2 * Copyright (c) 2007 Ariff Abdullah <ariff@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/param.h>
30 #include <sys/systm.h>
32 #include <sys/kernel.h>
33 #include <sys/malloc.h>
36 #ifdef HAVE_KERNEL_OPTION_HEADERS
40 #if defined(SND_DIAGNOSTIC) || defined(SND_DEBUG)
41 #include <dev/sound/pcm/sound.h>
44 #include <dev/sound/clone.h>
47 * So here we go again, another clonedevs manager. Unlike default clonedevs,
48 * this clone manager is designed to withstand various abusive behavior
49 * (such as 'while : ; do ls /dev/whatever ; done', etc.), reusable object
50 * after reaching certain expiration threshold, aggressive garbage collector,
51 * transparent device allocator and concurrency handling across multiple
52 * thread/proc. Due to limited information given by dev_clone EVENTHANDLER,
53 * we don't have much clues whether the caller wants a real open() or simply
54 * making fun of us with things like stat(), mtime() etc. Assuming that:
55 * 1) Time window between dev_clone EH <-> real open() should be small
56 * enough and 2) mtime()/stat() etc. always looks like a half way / stalled
57 * operation, we can decide whether a new cdev must be created, old
58 * (expired) cdev can be reused or an existing cdev can be shared.
60 * Most of the operations and logics are generic enough and can be applied
61 * on other places (such as if_tap, snp, etc). Perhaps this can be
62 * rearranged to complement clone_*(). However, due to this still being
63 * specific to the sound driver (and as a proof of concept on how it can be
64 * done), si_drv2 is used to keep the pointer of the clone list entry to
65 * avoid expensive lookup.
69 struct snd_clone_entry {
70 TAILQ_ENTRY(snd_clone_entry) link;
71 struct snd_clone *parent;
81 TAILQ_HEAD(link_head, snd_clone_entry) head;
92 #define SND_CLONE_ASSERT(x, y) do { \
97 #define SND_CLONE_ASSERT(...) KASSERT(__VA_ARGS__)
101 * Shamelessly ripped off from vfs_subr.c
102 * We need at least 1/HZ precision as default timestamping.
104 enum { SND_TSP_SEC, SND_TSP_HZ, SND_TSP_USEC, SND_TSP_NSEC };
106 static int snd_timestamp_precision = SND_TSP_HZ;
107 TUNABLE_INT("hw.snd.timestamp_precision", &snd_timestamp_precision);
110 snd_timestamp(struct timespec *tsp)
114 switch (snd_timestamp_precision) {
116 tsp->tv_sec = time_second;
124 TIMEVAL_TO_TIMESPEC(&tv, tsp);
130 snd_timestamp_precision = SND_TSP_HZ;
136 #if defined(SND_DIAGNOSTIC) || defined(SND_DEBUG)
138 sysctl_hw_snd_timestamp_precision(SYSCTL_HANDLER_ARGS)
142 val = snd_timestamp_precision;
143 err = sysctl_handle_int(oidp, &val, 0, req);
144 if (err == 0 && req->newptr != NULL) {
150 snd_timestamp_precision = val;
159 SYSCTL_PROC(_hw_snd, OID_AUTO, timestamp_precision, CTLTYPE_INT | CTLFLAG_RW,
160 0, sizeof(int), sysctl_hw_snd_timestamp_precision, "I",
161 "timestamp precision (0=s 1=hz 2=us 3=ns)");
165 * snd_clone_create() : Return opaque allocated clone manager.
168 snd_clone_create(int typemask, int maxunit, int deadline, uint32_t flags)
172 SND_CLONE_ASSERT(!(typemask & ~SND_CLONE_MAXUNIT),
173 ("invalid typemask: 0x%08x", typemask));
174 SND_CLONE_ASSERT(maxunit == -1 ||
175 !(maxunit & ~(~typemask & SND_CLONE_MAXUNIT)),
176 ("maxunit overflow: typemask=0x%08x maxunit=%d",
178 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_MASK),
179 ("invalid clone flags=0x%08x", flags));
181 c = malloc(sizeof(*c), M_DEVBUF, M_WAITOK | M_ZERO);
184 c->typemask = typemask;
185 c->maxunit = (maxunit == -1) ? (~typemask & SND_CLONE_MAXUNIT) :
187 c->deadline = deadline;
189 snd_timestamp(&c->tsp);
190 TAILQ_INIT(&c->head);
196 snd_clone_busy(struct snd_clone *c)
198 struct snd_clone_entry *ce;
200 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
205 TAILQ_FOREACH(ce, &c->head, link) {
206 if ((ce->flags & SND_CLONE_BUSY) ||
207 (ce->devt != NULL && ce->devt->si_threadcount != 0))
215 * snd_clone_enable()/disable() : Suspend/resume clone allocation through
216 * snd_clone_alloc(). Everything else will not be affected by this.
219 snd_clone_enable(struct snd_clone *c)
221 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
223 if (c->flags & SND_CLONE_ENABLE)
226 c->flags |= SND_CLONE_ENABLE;
232 snd_clone_disable(struct snd_clone *c)
234 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
236 if (!(c->flags & SND_CLONE_ENABLE))
239 c->flags &= ~SND_CLONE_ENABLE;
245 * Getters / Setters. Not worth explaining :)
248 snd_clone_getsize(struct snd_clone *c)
250 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
256 snd_clone_getmaxunit(struct snd_clone *c)
258 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
264 snd_clone_setmaxunit(struct snd_clone *c, int maxunit)
266 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
267 SND_CLONE_ASSERT(maxunit == -1 ||
268 !(maxunit & ~(~c->typemask & SND_CLONE_MAXUNIT)),
269 ("maxunit overflow: typemask=0x%08x maxunit=%d",
270 c->typemask, maxunit));
272 c->maxunit = (maxunit == -1) ? (~c->typemask & SND_CLONE_MAXUNIT) :
279 snd_clone_getdeadline(struct snd_clone *c)
281 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
283 return (c->deadline);
287 snd_clone_setdeadline(struct snd_clone *c, int deadline)
289 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
291 c->deadline = deadline;
293 return (c->deadline);
297 snd_clone_gettime(struct snd_clone *c, struct timespec *tsp)
299 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
300 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
308 snd_clone_getflags(struct snd_clone *c)
310 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
316 snd_clone_setflags(struct snd_clone *c, uint32_t flags)
318 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
319 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_MASK),
320 ("invalid clone flags=0x%08x", flags));
328 snd_clone_getdevtime(struct cdev *dev, struct timespec *tsp)
330 struct snd_clone_entry *ce;
332 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
333 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
339 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
347 snd_clone_getdevflags(struct cdev *dev)
349 struct snd_clone_entry *ce;
351 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
357 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
363 snd_clone_setdevflags(struct cdev *dev, uint32_t flags)
365 struct snd_clone_entry *ce;
367 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
368 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_DEVMASK),
369 ("invalid clone dev flags=0x%08x", flags));
375 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
382 /* Elapsed time conversion to ms */
383 #define SND_CLONE_ELAPSED(x, y) \
384 ((((x)->tv_sec - (y)->tv_sec) * 1000) + \
385 (((y)->tv_nsec > (x)->tv_nsec) ? \
386 (((1000000000L + (x)->tv_nsec - \
387 (y)->tv_nsec) / 1000000) - 1000) : \
388 (((x)->tv_nsec - (y)->tv_nsec) / 1000000)))
390 #define SND_CLONE_EXPIRED(x, y, z) \
391 ((x)->deadline < 1 || \
392 ((y)->tv_sec - (z)->tv_sec) > ((x)->deadline / 1000) || \
393 SND_CLONE_ELAPSED(y, z) > (x)->deadline)
396 * snd_clone_gc() : Garbage collector for stalled, expired objects. Refer to
397 * clone.h for explanations on GC settings.
400 snd_clone_gc(struct snd_clone *c)
402 struct snd_clone_entry *ce, *tce;
406 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
408 if (!(c->flags & SND_CLONE_GC_ENABLE) || c->size == 0)
414 * Bail out if the last clone handler was invoked below the deadline
417 if ((c->flags & SND_CLONE_GC_EXPIRED) &&
418 !SND_CLONE_EXPIRED(c, &now, &c->tsp))
424 * Visit each object in reverse order. If the object is still being
425 * referenced by a valid open(), skip it. Look for expired objects
426 * and either revoke its clone invocation status or mercilessly
429 TAILQ_FOREACH_REVERSE_SAFE(ce, &c->head, link_head, link, tce) {
430 if (!(ce->flags & SND_CLONE_BUSY) &&
431 (!(ce->flags & SND_CLONE_INVOKE) ||
432 SND_CLONE_EXPIRED(c, &now, &ce->tsp))) {
433 if ((c->flags & SND_CLONE_GC_REVOKE) ||
434 ce->devt->si_threadcount != 0) {
435 ce->flags &= ~SND_CLONE_INVOKE;
438 TAILQ_REMOVE(&c->head, ce, link);
439 destroy_dev(ce->devt);
447 /* return total pruned objects */
452 snd_clone_destroy(struct snd_clone *c)
454 struct snd_clone_entry *ce, *tmp;
456 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
458 ce = TAILQ_FIRST(&c->head);
460 tmp = TAILQ_NEXT(ce, link);
461 if (ce->devt != NULL)
462 destroy_dev(ce->devt);
471 * snd_clone_acquire() : The vital part of concurrency management. Must be
472 * called somewhere at the beginning of open() handler. ENODEV is not really
473 * fatal since it just tell the caller that this is not cloned stuff.
474 * EBUSY is *real*, don't forget that!
477 snd_clone_acquire(struct cdev *dev)
479 struct snd_clone_entry *ce;
481 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
487 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
489 ce->flags &= ~SND_CLONE_INVOKE;
491 if (ce->flags & SND_CLONE_BUSY)
494 ce->flags |= SND_CLONE_BUSY;
500 * snd_clone_release() : Release busy status. Must be called somewhere at
501 * the end of close() handler, or somewhere after fail open().
504 snd_clone_release(struct cdev *dev)
506 struct snd_clone_entry *ce;
508 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
514 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
516 ce->flags &= ~SND_CLONE_INVOKE;
518 if (!(ce->flags & SND_CLONE_BUSY))
521 ce->flags &= ~SND_CLONE_BUSY;
528 * snd_clone_ref/unref() : Garbage collector reference counter. To make
529 * garbage collector run automatically, the sequence must be something like
530 * this (both in open() and close() handlers):
532 * open() - 1) snd_clone_acquire()
533 * 2) .... check check ... if failed, snd_clone_release()
534 * 3) Success. Call snd_clone_ref()
536 * close() - 1) .... check check check ....
537 * 2) Success. snd_clone_release()
538 * 3) snd_clone_unref() . Garbage collector will run at this point
539 * if this is the last referenced object.
542 snd_clone_ref(struct cdev *dev)
544 struct snd_clone_entry *ce;
547 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
554 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
555 SND_CLONE_ASSERT(c->refcount >= 0, ("refcount < 0"));
557 return (++c->refcount);
561 snd_clone_unref(struct cdev *dev)
563 struct snd_clone_entry *ce;
566 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
573 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
574 SND_CLONE_ASSERT(c->refcount > 0, ("refcount <= 0"));
579 * Run automatic garbage collector, if needed.
581 if ((c->flags & SND_CLONE_GC_UNREF) &&
582 (!(c->flags & SND_CLONE_GC_LASTREF) ||
583 (c->refcount == 0 && (c->flags & SND_CLONE_GC_LASTREF))))
584 (void)snd_clone_gc(c);
586 return (c->refcount);
590 snd_clone_register(struct snd_clone_entry *ce, struct cdev *dev)
592 SND_CLONE_ASSERT(ce != NULL, ("NULL snd_clone_entry"));
593 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
594 SND_CLONE_ASSERT(dev->si_drv2 == NULL, ("dev->si_drv2 not NULL"));
595 SND_CLONE_ASSERT((ce->flags & SND_CLONE_ALLOC) == SND_CLONE_ALLOC,
596 ("invalid clone alloc flags=0x%08x", ce->flags));
597 SND_CLONE_ASSERT(ce->devt == NULL, ("ce->devt not NULL"));
598 SND_CLONE_ASSERT(ce->unit == dev2unit(dev),
599 ("invalid unit ce->unit=0x%08x dev2unit=0x%08x",
600 ce->unit, dev2unit(dev)));
602 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
606 ce->flags &= ~SND_CLONE_ALLOC;
607 ce->flags |= SND_CLONE_INVOKE;
610 struct snd_clone_entry *
611 snd_clone_alloc(struct snd_clone *c, struct cdev **dev, int *unit, int tmask)
613 struct snd_clone_entry *ce, *after, *bce, *cce, *nce, *tce;
615 int cunit, allocunit;
618 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
619 SND_CLONE_ASSERT(dev != NULL, ("NULL dev pointer"));
620 SND_CLONE_ASSERT((c->typemask & tmask) == tmask,
621 ("invalid tmask: typemask=0x%08x tmask=0x%08x",
622 c->typemask, tmask));
623 SND_CLONE_ASSERT(unit != NULL, ("NULL unit pointer"));
624 SND_CLONE_ASSERT(*unit == -1 || !(*unit & (c->typemask | tmask)),
625 ("typemask collision: typemask=0x%08x tmask=0x%08x *unit=%d",
626 c->typemask, tmask, *unit));
628 if (!(c->flags & SND_CLONE_ENABLE) ||
629 (*unit != -1 && *unit > c->maxunit))
634 bce = NULL; /* "b"usy candidate */
635 cce = NULL; /* "c"urthread/proc candidate */
636 nce = NULL; /* "n"ull, totally unbusy candidate */
637 tce = NULL; /* Last "t"ry candidate */
639 allocunit = (*unit == -1) ? 0 : *unit;
640 curpid = curthread->td_proc->p_pid;
644 TAILQ_FOREACH(ce, &c->head, link) {
646 * Sort incrementally according to device type.
648 if (tmask > (ce->unit & c->typemask)) {
652 } else if (tmask < (ce->unit & c->typemask))
656 * Shoot.. this is where the grumpiness begin. Just
657 * return immediately.
659 if (*unit != -1 && *unit == (ce->unit & ~tmask))
660 goto snd_clone_alloc_out;
664 * Simmilar device type. Sort incrementally according
665 * to allocation unit. While here, look for free slot
666 * and possible collision for new / future allocation.
668 if (*unit == -1 && (ce->unit & ~tmask) == allocunit)
670 if ((ce->unit & ~tmask) < allocunit)
674 * 1. Look for non busy, but keep track of the best
675 * possible busy cdev.
676 * 2. Look for the best (oldest referenced) entry that is
677 * in a same process / thread.
678 * 3. Look for the best (oldest referenced), absolute free
680 * 4. Lastly, look for the best (oldest referenced)
681 * any entries that doesn't fit with anything above.
683 if (ce->flags & SND_CLONE_BUSY) {
684 if (ce->devt != NULL && (bce == NULL ||
685 timespeccmp(&ce->tsp, &bce->tsp, <)))
689 if (ce->pid == curpid &&
690 (cce == NULL || timespeccmp(&ce->tsp, &cce->tsp, <)))
692 else if (!(ce->flags & SND_CLONE_INVOKE) &&
693 (nce == NULL || timespeccmp(&ce->tsp, &nce->tsp, <)))
695 else if (tce == NULL || timespeccmp(&ce->tsp, &tce->tsp, <))
699 goto snd_clone_alloc_new;
700 else if (cce != NULL) {
701 /* Same proc entry found, go for it */
703 goto snd_clone_alloc_out;
704 } else if (nce != NULL) {
706 * Next, try absolute free entry. If the calculated
707 * allocunit is smaller, create new entry instead.
709 if (allocunit < (nce->unit & ~tmask))
710 goto snd_clone_alloc_new;
712 goto snd_clone_alloc_out;
713 } else if (allocunit > c->maxunit) {
715 * Maximum allowable unit reached. Try returning any
716 * available cdev and hope for the best. If the lookup is
717 * done for things like stat(), mtime() etc. , things should
718 * be ok. Otherwise, open() handler should do further checks
719 * and decide whether to return correct error code or not.
723 goto snd_clone_alloc_out;
724 } else if (bce != NULL) {
726 goto snd_clone_alloc_out;
733 * No free entries found, and we still haven't reached maximum
734 * allowable units. Allocate, setup a minimal unique entry with busy
735 * status so nobody will monkey on this new entry. Unit magic is set
736 * right here to avoid collision with other contesting handler.
737 * The caller must be carefull here to maintain its own
738 * synchronization, as long as it will not conflict with malloc(9)
741 * That said, go figure.
743 ce = malloc(sizeof(*ce), M_DEVBUF,
744 ((c->flags & SND_CLONE_WAITOK) ? M_WAITOK : M_NOWAIT) | M_ZERO);
749 * We're being dense, ignorance is bliss,
750 * Super Regulatory Measure (TM).. TRY AGAIN!
754 goto snd_clone_alloc_out;
755 } else if (tce != NULL) {
757 goto snd_clone_alloc_out;
758 } else if (bce != NULL) {
760 goto snd_clone_alloc_out;
764 /* Setup new entry */
766 ce->unit = tmask | allocunit;
769 ce->flags |= SND_CLONE_ALLOC;
771 TAILQ_INSERT_AFTER(&c->head, after, ce, link);
773 TAILQ_INSERT_HEAD(&c->head, ce, link);
778 * Save new allocation unit for caller which will be used
787 * Set, mark, timestamp the entry if this is a truly free entry.
788 * Leave busy entry alone.
790 if (!(ce->flags & SND_CLONE_BUSY)) {
793 ce->flags |= SND_CLONE_INVOKE;