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
26 * $FreeBSD: head/sys/dev/sound/clone.c 193640 2009-06-07 19:12:08Z ariff $
29 #include <sys/param.h>
30 #include <sys/systm.h>
32 #include <sys/kernel.h>
33 #include <sys/malloc.h>
35 #include <sys/devfs.h>
37 #ifdef HAVE_KERNEL_OPTION_HEADERS
41 #include <dev/sound/pcm/sound.h>
42 #include <dev/sound/clone.h>
44 DEVFS_DECLARE_CLONE_BITMAP(dsp);
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(!(flags & ~SND_CLONE_MASK),
175 ("invalid clone flags=0x%08x", flags));
177 c = kmalloc(sizeof(*c), M_DEVBUF, M_WAITOK | M_ZERO);
180 c->typemask = typemask;
181 c->maxunit = (maxunit == -1) ? (~typemask & SND_CLONE_MAXUNIT) :
183 c->deadline = deadline;
185 snd_timestamp(&c->tsp);
186 TAILQ_INIT(&c->head);
192 snd_clone_busy(struct snd_clone *c)
194 struct snd_clone_entry *ce;
196 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
201 TAILQ_FOREACH(ce, &c->head, link) {
202 if (ce->flags & SND_CLONE_BUSY)
210 * snd_clone_enable()/disable() : Suspend/resume clone allocation through
211 * snd_clone_alloc(). Everything else will not be affected by this.
214 snd_clone_enable(struct snd_clone *c)
216 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
218 if (c->flags & SND_CLONE_ENABLE)
221 c->flags |= SND_CLONE_ENABLE;
227 snd_clone_disable(struct snd_clone *c)
229 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
231 if (!(c->flags & SND_CLONE_ENABLE))
234 c->flags &= ~SND_CLONE_ENABLE;
240 * Getters / Setters. Not worth explaining :)
243 snd_clone_getsize(struct snd_clone *c)
245 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
251 snd_clone_getmaxunit(struct snd_clone *c)
253 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
259 snd_clone_setmaxunit(struct snd_clone *c, int maxunit)
261 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
263 c->maxunit = (maxunit == -1) ? (~c->typemask & SND_CLONE_MAXUNIT) :
270 snd_clone_getdeadline(struct snd_clone *c)
272 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
274 return (c->deadline);
278 snd_clone_setdeadline(struct snd_clone *c, int deadline)
280 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
282 c->deadline = deadline;
284 return (c->deadline);
288 snd_clone_gettime(struct snd_clone *c, struct timespec *tsp)
290 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
291 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
299 snd_clone_getflags(struct snd_clone *c)
301 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
307 snd_clone_setflags(struct snd_clone *c, uint32_t flags)
309 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
310 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_MASK),
311 ("invalid clone flags=0x%08x", flags));
319 snd_clone_getdevtime(struct cdev *dev, struct timespec *tsp)
321 struct snd_clone_entry *ce;
323 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
324 SND_CLONE_ASSERT(tsp != NULL, ("NULL timespec"));
330 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
338 snd_clone_getdevflags(struct cdev *dev)
340 struct snd_clone_entry *ce;
342 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
348 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
354 snd_clone_setdevflags(struct cdev *dev, uint32_t flags)
356 struct snd_clone_entry *ce;
358 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
359 SND_CLONE_ASSERT(!(flags & ~SND_CLONE_DEVMASK),
360 ("invalid clone dev flags=0x%08x", flags));
366 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
373 /* Elapsed time conversion to ms */
374 #define SND_CLONE_ELAPSED(x, y) \
375 ((((x)->tv_sec - (y)->tv_sec) * 1000) + \
376 (((y)->tv_nsec > (x)->tv_nsec) ? \
377 (((1000000000L + (x)->tv_nsec - \
378 (y)->tv_nsec) / 1000000) - 1000) : \
379 (((x)->tv_nsec - (y)->tv_nsec) / 1000000)))
381 #define SND_CLONE_EXPIRED(x, y, z) \
382 ((x)->deadline < 1 || \
383 ((y)->tv_sec - (z)->tv_sec) > ((x)->deadline / 1000) || \
384 SND_CLONE_ELAPSED(y, z) > (x)->deadline)
387 * snd_clone_gc() : Garbage collector for stalled, expired objects. Refer to
388 * clone.h for explanations on GC settings.
391 snd_clone_gc(struct snd_clone *c)
393 struct snd_clone_entry *ce, *tce;
398 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
400 if (!(c->flags & SND_CLONE_GC_ENABLE) || c->size == 0)
406 * Bail out if the last clone handler was invoked below the deadline
409 if ((c->flags & SND_CLONE_GC_EXPIRED) &&
410 !SND_CLONE_EXPIRED(c, &now, &c->tsp))
416 * Visit each object in reverse order. If the object is still being
417 * referenced by a valid open(), skip it. Look for expired objects
418 * and either revoke its clone invocation status or mercilessly
421 TAILQ_FOREACH_REVERSE_MUTABLE(ce, &c->head, link_head, link, tce) {
422 if (!(ce->flags & SND_CLONE_BUSY) &&
423 (!(ce->flags & SND_CLONE_INVOKE) ||
424 SND_CLONE_EXPIRED(c, &now, &ce->tsp))) {
425 if (c->flags & SND_CLONE_GC_REVOKE) {
426 ce->flags &= ~SND_CLONE_INVOKE;
429 TAILQ_REMOVE(&c->head, ce, link);
430 subunit = PCMSUBUNIT(ce->devt);
431 destroy_dev(ce->devt);
432 devfs_clone_bitmap_put(&DEVFS_CLONE_BITMAP(dsp), subunit);
440 /* return total pruned objects */
445 snd_clone_destroy(struct snd_clone *c)
447 struct snd_clone_entry *ce, *tmp;
450 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
452 ce = TAILQ_FIRST(&c->head);
454 tmp = TAILQ_NEXT(ce, link);
455 if (ce->devt != NULL) {
456 subunit = PCMSUBUNIT(ce->devt);
457 destroy_dev(ce->devt);
458 devfs_clone_bitmap_put(&DEVFS_CLONE_BITMAP(dsp), subunit);
468 * snd_clone_acquire() : The vital part of concurrency management. Must be
469 * called somewhere at the beginning of open() handler. ENODEV is not really
470 * fatal since it just tell the caller that this is not cloned stuff.
471 * EBUSY is *real*, don't forget that!
474 snd_clone_acquire(struct cdev *dev)
476 struct snd_clone_entry *ce;
478 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
484 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
486 ce->flags &= ~SND_CLONE_INVOKE;
488 if (ce->flags & SND_CLONE_BUSY)
491 ce->flags |= SND_CLONE_BUSY;
497 * snd_clone_release() : Release busy status. Must be called somewhere at
498 * the end of close() handler, or somewhere after fail open().
501 snd_clone_release(struct cdev *dev)
503 struct snd_clone_entry *ce;
505 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
511 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
513 ce->flags &= ~SND_CLONE_INVOKE;
515 if (!(ce->flags & SND_CLONE_BUSY))
518 ce->flags &= ~SND_CLONE_BUSY;
525 * snd_clone_ref/unref() : Garbage collector reference counter. To make
526 * garbage collector run automatically, the sequence must be something like
527 * this (both in open() and close() handlers):
529 * open() - 1) snd_clone_acquire()
530 * 2) .... check check ... if failed, snd_clone_release()
531 * 3) Success. Call snd_clone_ref()
533 * close() - 1) .... check check check ....
534 * 2) Success. snd_clone_release()
535 * 3) snd_clone_unref() . Garbage collector will run at this point
536 * if this is the last referenced object.
539 snd_clone_ref(struct cdev *dev)
541 struct snd_clone_entry *ce;
544 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
551 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
552 SND_CLONE_ASSERT(c->refcount >= 0, ("refcount < 0"));
554 return (++c->refcount);
558 snd_clone_unref(struct cdev *dev)
560 struct snd_clone_entry *ce;
563 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
570 SND_CLONE_ASSERT(c != NULL, ("NULL parent"));
571 SND_CLONE_ASSERT(c->refcount > 0, ("refcount <= 0"));
576 * Run automatic garbage collector, if needed.
578 if ((c->flags & SND_CLONE_GC_UNREF) &&
579 (!(c->flags & SND_CLONE_GC_LASTREF) ||
580 (c->refcount == 0 && (c->flags & SND_CLONE_GC_LASTREF))))
581 (void)snd_clone_gc(c);
583 return (c->refcount);
587 snd_clone_register(struct snd_clone_entry *ce, struct cdev *dev)
589 SND_CLONE_ASSERT(ce != NULL, ("NULL snd_clone_entry"));
590 SND_CLONE_ASSERT(dev != NULL, ("NULL dev"));
591 SND_CLONE_ASSERT(dev->si_drv2 == NULL, ("dev->si_drv2 not NULL"));
592 SND_CLONE_ASSERT((ce->flags & SND_CLONE_ALLOC) == SND_CLONE_ALLOC,
593 ("invalid clone alloc flags=0x%08x", ce->flags));
594 SND_CLONE_ASSERT(ce->devt == NULL, ("ce->devt not NULL"));
595 #if 0 /* dev2unit doesn't make any sense on DragonFly */
596 SND_CLONE_ASSERT(ce->unit == dev2unit(dev),
597 ("invalid unit ce->unit=0x%08x dev2unit=0x%08x",
598 ce->unit, dev2unit(dev)));
601 SND_CLONE_ASSERT(ce->parent != NULL, ("NULL parent"));
605 ce->flags &= ~SND_CLONE_ALLOC;
606 ce->flags |= SND_CLONE_INVOKE;
609 struct snd_clone_entry *
610 snd_clone_alloc(struct snd_clone *c, struct cdev **dev, int *unit, int tmask)
612 struct snd_clone_entry *ce, *after, *bce, *cce, *nce, *tce;
614 int cunit, allocunit;
617 SND_CLONE_ASSERT(c != NULL, ("NULL snd_clone"));
618 SND_CLONE_ASSERT(dev != NULL, ("NULL dev pointer"));
619 SND_CLONE_ASSERT((c->typemask & tmask) == tmask,
620 ("invalid tmask: typemask=0x%08x tmask=0x%08x",
621 c->typemask, tmask));
622 SND_CLONE_ASSERT(unit != NULL, ("NULL unit pointer"));
623 SND_CLONE_ASSERT(*unit == -1 || !(*unit & (c->typemask | tmask)),
624 ("typemask collision: typemask=0x%08x tmask=0x%08x *unit=%d",
625 c->typemask, tmask, *unit));
627 if (!(c->flags & SND_CLONE_ENABLE) ||
628 (*unit != -1 && *unit > c->maxunit))
633 bce = NULL; /* "b"usy candidate */
634 cce = NULL; /* "c"urthread/proc candidate */
635 nce = NULL; /* "n"ull, totally unbusy candidate */
636 tce = NULL; /* Last "t"ry candidate */
638 allocunit = (*unit == -1) ? 0 : *unit;
639 curpid = curthread->td_proc->p_pid;
643 TAILQ_FOREACH(ce, &c->head, link) {
645 * Sort incrementally according to device type.
647 if (tmask > (ce->unit & c->typemask)) {
651 } else if (tmask < (ce->unit & c->typemask))
655 * Shoot.. this is where the grumpiness begin. Just
656 * return immediately.
658 if (*unit != -1 && *unit == (ce->unit & ~tmask))
659 goto snd_clone_alloc_out;
663 * Simmilar device type. Sort incrementally according
664 * to allocation unit. While here, look for free slot
665 * and possible collision for new / future allocation.
667 if (*unit == -1 && (ce->unit & ~tmask) == allocunit)
669 if ((ce->unit & ~tmask) < allocunit)
673 * 1. Look for non busy, but keep track of the best
674 * possible busy cdev.
675 * 2. Look for the best (oldest referenced) entry that is
676 * in a same process / thread.
677 * 3. Look for the best (oldest referenced), absolute free
679 * 4. Lastly, look for the best (oldest referenced)
680 * any entries that doesn't fit with anything above.
682 if (ce->flags & SND_CLONE_BUSY) {
683 if (ce->devt != NULL && (bce == NULL ||
684 timespeccmp(&ce->tsp, &bce->tsp, <)))
688 if (ce->pid == curpid &&
689 (cce == NULL || timespeccmp(&ce->tsp, &cce->tsp, <)))
691 else if (!(ce->flags & SND_CLONE_INVOKE) &&
692 (nce == NULL || timespeccmp(&ce->tsp, &nce->tsp, <)))
694 else if (tce == NULL || timespeccmp(&ce->tsp, &tce->tsp, <))
698 goto snd_clone_alloc_new;
699 else if (cce != NULL) {
700 /* Same proc entry found, go for it */
702 goto snd_clone_alloc_out;
703 } else if (nce != NULL) {
705 * Next, try absolute free entry. If the calculated
706 * allocunit is smaller, create new entry instead.
708 if (allocunit < (nce->unit & ~tmask))
709 goto snd_clone_alloc_new;
711 goto snd_clone_alloc_out;
712 } else if (allocunit > c->maxunit) {
714 * Maximum allowable unit reached. Try returning any
715 * available cdev and hope for the best. If the lookup is
716 * done for things like stat(), mtime() etc. , things should
717 * be ok. Otherwise, open() handler should do further checks
718 * and decide whether to return correct error code or not.
722 goto snd_clone_alloc_out;
723 } else if (bce != NULL) {
725 goto snd_clone_alloc_out;
732 * No free entries found, and we still haven't reached maximum
733 * allowable units. Allocate, setup a minimal unique entry with busy
734 * status so nobody will monkey on this new entry. Unit magic is set
735 * right here to avoid collision with other contesting handler.
736 * The caller must be carefull here to maintain its own
737 * synchronization, as long as it will not conflict with malloc(9)
740 * That said, go figure.
742 ce = kmalloc(sizeof(*ce), M_DEVBUF, M_WAITOK | M_ZERO);
747 * We're being dense, ignorance is bliss,
748 * Super Regulatory Measure (TM).. TRY AGAIN!
752 goto snd_clone_alloc_out;
753 } else if (tce != NULL) {
755 goto snd_clone_alloc_out;
756 } else if (bce != NULL) {
758 goto snd_clone_alloc_out;
762 /* Setup new entry */
764 ce->unit = tmask | allocunit;
767 ce->flags |= SND_CLONE_ALLOC;
769 TAILQ_INSERT_AFTER(&c->head, after, ce, link);
771 TAILQ_INSERT_HEAD(&c->head, ce, link);
776 * Save new allocation unit for caller which will be used
785 * Set, mark, timestamp the entry if this is a truly free entry.
786 * Leave busy entry alone.
788 if (!(ce->flags & SND_CLONE_BUSY)) {
791 ce->flags |= SND_CLONE_INVOKE;