592 lines
16 KiB
C
592 lines
16 KiB
C
/*
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* Copyright 1998 Massachusetts Institute of Technology
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose and without fee is hereby
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* granted, provided that both the above copyright notice and this
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* permission notice appear in all copies, that both the above
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* copyright notice and this permission notice appear in all
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* supporting documentation, and that the name of M.I.T. not be used
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* in advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission. M.I.T. makes
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* no representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied
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* warranty.
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*
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* THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
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* ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
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* SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: subr_rman.c,v 1.4 1999/01/02 11:34:55 bde Exp $
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*/
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/*
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* The kernel resource manager. This code is responsible for keeping track
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* of hardware resources which are apportioned out to various drivers.
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* It does not actually assign those resources, and it is not expected
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* that end-device drivers will call into this code directly. Rather,
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* the code which implements the buses that those devices are attached to,
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* and the code which manages CPU resources, will call this code, and the
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* end-device drivers will make upcalls to that code to actually perform
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* the allocation.
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*
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* There are two sorts of resources managed by this code. The first is
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* the more familiar array (RMAN_ARRAY) type; resources in this class
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* consist of a sequence of individually-allocatable objects which have
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* been numbered in some well-defined order. Most of the resources
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* are of this type, as it is the most familiar. The second type is
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* called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
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* resources in which each instance is indistinguishable from every
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* other instance). The principal anticipated application of gauges
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* is in the context of power consumption, where a bus may have a specific
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* power budget which all attached devices share. RMAN_GAUGE is not
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* implemented yet.
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*
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* For array resources, we make one simplifying assumption: two clients
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* sharing the same resource must use the same range of indices. That
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* is to say, sharing of overlapping-but-not-identical regions is not
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* permitted.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/rman.h>
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#include <sys/bus.h> /* XXX debugging */
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MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
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struct rman_head rman_head;
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#ifndef NULL_SIMPLELOCKS
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static struct simplelock rman_lock; /* mutex to protect rman_head */
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#endif
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static int int_rman_activate_resource(struct rman *rm, struct resource *r,
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struct resource **whohas);
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static int int_rman_release_resource(struct rman *rm, struct resource *r);
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#define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head))
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int
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rman_init(struct rman *rm)
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{
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static int once;
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if (once == 0) {
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once = 1;
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TAILQ_INIT(&rman_head);
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simple_lock_init(&rman_lock);
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}
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if (rm->rm_type == RMAN_UNINIT)
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panic("rman_init");
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if (rm->rm_type == RMAN_GAUGE)
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panic("implement RMAN_GAUGE");
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CIRCLEQ_INIT(&rm->rm_list);
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rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
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if (rm->rm_slock == 0)
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return ENOMEM;
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simple_lock_init(rm->rm_slock);
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simple_lock(&rman_lock);
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TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
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simple_unlock(&rman_lock);
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return 0;
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}
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/*
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* NB: this interface is not robust against programming errors which
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* add multiple copies of the same region.
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*/
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int
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rman_manage_region(struct rman *rm, u_long start, u_long end)
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{
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struct resource *r, *s;
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r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
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if (r == 0)
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return ENOMEM;
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r->r_sharehead = 0;
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r->r_start = start;
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r->r_end = end;
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r->r_flags = 0;
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r->r_dev = 0;
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r->r_rm = rm;
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simple_lock(rm->rm_slock);
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for (s = rm->rm_list.cqh_first;
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!CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
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s = s->r_link.cqe_next)
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;
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if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
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CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
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} else {
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CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
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}
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simple_unlock(rm->rm_slock);
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return 0;
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}
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int
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rman_fini(struct rman *rm)
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{
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struct resource *r;
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simple_lock(rm->rm_slock);
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for (r = rm->rm_list.cqh_first; !CIRCLEQ_TERMCOND(r, rm->rm_list);
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r = r->r_link.cqe_next) {
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if (r->r_flags & RF_ALLOCATED)
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return EBUSY;
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}
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/*
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* There really should only be one of these if we are in this
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* state and the code is working properly, but it can't hurt.
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*/
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for (r = rm->rm_list.cqh_first; !CIRCLEQ_TERMCOND(r, rm->rm_list);
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r = rm->rm_list.cqh_first) {
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CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
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free(r, M_RMAN);
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}
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simple_unlock(rm->rm_slock);
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simple_lock(&rman_lock);
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TAILQ_REMOVE(&rman_head, rm, rm_link);
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simple_unlock(&rman_lock);
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free(rm->rm_slock, M_RMAN);
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return 0;
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}
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struct resource *
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rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
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u_int flags, struct device *dev)
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{
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u_int want_activate;
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struct resource *r, *s, *rv;
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u_long rstart, rend;
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rv = 0;
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#ifdef RMAN_DEBUG
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printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
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"%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
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count, flags, device_get_name(dev), device_get_unit(dev));
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#endif /* RMAN_DEBUG */
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want_activate = (flags & RF_ACTIVE);
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flags &= ~RF_ACTIVE;
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simple_lock(rm->rm_slock);
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for (r = rm->rm_list.cqh_first;
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!CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
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r = r->r_link.cqe_next)
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;
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if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
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#ifdef RMAN_DEBUG
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printf("could not find a region\n");
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#endif RMAN_DEBUG
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goto out;
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}
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/*
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* First try to find an acceptable totally-unshared region.
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*/
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for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
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s = s->r_link.cqe_next) {
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#ifdef RMAN_DEBUG
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printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
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#endif /* RMAN_DEBUG */
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if (s->r_start > end) {
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#ifdef RMAN_DEBUG
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printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
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#endif /* RMAN_DEBUG */
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break;
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}
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if (s->r_flags & RF_ALLOCATED) {
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#ifdef RMAN_DEBUG
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printf("region is allocated\n");
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#endif /* RMAN_DEBUG */
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continue;
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}
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rstart = max(s->r_start, start);
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rend = min(s->r_end, max(start + count, end));
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#ifdef RMAN_DEBUG
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printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
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rstart, rend, (rend - rstart + 1), count);
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#endif /* RMAN_DEBUG */
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if ((rend - rstart + 1) >= count) {
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#ifdef RMAN_DEBUG
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printf("candidate region: [%#lx, %#lx], size %#lx\n",
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rend, rstart, (rend - rstart + 1));
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#endif /* RMAN_DEBUG */
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if ((s->r_end - s->r_start + 1) == count) {
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#ifdef RMAN_DEBUG
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printf("candidate region is entire chunk\n");
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#endif /* RMAN_DEBUG */
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rv = s;
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rv->r_flags |= RF_ALLOCATED;
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rv->r_dev = dev;
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goto out;
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}
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/*
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* If s->r_start < rstart and
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* s->r_end > rstart + count - 1, then
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* we need to split the region into three pieces
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* (the middle one will get returned to the user).
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* Otherwise, we are allocating at either the
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* beginning or the end of s, so we only need to
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* split it in two. The first case requires
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* two new allocations; the second requires but one.
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*/
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rv = malloc(sizeof *r, M_RMAN, M_NOWAIT);
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if (rv == 0)
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goto out;
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rv->r_start = rstart;
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rv->r_end = rstart + count - 1;
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rv->r_flags = flags | RF_ALLOCATED;
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rv->r_dev = dev;
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rv->r_sharehead = 0;
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if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
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#ifdef RMAN_DEBUG
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printf("splitting region in three parts: "
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"[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
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s->r_start, rv->r_start - 1,
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rv->r_start, rv->r_end,
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rv->r_end + 1, s->r_end);
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#endif /* RMAN_DEBUG */
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/*
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* We are allocating in the middle.
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*/
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r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
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if (r == 0) {
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free(rv, M_RMAN);
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rv = 0;
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goto out;
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}
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r->r_start = rv->r_end + 1;
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r->r_end = s->r_end;
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r->r_flags = s->r_flags;
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r->r_dev = 0;
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r->r_sharehead = 0;
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s->r_end = rv->r_start - 1;
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CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
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r_link);
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CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
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r_link);
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} else if (s->r_start == rv->r_start) {
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#ifdef RMAN_DEBUG
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printf("allocating from the beginning\n");
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#endif /* RMAN_DEBUG */
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/*
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* We are allocating at the beginning.
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*/
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s->r_start = rv->r_end + 1;
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CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
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r_link);
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} else {
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#ifdef RMAN_DEBUG
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printf("allocating at the end\n");
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#endif /* RMAN_DEBUG */
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/*
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* We are allocating at the end.
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*/
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s->r_end = rv->r_start - 1;
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CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
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r_link);
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}
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goto out;
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}
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}
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/*
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* Now find an acceptable shared region, if the client's requirements
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* allow sharing. By our implementation restriction, a candidate
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* region must match exactly by both size and sharing type in order
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* to be considered compatible with the client's request. (The
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* former restriction could probably be lifted without too much
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* additional work, but this does not seem warranted.)
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*/
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#ifdef RMAN_DEBUG
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printf("no unshared regions found\n");
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#endif /* RMAN_DEBUG */
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if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
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goto out;
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for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
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s = s->r_link.cqe_next) {
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if (s->r_start > end)
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break;
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if ((s->r_flags & flags) != flags)
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continue;
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rstart = max(s->r_start, start);
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rend = min(s->r_end, max(start + count, end));
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if (s->r_start >= start && s->r_end <= end
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&& (s->r_end - s->r_start + 1) == count) {
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rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
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if (rv == 0)
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goto out;
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rv->r_start = s->r_start;
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rv->r_end = s->r_end;
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rv->r_flags = s->r_flags &
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(RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
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rv->r_dev = dev;
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rv->r_rm = rm;
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if (s->r_sharehead == 0) {
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s->r_sharehead = malloc(sizeof *s->r_sharehead,
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M_RMAN, M_NOWAIT);
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if (s->r_sharehead == 0) {
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free(rv, M_RMAN);
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rv = 0;
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goto out;
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}
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LIST_INIT(s->r_sharehead);
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LIST_INSERT_HEAD(s->r_sharehead, s,
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r_sharelink);
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s->r_flags |= RF_FIRSTSHARE;
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}
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rv->r_sharehead = s->r_sharehead;
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LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
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goto out;
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}
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}
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/*
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* We couldn't find anything.
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*/
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out:
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/*
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* If the user specified RF_ACTIVE in the initial flags,
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* which is reflected in `want_activate', we attempt to atomically
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* activate the resource. If this fails, we release the resource
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* and indicate overall failure. (This behavior probably doesn't
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* make sense for RF_TIMESHARE-type resources.)
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*/
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if (rv && want_activate) {
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struct resource *whohas;
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if (int_rman_activate_resource(rm, rv, &whohas)) {
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int_rman_release_resource(rm, rv);
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rv = 0;
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}
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}
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simple_unlock(rm->rm_slock);
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return (rv);
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}
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static int
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int_rman_activate_resource(struct rman *rm, struct resource *r,
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struct resource **whohas)
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{
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struct resource *s;
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int ok;
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/*
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* If we are not timesharing, then there is nothing much to do.
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* If we already have the resource, then there is nothing at all to do.
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* If we are not on a sharing list with anybody else, then there is
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* little to do.
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*/
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if ((r->r_flags & RF_TIMESHARE) == 0
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|| (r->r_flags & RF_ACTIVE) != 0
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|| r->r_sharehead == 0) {
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r->r_flags |= RF_ACTIVE;
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return 0;
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}
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ok = 1;
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for (s = r->r_sharehead->lh_first; s && ok;
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s = s->r_sharelink.le_next) {
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if ((s->r_flags & RF_ACTIVE) != 0) {
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ok = 0;
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*whohas = s;
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}
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}
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if (ok) {
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r->r_flags |= RF_ACTIVE;
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return 0;
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}
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return EBUSY;
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}
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int
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rman_activate_resource(struct resource *r)
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{
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int rv;
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struct resource *whohas;
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struct rman *rm;
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rm = r->r_rm;
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simple_lock(rm->rm_slock);
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rv = int_rman_activate_resource(rm, r, &whohas);
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simple_unlock(rm->rm_slock);
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return rv;
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}
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int
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rman_await_resource(struct resource *r, int pri, int timo)
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{
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int rv, s;
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struct resource *whohas;
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struct rman *rm;
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rm = r->r_rm;
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for (;;) {
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simple_lock(rm->rm_slock);
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rv = int_rman_activate_resource(rm, r, &whohas);
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if (rv != EBUSY)
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return (rv);
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if (r->r_sharehead == 0)
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panic("rman_await_resource");
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/*
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* splhigh hopefully will prevent a race between
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* simple_unlock and tsleep where a process
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* could conceivably get in and release the resource
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* before we have a chance to sleep on it.
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*/
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s = splhigh();
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whohas->r_flags |= RF_WANTED;
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simple_unlock(rm->rm_slock);
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rv = tsleep(r->r_sharehead, pri, "rmwait", timo);
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if (rv) {
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splx(s);
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return rv;
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}
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simple_lock(rm->rm_slock);
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splx(s);
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}
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}
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int
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rman_deactivate_resource(struct resource *r)
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{
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struct rman *rm;
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rm = r->r_rm;
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simple_lock(rm->rm_slock);
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r->r_flags &= ~RF_ACTIVE;
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if (r->r_flags & RF_WANTED) {
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r->r_flags &= ~RF_WANTED;
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wakeup(r->r_sharehead);
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}
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simple_unlock(rm->rm_slock);
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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);
|
|
}
|