1 /* 2 * Copyright 1998 Massachusetts Institute of Technology 3 * 4 * Permission to use, copy, modify, and distribute this software and 5 * its documentation for any purpose and without fee is hereby 6 * granted, provided that both the above copyright notice and this 7 * permission notice appear in all copies, that both the above 8 * copyright notice and this permission notice appear in all 9 * supporting documentation, and that the name of M.I.T. not be used 10 * in advertising or publicity pertaining to distribution of the 11 * software without specific, written prior permission. M.I.T. makes 12 * no representations about the suitability of this software for any 13 * purpose. It is provided "as is" without express or implied 14 * warranty. 15 * 16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS 17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE, 18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT 20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $Id: subr_rman.c,v 1.3 1998/12/07 21:58:29 archie Exp $ 30 */ 31 32 /* 33 * The kernel resource manager. This code is responsible for keeping track 34 * of hardware resources which are apportioned out to various drivers. 35 * It does not actually assign those resources, and it is not expected 36 * that end-device drivers will call into this code directly. Rather, 37 * the code which implements the buses that those devices are attached to, 38 * and the code which manages CPU resources, will call this code, and the 39 * end-device drivers will make upcalls to that code to actually perform 40 * the allocation. 41 * 42 * There are two sorts of resources managed by this code. The first is 43 * the more familiar array (RMAN_ARRAY) type; resources in this class 44 * consist of a sequence of individually-allocatable objects which have 45 * been numbered in some well-defined order. Most of the resources 46 * are of this type, as it is the most familiar. The second type is 47 * called a gauge (RMAN_GAUGE), and models fungible resources (i.e., 48 * resources in which each instance is indistinguishable from every 49 * other instance). The principal anticipated application of gauges 50 * is in the context of power consumption, where a bus may have a specific 51 * power budget which all attached devices share. RMAN_GAUGE is not 52 * implemented yet. 53 * 54 * For array resources, we make one simplifying assumption: two clients 55 * sharing the same resource must use the same range of indices. That 56 * is to say, sharing of overlapping-but-not-identical regions is not 57 * permitted. 58 */ 59 60 #include <sys/param.h> 61 #include <sys/systm.h> 62 #include <sys/kernel.h> 63 #include <sys/lock.h> 64 #include <sys/malloc.h> 65 #include <sys/rman.h> 66 #include <sys/bus.h> /* XXX debugging */ 67 68 MALLOC_DEFINE(M_RMAN, "rman", "Resource manager"); 69 70 struct rman_head rman_head; 71 #ifndef NULL_SIMPLELOCKS 72 static struct simplelock rman_lock; /* mutex to protect rman_head */ 73 #endif 74 static int int_rman_activate_resource(struct rman *rm, struct resource *r, 75 struct resource **whohas); 76 static int int_rman_release_resource(struct rman *rm, struct resource *r); 77 78 #define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head)) 79 80 int 81 rman_init(struct rman *rm) 82 { 83 static int once; 84 85 if (once == 0) { 86 once = 1; 87 TAILQ_INIT(&rman_head); 88 simple_lock_init(&rman_lock); 89 } 90 91 if (rm->rm_type == RMAN_UNINIT) 92 panic("rman_init"); 93 if (rm->rm_type == RMAN_GAUGE) 94 panic("implement RMAN_GAUGE"); 95 96 CIRCLEQ_INIT(&rm->rm_list); 97 rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT); 98 if (rm->rm_slock == 0) 99 return ENOMEM; 100 simple_lock_init(rm->rm_slock); 101 102 simple_lock(&rman_lock); 103 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link); 104 simple_unlock(&rman_lock); 105 return 0; 106 } 107 108 /* 109 * NB: this interface is not robust against programming errors which 110 * add multiple copies of the same region. 111 */ 112 int 113 rman_manage_region(struct rman *rm, u_long start, u_long end) 114 { 115 struct resource *r, *s; 116 117 r = malloc(sizeof *r, M_RMAN, M_NOWAIT); 118 if (r == 0) 119 return ENOMEM; 120 r->r_sharehead = 0; 121 r->r_start = start; 122 r->r_end = end; 123 r->r_flags = 0; 124 r->r_dev = 0; 125 r->r_rm = rm; 126 127 simple_lock(rm->rm_slock); 128 for (s = rm->rm_list.cqh_first; 129 !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start; 130 s = s->r_link.cqe_next) 131 ; 132 133 if (CIRCLEQ_TERMCOND(s, rm->rm_list)) { 134 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link); 135 } else { 136 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link); 137 } 138 139 simple_unlock(rm->rm_slock); 140 return 0; 141 } 142 143 int 144 rman_fini(struct rman *rm) 145 { 146 struct resource *r; 147 148 simple_lock(rm->rm_slock); 149 for (r = rm->rm_list.cqh_first; !CIRCLEQ_TERMCOND(r, rm->rm_list); 150 r = r->r_link.cqe_next) { 151 if (r->r_flags & RF_ALLOCATED) 152 return EBUSY; 153 } 154 155 /* 156 * There really should only be one of these if we are in this 157 * state and the code is working properly, but it can't hurt. 158 */ 159 for (r = rm->rm_list.cqh_first; !CIRCLEQ_TERMCOND(r, rm->rm_list); 160 r = rm->rm_list.cqh_first) { 161 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 162 free(r, M_RMAN); 163 } 164 simple_unlock(rm->rm_slock); 165 simple_lock(&rman_lock); 166 TAILQ_REMOVE(&rman_head, rm, rm_link); 167 simple_unlock(&rman_lock); 168 free(rm->rm_slock, M_RMAN); 169 170 return 0; 171 } 172 173 struct resource * 174 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, 175 u_int flags, struct device *dev) 176 { 177 u_int want_activate; 178 struct resource *r, *s, *rv; 179 u_long rstart, rend; 180 181 rv = 0; 182 183 #ifdef RMAN_DEBUG 184 printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length " 185 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end, 186 count, flags, device_get_name(dev), device_get_unit(dev)); 187 #endif /* RMAN_DEBUG */ 188 want_activate = (flags & RF_ACTIVE); 189 flags &= ~RF_ACTIVE; 190 191 simple_lock(rm->rm_slock); 192 193 for (r = rm->rm_list.cqh_first; 194 !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start; 195 r = r->r_link.cqe_next) 196 ; 197 198 if (CIRCLEQ_TERMCOND(r, rm->rm_list)) { 199 #ifdef RMAN_DEBUG 200 printf("could not find a region\n"); 201 #endif RMAN_DEBUG 202 goto out; 203 } 204 205 /* 206 * First try to find an acceptable totally-unshared region. 207 */ 208 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list); 209 s = s->r_link.cqe_next) { 210 #ifdef RMAN_DEBUG 211 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end); 212 #endif /* RMAN_DEBUG */ 213 if (s->r_start > end) { 214 #ifdef RMAN_DEBUG 215 printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end); 216 #endif /* RMAN_DEBUG */ 217 break; 218 } 219 if (s->r_flags & RF_ALLOCATED) { 220 #ifdef RMAN_DEBUG 221 printf("region is allocated\n"); 222 #endif /* RMAN_DEBUG */ 223 continue; 224 } 225 rstart = max(s->r_start, start); 226 rend = min(s->r_end, max(start + count, end)); 227 #ifdef RMAN_DEBUG 228 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n", 229 rstart, rend, (rend - rstart + 1), count); 230 #endif /* RMAN_DEBUG */ 231 232 if ((rend - rstart + 1) >= count) { 233 #ifdef RMAN_DEBUG 234 printf("candidate region: [%#lx, %#lx], size %#lx\n", 235 rend, rstart, (rend - rstart + 1)); 236 #endif /* RMAN_DEBUG */ 237 if ((s->r_end - s->r_start + 1) == count) { 238 #ifdef RMAN_DEBUG 239 printf("candidate region is entire chunk\n"); 240 #endif /* RMAN_DEBUG */ 241 rv = s; 242 rv->r_flags |= RF_ALLOCATED; 243 rv->r_dev = dev; 244 goto out; 245 } 246 247 /* 248 * If s->r_start < rstart and 249 * s->r_end > rstart + count - 1, then 250 * we need to split the region into three pieces 251 * (the middle one will get returned to the user). 252 * Otherwise, we are allocating at either the 253 * beginning or the end of s, so we only need to 254 * split it in two. The first case requires 255 * two new allocations; the second requires but one. 256 */ 257 rv = malloc(sizeof *r, M_RMAN, M_NOWAIT); 258 if (rv == 0) 259 goto out; 260 rv->r_start = rstart; 261 rv->r_end = rstart + count - 1; 262 rv->r_flags = flags | RF_ALLOCATED; 263 rv->r_dev = dev; 264 rv->r_sharehead = 0; 265 266 if (s->r_start < rv->r_start && s->r_end > rv->r_end) { 267 #ifdef RMAN_DEBUG 268 printf("splitting region in three parts: " 269 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n", 270 s->r_start, rv->r_start - 1, 271 rv->r_start, rv->r_end, 272 rv->r_end + 1, s->r_end); 273 #endif /* RMAN_DEBUG */ 274 /* 275 * We are allocating in the middle. 276 */ 277 r = malloc(sizeof *r, M_RMAN, M_NOWAIT); 278 if (r == 0) { 279 free(rv, M_RMAN); 280 rv = 0; 281 goto out; 282 } 283 r->r_start = rv->r_end + 1; 284 r->r_end = s->r_end; 285 r->r_flags = s->r_flags; 286 r->r_dev = 0; 287 r->r_sharehead = 0; 288 s->r_end = rv->r_start - 1; 289 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv, 290 r_link); 291 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r, 292 r_link); 293 } else if (s->r_start == rv->r_start) { 294 #ifdef RMAN_DEBUG 295 printf("allocating from the beginning\n"); 296 #endif /* RMAN_DEBUG */ 297 /* 298 * We are allocating at the beginning. 299 */ 300 s->r_start = rv->r_end + 1; 301 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv, 302 r_link); 303 } else { 304 #ifdef RMAN_DEBUG 305 printf("allocating at the end\n"); 306 #endif /* RMAN_DEBUG */ 307 /* 308 * We are allocating at the end. 309 */ 310 s->r_end = rv->r_start - 1; 311 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv, 312 r_link); 313 } 314 goto out; 315 } 316 } 317 318 /* 319 * Now find an acceptable shared region, if the client's requirements 320 * allow sharing. By our implementation restriction, a candidate 321 * region must match exactly by both size and sharing type in order 322 * to be considered compatible with the client's request. (The 323 * former restriction could probably be lifted without too much 324 * additional work, but this does not seem warranted.) 325 */ 326 #ifdef RMAN_DEBUG 327 printf("no unshared regions found\n"); 328 #endif /* RMAN_DEBUG */ 329 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0) 330 goto out; 331 332 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list); 333 s = s->r_link.cqe_next) { 334 if (s->r_start > end) 335 break; 336 if ((s->r_flags & flags) != flags) 337 continue; 338 rstart = max(s->r_start, start); 339 rend = min(s->r_end, max(start + count, end)); 340 if (s->r_start >= start && s->r_end <= end 341 && (s->r_end - s->r_start + 1) == count) { 342 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT); 343 if (rv == 0) 344 goto out; 345 rv->r_start = s->r_start; 346 rv->r_end = s->r_end; 347 rv->r_flags = s->r_flags & 348 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE); 349 rv->r_dev = dev; 350 rv->r_rm = rm; 351 if (s->r_sharehead == 0) { 352 s->r_sharehead = malloc(sizeof *s->r_sharehead, 353 M_RMAN, M_NOWAIT); 354 if (s->r_sharehead == 0) { 355 free(rv, M_RMAN); 356 rv = 0; 357 goto out; 358 } 359 LIST_INIT(s->r_sharehead); 360 LIST_INSERT_HEAD(s->r_sharehead, s, 361 r_sharelink); 362 s->r_flags = RF_FIRSTSHARE; 363 } 364 rv->r_sharehead = s->r_sharehead; 365 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink); 366 goto out; 367 } 368 } 369 370 /* 371 * We couldn't find anything. 372 */ 373 out: 374 /* 375 * If the user specified RF_ACTIVE in the initial flags, 376 * which is reflected in `want_activate', we attempt to atomically 377 * activate the resource. If this fails, we release the resource 378 * and indicate overall failure. (This behavior probably doesn't 379 * make sense for RF_TIMESHARE-type resources.) 380 */ 381 if (rv && want_activate) { 382 struct resource *whohas; 383 if (int_rman_activate_resource(rm, rv, &whohas)) { 384 int_rman_release_resource(rm, rv); 385 rv = 0; 386 } 387 } 388 389 simple_unlock(rm->rm_slock); 390 return (rv); 391 } 392 393 static int 394 int_rman_activate_resource(struct rman *rm, struct resource *r, 395 struct resource **whohas) 396 { 397 struct resource *s; 398 int ok; 399 400 /* 401 * If we are not timesharing, then there is nothing much to do. 402 * If we already have the resource, then there is nothing at all to do. 403 * If we are not on a sharing list with anybody else, then there is 404 * little to do. 405 */ 406 if ((r->r_flags & RF_TIMESHARE) == 0 407 || (r->r_flags & RF_ACTIVE) != 0 408 || r->r_sharehead == 0) { 409 r->r_flags |= RF_ACTIVE; 410 return 0; 411 } 412 413 ok = 1; 414 for (s = r->r_sharehead->lh_first; s && ok; 415 s = s->r_sharelink.le_next) { 416 if ((s->r_flags & RF_ACTIVE) != 0) { 417 ok = 0; 418 *whohas = s; 419 } 420 } 421 if (ok) { 422 r->r_flags |= RF_ACTIVE; 423 return 0; 424 } 425 return EBUSY; 426 } 427 428 int 429 rman_activate_resource(struct resource *r) 430 { 431 int rv; 432 struct resource *whohas; 433 struct rman *rm; 434 435 rm = r->r_rm; 436 simple_lock(rm->rm_slock); 437 rv = int_rman_activate_resource(rm, r, &whohas); 438 simple_unlock(rm->rm_slock); 439 return rv; 440 } 441 442 int 443 rman_await_resource(struct resource *r, int pri, int timo) 444 { 445 int rv, s; 446 struct resource *whohas; 447 struct rman *rm; 448 449 rm = r->r_rm; 450 for (;;) { 451 simple_lock(rm->rm_slock); 452 rv = int_rman_activate_resource(rm, r, &whohas); 453 if (rv != EBUSY) 454 return (rv); 455 456 if (r->r_sharehead == 0) 457 panic("rman_await_resource"); 458 /* 459 * splhigh hopefully will prevent a race between 460 * simple_unlock and tsleep where a process 461 * could conceivably get in and release the resource 462 * before we have a chance to sleep on it. 463 */ 464 s = splhigh(); 465 whohas->r_flags |= RF_WANTED; 466 simple_unlock(rm->rm_slock); 467 rv = tsleep(r->r_sharehead, pri, "rmwait", timo); 468 if (rv) { 469 splx(s); 470 return rv; 471 } 472 simple_lock(rm->rm_slock); 473 splx(s); 474 } 475 } 476 477 int 478 rman_deactivate_resource(struct resource *r) 479 { 480 struct rman *rm; 481 482 rm = r->r_rm; 483 simple_lock(rm->rm_slock); 484 r->r_flags &= ~RF_ACTIVE; 485 if (r->r_flags & RF_WANTED) { 486 r->r_flags &= ~RF_WANTED; 487 wakeup(r->r_sharehead); 488 } 489 simple_unlock(rm->rm_slock); 490 return 0; 491 } 492 493 static int 494 int_rman_release_resource(struct rman *rm, struct resource *r) 495 { 496 struct resource *s, *t; 497 498 if (r->r_flags & RF_ACTIVE) 499 return EBUSY; 500 501 /* 502 * Check for a sharing list first. If there is one, then we don't 503 * have to think as hard. 504 */ 505 if (r->r_sharehead) { 506 /* 507 * If a sharing list exists, then we know there are at 508 * least two sharers. 509 * 510 * If we are in the main circleq, appoint someone else. 511 */ 512 LIST_REMOVE(r, r_sharelink); 513 s = r->r_sharehead->lh_first; 514 if (r->r_flags & RF_FIRSTSHARE) { 515 s->r_flags |= RF_FIRSTSHARE; 516 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link); 517 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 518 } 519 520 /* 521 * Make sure that the sharing list goes away completely 522 * if the resource is no longer being shared at all. 523 */ 524 if (s->r_sharelink.le_next == 0) { 525 free(s->r_sharehead, M_RMAN); 526 s->r_sharehead = 0; 527 s->r_flags &= ~RF_FIRSTSHARE; 528 } 529 goto out; 530 } 531 532 /* 533 * Look at the adjacent resources in the list and see if our 534 * segment can be merged with any of them. 535 */ 536 s = r->r_link.cqe_prev; 537 t = r->r_link.cqe_next; 538 539 if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0 540 && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) { 541 /* 542 * Merge all three segments. 543 */ 544 s->r_end = t->r_end; 545 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 546 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link); 547 free(t, M_RMAN); 548 } else if (s != (void *)&rm->rm_list 549 && (s->r_flags & RF_ALLOCATED) == 0) { 550 /* 551 * Merge previous segment with ours. 552 */ 553 s->r_end = r->r_end; 554 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 555 } else if (t != (void *)&rm->rm_list 556 && (t->r_flags & RF_ALLOCATED) == 0) { 557 /* 558 * Merge next segment with ours. 559 */ 560 t->r_start = r->r_start; 561 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 562 } else { 563 /* 564 * At this point, we know there is nothing we 565 * can potentially merge with, because on each 566 * side, there is either nothing there or what is 567 * there is still allocated. In that case, we don't 568 * want to remove r from the list; we simply want to 569 * change it to an unallocated region and return 570 * without freeing anything. 571 */ 572 r->r_flags &= ~RF_ALLOCATED; 573 return 0; 574 } 575 576 out: 577 free(r, M_RMAN); 578 return 0; 579 } 580 581 int 582 rman_release_resource(struct resource *r) 583 { 584 int rv; 585 struct rman *rm = r->r_rm; 586 587 simple_lock(rm->rm_slock); 588 rv = int_rman_release_resource(rm, r); 589 simple_unlock(rm->rm_slock); 590 return (rv); 591 } 592