The new resource manager, hopefully in a reasonably stable form.

1 files changed, 589 insertions, 0 deletions

diff --git a/sys/kern/subr_rman.c b/sys/kern/subr_rman.c
new file mode 100644
index 0000000..c0d4620
--- /dev/null
+++ b/sys/kern/subr_rman.c
@@ -0,0 +1,589 @@
+/*
+ * Copyright 1998 Massachusetts Institute of Technology
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose and without fee is hereby
+ * granted, provided that both the above copyright notice and this
+ * permission notice appear in all copies, that both the above
+ * copyright notice and this permission notice appear in all
+ * supporting documentation, and that the name of M.I.T. not be used
+ * in advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.  M.I.T. makes
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied
+ * warranty.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
+ * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
+ * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$Id$
+ */
+
+/*
+ * The kernel resource manager.  This code is responsible for keeping track
+ * of hardware resources which are apportioned out to various drivers.
+ * It does not actually assign those resources, and it is not expected
+ * that end-device drivers will call into this code directly.  Rather,
+ * the code which implements the buses that those devices are attached to,
+ * and the code which manages CPU resources, will call this code, and the
+ * end-device drivers will make upcalls to that code to actually perform
+ * the allocation.
+ *
+ * There are two sorts of resources managed by this code.  The first is
+ * the more familiar array (RMAN_ARRAY) type; resources in this class
+ * consist of a sequence of individually-allocatable objects which have
+ * been numbered in some well-defined order.  Most of the resources
+ * are of this type, as it is the most familiar.  The second type is
+ * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
+ * resources in which each instance is indistinguishable from every
+ * other instance).  The principal anticipated application of gauges
+ * is in the context of power consumption, where a bus may have a specific
+ * power budget which all attached devices share.  RMAN_GAUGE is not
+ * implemented yet.
+ *
+ * For array resources, we make one simplifying assumption: two clients
+ * sharing the same resource must use the same range of indices.  That
+ * is to say, sharing of overlapping-but-not-identical regions is not
+ * permitted.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/rman.h>
+#include <sys/bus.h>		/* XXX debugging */
+
+MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
+
+struct	rman_head rman_head;
+static	struct simplelock rman_lock; /* mutex to protect rman_head */
+static	int int_rman_activate_resource(struct rman *rm, struct resource *r,
+				       struct resource **whohas);
+static	int int_rman_release_resource(struct rman *rm, struct resource *r);
+
+#define	CIRCLEQ_TERMCOND(var, head)	(var == (void *)&(head))
+
+int
+rman_init(struct rman *rm)
+{
+	static int once;
+	struct resource *r;
+
+	if (once == 0) {
+		once = 1;
+		TAILQ_INIT(&rman_head);
+		simple_lock_init(&rman_lock);
+	}
+
+	if (rm->rm_type == RMAN_UNINIT)
+		panic("rman_init");
+	if (rm->rm_type == RMAN_GAUGE)
+		panic("implement RMAN_GAUGE");
+
+	CIRCLEQ_INIT(&rm->rm_list);
+	rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
+	if (rm->rm_slock == 0)
+		return ENOMEM;
+	simple_lock_init(rm->rm_slock);
+
+	simple_lock(&rman_lock);
+	TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
+	simple_unlock(&rman_lock);
+	return 0;
+}
+
+/*
+ * NB: this interface is not robust against programming errors which
+ * add multiple copies of the same region.
+ */
+int
+rman_manage_region(struct rman *rm, u_long start, u_long end)
+{
+	struct resource *r, *s;
+
+	r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
+	if (r == 0)
+		return ENOMEM;
+	r->r_sharehead = 0;
+	r->r_start = start;
+	r->r_end = end;
+	r->r_flags = 0;
+	r->r_dev = 0;
+	r->r_rm = rm;
+
+	simple_lock(rm->rm_slock);
+	for (s = rm->rm_list.cqh_first;	
+	     !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
+	     s = s->r_link.cqe_next)
+		;
+
+	if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
+		CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
+	} else {
+		CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
+	}
+
+	simple_unlock(rm->rm_slock);
+	return 0;
+}
+
+int
+rman_fini(struct rman *rm)
+{
+	struct resource *r;
+
+	simple_lock(rm->rm_slock);
+	for (r = rm->rm_list.cqh_first;	!CIRCLEQ_TERMCOND(r, rm->rm_list);
+	     r = r->r_link.cqe_next) {
+		if (r->r_flags & RF_ALLOCATED)
+			return EBUSY;
+	}
+
+	/*
+	 * There really should only be one of these if we are in this
+	 * state and the code is working properly, but it can't hurt.
+	 */
+	for (r = rm->rm_list.cqh_first;	!CIRCLEQ_TERMCOND(r, rm->rm_list);
+	     r = rm->rm_list.cqh_first) {
+		CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
+		free(r, M_RMAN);
+	}
+	simple_unlock(rm->rm_slock);
+	simple_lock(&rman_lock);
+	TAILQ_REMOVE(&rman_head, rm, rm_link);
+	simple_unlock(&rman_lock);
+	free(rm->rm_slock, M_RMAN);
+
+	return 0;
+}
+
+struct resource *
+rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
+		      u_int flags, struct device *dev)
+{
+	u_int	want_activate;
+	struct	resource *r, *s, *rv;
+	u_long	rstart, rend;
+
+	rv = 0;
+
+#ifdef RMAN_DEBUG
+	printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
+	       "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
+	       count, flags, device_get_name(dev), device_get_unit(dev));
+#endif /* RMAN_DEBUG */
+	want_activate = (flags & RF_ACTIVE);
+	flags &= ~RF_ACTIVE;
+
+	simple_lock(rm->rm_slock);
+
+	for (r = rm->rm_list.cqh_first; 
+	     !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
+	     r = r->r_link.cqe_next)
+		;
+
+	if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
+#ifdef RMAN_DEBUG
+		printf("could not find a region\n");
+#endif RMAN_DEBUG
+		goto out;
+	}
+
+	/*
+	 * First try to find an acceptable totally-unshared region.
+	 */
+	for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
+	     s = s->r_link.cqe_next) {
+#ifdef RMAN_DEBUG
+		printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
+#endif /* RMAN_DEBUG */
+		if (s->r_start > end) {
+#ifdef RMAN_DEBUG
+			printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
+#endif /* RMAN_DEBUG */
+			break;
+		}
+		if (s->r_flags & RF_ALLOCATED) {
+#ifdef RMAN_DEBUG
+			printf("region is allocated\n");
+#endif /* RMAN_DEBUG */
+			continue;
+		}
+		rstart = max(s->r_start, start);
+		rend = min(s->r_end, max(start + count, end));
+#ifdef RMAN_DEBUG
+		printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
+		       rstart, rend, (rend - rstart + 1), count);
+#endif /* RMAN_DEBUG */
+
+		if ((rend - rstart + 1) >= count) {
+#ifdef RMAN_DEBUG
+			printf("candidate region: [%#lx, %#lx], size %#lx\n",
+			       rend, rstart, (rend - rstart + 1));
+#endif /* RMAN_DEBUG */
+			if ((s->r_end - s->r_start + 1) == count) {
+#ifdef RMAN_DEBUG
+				printf("candidate region is entire chunk\n");
+#endif /* RMAN_DEBUG */
+				rv = s;
+				rv->r_flags |= RF_ALLOCATED;
+				rv->r_dev = dev;
+				goto out;
+			}
+
+			/*
+			 * If s->r_start < rstart and
+			 *    s->r_end > rstart + count - 1, then
+			 * we need to split the region into three pieces
+			 * (the middle one will get returned to the user).
+			 * Otherwise, we are allocating at either the
+			 * beginning or the end of s, so we only need to
+			 * split it in two.  The first case requires
+			 * two new allocations; the second requires but one.
+			 */
+			rv = malloc(sizeof *r, M_RMAN, M_NOWAIT);
+			if (rv == 0)
+				goto out;
+			rv->r_start = rstart;
+			rv->r_end = rstart + count - 1;
+			rv->r_flags = flags | RF_ALLOCATED;
+			rv->r_dev = dev;
+			rv->r_sharehead = 0;
+			
+			if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
+#ifdef RMAN_DEBUG
+				printf("splitting region in three parts: "
+				       "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
+				       s->r_start, rv->r_start - 1,
+				       rv->r_start, rv->r_end,
+				       rv->r_end + 1, s->r_end);
+#endif /* RMAN_DEBUG */
+				/*
+				 * We are allocating in the middle.
+				 */
+				r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
+				if (r == 0) {
+					free(rv, M_RMAN);
+					rv = 0;
+					goto out;
+				}
+				r->r_start = rv->r_end + 1;
+				r->r_end = s->r_end;
+				r->r_flags = s->r_flags;
+				r->r_dev = 0;
+				r->r_sharehead = 0;
+				s->r_end = rv->r_start - 1;
+				CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
+						     r_link);
+				CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
+						     r_link);
+			} else if (s->r_start == rv->r_start) {
+#ifdef RMAN_DEBUG
+				printf("allocating from the beginning\n");
+#endif /* RMAN_DEBUG */
+				/*
+				 * We are allocating at the beginning.
+				 */
+				s->r_start = rv->r_end + 1;
+				CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
+						      r_link);
+			} else {
+#ifdef RMAN_DEBUG
+				printf("allocating at the end\n");
+#endif /* RMAN_DEBUG */
+				/*
+				 * We are allocating at the end.
+				 */
+				s->r_end = rv->r_start - 1;
+				CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
+						     r_link);
+			}
+			goto out;
+		}
+	}
+
+	/*
+	 * Now find an acceptable shared region, if the client's requirements
+	 * allow sharing.  By our implementation restriction, a candidate
+	 * region must match exactly by both size and sharing type in order
+	 * to be considered compatible with the client's request.  (The
+	 * former restriction could probably be lifted without too much
+	 * additional work, but this does not seem warranted.)
+	 */
+#ifdef RMAN_DEBUG
+	printf("no unshared regions found\n");
+#endif /* RMAN_DEBUG */
+	if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
+		goto out;
+
+	for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
+	     s = s->r_link.cqe_next) {
+		if (s->r_start > end)
+			break;
+		if ((s->r_flags & flags) != flags)
+			continue;
+		rstart = max(s->r_start, start);
+		rend = min(s->r_end, max(start + count, end));
+		if (s->r_start >= start && s->r_end <= end
+		    && (s->r_end - s->r_start + 1) == count) {
+			rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
+			if (rv == 0)
+				goto out;
+			rv->r_start = s->r_start;
+			rv->r_end = s->r_end;
+			rv->r_flags = s->r_flags & 
+				(RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
+			rv->r_dev = dev;
+			rv->r_rm = rm;
+			if (s->r_sharehead == 0) {
+				s->r_sharehead = malloc(sizeof *s->r_sharehead,
+							M_RMAN, M_NOWAIT);
+				if (s->r_sharehead == 0) {
+					free(rv, M_RMAN);
+					rv = 0;
+					goto out;
+				}
+				LIST_INIT(s->r_sharehead);
+				LIST_INSERT_HEAD(s->r_sharehead, s, 
+						 r_sharelink);
+				s->r_flags = RF_FIRSTSHARE;
+			}
+			rv->r_sharehead = s->r_sharehead;
+			LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
+			goto out;
+		}
+	}
+
+	/*
+	 * We couldn't find anything.
+	 */
+out:
+	/*
+	 * If the user specified RF_ACTIVE in the initial flags,
+	 * which is reflected in `want_activate', we attempt to atomically
+	 * activate the resource.  If this fails, we release the resource
+	 * and indicate overall failure.  (This behavior probably doesn't
+	 * make sense for RF_TIMESHARE-type resources.)
+	 */
+	if (rv && want_activate) {
+		struct resource *whohas;
+		if (int_rman_activate_resource(rm, rv, &whohas)) {
+			int_rman_release_resource(rm, rv);
+			rv = 0;
+		}
+	}
+			
+	simple_unlock(rm->rm_slock);
+	return (rv);
+}
+
+static int
+int_rman_activate_resource(struct rman *rm, struct resource *r,
+			   struct resource **whohas)
+{
+	struct resource *s;
+	int ok;
+
+	/*
+	 * If we are not timesharing, then there is nothing much to do.
+	 * If we already have the resource, then there is nothing at all to do.
+	 * If we are not on a sharing list with anybody else, then there is
+	 * little to do.
+	 */
+	if ((r->r_flags & RF_TIMESHARE) == 0
+	    || (r->r_flags & RF_ACTIVE) != 0
+	    || r->r_sharehead == 0) {
+		r->r_flags |= RF_ACTIVE;
+		return 0;
+	}
+
+	ok = 1;
+	for (s = r->r_sharehead->lh_first; s && ok;
+	     s = s->r_sharelink.le_next) {
+		if ((s->r_flags & RF_ACTIVE) != 0) {
+			ok = 0;
+			*whohas = s;
+		}
+	}
+	if (ok) {
+		r->r_flags |= RF_ACTIVE;
+		return 0;
+	}
+	return EBUSY;
+}
+
+int
+rman_activate_resource(struct resource *r)
+{
+	int rv;
+	struct resource *whohas;
+	struct rman *rm;
+
+	rm = r->r_rm;
+	simple_lock(rm->rm_slock);
+	rv = int_rman_activate_resource(rm, r, &whohas);
+	simple_unlock(rm->rm_slock);
+	return rv;
+}
+
+int
+rman_await_resource(struct resource *r, int pri, int timo)
+{
+	int	rv, s;
+	struct	resource *whohas;
+	struct	rman *rm;
+
+	rm = r->r_rm;
+	for (;;) {
+		simple_lock(rm->rm_slock);
+		rv = int_rman_activate_resource(rm, r, &whohas);
+		if (rv != EBUSY)
+			return (rv);
+
+		if (r->r_sharehead == 0)
+			panic("rman_await_resource");
+		/*
+		 * splhigh hopefully will prevent a race between
+		 * simple_unlock and tsleep where a process
+		 * could conceivably get in and release the resource
+		 * before we have a chance to sleep on it.
+		 */
+		s = splhigh();
+		whohas->r_flags |= RF_WANTED;
+		simple_unlock(rm->rm_slock);
+		rv = tsleep(r->r_sharehead, pri, "rmwait", timo);
+		if (rv) {
+			splx(s);
+			return rv;
+		}
+		simple_lock(rm->rm_slock);
+		splx(s);
+	}
+}
+
+int
+rman_deactivate_resource(struct resource *r)
+{
+	struct	rman *rm;
+
+	rm = r->r_rm;
+	simple_lock(rm->rm_slock);
+	r->r_flags &= ~RF_ACTIVE;
+	if (r->r_flags & RF_WANTED) {
+		r->r_flags &= ~RF_WANTED;
+		wakeup(r->r_sharehead);
+	}
+	simple_unlock(rm->rm_slock);
+	return 0;
+}
+
+static int
+int_rman_release_resource(struct rman *rm, struct resource *r)
+{
+	struct	resource *s, *t;
+
+	if (r->r_flags & RF_ACTIVE)
+		return EBUSY;
+
+	/*
+	 * Check for a sharing list first.  If there is one, then we don't
+	 * have to think as hard.
+	 */
+	if (r->r_sharehead) {
+		/*
+		 * If a sharing list exists, then we know there are at
+		 * least two sharers.
+		 *
+		 * If we are in the main circleq, appoint someone else.
+		 */
+		LIST_REMOVE(r, r_sharelink);
+		s = r->r_sharehead->lh_first;
+		if (r->r_flags & RF_FIRSTSHARE) {
+			s->r_flags |= RF_FIRSTSHARE;
+			CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
+			CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
+		}
+
+		/*
+		 * Make sure that the sharing list goes away completely
+		 * if the resource is no longer being shared at all.
+		 */
+		if (s->r_sharelink.le_next == 0) {
+			free(s->r_sharehead, M_RMAN);
+			s->r_sharehead = 0;
+			s->r_flags &= ~RF_FIRSTSHARE;
+		}
+		goto out;
+	}
+
+	/*
+	 * Look at the adjacent resources in the list and see if our
+	 * segment can be merged with any of them.
+	 */
+	s = r->r_link.cqe_prev;
+	t = r->r_link.cqe_next;
+
+	if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
+	    && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
+		/*
+		 * Merge all three segments.
+		 */
+		s->r_end = t->r_end;
+		CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
+		CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
+		free(t, M_RMAN);
+	} else if (s != (void *)&rm->rm_list
+		   && (s->r_flags & RF_ALLOCATED) == 0) {
+		/*
+		 * Merge previous segment with ours.
+		 */
+		s->r_end = r->r_end;
+		CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
+	} else if (t != (void *)&rm->rm_list
+		   && (t->r_flags & RF_ALLOCATED) == 0) {
+		/*
+		 * Merge next segment with ours.
+		 */
+		t->r_start = r->r_start;
+		CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
+	} else {
+		/*
+		 * At this point, we know there is nothing we
+		 * can potentially merge with, because on each
+		 * side, there is either nothing there or what is
+		 * there is still allocated.  In that case, we don't
+		 * want to remove r from the list; we simply want to
+		 * change it to an unallocated region and return
+		 * without freeing anything.
+		 */
+		r->r_flags &= ~RF_ALLOCATED;
+		return 0;
+	}
+
+out:
+	free(r, M_RMAN);
+	return 0;
+}
+
+int
+rman_release_resource(struct resource *r)
+{
+	int	rv;
+	struct	rman *rm = r->r_rm;
+
+	simple_lock(rm->rm_slock);
+	rv = int_rman_release_resource(rm, r);
+	simple_unlock(rm->rm_slock);
+	return (rv);
+}