2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2007 Ariff Abdullah <ariff@FreeBSD.org>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 #include <sys/param.h>
32 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 #include <sys/malloc.h>
38 #ifdef HAVE_KERNEL_OPTION_HEADERS
42 #if defined(SND_DIAGNOSTIC) || defined(SND_DEBUG)
43 #include <dev/sound/pcm/sound.h>
46 #include <dev/sound/clone.h>
49 * So here we go again, another clonedevs manager. Unlike default clonedevs,
50 * this clone manager is designed to withstand various abusive behavior
51 * (such as 'while : ; do ls /dev/whatever ; done', etc.), reusable object
52 * after reaching certain expiration threshold, aggressive garbage collector,
53 * transparent device allocator and concurrency handling across multiple
54 * thread/proc. Due to limited information given by dev_clone EVENTHANDLER,
55 * we don't have much clues whether the caller wants a real open() or simply
56 * making fun of us with things like stat(), mtime() etc. Assuming that:
57 * 1) Time window between dev_clone EH <-> real open() should be small
58 * enough and 2) mtime()/stat() etc. always looks like a half way / stalled
59 * operation, we can decide whether a new cdev must be created, old
60 * (expired) cdev can be reused or an existing cdev can be shared.
62 * Most of the operations and logics are generic enough and can be applied
63 * on other places (such as if_tap, snp, etc). Perhaps this can be
64 * rearranged to complement clone_*(). However, due to this still being
65 * specific to the sound driver (and as a proof of concept on how it can be
66 * done), si_drv2 is used to keep the pointer of the clone list entry to
67 * avoid expensive lookup.
71 struct snd_clone_entry {
72 TAILQ_ENTRY(snd_clone_entry) link;
73 struct snd_clone *parent;
83 TAILQ_HEAD(link_head, snd_clone_entry) head;
94 #define SND_CLONE_ASSERT(x, y) do { \
99 #define SND_CLONE_ASSERT(...) KASSERT(__VA_ARGS__)
103 * Shamelessly ripped off from vfs_subr.c
104 * We need at least 1/HZ precision as default timestamping.
106 enum { SND_TSP_SEC, SND_TSP_HZ, SND_TSP_USEC, SND_TSP_NSEC };
108 static int snd_timestamp_precision = SND_TSP_HZ;
109 TUNABLE_INT("hw.snd.timestamp_precision", &snd_timestamp_precision);
112 snd_timestamp(struct timespec *tsp)
116 switch (snd_timestamp_precision) {
118 tsp->tv_sec = time_second;
126 TIMEVAL_TO_TIMESPEC(&tv, tsp);
132 snd_timestamp_precision = SND_TSP_HZ;
138 #if defined(SND_DIAGNOSTIC) || defined(SND_DEBUG)
140 sysctl_hw_snd_timestamp_precision(SYSCTL_HANDLER_ARGS)
144 val = snd_timestamp_precision;
145 err = sysctl_handle_int(oidp, &val, 0, req);
146 if (err == 0 && req->newptr != NULL) {
152 snd_timestamp_precision = val;
161 SYSCTL_PROC(_hw_snd, OID_AUTO, timestamp_precision, CTLTYPE_INT | CTLFLAG_RW,
162 0, sizeof(int), sysctl_hw_snd_timestamp_precision, "I",
163 "timestamp precision (0=s 1=hz 2=us 3=ns)");
167 * snd_clone_create() : Return opaque allocated clone manager.
170 snd_clone_create(int typemask, int maxunit, int deadline, uint32_t flags)
174 SND_CLONE_ASSERT(!(typemask & ~SND_CLONE_MAXUNIT),
175 ("invalid typemask: 0x%08x", typemask));
176 SND_CLONE_ASSERT(maxunit == -1 ||
177 !(maxunit & ~(~typemask & SND_CLONE_MAXUNIT)),
178 ("maxunit overflow: typemask=0x%08x maxunit=%d",
180 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_MASK),
181 ("invalid clone flags=0x%08x", flags));
183 c = malloc(sizeof(*c), M_DEVBUF, M_WAITOK | M_ZERO);
186 c->typemask = typemask;
187 c->maxunit = (maxunit == -1) ? (~typemask & SND_CLONE_MAXUNIT) :
189 c->deadline = deadline;
191 snd_timestamp(&c->tsp);
192 TAILQ_INIT(&c->head);
198 snd_clone_busy(struct snd_clone *c)
200 struct snd_clone_entry *ce;
202 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
207 TAILQ_FOREACH(ce, &c->head, link) {
208 if ((ce->flags & SND_CLONE_BUSY) ||
209 (ce->devt != NULL && ce->devt->si_threadcount != 0))
217 * snd_clone_enable()/disable() : Suspend/resume clone allocation through
218 * snd_clone_alloc(). Everything else will not be affected by this.
221 snd_clone_enable(struct snd_clone *c)
223 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
225 if (c->flags & SND_CLONE_ENABLE)
228 c->flags |= SND_CLONE_ENABLE;
234 snd_clone_disable(struct snd_clone *c)
236 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
238 if (!(c->flags & SND_CLONE_ENABLE))
241 c->flags &= ~SND_CLONE_ENABLE;
247 * Getters / Setters. Not worth explaining :)
250 snd_clone_getsize(struct snd_clone *c)
252 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
258 snd_clone_getmaxunit(struct snd_clone *c)
260 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
266 snd_clone_setmaxunit(struct snd_clone *c, int maxunit)
268 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
269 SND_CLONE_ASSERT(maxunit == -1 ||
270 !(maxunit & ~(~c->typemask & SND_CLONE_MAXUNIT)),
271 ("maxunit overflow: typemask=0x%08x maxunit=%d",
272 c->typemask, maxunit));
274 c->maxunit = (maxunit == -1) ? (~c->typemask & SND_CLONE_MAXUNIT) :
281 snd_clone_getdeadline(struct snd_clone *c)
283 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
285 return (c->deadline);
289 snd_clone_setdeadline(struct snd_clone *c, int deadline)
291 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
293 c->deadline = deadline;
295 return (c->deadline);
299 snd_clone_gettime(struct snd_clone *c, struct timespec *tsp)
301 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
302 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
310 snd_clone_getflags(struct snd_clone *c)
312 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
318 snd_clone_setflags(struct snd_clone *c, uint32_t flags)
320 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
321 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_MASK),
322 ("invalid clone flags=0x%08x", flags));
330 snd_clone_getdevtime(struct cdev *dev, struct timespec *tsp)
332 struct snd_clone_entry *ce;
334 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
335 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
341 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
349 snd_clone_getdevflags(struct cdev *dev)
351 struct snd_clone_entry *ce;
353 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
359 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
365 snd_clone_setdevflags(struct cdev *dev, uint32_t flags)
367 struct snd_clone_entry *ce;
369 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
370 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_DEVMASK),
371 ("invalid clone dev flags=0x%08x", flags));
377 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
384 /* Elapsed time conversion to ms */
385 #define SND_CLONE_ELAPSED(x, y) \
386 ((((x)->tv_sec - (y)->tv_sec) * 1000) + \
387 (((y)->tv_nsec > (x)->tv_nsec) ? \
388 (((1000000000L + (x)->tv_nsec - \
389 (y)->tv_nsec) / 1000000) - 1000) : \
390 (((x)->tv_nsec - (y)->tv_nsec) / 1000000)))
392 #define SND_CLONE_EXPIRED(x, y, z) \
393 ((x)->deadline < 1 || \
394 ((y)->tv_sec - (z)->tv_sec) > ((x)->deadline / 1000) || \
395 SND_CLONE_ELAPSED(y, z) > (x)->deadline)
398 * snd_clone_gc() : Garbage collector for stalled, expired objects. Refer to
399 * clone.h for explanations on GC settings.
402 snd_clone_gc(struct snd_clone *c)
404 struct snd_clone_entry *ce, *tce;
408 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
410 if (!(c->flags & SND_CLONE_GC_ENABLE) || c->size == 0)
416 * Bail out if the last clone handler was invoked below the deadline
419 if ((c->flags & SND_CLONE_GC_EXPIRED) &&
420 !SND_CLONE_EXPIRED(c, &now, &c->tsp))
426 * Visit each object in reverse order. If the object is still being
427 * referenced by a valid open(), skip it. Look for expired objects
428 * and either revoke its clone invocation status or mercilessly
431 TAILQ_FOREACH_REVERSE_SAFE(ce, &c->head, link_head, link, tce) {
432 if (!(ce->flags & SND_CLONE_BUSY) &&
433 (!(ce->flags & SND_CLONE_INVOKE) ||
434 SND_CLONE_EXPIRED(c, &now, &ce->tsp))) {
435 if ((c->flags & SND_CLONE_GC_REVOKE) ||
436 ce->devt->si_threadcount != 0) {
437 ce->flags &= ~SND_CLONE_INVOKE;
440 TAILQ_REMOVE(&c->head, ce, link);
441 destroy_dev(ce->devt);
449 /* return total pruned objects */
454 snd_clone_destroy(struct snd_clone *c)
456 struct snd_clone_entry *ce, *tmp;
458 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
460 ce = TAILQ_FIRST(&c->head);
462 tmp = TAILQ_NEXT(ce, link);
463 if (ce->devt != NULL)
464 destroy_dev(ce->devt);
473 * snd_clone_acquire() : The vital part of concurrency management. Must be
474 * called somewhere at the beginning of open() handler. ENODEV is not really
475 * fatal since it just tell the caller that this is not cloned stuff.
476 * EBUSY is *real*, don't forget that!
479 snd_clone_acquire(struct cdev *dev)
481 struct snd_clone_entry *ce;
483 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
489 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
491 ce->flags &= ~SND_CLONE_INVOKE;
493 if (ce->flags & SND_CLONE_BUSY)
496 ce->flags |= SND_CLONE_BUSY;
502 * snd_clone_release() : Release busy status. Must be called somewhere at
503 * the end of close() handler, or somewhere after fail open().
506 snd_clone_release(struct cdev *dev)
508 struct snd_clone_entry *ce;
510 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
516 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
518 ce->flags &= ~SND_CLONE_INVOKE;
520 if (!(ce->flags & SND_CLONE_BUSY))
523 ce->flags &= ~SND_CLONE_BUSY;
530 * snd_clone_ref/unref() : Garbage collector reference counter. To make
531 * garbage collector run automatically, the sequence must be something like
532 * this (both in open() and close() handlers):
534 * open() - 1) snd_clone_acquire()
535 * 2) .... check check ... if failed, snd_clone_release()
536 * 3) Success. Call snd_clone_ref()
538 * close() - 1) .... check check check ....
539 * 2) Success. snd_clone_release()
540 * 3) snd_clone_unref() . Garbage collector will run at this point
541 * if this is the last referenced object.
544 snd_clone_ref(struct cdev *dev)
546 struct snd_clone_entry *ce;
549 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
556 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
557 SND_CLONE_ASSERT(c->refcount >= 0, ("refcount < 0"));
559 return (++c->refcount);
563 snd_clone_unref(struct cdev *dev)
565 struct snd_clone_entry *ce;
568 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
575 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
576 SND_CLONE_ASSERT(c->refcount > 0, ("refcount <= 0"));
581 * Run automatic garbage collector, if needed.
583 if ((c->flags & SND_CLONE_GC_UNREF) &&
584 (!(c->flags & SND_CLONE_GC_LASTREF) ||
585 (c->refcount == 0 && (c->flags & SND_CLONE_GC_LASTREF))))
586 (void)snd_clone_gc(c);
588 return (c->refcount);
592 snd_clone_register(struct snd_clone_entry *ce, struct cdev *dev)
594 SND_CLONE_ASSERT(ce != NULL, ("NULL snd_clone_entry"));
595 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
596 SND_CLONE_ASSERT(dev->si_drv2 == NULL, ("dev->si_drv2 not NULL"));
597 SND_CLONE_ASSERT((ce->flags & SND_CLONE_ALLOC) == SND_CLONE_ALLOC,
598 ("invalid clone alloc flags=0x%08x", ce->flags));
599 SND_CLONE_ASSERT(ce->devt == NULL, ("ce->devt not NULL"));
600 SND_CLONE_ASSERT(ce->unit == dev2unit(dev),
601 ("invalid unit ce->unit=0x%08x dev2unit=0x%08x",
602 ce->unit, dev2unit(dev)));
604 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
608 ce->flags &= ~SND_CLONE_ALLOC;
609 ce->flags |= SND_CLONE_INVOKE;
612 struct snd_clone_entry *
613 snd_clone_alloc(struct snd_clone *c, struct cdev **dev, int *unit, int tmask)
615 struct snd_clone_entry *ce, *after, *bce, *cce, *nce, *tce;
617 int cunit, allocunit;
620 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
621 SND_CLONE_ASSERT(dev != NULL, ("NULL dev pointer"));
622 SND_CLONE_ASSERT((c->typemask & tmask) == tmask,
623 ("invalid tmask: typemask=0x%08x tmask=0x%08x",
624 c->typemask, tmask));
625 SND_CLONE_ASSERT(unit != NULL, ("NULL unit pointer"));
626 SND_CLONE_ASSERT(*unit == -1 || !(*unit & (c->typemask | tmask)),
627 ("typemask collision: typemask=0x%08x tmask=0x%08x *unit=%d",
628 c->typemask, tmask, *unit));
630 if (!(c->flags & SND_CLONE_ENABLE) ||
631 (*unit != -1 && *unit > c->maxunit))
636 bce = NULL; /* "b"usy candidate */
637 cce = NULL; /* "c"urthread/proc candidate */
638 nce = NULL; /* "n"ull, totally unbusy candidate */
639 tce = NULL; /* Last "t"ry candidate */
641 allocunit = (*unit == -1) ? 0 : *unit;
642 curpid = curthread->td_proc->p_pid;
646 TAILQ_FOREACH(ce, &c->head, link) {
648 * Sort incrementally according to device type.
650 if (tmask > (ce->unit & c->typemask)) {
654 } else if (tmask < (ce->unit & c->typemask))
658 * Shoot.. this is where the grumpiness begin. Just
659 * return immediately.
661 if (*unit != -1 && *unit == (ce->unit & ~tmask))
662 goto snd_clone_alloc_out;
666 * Simmilar device type. Sort incrementally according
667 * to allocation unit. While here, look for free slot
668 * and possible collision for new / future allocation.
670 if (*unit == -1 && (ce->unit & ~tmask) == allocunit)
672 if ((ce->unit & ~tmask) < allocunit)
676 * 1. Look for non busy, but keep track of the best
677 * possible busy cdev.
678 * 2. Look for the best (oldest referenced) entry that is
679 * in a same process / thread.
680 * 3. Look for the best (oldest referenced), absolute free
682 * 4. Lastly, look for the best (oldest referenced)
683 * any entries that doesn't fit with anything above.
685 if (ce->flags & SND_CLONE_BUSY) {
686 if (ce->devt != NULL && (bce == NULL ||
687 timespeccmp(&ce->tsp, &bce->tsp, <)))
691 if (ce->pid == curpid &&
692 (cce == NULL || timespeccmp(&ce->tsp, &cce->tsp, <)))
694 else if (!(ce->flags & SND_CLONE_INVOKE) &&
695 (nce == NULL || timespeccmp(&ce->tsp, &nce->tsp, <)))
697 else if (tce == NULL || timespeccmp(&ce->tsp, &tce->tsp, <))
701 goto snd_clone_alloc_new;
702 else if (cce != NULL) {
703 /* Same proc entry found, go for it */
705 goto snd_clone_alloc_out;
706 } else if (nce != NULL) {
708 * Next, try absolute free entry. If the calculated
709 * allocunit is smaller, create new entry instead.
711 if (allocunit < (nce->unit & ~tmask))
712 goto snd_clone_alloc_new;
714 goto snd_clone_alloc_out;
715 } else if (allocunit > c->maxunit) {
717 * Maximum allowable unit reached. Try returning any
718 * available cdev and hope for the best. If the lookup is
719 * done for things like stat(), mtime() etc. , things should
720 * be ok. Otherwise, open() handler should do further checks
721 * and decide whether to return correct error code or not.
725 goto snd_clone_alloc_out;
726 } else if (bce != NULL) {
728 goto snd_clone_alloc_out;
735 * No free entries found, and we still haven't reached maximum
736 * allowable units. Allocate, setup a minimal unique entry with busy
737 * status so nobody will monkey on this new entry. Unit magic is set
738 * right here to avoid collision with other contesting handler.
739 * The caller must be carefull here to maintain its own
740 * synchronization, as long as it will not conflict with malloc(9)
743 * That said, go figure.
745 ce = malloc(sizeof(*ce), M_DEVBUF,
746 ((c->flags & SND_CLONE_WAITOK) ? M_WAITOK : M_NOWAIT) | M_ZERO);
751 * We're being dense, ignorance is bliss,
752 * Super Regulatory Measure (TM).. TRY AGAIN!
756 goto snd_clone_alloc_out;
757 } else if (tce != NULL) {
759 goto snd_clone_alloc_out;
760 } else if (bce != NULL) {
762 goto snd_clone_alloc_out;
766 /* Setup new entry */
768 ce->unit = tmask | allocunit;
771 ce->flags |= SND_CLONE_ALLOC;
773 TAILQ_INSERT_AFTER(&c->head, after, ce, link);
775 TAILQ_INSERT_HEAD(&c->head, ce, link);
780 * Save new allocation unit for caller which will be used
789 * Set, mark, timestamp the entry if this is a truly free entry.
790 * Leave busy entry alone.
792 if (!(ce->flags & SND_CLONE_BUSY)) {
795 ce->flags |= SND_CLONE_INVOKE;