kern_conf.c revision 111600 
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 111600 2003-02-27 07:40:44Z 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/*
47 * This is the number of hash-buckets.  Experiements with 'real-life'
48 * udev_t's show that a prime halfway between two powers of two works
49 * best.
50 */
51#define DEVT_HASH 83
52
53/* The number of dev_t's we can create before malloc(9) kick in.  */
54#define DEVT_STASH 50
55
56static struct cdev devt_stash[DEVT_STASH];
57
58static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
59
60static LIST_HEAD(, cdev) dev_free;
61
62devfs_create_t *devfs_create_hook;
63devfs_destroy_t *devfs_destroy_hook;
64
65static int ready_for_devs;
66
67static int free_devt;
68SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
69
70/* Define a dead_cdevsw for use when devices leave unexpectedly. */
71
72static int
73enxio(void)
74{
75	return (ENXIO);
76}
77
78#define dead_open	(d_open_t *)enxio
79#define dead_close	(d_close_t *)enxio
80#define dead_read	(d_read_t *)enxio
81#define dead_write	(d_write_t *)enxio
82#define dead_ioctl	(d_ioctl_t *)enxio
83#define dead_poll	nopoll
84#define dead_mmap	nommap
85
86static void
87dead_strategy(struct bio *bp)
88{
89
90	biofinish(bp, NULL, ENXIO);
91}
92
93#define dead_dump	(dumper_t *)enxio
94
95static int
96dead_psize(dev_t dev)
97{
98
99	return (-1);
100}
101
102#define dead_kqfilter	(d_kqfilter_t *)enxio
103
104static struct cdevsw dead_cdevsw = {
105	/* open */	dead_open,
106	/* close */	dead_close,
107	/* read */	dead_read,
108	/* write */	dead_write,
109	/* ioctl */	dead_ioctl,
110	/* poll */	dead_poll,
111	/* mmap */	dead_mmap,
112	/* strategy */	dead_strategy,
113	/* name */	"dead",
114	/* maj */	255,
115	/* dump */	dead_dump,
116	/* psize */	dead_psize,
117	/* flags */	0,
118	/* kqfilter */	dead_kqfilter
119};
120
121
122struct cdevsw *
123devsw(dev_t dev)
124{
125	if (dev->si_devsw)
126		return (dev->si_devsw);
127	return (&dead_cdevsw);
128}
129
130/*
131 * dev_t and u_dev_t primitives
132 */
133
134int
135major(dev_t x)
136{
137	if (x == NODEV)
138		return NOUDEV;
139	return((x->si_udev >> 8) & 0xff);
140}
141
142int
143minor(dev_t x)
144{
145	if (x == NODEV)
146		return NOUDEV;
147	return(x->si_udev & 0xffff00ff);
148}
149
150int
151dev2unit(dev_t x)
152{
153	int i;
154
155	if (x == NODEV)
156		return NOUDEV;
157	i = minor(x);
158	return ((i & 0xff) | (i >> 8));
159}
160
161int
162unit2minor(int unit)
163{
164
165	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
166	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
167}
168
169static dev_t
170allocdev(void)
171{
172	static int stashed;
173	struct cdev *si;
174
175	if (LIST_FIRST(&dev_free)) {
176		si = LIST_FIRST(&dev_free);
177		LIST_REMOVE(si, si_hash);
178	} else if (stashed >= DEVT_STASH) {
179		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
180		    M_USE_RESERVE | M_ZERO | M_WAITOK);
181	} else {
182		si = devt_stash + stashed++;
183		bzero(si, sizeof *si);
184		si->si_flags |= SI_STASHED;
185	}
186	si->__si_namebuf[0] = '\0';
187	si->si_name = si->__si_namebuf;
188	LIST_INIT(&si->si_children);
189	TAILQ_INIT(&si->si_snapshots);
190	return (si);
191}
192
193dev_t
194makedev(int x, int y)
195{
196	struct cdev *si;
197	udev_t	udev;
198	int hash;
199
200	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
201		panic("makedev of NOUDEV");
202	udev = (x << 8) | y;
203	hash = udev % DEVT_HASH;
204	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
205		if (si->si_udev == udev)
206			return (si);
207	}
208	si = allocdev();
209	si->si_udev = udev;
210	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
211        return (si);
212}
213
214void
215freedev(dev_t dev)
216{
217
218	if (!free_devt)
219		return;
220	if (SLIST_FIRST(&dev->si_hlist))
221		return;
222	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
223		return;
224	LIST_REMOVE(dev, si_hash);
225	if (dev->si_flags & SI_STASHED) {
226		bzero(dev, sizeof(*dev));
227		dev->si_flags |= SI_STASHED;
228		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
229	} else {
230		FREE(dev, M_DEVT);
231	}
232}
233
234udev_t
235dev2udev(dev_t x)
236{
237	if (x == NODEV)
238		return NOUDEV;
239	return (x->si_udev);
240}
241
242dev_t
243udev2dev(udev_t x, int b)
244{
245
246	if (x == NOUDEV)
247		return (NODEV);
248	switch (b) {
249		case 0:
250			return makedev(umajor(x), uminor(x));
251		case 1:
252			return (NODEV);
253		default:
254			Debugger("udev2dev(...,X)");
255			return NODEV;
256	}
257}
258
259int
260uminor(udev_t dev)
261{
262	return(dev & 0xffff00ff);
263}
264
265int
266umajor(udev_t dev)
267{
268	return((dev & 0xff00) >> 8);
269}
270
271udev_t
272makeudev(int x, int y)
273{
274        return ((x << 8) | y);
275}
276
277dev_t
278make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
279{
280	dev_t	dev;
281	va_list ap;
282	int i;
283
284	KASSERT(umajor(makeudev(devsw->d_maj, minor)) == devsw->d_maj,
285	    ("Invalid minor (%d) in make_dev", minor));
286
287	if (!ready_for_devs) {
288		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
289		       fmt);
290		/* XXX panic here once drivers are cleaned up */
291	}
292
293	dev = makedev(devsw->d_maj, minor);
294	if (dev->si_flags & SI_NAMED) {
295		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
296		    dev->si_name);
297		panic("don't do that");
298		return (dev);
299	}
300	va_start(ap, fmt);
301	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
302	if (i > (sizeof dev->__si_namebuf - 1)) {
303		printf("WARNING: Device name truncated! (%s)",
304		    dev->__si_namebuf);
305	}
306	va_end(ap);
307	dev->si_devsw = devsw;
308	dev->si_uid = uid;
309	dev->si_gid = gid;
310	dev->si_mode = perms;
311	dev->si_flags |= SI_NAMED;
312
313	if (devfs_create_hook)
314		devfs_create_hook(dev);
315	return (dev);
316}
317
318int
319dev_named(dev_t pdev, const char *name)
320{
321	dev_t cdev;
322
323	if (strcmp(devtoname(pdev), name) == 0)
324		return (1);
325	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
326		if (strcmp(devtoname(cdev), name) == 0)
327			return (1);
328	return (0);
329}
330
331void
332dev_depends(dev_t pdev, dev_t cdev)
333{
334
335	cdev->si_parent = pdev;
336	cdev->si_flags |= SI_CHILD;
337	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
338}
339
340dev_t
341make_dev_alias(dev_t pdev, const char *fmt, ...)
342{
343	dev_t	dev;
344	va_list ap;
345	int i;
346
347	dev = allocdev();
348	dev->si_flags |= SI_ALIAS;
349	dev->si_flags |= SI_NAMED;
350	dev_depends(pdev, dev);
351	va_start(ap, fmt);
352	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
353	if (i > (sizeof dev->__si_namebuf - 1)) {
354		printf("WARNING: Device name truncated! (%s)",
355		    dev->__si_namebuf);
356	}
357	va_end(ap);
358
359	if (devfs_create_hook)
360		devfs_create_hook(dev);
361	return (dev);
362}
363
364void
365revoke_and_destroy_dev(dev_t dev)
366{
367	struct vnode *vp;
368
369	GIANT_REQUIRED;
370
371	vp = SLIST_FIRST(&dev->si_hlist);
372	if (vp != NULL)
373		VOP_REVOKE(vp, REVOKEALL);
374	destroy_dev(dev);
375}
376
377void
378destroy_dev(dev_t dev)
379{
380
381	if (!(dev->si_flags & SI_NAMED)) {
382		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
383		    major(dev), minor(dev));
384		panic("don't do that");
385		return;
386	}
387
388	if (devfs_destroy_hook)
389		devfs_destroy_hook(dev);
390	if (dev->si_flags & SI_CHILD) {
391		LIST_REMOVE(dev, si_siblings);
392		dev->si_flags &= ~SI_CHILD;
393	}
394	while (!LIST_EMPTY(&dev->si_children))
395		destroy_dev(LIST_FIRST(&dev->si_children));
396	dev->si_drv1 = 0;
397	dev->si_drv2 = 0;
398	dev->si_devsw = 0;
399	bzero(&dev->__si_u, sizeof(dev->__si_u));
400	dev->si_flags &= ~SI_NAMED;
401	dev->si_flags &= ~SI_ALIAS;
402	freedev(dev);
403}
404
405const char *
406devtoname(dev_t dev)
407{
408	char *p;
409	int mynor;
410
411	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
412		p = dev->si_name;
413		if (devsw(dev))
414			sprintf(p, "#%s/", devsw(dev)->d_name);
415		else
416			sprintf(p, "#%d/", major(dev));
417		p += strlen(p);
418		mynor = minor(dev);
419		if (mynor < 0 || mynor > 255)
420			sprintf(p, "%#x", (u_int)mynor);
421		else
422			sprintf(p, "%d", mynor);
423	}
424	return (dev->si_name);
425}
426
427int
428dev_stdclone(char *name, char **namep, const char *stem, int *unit)
429{
430	int u, i;
431
432	i = strlen(stem);
433	if (bcmp(stem, name, i) != 0)
434		return (0);
435	if (!isdigit(name[i]))
436		return (0);
437	u = 0;
438	if (name[i] == '0' && isdigit(name[i+1]))
439		return (0);
440	while (isdigit(name[i])) {
441		u *= 10;
442		u += name[i++] - '0';
443	}
444	if (u > 0xffffff)
445		return (0);
446	*unit = u;
447	if (namep)
448		*namep = &name[i];
449	if (name[i])
450		return (2);
451	return (1);
452}
453
454/*
455 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
456 * the name, if any, registered by the device driver.
457 */
458static int
459sysctl_devname(SYSCTL_HANDLER_ARGS)
460{
461	int error;
462	udev_t ud;
463	dev_t dev;
464
465	error = SYSCTL_IN(req, &ud, sizeof (ud));
466	if (error)
467		return (error);
468	if (ud == NOUDEV)
469		return(EINVAL);
470	dev = makedev(umajor(ud), uminor(ud));
471	if (dev->si_name[0] == '\0')
472		error = ENOENT;
473	else
474		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
475	freedev(dev);
476	return (error);
477}
478
479SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
480	NULL, 0, sysctl_devname, "", "devname(3) handler");
481
482/*
483 * Set ready_for_devs; prior to this point, device creation is not allowed.
484 */
485static void
486dev_set_ready(void *junk)
487{
488	ready_for_devs = 1;
489}
490
491SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
492