freebsd-skq/sys/kern/subr_rman.c
bmilekic f364d4ac36 Change and clean the mutex lock interface.
mtx_enter(lock, type) becomes:

mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)

similarily, for releasing a lock, we now have:

mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.

The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.

Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:

MTX_QUIET and MTX_NOSWITCH

The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:

mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.

Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.

Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.

Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.

Finally, caught up to the interface changes in all sys code.

Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00

602 lines
16 KiB
C

/*
* 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.
*
* $FreeBSD$
*/
/*
* 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/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/bus.h> /* XXX debugging */
#include <machine/bus.h>
#include <sys/rman.h>
#ifdef RMAN_DEBUG
#define DPRINTF(params) printf##params
#else
#define DPRINTF(params)
#endif
static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
struct rman_head rman_head;
static struct mtx rman_mtx; /* mutex to protect rman_head */
static int int_rman_activate_resource(struct rman *rm, struct resource *r,
struct resource **whohas);
static int int_rman_deactivate_resource(struct resource *r);
static int int_rman_release_resource(struct rman *rm, struct resource *r);
int
rman_init(struct rman *rm)
{
static int once;
if (once == 0) {
once = 1;
TAILQ_INIT(&rman_head);
mtx_init(&rman_mtx, "rman head", MTX_DEF);
}
if (rm->rm_type == RMAN_UNINIT)
panic("rman_init");
if (rm->rm_type == RMAN_GAUGE)
panic("implement RMAN_GAUGE");
TAILQ_INIT(&rm->rm_list);
rm->rm_mtx = malloc(sizeof *rm->rm_mtx, M_RMAN, M_NOWAIT);
if (rm->rm_mtx == 0)
return ENOMEM;
mtx_init(rm->rm_mtx, "rman", MTX_DEF);
mtx_lock(&rman_mtx);
TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
mtx_unlock(&rman_mtx);
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 | M_ZERO);
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;
mtx_lock(rm->rm_mtx);
for (s = TAILQ_FIRST(&rm->rm_list);
s && s->r_end < r->r_start;
s = TAILQ_NEXT(s, r_link))
;
if (s == NULL) {
TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
} else {
TAILQ_INSERT_BEFORE(s, r, r_link);
}
mtx_unlock(rm->rm_mtx);
return 0;
}
int
rman_fini(struct rman *rm)
{
struct resource *r;
mtx_lock(rm->rm_mtx);
TAILQ_FOREACH(r, &rm->rm_list, r_link) {
if (r->r_flags & RF_ALLOCATED) {
mtx_unlock(rm->rm_mtx);
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.
*/
while (!TAILQ_EMPTY(&rm->rm_list)) {
r = TAILQ_FIRST(&rm->rm_list);
TAILQ_REMOVE(&rm->rm_list, r, r_link);
free(r, M_RMAN);
}
mtx_unlock(rm->rm_mtx);
mtx_lock(&rman_mtx);
TAILQ_REMOVE(&rman_head, rm, rm_link);
mtx_unlock(&rman_mtx);
mtx_destroy(rm->rm_mtx);
free(rm->rm_mtx, 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;
DPRINTF(("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)));
want_activate = (flags & RF_ACTIVE);
flags &= ~RF_ACTIVE;
mtx_lock(rm->rm_mtx);
for (r = TAILQ_FIRST(&rm->rm_list);
r && r->r_end < start;
r = TAILQ_NEXT(r, r_link))
;
if (r == NULL) {
DPRINTF(("could not find a region\n"));
goto out;
}
/*
* First try to find an acceptable totally-unshared region.
*/
for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
if (s->r_start > end) {
DPRINTF(("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end));
break;
}
if (s->r_flags & RF_ALLOCATED) {
DPRINTF(("region is allocated\n"));
continue;
}
rstart = max(s->r_start, start);
rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
~((1ul << RF_ALIGNMENT(flags)) - 1);
rend = min(s->r_end, max(rstart + count, end));
DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
rstart, rend, (rend - rstart + 1), count));
if ((rend - rstart + 1) >= count) {
DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
rend, rstart, (rend - rstart + 1)));
if ((s->r_end - s->r_start + 1) == count) {
DPRINTF(("candidate region is entire chunk\n"));
rv = s;
rv->r_flags |= RF_ALLOCATED | flags;
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 *rv, M_RMAN, M_NOWAIT | M_ZERO);
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;
rv->r_rm = rm;
if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
DPRINTF(("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));
/*
* We are allocating in the middle.
*/
r = malloc(sizeof *r, M_RMAN, M_NOWAIT|M_ZERO);
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;
r->r_rm = rm;
s->r_end = rv->r_start - 1;
TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
r_link);
TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
r_link);
} else if (s->r_start == rv->r_start) {
DPRINTF(("allocating from the beginning\n"));
/*
* We are allocating at the beginning.
*/
s->r_start = rv->r_end + 1;
TAILQ_INSERT_BEFORE(s, rv, r_link);
} else {
DPRINTF(("allocating at the end\n"));
/*
* We are allocating at the end.
*/
s->r_end = rv->r_start - 1;
TAILQ_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.)
*/
DPRINTF(("no unshared regions found\n"));
if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
goto out;
for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
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 | M_ZERO);
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 | M_ZERO);
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;
}
}
mtx_unlock(rm->rm_mtx);
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 = LIST_FIRST(r->r_sharehead); s && ok;
s = LIST_NEXT(s, r_sharelink)) {
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;
mtx_lock(rm->rm_mtx);
rv = int_rman_activate_resource(rm, r, &whohas);
mtx_unlock(rm->rm_mtx);
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 (;;) {
mtx_lock(rm->rm_mtx);
rv = int_rman_activate_resource(rm, r, &whohas);
if (rv != EBUSY)
return (rv); /* returns with mutex held */
if (r->r_sharehead == 0)
panic("rman_await_resource");
/*
* splhigh hopefully will prevent a race between
* mtx_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;
mtx_unlock(rm->rm_mtx);
rv = tsleep(r->r_sharehead, pri, "rmwait", timo);
if (rv) {
splx(s);
return rv;
}
mtx_lock(rm->rm_mtx);
splx(s);
}
}
static int
int_rman_deactivate_resource(struct resource *r)
{
struct rman *rm;
rm = r->r_rm;
r->r_flags &= ~RF_ACTIVE;
if (r->r_flags & RF_WANTED) {
r->r_flags &= ~RF_WANTED;
wakeup(r->r_sharehead);
}
return 0;
}
int
rman_deactivate_resource(struct resource *r)
{
struct rman *rm;
rm = r->r_rm;
mtx_lock(rm->rm_mtx);
int_rman_deactivate_resource(r);
mtx_unlock(rm->rm_mtx);
return 0;
}
static int
int_rman_release_resource(struct rman *rm, struct resource *r)
{
struct resource *s, *t;
if (r->r_flags & RF_ACTIVE)
int_rman_deactivate_resource(r);
/*
* 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 = LIST_FIRST(r->r_sharehead);
if (r->r_flags & RF_FIRSTSHARE) {
s->r_flags |= RF_FIRSTSHARE;
TAILQ_INSERT_BEFORE(r, s, r_link);
TAILQ_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 (LIST_NEXT(s, r_sharelink) == 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 = TAILQ_PREV(r, resource_head, r_link);
t = TAILQ_NEXT(r, r_link);
if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0
&& t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
/*
* Merge all three segments.
*/
s->r_end = t->r_end;
TAILQ_REMOVE(&rm->rm_list, r, r_link);
TAILQ_REMOVE(&rm->rm_list, t, r_link);
free(t, M_RMAN);
} else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) {
/*
* Merge previous segment with ours.
*/
s->r_end = r->r_end;
TAILQ_REMOVE(&rm->rm_list, r, r_link);
} else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
/*
* Merge next segment with ours.
*/
t->r_start = r->r_start;
TAILQ_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;
mtx_lock(rm->rm_mtx);
rv = int_rman_release_resource(rm, r);
mtx_unlock(rm->rm_mtx);
return (rv);
}
uint32_t
rman_make_alignment_flags(uint32_t size)
{
int i;
/*
* Find the hightest bit set, and add one if more than one bit
* set. We're effectively computing the ceil(log2(size)) here.
*/
for (i = 32; i > 0; i--)
if ((1 << i) & size)
break;
if (~(1 << i) & size)
i++;
return(RF_ALIGNMENT_LOG2(i));
}