kern_conf.c revision 120506 
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 120506 2003-09-27 12:01:01Z 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/ctype.h>
43#include <machine/stdarg.h>
44
45static MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
46
47/* Built at compile time from sys/conf/majors */
48extern unsigned char reserved_majors[256];
49
50/*
51 * This is the number of hash-buckets.  Experiements with 'real-life'
52 * udev_t's show that a prime halfway between two powers of two works
53 * best.
54 */
55#define DEVT_HASH 83
56
57/* The number of dev_t's we can create before malloc(9) kick in.  */
58#define DEVT_STASH 50
59
60static struct cdev devt_stash[DEVT_STASH];
61
62static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
63
64static LIST_HEAD(, cdev) dev_free;
65
66static int ready_for_devs;
67
68static int free_devt;
69SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
70
71/* Define a dead_cdevsw for use when devices leave unexpectedly. */
72
73static int
74enxio(void)
75{
76	return (ENXIO);
77}
78
79#define dead_open	(d_open_t *)enxio
80#define dead_close	(d_close_t *)enxio
81#define dead_read	(d_read_t *)enxio
82#define dead_write	(d_write_t *)enxio
83#define dead_ioctl	(d_ioctl_t *)enxio
84#define dead_poll	nopoll
85#define dead_mmap	nommap
86
87static void
88dead_strategy(struct bio *bp)
89{
90
91	biofinish(bp, NULL, ENXIO);
92}
93
94#define dead_dump	(dumper_t *)enxio
95
96#define dead_kqfilter	(d_kqfilter_t *)enxio
97
98static struct cdevsw dead_cdevsw = {
99	.d_open =	dead_open,
100	.d_close =	dead_close,
101	.d_read =	dead_read,
102	.d_write =	dead_write,
103	.d_ioctl =	dead_ioctl,
104	.d_poll =	dead_poll,
105	.d_mmap =	dead_mmap,
106	.d_strategy =	dead_strategy,
107	.d_name =	"dead",
108	.d_maj =	255,
109	.d_dump =	dead_dump,
110	.d_kqfilter =	dead_kqfilter
111};
112
113
114struct cdevsw *
115devsw(dev_t dev)
116{
117	if (dev->si_devsw)
118		return (dev->si_devsw);
119	return (&dead_cdevsw);
120}
121
122/*
123 * dev_t and u_dev_t primitives
124 */
125
126int
127major(dev_t x)
128{
129	if (x == NODEV)
130		return NOUDEV;
131	return((x->si_udev >> 8) & 0xff);
132}
133
134int
135minor(dev_t x)
136{
137	if (x == NODEV)
138		return NOUDEV;
139	return(x->si_udev & 0xffff00ff);
140}
141
142int
143dev2unit(dev_t x)
144{
145	int i;
146
147	if (x == NODEV)
148		return NOUDEV;
149	i = minor(x);
150	return ((i & 0xff) | (i >> 8));
151}
152
153int
154unit2minor(int unit)
155{
156
157	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
158	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
159}
160
161static dev_t
162allocdev(void)
163{
164	static int stashed;
165	struct cdev *si;
166
167	if (LIST_FIRST(&dev_free)) {
168		si = LIST_FIRST(&dev_free);
169		LIST_REMOVE(si, si_hash);
170	} else if (stashed >= DEVT_STASH) {
171		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
172		    M_USE_RESERVE | M_ZERO | M_WAITOK);
173	} else {
174		si = devt_stash + stashed++;
175		bzero(si, sizeof *si);
176		si->si_flags |= SI_STASHED;
177	}
178	si->__si_namebuf[0] = '\0';
179	si->si_name = si->__si_namebuf;
180	LIST_INIT(&si->si_children);
181	TAILQ_INIT(&si->si_snapshots);
182	return (si);
183}
184
185dev_t
186makedev(int x, int y)
187{
188	struct cdev *si;
189	udev_t	udev;
190	int hash;
191
192	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
193		panic("makedev of NOUDEV");
194	udev = (x << 8) | y;
195	hash = udev % DEVT_HASH;
196	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
197		if (si->si_udev == udev)
198			return (si);
199	}
200	si = allocdev();
201	si->si_udev = udev;
202	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
203        return (si);
204}
205
206void
207freedev(dev_t dev)
208{
209
210	if (!free_devt)
211		return;
212	if (SLIST_FIRST(&dev->si_hlist))
213		return;
214	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
215		return;
216	LIST_REMOVE(dev, si_hash);
217	if (dev->si_flags & SI_STASHED) {
218		bzero(dev, sizeof(*dev));
219		dev->si_flags |= SI_STASHED;
220		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
221	} else {
222		FREE(dev, M_DEVT);
223	}
224}
225
226udev_t
227dev2udev(dev_t x)
228{
229	if (x == NODEV)
230		return NOUDEV;
231	return (x->si_udev);
232}
233
234dev_t
235udev2dev(udev_t x, int b)
236{
237
238	if (x == NOUDEV)
239		return (NODEV);
240	switch (b) {
241		case 0:
242			return makedev(umajor(x), uminor(x));
243		case 1:
244			return (NODEV);
245		default:
246			Debugger("udev2dev(...,X)");
247			return NODEV;
248	}
249}
250
251int
252uminor(udev_t dev)
253{
254	return(dev & 0xffff00ff);
255}
256
257int
258umajor(udev_t dev)
259{
260	return((dev & 0xff00) >> 8);
261}
262
263udev_t
264makeudev(int x, int y)
265{
266        return ((x << 8) | y);
267}
268
269dev_t
270make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
271{
272	dev_t	dev;
273	va_list ap;
274	int i;
275
276	KASSERT((minor & ~0xffff00ff) == 0,
277	    ("Invalid minor (0x%x) in make_dev", minor));
278
279	if (devsw->d_open == NULL)	devsw->d_open = nullopen;
280	if (devsw->d_close == NULL)	devsw->d_close = nullclose;
281	if (devsw->d_read == NULL)	devsw->d_read = noread;
282	if (devsw->d_write == NULL)	devsw->d_write = nowrite;
283	if (devsw->d_ioctl == NULL)	devsw->d_ioctl = noioctl;
284	if (devsw->d_poll == NULL)	devsw->d_poll = nopoll;
285	if (devsw->d_mmap == NULL)	devsw->d_mmap = nommap;
286	if (devsw->d_strategy == NULL)	devsw->d_strategy = nostrategy;
287	if (devsw->d_dump == NULL)	devsw->d_dump = nodump;
288	if (devsw->d_kqfilter == NULL)	devsw->d_kqfilter = nokqfilter;
289
290	if (devsw->d_maj == MAJOR_AUTO) {
291		for (i = NUMCDEVSW - 1; i > 0; i--)
292			if (reserved_majors[i] != i)
293				break;
294		KASSERT(i > 0, ("Out of major numbers (%s)", devsw->d_name));
295		devsw->d_maj = i;
296		reserved_majors[i] = i;
297	} else {
298		if (devsw->d_maj == 256)	/* XXX: tty_cons.c is magic */
299			devsw->d_maj = 0;
300		KASSERT(devsw->d_maj >= 0 && devsw->d_maj < 256,
301		    ("Invalid major (%d) in make_dev", devsw->d_maj));
302		if (reserved_majors[devsw->d_maj] != devsw->d_maj) {
303			printf("WARNING: driver \"%s\" used %s %d\n",
304			    devsw->d_name, "unreserved major device number",
305			    devsw->d_maj);
306			reserved_majors[devsw->d_maj] = devsw->d_maj;
307		}
308	}
309
310	if (!ready_for_devs) {
311		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
312		       fmt);
313		/* XXX panic here once drivers are cleaned up */
314	}
315
316	dev = makedev(devsw->d_maj, minor);
317	if (dev->si_flags & SI_NAMED) {
318		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
319		    dev->si_name);
320		panic("don't do that");
321	}
322	va_start(ap, fmt);
323	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
324	if (i > (sizeof dev->__si_namebuf - 1)) {
325		printf("WARNING: Device name truncated! (%s)",
326		    dev->__si_namebuf);
327	}
328	va_end(ap);
329	dev->si_devsw = devsw;
330	dev->si_uid = uid;
331	dev->si_gid = gid;
332	dev->si_mode = perms;
333	dev->si_flags |= SI_NAMED;
334
335	devfs_create(dev);
336	return (dev);
337}
338
339int
340dev_named(dev_t pdev, const char *name)
341{
342	dev_t cdev;
343
344	if (strcmp(devtoname(pdev), name) == 0)
345		return (1);
346	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
347		if (strcmp(devtoname(cdev), name) == 0)
348			return (1);
349	return (0);
350}
351
352void
353dev_depends(dev_t pdev, dev_t cdev)
354{
355
356	cdev->si_parent = pdev;
357	cdev->si_flags |= SI_CHILD;
358	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
359}
360
361dev_t
362make_dev_alias(dev_t pdev, const char *fmt, ...)
363{
364	dev_t	dev;
365	va_list ap;
366	int i;
367
368	dev = allocdev();
369	dev->si_flags |= SI_ALIAS;
370	dev->si_flags |= SI_NAMED;
371	dev_depends(pdev, dev);
372	va_start(ap, fmt);
373	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
374	if (i > (sizeof dev->__si_namebuf - 1)) {
375		printf("WARNING: Device name truncated! (%s)",
376		    dev->__si_namebuf);
377	}
378	va_end(ap);
379
380	devfs_create(dev);
381	return (dev);
382}
383
384void
385revoke_and_destroy_dev(dev_t dev)
386{
387	struct vnode *vp;
388
389	GIANT_REQUIRED;
390
391	vp = SLIST_FIRST(&dev->si_hlist);
392	if (vp != NULL)
393		VOP_REVOKE(vp, REVOKEALL);
394	destroy_dev(dev);
395}
396
397void
398destroy_dev(dev_t dev)
399{
400
401	if (!(dev->si_flags & SI_NAMED)) {
402		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
403		    major(dev), minor(dev));
404		panic("don't do that");
405	}
406
407	devfs_destroy(dev);
408	if (dev->si_flags & SI_CHILD) {
409		LIST_REMOVE(dev, si_siblings);
410		dev->si_flags &= ~SI_CHILD;
411	}
412	while (!LIST_EMPTY(&dev->si_children))
413		destroy_dev(LIST_FIRST(&dev->si_children));
414	dev->si_drv1 = 0;
415	dev->si_drv2 = 0;
416	dev->si_devsw = 0;
417	bzero(&dev->__si_u, sizeof(dev->__si_u));
418	dev->si_flags &= ~SI_NAMED;
419	dev->si_flags &= ~SI_ALIAS;
420	freedev(dev);
421}
422
423const char *
424devtoname(dev_t dev)
425{
426	char *p;
427	int mynor;
428
429	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
430		p = dev->si_name;
431		if (devsw(dev))
432			sprintf(p, "#%s/", devsw(dev)->d_name);
433		else
434			sprintf(p, "#%d/", major(dev));
435		p += strlen(p);
436		mynor = minor(dev);
437		if (mynor < 0 || mynor > 255)
438			sprintf(p, "%#x", (u_int)mynor);
439		else
440			sprintf(p, "%d", mynor);
441	}
442	return (dev->si_name);
443}
444
445int
446dev_stdclone(char *name, char **namep, const char *stem, int *unit)
447{
448	int u, i;
449
450	i = strlen(stem);
451	if (bcmp(stem, name, i) != 0)
452		return (0);
453	if (!isdigit(name[i]))
454		return (0);
455	u = 0;
456	if (name[i] == '0' && isdigit(name[i+1]))
457		return (0);
458	while (isdigit(name[i])) {
459		u *= 10;
460		u += name[i++] - '0';
461	}
462	if (u > 0xffffff)
463		return (0);
464	*unit = u;
465	if (namep)
466		*namep = &name[i];
467	if (name[i])
468		return (2);
469	return (1);
470}
471
472/*
473 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
474 * the name, if any, registered by the device driver.
475 */
476static int
477sysctl_devname(SYSCTL_HANDLER_ARGS)
478{
479	int error;
480	udev_t ud;
481	dev_t dev;
482
483	error = SYSCTL_IN(req, &ud, sizeof (ud));
484	if (error)
485		return (error);
486	if (ud == NOUDEV)
487		return(EINVAL);
488	dev = makedev(umajor(ud), uminor(ud));
489	if (dev->si_name[0] == '\0')
490		error = ENOENT;
491	else
492		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
493	freedev(dev);
494	return (error);
495}
496
497SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
498	NULL, 0, sysctl_devname, "", "devname(3) handler");
499
500/*
501 * Set ready_for_devs; prior to this point, device creation is not allowed.
502 */
503static void
504dev_set_ready(void *junk)
505{
506	ready_for_devs = 1;
507}
508
509SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
510