freem(m); 201 return NULL; /* mbuf chain too short */ 202 } 203 204 /* 205 * easy cases first. 206 * we need to use m_copydata() to get data from <n->m_next, 0>. 207 */ 208 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 209 && writable) { 210 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 211 n->m_len += tlen; 212 m_adj(n->m_next, tlen); 213 goto ok; 214 } 215 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 216 && writable) { 217 n->m_next->m_data -= hlen; 218 n->m_next->m_len += hlen; 219 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 220 n->m_len -= hlen; 221 n = n->m_next; 222 off = 0; 223 goto ok; 224 } 225 226 /* 227 * now, we need to do the hard way. don't m_copy as there's no room 228 * on both end. 229 */ 230 MGET(o, M_DONTWAIT, m->m_type); 231 if (o && len > MLEN) { 232 MCLGET(o, M_DONTWAIT); 233 if ((o->m_flags & M_EXT) == 0) { 234 m_free(o); 235 o = NULL; 236 } 237 } 238 if (!o) { 239 m_freem(m); 240 return NULL; /* ENOBUFS */ 241 } 242 /* get hlen from <n, off> into <o, 0> */ 243 o->m_len = hlen; 244 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 245 n->m_len -= hlen; 246 /* get tlen from <n->m_next, 0> into <o, hlen> */ 247 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 248 o->m_len += tlen; 249 m_adj(n->m_next, tlen); 250 o->m_next = n->m_next; 251 n->m_next = o; 252 n = o; 253 off = 0; 254 255 ok: 256 #ifdef PULLDOWN_DEBUG 257 { 258 struct mbuf *t; 259 printf("after:"); 260 for (t = m; t; t = t->m_next) 261 printf("%c%d", t == n ? '*' : ' ', t->m_len); 262 printf(" (off=%d)\n", off); 263 } 264 #endif 265 if (offp) 266 *offp = off; 267 return n; 268 } 269 270 static struct mbuf * 271 m_dup1(struct mbuf *m, int off, int len, int wait) 272 { 273 struct mbuf *n; 274 int l; 275 int copyhdr; 276 277 if (len > MCLBYTES) 278 return NULL; 279 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) { 280 copyhdr = 1; 281 MGETHDR(n, wait, m->m_type); 282 l = MHLEN; 283 } else { 284 copyhdr = 0; 285 MGET(n, wait, m->m_type); 286 l = MLEN; 287 } 288 if (n && len > l) { 289 MCLGET(n, wait); 290 if ((n->m_flags & M_EXT) == 0) { 291 m_free(n); 292 n = NULL; 293 } 294 } 295 if (!n) 296 return NULL; 297 298 if (copyhdr) 299 M_COPY_PKTHDR(n, m); 300 m_copydata(m, off, len, mtod(n, caddr_t)); 301 return n; 302 } 303 304 /* 305 * pkthdr.aux chain manipulation. 306 * we don't allow clusters at this moment. 307 */ 308 struct mbuf * 309 m_aux_add2(struct mbuf *m, int af, int type, void *p) 310 { 311 struct mbuf *n; 312 struct mauxtag *t; 313 314 if ((m->m_flags & M_PKTHDR) == 0) 315 return NULL; 316 317 n = m_aux_find(m, af, type); 318 if (n) 319 return n; 320 321 MGET(n, M_DONTWAIT, m->m_type); 322 if (n == NULL) 323 return NULL; 324 325 t = mtod(n, struct mauxtag *); 326 bzero(t, sizeof(*t)); 327 t->af = af; 328 t->type = type; 329 t->p = p; 330 n->m_data += sizeof(struct mauxtag); 331 n->m_len = 0; 332 n->m_next = m->m_pkthdr.aux; 333 m->m_pkthdr.aux = n; 334 return n; 335 } 336 337 struct mbuf * 338 m_aux_find2(struct mbuf *m, int af, int type, void *p) 339 { 340 struct mbuf *n; 341 struct mauxtag *t; 342 343 if ((m->m_flags & M_PKTHDR) == 0) 344 return NULL; 345 346 for (n = m->m_pkthdr.aux; n; n = n->m_next) { 347 t = (struct mauxtag *)n->m_dat; 348 if (n->m_data != ((caddr_t)t) + sizeof(struct mauxtag)) { 349 printf("m_aux_find: invalid m_data for mbuf=%p (%p %p)\n", n, t, n->m_data); 350 continue; 351 } 352 if (t->af == af && t->type == type && t->p == p) 353 return n; 354 } 355 return NULL; 356 } 357 358 struct mbuf * 359 m_aux_find(struct mbuf *m, int af, int type) 360 { 361 362 return m_aux_find2(m, af, type, NULL); 363 } 364 365 struct mbuf * 366 m_aux_add(struct mbuf *m, int af, int type) 367 { 368 369 return m_aux_add2(m, af, type, NULL); 370 } 371 372 void 373 m_aux_delete(struct mbuf *m, struct mbuf *victim) 374 { 375 struct mbuf *n, *prev, *next; 376 struct mauxtag *t; 377 378 if ((m->m_flags & M_PKTHDR) == 0) 379 return; 380 381 prev = NULL; 382 n = m->m_pkthdr.aux; 383 while (n) { 384 t = (struct mauxtag *)n->m_dat; 385 next = n->m_next; 386 if (n->m_data != ((caddr_t)t) + sizeof(struct mauxtag)) { 387 printf("m_aux_delete: invalid m_data for mbuf=%p (%p %p)\n", n, t, n->m_data); 388 prev = n; 389 n = next; 390 continue; 391 } 392 if (n == victim) { 393 if (prev) 394 prev->m_next = n->m_next; 395 else 396 m->m_pkthdr.aux = n->m_next; 397 n->m_next = NULL; 398 m_free(n); 399 } else 400 prev = n; 401 n = next; 402 } 403 } 404