kern_conf.c revision 111622 
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 * $FreeBSD: head/sys/kern/kern_conf.c 111622 2003-02-27 14:46:51Z phk $
27 */
28
29#include <sys/param.h>
30#include <sys/kernel.h>
31#include <sys/systm.h>
32#include <sys/bio.h>
33#include <sys/lock.h>
34#include <sys/mutex.h>
35#include <sys/sysctl.h>
36#include <sys/module.h>
37#include <sys/malloc.h>
38#include <sys/conf.h>
39#include <sys/vnode.h>
40#include <sys/queue.h>
41#include <sys/ctype.h>
42#include <machine/stdarg.h>
43
44static MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
45
46/* Built at compile time from sys/conf/majors */
47extern unsigned char reserved_majors[256];
48
49/*
50 * This is the number of hash-buckets.  Experiements with 'real-life'
51 * udev_t's show that a prime halfway between two powers of two works
52 * best.
53 */
54#define DEVT_HASH 83
55
56/* The number of dev_t's we can create before malloc(9) kick in.  */
57#define DEVT_STASH 50
58
59static struct cdev devt_stash[DEVT_STASH];
60
61static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
62
63static LIST_HEAD(, cdev) dev_free;
64
65devfs_create_t *devfs_create_hook;
66devfs_destroy_t *devfs_destroy_hook;
67
68static int ready_for_devs;
69
70static int free_devt;
71SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
72
73/* Define a dead_cdevsw for use when devices leave unexpectedly. */
74
75static int
76enxio(void)
77{
78	return (ENXIO);
79}
80
81#define dead_open	(d_open_t *)enxio
82#define dead_close	(d_close_t *)enxio
83#define dead_read	(d_read_t *)enxio
84#define dead_write	(d_write_t *)enxio
85#define dead_ioctl	(d_ioctl_t *)enxio
86#define dead_poll	nopoll
87#define dead_mmap	nommap
88
89static void
90dead_strategy(struct bio *bp)
91{
92
93	biofinish(bp, NULL, ENXIO);
94}
95
96#define dead_dump	(dumper_t *)enxio
97
98static int
99dead_psize(dev_t dev)
100{
101
102	return (-1);
103}
104
105#define dead_kqfilter	(d_kqfilter_t *)enxio
106
107static struct cdevsw dead_cdevsw = {
108	/* open */	dead_open,
109	/* close */	dead_close,
110	/* read */	dead_read,
111	/* write */	dead_write,
112	/* ioctl */	dead_ioctl,
113	/* poll */	dead_poll,
114	/* mmap */	dead_mmap,
115	/* strategy */	dead_strategy,
116	/* name */	"dead",
117	/* maj */	255,
118	/* dump */	dead_dump,
119	/* psize */	dead_psize,
120	/* flags */	0,
121	/* kqfilter */	dead_kqfilter
122};
123
124
125struct cdevsw *
126devsw(dev_t dev)
127{
128	if (dev->si_devsw)
129		return (dev->si_devsw);
130	return (&dead_cdevsw);
131}
132
133/*
134 * dev_t and u_dev_t primitives
135 */
136
137int
138major(dev_t x)
139{
140	if (x == NODEV)
141		return NOUDEV;
142	return((x->si_udev >> 8) & 0xff);
143}
144
145int
146minor(dev_t x)
147{
148	if (x == NODEV)
149		return NOUDEV;
150	return(x->si_udev & 0xffff00ff);
151}
152
153int
154dev2unit(dev_t x)
155{
156	int i;
157
158	if (x == NODEV)
159		return NOUDEV;
160	i = minor(x);
161	return ((i & 0xff) | (i >> 8));
162}
163
164int
165unit2minor(int unit)
166{
167
168	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
169	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
170}
171
172static dev_t
173allocdev(void)
174{
175	static int stashed;
176	struct cdev *si;
177
178	if (LIST_FIRST(&dev_free)) {
179		si = LIST_FIRST(&dev_free);
180		LIST_REMOVE(si, si_hash);
181	} else if (stashed >= DEVT_STASH) {
182		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
183		    M_USE_RESERVE | M_ZERO | M_WAITOK);
184	} else {
185		si = devt_stash + stashed++;
186		bzero(si, sizeof *si);
187		si->si_flags |= SI_STASHED;
188	}
189	si->__si_namebuf[0] = '\0';
190	si->si_name = si->__si_namebuf;
191	LIST_INIT(&si->si_children);
192	TAILQ_INIT(&si->si_snapshots);
193	return (si);
194}
195
196dev_t
197makedev(int x, int y)
198{
199	struct cdev *si;
200	udev_t	udev;
201	int hash;
202
203	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
204		panic("makedev of NOUDEV");
205	udev = (x << 8) | y;
206	hash = udev % DEVT_HASH;
207	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
208		if (si->si_udev == udev)
209			return (si);
210	}
211	si = allocdev();
212	si->si_udev = udev;
213	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
214        return (si);
215}
216
217void
218freedev(dev_t dev)
219{
220
221	if (!free_devt)
222		return;
223	if (SLIST_FIRST(&dev->si_hlist))
224		return;
225	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
226		return;
227	LIST_REMOVE(dev, si_hash);
228	if (dev->si_flags & SI_STASHED) {
229		bzero(dev, sizeof(*dev));
230		dev->si_flags |= SI_STASHED;
231		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
232	} else {
233		FREE(dev, M_DEVT);
234	}
235}
236
237udev_t
238dev2udev(dev_t x)
239{
240	if (x == NODEV)
241		return NOUDEV;
242	return (x->si_udev);
243}
244
245dev_t
246udev2dev(udev_t x, int b)
247{
248
249	if (x == NOUDEV)
250		return (NODEV);
251	switch (b) {
252		case 0:
253			return makedev(umajor(x), uminor(x));
254		case 1:
255			return (NODEV);
256		default:
257			Debugger("udev2dev(...,X)");
258			return NODEV;
259	}
260}
261
262int
263uminor(udev_t dev)
264{
265	return(dev & 0xffff00ff);
266}
267
268int
269umajor(udev_t dev)
270{
271	return((dev & 0xff00) >> 8);
272}
273
274udev_t
275makeudev(int x, int y)
276{
277        return ((x << 8) | y);
278}
279
280dev_t
281make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
282{
283	dev_t	dev;
284	va_list ap;
285	int i;
286
287	KASSERT((minor & ~0xffff00ff) == 0,
288	    ("Invalid minor (0x%x) in make_dev", minor));
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		printf("Allocating major#%d to \"%s\"\n", i, devsw->d_name);
296		devsw->d_maj = i;
297		reserved_majors[i] = i;
298	}
299
300	if (!ready_for_devs) {
301		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
302		       fmt);
303		/* XXX panic here once drivers are cleaned up */
304	}
305
306	dev = makedev(devsw->d_maj, minor);
307	if (dev->si_flags & SI_NAMED) {
308		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
309		    dev->si_name);
310		panic("don't do that");
311		return (dev);
312	}
313	va_start(ap, fmt);
314	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
315	if (i > (sizeof dev->__si_namebuf - 1)) {
316		printf("WARNING: Device name truncated! (%s)",
317		    dev->__si_namebuf);
318	}
319	va_end(ap);
320	dev->si_devsw = devsw;
321	dev->si_uid = uid;
322	dev->si_gid = gid;
323	dev->si_mode = perms;
324	dev->si_flags |= SI_NAMED;
325
326	if (devfs_create_hook)
327		devfs_create_hook(dev);
328	return (dev);
329}
330
331int
332dev_named(dev_t pdev, const char *name)
333{
334	dev_t cdev;
335
336	if (strcmp(devtoname(pdev), name) == 0)
337		return (1);
338	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
339		if (strcmp(devtoname(cdev), name) == 0)
340			return (1);
341	return (0);
342}
343
344void
345dev_depends(dev_t pdev, dev_t cdev)
346{
347
348	cdev->si_parent = pdev;
349	cdev->si_flags |= SI_CHILD;
350	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
351}
352
353dev_t
354make_dev_alias(dev_t pdev, const char *fmt, ...)
355{
356	dev_t	dev;
357	va_list ap;
358	int i;
359
360	dev = allocdev();
361	dev->si_flags |= SI_ALIAS;
362	dev->si_flags |= SI_NAMED;
363	dev_depends(pdev, dev);
364	va_start(ap, fmt);
365	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
366	if (i > (sizeof dev->__si_namebuf - 1)) {
367		printf("WARNING: Device name truncated! (%s)",
368		    dev->__si_namebuf);
369	}
370	va_end(ap);
371
372	if (devfs_create_hook)
373		devfs_create_hook(dev);
374	return (dev);
375}
376
377void
378revoke_and_destroy_dev(dev_t dev)
379{
380	struct vnode *vp;
381
382	GIANT_REQUIRED;
383
384	vp = SLIST_FIRST(&dev->si_hlist);
385	if (vp != NULL)
386		VOP_REVOKE(vp, REVOKEALL);
387	destroy_dev(dev);
388}
389
390void
391destroy_dev(dev_t dev)
392{
393
394	if (!(dev->si_flags & SI_NAMED)) {
395		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
396		    major(dev), minor(dev));
397		panic("don't do that");
398		return;
399	}
400
401	if (devfs_destroy_hook)
402		devfs_destroy_hook(dev);
403	if (dev->si_flags & SI_CHILD) {
404		LIST_REMOVE(dev, si_siblings);
405		dev->si_flags &= ~SI_CHILD;
406	}
407	while (!LIST_EMPTY(&dev->si_children))
408		destroy_dev(LIST_FIRST(&dev->si_children));
409	dev->si_drv1 = 0;
410	dev->si_drv2 = 0;
411	dev->si_devsw = 0;
412	bzero(&dev->__si_u, sizeof(dev->__si_u));
413	dev->si_flags &= ~SI_NAMED;
414	dev->si_flags &= ~SI_ALIAS;
415	freedev(dev);
416}
417
418const char *
419devtoname(dev_t dev)
420{
421	char *p;
422	int mynor;
423
424	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
425		p = dev->si_name;
426		if (devsw(dev))
427			sprintf(p, "#%s/", devsw(dev)->d_name);
428		else
429			sprintf(p, "#%d/", major(dev));
430		p += strlen(p);
431		mynor = minor(dev);
432		if (mynor < 0 || mynor > 255)
433			sprintf(p, "%#x", (u_int)mynor);
434		else
435			sprintf(p, "%d", mynor);
436	}
437	return (dev->si_name);
438}
439
440int
441dev_stdclone(char *name, char **namep, const char *stem, int *unit)
442{
443	int u, i;
444
445	i = strlen(stem);
446	if (bcmp(stem, name, i) != 0)
447		return (0);
448	if (!isdigit(name[i]))
449		return (0);
450	u = 0;
451	if (name[i] == '0' && isdigit(name[i+1]))
452		return (0);
453	while (isdigit(name[i])) {
454		u *= 10;
455		u += name[i++] - '0';
456	}
457	if (u > 0xffffff)
458		return (0);
459	*unit = u;
460	if (namep)
461		*namep = &name[i];
462	if (name[i])
463		return (2);
464	return (1);
465}
466
467/*
468 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
469 * the name, if any, registered by the device driver.
470 */
471static int
472sysctl_devname(SYSCTL_HANDLER_ARGS)
473{
474	int error;
475	udev_t ud;
476	dev_t dev;
477
478	error = SYSCTL_IN(req, &ud, sizeof (ud));
479	if (error)
480		return (error);
481	if (ud == NOUDEV)
482		return(EINVAL);
483	dev = makedev(umajor(ud), uminor(ud));
484	if (dev->si_name[0] == '\0')
485		error = ENOENT;
486	else
487		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
488	freedev(dev);
489	return (error);
490}
491
492SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
493	NULL, 0, sysctl_devname, "", "devname(3) handler");
494
495/*
496 * Set ready_for_devs; prior to this point, device creation is not allowed.
497 */
498static void
499dev_set_ready(void *junk)
500{
501	ready_for_devs = 1;
502}
503
504SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
505