kern_conf.c revision 135712 
1/*-
2 * Copyright (c) 1999-2002 Poul-Henning Kamp
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
13 *
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
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/kern_conf.c 135712 2004-09-24 06:29:23Z phk $");
29
30#include <sys/param.h>
31#include <sys/kernel.h>
32#include <sys/systm.h>
33#include <sys/bio.h>
34#include <sys/lock.h>
35#include <sys/mutex.h>
36#include <sys/sysctl.h>
37#include <sys/module.h>
38#include <sys/malloc.h>
39#include <sys/conf.h>
40#include <sys/vnode.h>
41#include <sys/queue.h>
42#include <sys/poll.h>
43#include <sys/ctype.h>
44#include <sys/tty.h>
45#include <machine/stdarg.h>
46
47static MALLOC_DEFINE(M_DEVT, "cdev", "cdev storage");
48
49/* Built at compile time from sys/conf/majors */
50extern unsigned char reserved_majors[256];
51
52/*
53 * This is the number of hash-buckets.  Experiments with 'real-life'
54 * dev_t's show that a prime halfway between two powers of two works
55 * best.
56 */
57#define DEVT_HASH 83
58
59/* The number of struct cdev *'s we can create before malloc(9) kick in.  */
60#define DEVT_STASH 50
61
62static struct cdev devt_stash[DEVT_STASH];
63
64static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
65
66static LIST_HEAD(, cdev) dev_free;
67
68static int free_devt;
69SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
70
71static struct mtx devmtx;
72static void freedev(struct cdev *dev);
73static struct cdev *newdev(int x, int y);
74
75
76void
77dev_lock(void)
78{
79	if (!mtx_initialized(&devmtx))
80		mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
81	mtx_lock(&devmtx);
82}
83
84void
85dev_unlock(void)
86{
87
88	mtx_unlock(&devmtx);
89}
90
91void
92dev_ref(struct cdev *dev)
93{
94
95	dev_lock();
96	dev->si_refcount++;
97	dev_unlock();
98}
99
100void
101dev_rel(struct cdev *dev)
102{
103
104	dev->si_refcount--;
105	KASSERT(dev->si_refcount >= 0,
106	    ("dev_rel(%s) gave negative count", devtoname(dev)));
107	if (dev->si_devsw == NULL && dev->si_refcount == 0) {
108		LIST_REMOVE(dev, si_list);
109		freedev(dev);
110	}
111}
112struct cdevsw *
113dev_refthread(struct cdev *dev)
114{
115	struct cdevsw *csw;
116
117	mtx_assert(&devmtx, MA_NOTOWNED);
118	dev_lock();
119	csw = dev->si_devsw;
120	if (csw != NULL)
121		dev->si_threadcount++;
122	dev_unlock();
123	return (csw);
124}
125
126void
127dev_relthread(struct cdev *dev)
128{
129
130	mtx_assert(&devmtx, MA_NOTOWNED);
131	dev_lock();
132	dev->si_threadcount--;
133	dev_unlock();
134}
135
136int
137nullop(void)
138{
139
140	return (0);
141}
142
143int
144eopnotsupp(void)
145{
146
147	return (EOPNOTSUPP);
148}
149
150static int
151enxio(void)
152{
153	return (ENXIO);
154}
155
156static int
157enodev(void)
158{
159	return (ENODEV);
160}
161
162/* Define a dead_cdevsw for use when devices leave unexpectedly. */
163
164#define dead_open	(d_open_t *)enxio
165#define dead_close	(d_close_t *)enxio
166#define dead_read	(d_read_t *)enxio
167#define dead_write	(d_write_t *)enxio
168#define dead_ioctl	(d_ioctl_t *)enxio
169#define dead_poll	(d_poll_t *)enodev
170#define dead_mmap	(d_mmap_t *)enodev
171
172static void
173dead_strategy(struct bio *bp)
174{
175
176	biofinish(bp, NULL, ENXIO);
177}
178
179#define dead_dump	(dumper_t *)enxio
180#define dead_kqfilter	(d_kqfilter_t *)enxio
181
182static struct cdevsw dead_cdevsw = {
183	.d_version =	D_VERSION,
184	.d_flags =	D_NEEDGIANT, /* XXX: does dead_strategy need this ? */
185	.d_open =	dead_open,
186	.d_close =	dead_close,
187	.d_read =	dead_read,
188	.d_write =	dead_write,
189	.d_ioctl =	dead_ioctl,
190	.d_poll =	dead_poll,
191	.d_mmap =	dead_mmap,
192	.d_strategy =	dead_strategy,
193	.d_name =	"dead",
194	.d_maj =	255,
195	.d_dump =	dead_dump,
196	.d_kqfilter =	dead_kqfilter
197};
198
199/* Default methods if driver does not specify method */
200
201#define null_open	(d_open_t *)nullop
202#define null_close	(d_close_t *)nullop
203#define no_read		(d_read_t *)enodev
204#define no_write	(d_write_t *)enodev
205#define no_ioctl	(d_ioctl_t *)enodev
206#define no_mmap		(d_mmap_t *)enodev
207#define no_kqfilter	(d_kqfilter_t *)enodev
208
209static void
210no_strategy(struct bio *bp)
211{
212
213	biofinish(bp, NULL, ENODEV);
214}
215
216static int
217no_poll(struct cdev *dev __unused, int events, struct thread *td __unused)
218{
219	/*
220	 * Return true for read/write.  If the user asked for something
221	 * special, return POLLNVAL, so that clients have a way of
222	 * determining reliably whether or not the extended
223	 * functionality is present without hard-coding knowledge
224	 * of specific filesystem implementations.
225	 * Stay in sync with vop_nopoll().
226	 */
227	if (events & ~POLLSTANDARD)
228		return (POLLNVAL);
229
230	return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
231}
232
233#define no_dump		(dumper_t *)enodev
234
235struct cdevsw *
236devsw(struct cdev *dev)
237{
238	if (dev->si_devsw != NULL)
239		return (dev->si_devsw);
240	return (&dead_cdevsw);
241}
242
243/*
244 * struct cdev * and u_dev_t primitives
245 */
246
247int
248major(struct cdev *x)
249{
250	if (x == NULL)
251		return NODEV;
252	return((x->si_udev >> 8) & 0xff);
253}
254
255int
256minor(struct cdev *x)
257{
258	if (x == NULL)
259		return NODEV;
260	return(x->si_udev & 0xffff00ff);
261}
262
263int
264dev2unit(struct cdev *x)
265{
266	int i;
267
268	if (x == NULL)
269		return NODEV;
270	i = minor(x);
271	return ((i & 0xff) | (i >> 8));
272}
273
274int
275unit2minor(int unit)
276{
277
278	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
279	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
280}
281
282static struct cdev *
283allocdev(void)
284{
285	static int stashed;
286	struct cdev *si;
287
288	if (LIST_FIRST(&dev_free)) {
289		si = LIST_FIRST(&dev_free);
290		LIST_REMOVE(si, si_hash);
291	} else if (stashed >= DEVT_STASH) {
292		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
293		    M_USE_RESERVE | M_ZERO | M_WAITOK);
294	} else {
295		si = devt_stash + stashed++;
296		bzero(si, sizeof *si);
297		si->si_flags |= SI_STASHED;
298	}
299	si->__si_namebuf[0] = '\0';
300	si->si_name = si->__si_namebuf;
301	LIST_INIT(&si->si_children);
302	return (si);
303}
304
305static struct cdev *
306newdev(int x, int y)
307{
308	struct cdev *si;
309	dev_t	udev;
310	int hash;
311
312	if (x == umajor(NODEV) && y == uminor(NODEV))
313		panic("newdev of NODEV");
314	udev = (x << 8) | y;
315	hash = udev % DEVT_HASH;
316	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
317		if (si->si_udev == udev)
318			return (si);
319	}
320	si = allocdev();
321	si->si_udev = udev;
322	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
323	return (si);
324}
325
326static void
327freedev(struct cdev *dev)
328{
329
330	if (dev->si_flags & SI_STASHED) {
331		bzero(dev, sizeof(*dev));
332		dev->si_flags |= SI_STASHED;
333		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
334	} else {
335		FREE(dev, M_DEVT);
336	}
337}
338
339dev_t
340dev2udev(struct cdev *x)
341{
342	if (x == NULL)
343		return (NODEV);
344	return (x->si_udev);
345}
346
347struct cdev *
348findcdev(dev_t udev)
349{
350	struct cdev *si;
351	int hash;
352
353	if (udev == NODEV)
354		return (NULL);
355	hash = udev % DEVT_HASH;
356	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
357		if (si->si_udev == udev)
358			return (si);
359	}
360	return (NULL);
361}
362
363int
364uminor(dev_t dev)
365{
366	return (dev & 0xffff00ff);
367}
368
369int
370umajor(dev_t dev)
371{
372	return ((dev & 0xff00) >> 8);
373}
374
375static void
376find_major(struct cdevsw *devsw)
377{
378	int i;
379
380	for (i = NUMCDEVSW - 1; i > 0; i--)
381		if (reserved_majors[i] != i)
382			break;
383	KASSERT(i > 0, ("Out of major numbers (%s)", devsw->d_name));
384	devsw->d_maj = i;
385	reserved_majors[i] = i;
386	devsw->d_flags |= D_ALLOCMAJ;
387}
388
389static void
390fini_cdevsw(struct cdevsw *devsw)
391{
392	if (devsw->d_flags & D_ALLOCMAJ) {
393		reserved_majors[devsw->d_maj] = 0;
394		devsw->d_maj = MAJOR_AUTO;
395		devsw->d_flags &= ~D_ALLOCMAJ;
396	} else if (devsw->d_maj == 0)
397		devsw->d_maj = 256;
398	devsw->d_flags &= ~D_INIT;
399}
400
401static void
402prep_cdevsw(struct cdevsw *devsw)
403{
404
405	dev_lock();
406
407	if (devsw->d_version != D_VERSION_00) {
408		printf(
409		    "WARNING: Device driver \"%s\" has wrong version %s\n",
410		    devsw->d_name, "and is disabled.  Recompile KLD module.");
411		devsw->d_open = dead_open;
412		devsw->d_close = dead_close;
413		devsw->d_read = dead_read;
414		devsw->d_write = dead_write;
415		devsw->d_ioctl = dead_ioctl;
416		devsw->d_poll = dead_poll;
417		devsw->d_mmap = dead_mmap;
418		devsw->d_strategy = dead_strategy;
419		devsw->d_dump = dead_dump;
420		devsw->d_kqfilter = dead_kqfilter;
421	}
422
423	if (devsw->d_flags & D_TTY) {
424		if (devsw->d_ioctl == NULL)	devsw->d_ioctl = ttyioctl;
425		if (devsw->d_read == NULL)	devsw->d_read = ttyread;
426		if (devsw->d_write == NULL)	devsw->d_write = ttywrite;
427		if (devsw->d_kqfilter == NULL)	devsw->d_kqfilter = ttykqfilter;
428		if (devsw->d_poll == NULL)	devsw->d_poll = ttypoll;
429	}
430
431	if (devsw->d_open == NULL)	devsw->d_open = null_open;
432	if (devsw->d_close == NULL)	devsw->d_close = null_close;
433	if (devsw->d_read == NULL)	devsw->d_read = no_read;
434	if (devsw->d_write == NULL)	devsw->d_write = no_write;
435	if (devsw->d_ioctl == NULL)	devsw->d_ioctl = no_ioctl;
436	if (devsw->d_poll == NULL)	devsw->d_poll = no_poll;
437	if (devsw->d_mmap == NULL)	devsw->d_mmap = no_mmap;
438	if (devsw->d_strategy == NULL)	devsw->d_strategy = no_strategy;
439	if (devsw->d_dump == NULL)	devsw->d_dump = no_dump;
440	if (devsw->d_kqfilter == NULL)	devsw->d_kqfilter = no_kqfilter;
441
442	LIST_INIT(&devsw->d_devs);
443
444	devsw->d_flags |= D_INIT;
445
446	if (devsw->d_maj == MAJOR_AUTO) {
447		find_major(devsw);
448	} else {
449		if (devsw->d_maj == 256)	/* XXX: tty_cons.c is magic */
450			devsw->d_maj = 0;
451		KASSERT(devsw->d_maj >= 0 && devsw->d_maj < 256,
452		    ("Invalid major (%d) in make_dev", devsw->d_maj));
453		if (reserved_majors[devsw->d_maj] != devsw->d_maj) {
454			printf("WARNING: driver \"%s\" used %s %d\n",
455			    devsw->d_name, "unreserved major device number",
456			    devsw->d_maj);
457			reserved_majors[devsw->d_maj] = devsw->d_maj;
458		}
459	}
460	dev_unlock();
461}
462
463struct cdev *
464make_dev(struct cdevsw *devsw, int minornr, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
465{
466	struct cdev *dev;
467	va_list ap;
468	int i;
469
470	KASSERT((minornr & ~0xffff00ff) == 0,
471	    ("Invalid minor (0x%x) in make_dev", minornr));
472
473	if (!(devsw->d_flags & D_INIT))
474		prep_cdevsw(devsw);
475	dev = newdev(devsw->d_maj, minornr);
476	if (dev->si_flags & SI_CHEAPCLONE &&
477	    dev->si_flags & SI_NAMED &&
478	    dev->si_devsw == devsw) {
479		/*
480		 * This is allowed as it removes races and generally
481		 * simplifies cloning devices.
482		 * XXX: still ??
483		 */
484		return (dev);
485	}
486	dev_lock();
487	KASSERT(!(dev->si_flags & SI_NAMED),
488	    ("make_dev() by driver %s on pre-existing device (maj=%d, min=%d, name=%s)",
489	    devsw->d_name, major(dev), minor(dev), devtoname(dev)));
490
491	va_start(ap, fmt);
492	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
493	if (i > (sizeof dev->__si_namebuf - 1)) {
494		printf("WARNING: Device name truncated! (%s)\n",
495		    dev->__si_namebuf);
496	}
497	va_end(ap);
498	dev->si_devsw = devsw;
499	dev->si_uid = uid;
500	dev->si_gid = gid;
501	dev->si_mode = perms;
502	dev->si_flags |= SI_NAMED;
503
504	LIST_INSERT_HEAD(&devsw->d_devs, dev, si_list);
505	devfs_create(dev);
506	dev_unlock();
507	return (dev);
508}
509
510int
511dev_named(struct cdev *pdev, const char *name)
512{
513	struct cdev *cdev;
514
515	if (strcmp(devtoname(pdev), name) == 0)
516		return (1);
517	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
518		if (strcmp(devtoname(cdev), name) == 0)
519			return (1);
520	return (0);
521}
522
523void
524dev_depends(struct cdev *pdev, struct cdev *cdev)
525{
526
527	dev_lock();
528	cdev->si_parent = pdev;
529	cdev->si_flags |= SI_CHILD;
530	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
531	dev_unlock();
532}
533
534struct cdev *
535make_dev_alias(struct cdev *pdev, const char *fmt, ...)
536{
537	struct cdev *dev;
538	va_list ap;
539	int i;
540
541	dev = allocdev();
542	dev_lock();
543	dev->si_flags |= SI_ALIAS;
544	dev->si_flags |= SI_NAMED;
545	va_start(ap, fmt);
546	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
547	if (i > (sizeof dev->__si_namebuf - 1)) {
548		printf("WARNING: Device name truncated! (%s)\n",
549		    dev->__si_namebuf);
550	}
551	va_end(ap);
552
553	devfs_create(dev);
554	dev_unlock();
555	dev_depends(pdev, dev);
556	return (dev);
557}
558
559static void
560idestroy_dev(struct cdev *dev)
561{
562	if (!(dev->si_flags & SI_NAMED)) {
563		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
564		    major(dev), minor(dev));
565		panic("don't do that");
566	}
567
568	devfs_destroy(dev);
569
570	/* Remove name marking */
571	dev->si_flags &= ~SI_NAMED;
572
573	/* If we are a child, remove us from the parents list */
574	if (dev->si_flags & SI_CHILD) {
575		LIST_REMOVE(dev, si_siblings);
576		dev->si_flags &= ~SI_CHILD;
577	}
578
579	/* Kill our children */
580	while (!LIST_EMPTY(&dev->si_children))
581		idestroy_dev(LIST_FIRST(&dev->si_children));
582
583	/* Remove from clone list */
584	if (dev->si_flags & SI_CLONELIST) {
585		LIST_REMOVE(dev, si_clone);
586		dev->si_flags &= ~SI_CLONELIST;
587	}
588
589	if (!(dev->si_flags & SI_ALIAS)) {
590		/* Remove from cdevsw list */
591		LIST_REMOVE(dev, si_list);
592
593		/* If cdevsw has no struct cdev *'s, clean it */
594		if (LIST_EMPTY(&dev->si_devsw->d_devs))
595			fini_cdevsw(dev->si_devsw);
596
597		LIST_REMOVE(dev, si_hash);
598	}
599	dev->si_drv1 = 0;
600	dev->si_drv2 = 0;
601	dev->si_devsw = NULL;
602	bzero(&dev->__si_u, sizeof(dev->__si_u));
603	dev->si_flags &= ~SI_ALIAS;
604	if (dev->si_refcount > 0) {
605		LIST_INSERT_HEAD(&dead_cdevsw.d_devs, dev, si_list);
606	} else {
607		freedev(dev);
608	}
609}
610
611void
612destroy_dev(struct cdev *dev)
613{
614
615	dev_lock();
616	idestroy_dev(dev);
617	dev_unlock();
618}
619
620const char *
621devtoname(struct cdev *dev)
622{
623	char *p;
624	struct cdevsw *csw;
625	int mynor;
626
627	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
628		p = dev->si_name;
629		sprintf(p, "#%d", major(dev));
630		p += strlen(p);
631		csw = dev_refthread(dev);
632		if (csw != NULL) {
633			sprintf(p, "(%s)", csw->d_name);
634			dev_relthread(dev);
635		}
636		p += strlen(p);
637		mynor = minor(dev);
638		if (mynor < 0 || mynor > 255)
639			sprintf(p, "/%#x", (u_int)mynor);
640		else
641			sprintf(p, "/%d", mynor);
642	}
643	return (dev->si_name);
644}
645
646int
647dev_stdclone(char *name, char **namep, const char *stem, int *unit)
648{
649	int u, i;
650
651	i = strlen(stem);
652	if (bcmp(stem, name, i) != 0)
653		return (0);
654	if (!isdigit(name[i]))
655		return (0);
656	u = 0;
657	if (name[i] == '0' && isdigit(name[i+1]))
658		return (0);
659	while (isdigit(name[i])) {
660		u *= 10;
661		u += name[i++] - '0';
662	}
663	if (u > 0xffffff)
664		return (0);
665	*unit = u;
666	if (namep)
667		*namep = &name[i];
668	if (name[i])
669		return (2);
670	return (1);
671}
672
673/*
674 * Helper functions for cloning device drivers.
675 *
676 * The objective here is to make it unnecessary for the device drivers to
677 * use rman or similar to manage their unit number space.  Due to the way
678 * we do "on-demand" devices, using rman or other "private" methods
679 * will be very tricky to lock down properly once we lock down this file.
680 *
681 * Instead we give the drivers these routines which puts the struct cdev *'s
682 * that are to be managed on their own list, and gives the driver the ability
683 * to ask for the first free unit number or a given specified unit number.
684 *
685 * In addition these routines support paired devices (pty, nmdm and similar)
686 * by respecting a number of "flag" bits in the minor number.
687 *
688 */
689
690struct clonedevs {
691	LIST_HEAD(,cdev)	head;
692};
693
694void
695clone_setup(struct clonedevs **cdp)
696{
697
698	*cdp = malloc(sizeof **cdp, M_DEVBUF, M_WAITOK | M_ZERO);
699	LIST_INIT(&(*cdp)->head);
700}
701
702int
703clone_create(struct clonedevs **cdp, struct cdevsw *csw, int *up, struct cdev **dp, u_int extra)
704{
705	struct clonedevs *cd;
706	struct cdev *dev, *dl, *de;
707	int unit, low, u;
708
709	KASSERT(*cdp != NULL,
710	    ("clone_setup() not called in driver \"%s\"", csw->d_name));
711	KASSERT(!(extra & CLONE_UNITMASK),
712	    ("Illegal extra bits (0x%x) in clone_create", extra));
713	KASSERT(*up <= CLONE_UNITMASK,
714	    ("Too high unit (0x%x) in clone_create", *up));
715
716	if (csw->d_maj == MAJOR_AUTO)
717		find_major(csw);
718
719	/*
720	 * Search the list for a lot of things in one go:
721	 *   A preexisting match is returned immediately.
722	 *   The lowest free unit number if we are passed -1, and the place
723	 *	 in the list where we should insert that new element.
724	 *   The place to insert a specified unit number, if applicable
725	 *       the end of the list.
726	 */
727	unit = *up;
728	low = extra;
729	de = dl = NULL;
730	cd = *cdp;
731	LIST_FOREACH(dev, &cd->head, si_clone) {
732		u = dev2unit(dev);
733		if (u == (unit | extra)) {
734			*dp = dev;
735			return (0);
736		}
737		if (unit == -1 && u == low) {
738			low++;
739			de = dev;
740			continue;
741		}
742		if (u > (unit | extra)) {
743			dl = dev;
744			break;
745		}
746		de = dev;
747	}
748	if (unit == -1)
749		unit = low & CLONE_UNITMASK;
750	dev = newdev(csw->d_maj, unit2minor(unit | extra));
751	KASSERT(!(dev->si_flags & SI_CLONELIST),
752	    ("Dev %p should not be on clonelist", dev));
753	if (dl != NULL)
754		LIST_INSERT_BEFORE(dl, dev, si_clone);
755	else if (de != NULL)
756		LIST_INSERT_AFTER(de, dev, si_clone);
757	else
758		LIST_INSERT_HEAD(&cd->head, dev, si_clone);
759	dev->si_flags |= SI_CLONELIST;
760	*up = unit;
761	return (1);
762}
763
764/*
765 * Kill everything still on the list.  The driver should already have
766 * disposed of any softc hung of the struct cdev *'s at this time.
767 */
768void
769clone_cleanup(struct clonedevs **cdp)
770{
771	struct cdev *dev, *tdev;
772	struct clonedevs *cd;
773
774	cd = *cdp;
775	if (cd == NULL)
776		return;
777	LIST_FOREACH_SAFE(dev, &cd->head, si_clone, tdev) {
778		KASSERT(dev->si_flags & SI_NAMED,
779		    ("Driver has goofed in cloning underways udev %x", dev->si_udev));
780		destroy_dev(dev);
781	}
782	free(cd, M_DEVBUF);
783	*cdp = NULL;
784}
785
786/*
787 * Helper sysctl for devname(3).  We're given a struct cdev * and return
788 * the name, if any, registered by the device driver.
789 */
790static int
791sysctl_devname(SYSCTL_HANDLER_ARGS)
792{
793	int error;
794	dev_t ud;
795	struct cdev *dev;
796
797	error = SYSCTL_IN(req, &ud, sizeof (ud));
798	if (error)
799		return (error);
800	if (ud == NODEV)
801		return(EINVAL);
802	dev = findcdev(ud);
803	if (dev == NULL)
804		error = ENOENT;
805	else
806		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
807	return (error);
808}
809
810SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
811	NULL, 0, sysctl_devname, "", "devname(3) handler");
812