2 * Copyright 1998 Massachusetts Institute of Technology
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29 * $FreeBSD: src/sys/kern/subr_rman.c,v 1.10.2.1 2001/06/05 08:06:08 imp Exp $
30 * $DragonFly: src/sys/kern/subr_rman.c,v 1.10 2006/10/25 20:56:02 dillon Exp $
34 * The kernel resource manager. This code is responsible for keeping track
35 * of hardware resources which are apportioned out to various drivers.
36 * It does not actually assign those resources, and it is not expected
37 * that end-device drivers will call into this code directly. Rather,
38 * the code which implements the buses that those devices are attached to,
39 * and the code which manages CPU resources, will call this code, and the
40 * end-device drivers will make upcalls to that code to actually perform
43 * There are two sorts of resources managed by this code. The first is
44 * the more familiar array (RMAN_ARRAY) type; resources in this class
45 * consist of a sequence of individually-allocatable objects which have
46 * been numbered in some well-defined order. Most of the resources
47 * are of this type, as it is the most familiar. The second type is
48 * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
49 * resources in which each instance is indistinguishable from every
50 * other instance). The principal anticipated application of gauges
51 * is in the context of power consumption, where a bus may have a specific
52 * power budget which all attached devices share. RMAN_GAUGE is not
55 * For array resources, we make one simplifying assumption: two clients
56 * sharing the same resource must use the same range of indices. That
57 * is to say, sharing of overlapping-but-not-identical regions is not
61 #include <sys/param.h>
62 #include <sys/systm.h>
63 #include <sys/kernel.h>
65 #include <sys/malloc.h>
66 #include <sys/bus.h> /* XXX debugging */
69 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
71 struct rman_head rman_head;
72 static struct lwkt_token rman_tok; /* mutex to protect rman_head */
73 static int int_rman_activate_resource(struct rman *rm, struct resource *r,
74 struct resource **whohas);
75 static int int_rman_deactivate_resource(struct resource *r);
76 static int int_rman_release_resource(struct rman *rm, struct resource *r);
78 #define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head))
81 rman_init(struct rman *rm)
88 TAILQ_INIT(&rman_head);
89 lwkt_token_init(&rman_tok);
92 if (rm->rm_type == RMAN_UNINIT)
94 if (rm->rm_type == RMAN_GAUGE)
95 panic("implement RMAN_GAUGE");
97 CIRCLEQ_INIT(&rm->rm_list);
98 rm->rm_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
99 if (rm->rm_slock == NULL)
101 lwkt_token_init(rm->rm_slock);
103 lwkt_gettoken(&ilock, &rman_tok);
104 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
105 lwkt_reltoken(&ilock);
110 * NB: this interface is not robust against programming errors which
111 * add multiple copies of the same region.
114 rman_manage_region(struct rman *rm, u_long start, u_long end)
116 struct resource *r, *s;
119 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
130 lwkt_gettoken(&ilock, rm->rm_slock);
131 for (s = CIRCLEQ_FIRST(&rm->rm_list);
132 !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
133 s = CIRCLEQ_NEXT(s, r_link))
136 if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
137 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
139 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
142 lwkt_reltoken(&ilock);
147 rman_fini(struct rman *rm)
152 lwkt_gettoken(&ilock, rm->rm_slock);
153 CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
154 if (r->r_flags & RF_ALLOCATED) {
155 lwkt_reltoken(&ilock);
161 * There really should only be one of these if we are in this
162 * state and the code is working properly, but it can't hurt.
164 while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
165 r = CIRCLEQ_FIRST(&rm->rm_list);
166 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
169 lwkt_reltoken(&ilock);
170 /* XXX what's the point of this if we are going to free the struct? */
171 lwkt_gettoken(&ilock, &rman_tok);
172 TAILQ_REMOVE(&rman_head, rm, rm_link);
173 lwkt_reltoken(&ilock);
174 kfree(rm->rm_slock, M_RMAN);
180 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
181 u_int flags, struct device *dev)
184 struct resource *r, *s, *rv;
191 printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
192 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
193 count, flags, device_get_name(dev), device_get_unit(dev));
194 #endif /* RMAN_DEBUG */
195 want_activate = (flags & RF_ACTIVE);
198 lwkt_gettoken(&ilock, rm->rm_slock);
200 for (r = CIRCLEQ_FIRST(&rm->rm_list);
201 !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
202 r = CIRCLEQ_NEXT(r, r_link))
205 if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
207 printf("could not find a region\n");
213 * First try to find an acceptable totally-unshared region.
215 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
216 s = CIRCLEQ_NEXT(s, r_link)) {
218 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
219 #endif /* RMAN_DEBUG */
220 if (s->r_start > end) {
222 printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
223 #endif /* RMAN_DEBUG */
226 if (s->r_flags & RF_ALLOCATED) {
228 printf("region is allocated\n");
229 #endif /* RMAN_DEBUG */
232 rstart = max(s->r_start, start);
233 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
234 ~((1ul << RF_ALIGNMENT(flags)) - 1);
235 rend = min(s->r_end, max(start + count, end));
237 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
238 rstart, rend, (rend - rstart + 1), count);
239 #endif /* RMAN_DEBUG */
241 if ((rend - rstart + 1) >= count) {
243 printf("candidate region: [%#lx, %#lx], size %#lx\n",
244 rend, rstart, (rend - rstart + 1));
245 #endif /* RMAN_DEBUG */
246 if ((s->r_end - s->r_start + 1) == count) {
248 printf("candidate region is entire chunk\n");
249 #endif /* RMAN_DEBUG */
251 rv->r_flags |= RF_ALLOCATED | flags;
257 * If s->r_start < rstart and
258 * s->r_end > rstart + count - 1, then
259 * we need to split the region into three pieces
260 * (the middle one will get returned to the user).
261 * Otherwise, we are allocating at either the
262 * beginning or the end of s, so we only need to
263 * split it in two. The first case requires
264 * two new allocations; the second requires but one.
266 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
269 bzero(rv, sizeof *rv);
270 rv->r_start = rstart;
271 rv->r_end = rstart + count - 1;
272 rv->r_flags = flags | RF_ALLOCATED;
277 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
279 printf("splitting region in three parts: "
280 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
281 s->r_start, rv->r_start - 1,
282 rv->r_start, rv->r_end,
283 rv->r_end + 1, s->r_end);
284 #endif /* RMAN_DEBUG */
286 * We are allocating in the middle.
288 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
295 r->r_start = rv->r_end + 1;
297 r->r_flags = s->r_flags;
301 s->r_end = rv->r_start - 1;
302 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
304 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
306 } else if (s->r_start == rv->r_start) {
308 printf("allocating from the beginning\n");
309 #endif /* RMAN_DEBUG */
311 * We are allocating at the beginning.
313 s->r_start = rv->r_end + 1;
314 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
318 printf("allocating at the end\n");
319 #endif /* RMAN_DEBUG */
321 * We are allocating at the end.
323 s->r_end = rv->r_start - 1;
324 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
332 * Now find an acceptable shared region, if the client's requirements
333 * allow sharing. By our implementation restriction, a candidate
334 * region must match exactly by both size and sharing type in order
335 * to be considered compatible with the client's request. (The
336 * former restriction could probably be lifted without too much
337 * additional work, but this does not seem warranted.)
340 printf("no unshared regions found\n");
341 #endif /* RMAN_DEBUG */
342 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
345 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
346 s = CIRCLEQ_NEXT(s, r_link)) {
347 if (s->r_start > end)
349 if ((s->r_flags & flags) != flags)
351 rstart = max(s->r_start, start);
352 rend = min(s->r_end, max(start + count, end));
353 if (s->r_start >= start && s->r_end <= end
354 && (s->r_end - s->r_start + 1) == count) {
355 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
358 bzero(rv, sizeof *rv);
359 rv->r_start = s->r_start;
360 rv->r_end = s->r_end;
361 rv->r_flags = s->r_flags &
362 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
365 if (s->r_sharehead == 0) {
366 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
368 if (s->r_sharehead == 0) {
373 bzero(s->r_sharehead, sizeof *s->r_sharehead);
374 LIST_INIT(s->r_sharehead);
375 LIST_INSERT_HEAD(s->r_sharehead, s,
377 s->r_flags |= RF_FIRSTSHARE;
379 rv->r_sharehead = s->r_sharehead;
380 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
386 * We couldn't find anything.
390 * If the user specified RF_ACTIVE in the initial flags,
391 * which is reflected in `want_activate', we attempt to atomically
392 * activate the resource. If this fails, we release the resource
393 * and indicate overall failure. (This behavior probably doesn't
394 * make sense for RF_TIMESHARE-type resources.)
396 if (rv && want_activate) {
397 struct resource *whohas;
398 if (int_rman_activate_resource(rm, rv, &whohas)) {
399 int_rman_release_resource(rm, rv);
403 lwkt_reltoken(&ilock);
408 int_rman_activate_resource(struct rman *rm, struct resource *r,
409 struct resource **whohas)
415 * If we are not timesharing, then there is nothing much to do.
416 * If we already have the resource, then there is nothing at all to do.
417 * If we are not on a sharing list with anybody else, then there is
420 if ((r->r_flags & RF_TIMESHARE) == 0
421 || (r->r_flags & RF_ACTIVE) != 0
422 || r->r_sharehead == 0) {
423 r->r_flags |= RF_ACTIVE;
428 for (s = LIST_FIRST(r->r_sharehead); s && ok;
429 s = LIST_NEXT(s, r_sharelink)) {
430 if ((s->r_flags & RF_ACTIVE) != 0) {
436 r->r_flags |= RF_ACTIVE;
443 rman_activate_resource(struct resource *r)
446 struct resource *whohas;
451 lwkt_gettoken(&ilock, rm->rm_slock);
452 rv = int_rman_activate_resource(rm, r, &whohas);
453 lwkt_reltoken(&ilock);
461 rman_await_resource(struct resource *r, lwkt_tokref_t ilock, int slpflags, int timo)
464 struct resource *whohas;
469 lwkt_gettoken(ilock, rm->rm_slock);
470 rv = int_rman_activate_resource(rm, r, &whohas);
472 return (rv); /* returns with ilock held */
474 if (r->r_sharehead == 0)
475 panic("rman_await_resource");
477 * A critical section will hopefully will prevent a race
478 * between lwkt_reltoken and tsleep where a process
479 * could conceivably get in and release the resource
480 * before we have a chance to sleep on it. YYY
483 whohas->r_flags |= RF_WANTED;
484 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
486 lwkt_reltoken(ilock);
497 int_rman_deactivate_resource(struct resource *r)
502 r->r_flags &= ~RF_ACTIVE;
503 if (r->r_flags & RF_WANTED) {
504 r->r_flags &= ~RF_WANTED;
505 wakeup(r->r_sharehead);
511 rman_deactivate_resource(struct resource *r)
517 lwkt_gettoken(&ilock, rm->rm_slock);
518 int_rman_deactivate_resource(r);
519 lwkt_reltoken(&ilock);
524 int_rman_release_resource(struct rman *rm, struct resource *r)
526 struct resource *s, *t;
528 if (r->r_flags & RF_ACTIVE)
529 int_rman_deactivate_resource(r);
532 * Check for a sharing list first. If there is one, then we don't
533 * have to think as hard.
535 if (r->r_sharehead) {
537 * If a sharing list exists, then we know there are at
540 * If we are in the main circleq, appoint someone else.
542 LIST_REMOVE(r, r_sharelink);
543 s = LIST_FIRST(r->r_sharehead);
544 if (r->r_flags & RF_FIRSTSHARE) {
545 s->r_flags |= RF_FIRSTSHARE;
546 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
547 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
551 * Make sure that the sharing list goes away completely
552 * if the resource is no longer being shared at all.
554 if (LIST_NEXT(s, r_sharelink) == 0) {
555 kfree(s->r_sharehead, M_RMAN);
557 s->r_flags &= ~RF_FIRSTSHARE;
563 * Look at the adjacent resources in the list and see if our
564 * segment can be merged with any of them.
566 s = CIRCLEQ_PREV(r, r_link);
567 t = CIRCLEQ_NEXT(r, r_link);
569 if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
570 && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
572 * Merge all three segments.
575 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
576 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
578 } else if (s != (void *)&rm->rm_list
579 && (s->r_flags & RF_ALLOCATED) == 0) {
581 * Merge previous segment with ours.
584 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
585 } else if (t != (void *)&rm->rm_list
586 && (t->r_flags & RF_ALLOCATED) == 0) {
588 * Merge next segment with ours.
590 t->r_start = r->r_start;
591 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
594 * At this point, we know there is nothing we
595 * can potentially merge with, because on each
596 * side, there is either nothing there or what is
597 * there is still allocated. In that case, we don't
598 * want to remove r from the list; we simply want to
599 * change it to an unallocated region and return
600 * without freeing anything.
602 r->r_flags &= ~RF_ALLOCATED;
612 rman_release_resource(struct resource *r)
614 struct rman *rm = r->r_rm;
618 lwkt_gettoken(&ilock, rm->rm_slock);
619 rv = int_rman_release_resource(rm, r);
620 lwkt_reltoken(&ilock);
625 rman_make_alignment_flags(uint32_t size)
630 * Find the hightest bit set, and add one if more than one bit
631 * set. We're effectively computing the ceil(log2(size)) here.
633 for (i = 32; i > 0; i--)
636 if (~(1 << i) & size)
639 return(RF_ALIGNMENT_LOG2(i));