kern_conf.c revision 111146 
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 111146 2003-02-19 22:51:33Z phk $
27 */
28
29#include <sys/param.h>
30#include <sys/kernel.h>
31#include <sys/systm.h>
32#include <sys/lock.h>
33#include <sys/mutex.h>
34#include <sys/sysctl.h>
35#include <sys/module.h>
36#include <sys/malloc.h>
37#include <sys/conf.h>
38#include <sys/vnode.h>
39#include <sys/queue.h>
40#include <sys/ctype.h>
41#include <machine/stdarg.h>
42
43static MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
44
45/*
46 * This is the number of hash-buckets.  Experiements with 'real-life'
47 * udev_t's show that a prime halfway between two powers of two works
48 * best.
49 */
50#define DEVT_HASH 83
51
52/* The number of dev_t's we can create before malloc(9) kick in.  */
53#define DEVT_STASH 50
54
55static struct cdev devt_stash[DEVT_STASH];
56
57static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
58
59static LIST_HEAD(, cdev) dev_free;
60
61devfs_create_t *devfs_create_hook;
62devfs_destroy_t *devfs_destroy_hook;
63
64static int ready_for_devs;
65
66static int free_devt;
67SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
68
69
70struct cdevsw *
71devsw(dev_t dev)
72{
73	if (dev->si_devsw)
74		return (dev->si_devsw);
75	if (dev->si_devsw)
76		return (dev->si_devsw);
77	return (NULL);
78}
79
80/*
81 *  Add a cdevsw entry
82 */
83
84int
85cdevsw_add(struct cdevsw *newentry)
86{
87
88	return (0);
89}
90
91/*
92 *  Remove a cdevsw entry
93 */
94
95int
96cdevsw_remove(struct cdevsw *oldentry)
97{
98
99	return 0;
100}
101
102/*
103 * dev_t and u_dev_t primitives
104 */
105
106int
107major(dev_t x)
108{
109	if (x == NODEV)
110		return NOUDEV;
111	return((x->si_udev >> 8) & 0xff);
112}
113
114int
115minor(dev_t x)
116{
117	if (x == NODEV)
118		return NOUDEV;
119	return(x->si_udev & 0xffff00ff);
120}
121
122int
123dev2unit(dev_t x)
124{
125	int i;
126
127	if (x == NODEV)
128		return NOUDEV;
129	i = minor(x);
130	return ((i & 0xff) | (i >> 8));
131}
132
133int
134unit2minor(int unit)
135{
136
137	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
138	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
139}
140
141static dev_t
142allocdev(void)
143{
144	static int stashed;
145	struct cdev *si;
146
147	if (LIST_FIRST(&dev_free)) {
148		si = LIST_FIRST(&dev_free);
149		LIST_REMOVE(si, si_hash);
150	} else if (stashed >= DEVT_STASH) {
151		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
152		    M_USE_RESERVE | M_ZERO | M_WAITOK);
153	} else {
154		si = devt_stash + stashed++;
155		bzero(si, sizeof *si);
156		si->si_flags |= SI_STASHED;
157	}
158	si->__si_namebuf[0] = '\0';
159	si->si_name = si->__si_namebuf;
160	LIST_INIT(&si->si_children);
161	TAILQ_INIT(&si->si_snapshots);
162	return (si);
163}
164
165dev_t
166makedev(int x, int y)
167{
168	struct cdev *si;
169	udev_t	udev;
170	int hash;
171
172	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
173		panic("makedev of NOUDEV");
174	udev = (x << 8) | y;
175	hash = udev % DEVT_HASH;
176	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
177		if (si->si_udev == udev)
178			return (si);
179	}
180	si = allocdev();
181	si->si_udev = udev;
182	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
183        return (si);
184}
185
186void
187freedev(dev_t dev)
188{
189
190	if (!free_devt)
191		return;
192	if (SLIST_FIRST(&dev->si_hlist))
193		return;
194	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
195		return;
196	LIST_REMOVE(dev, si_hash);
197	if (dev->si_flags & SI_STASHED) {
198		bzero(dev, sizeof(*dev));
199		dev->si_flags |= SI_STASHED;
200		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
201	} else {
202		FREE(dev, M_DEVT);
203	}
204}
205
206udev_t
207dev2udev(dev_t x)
208{
209	if (x == NODEV)
210		return NOUDEV;
211	return (x->si_udev);
212}
213
214dev_t
215udev2dev(udev_t x, int b)
216{
217
218	if (x == NOUDEV)
219		return (NODEV);
220	switch (b) {
221		case 0:
222			return makedev(umajor(x), uminor(x));
223		case 1:
224			return (NODEV);
225		default:
226			Debugger("udev2dev(...,X)");
227			return NODEV;
228	}
229}
230
231int
232uminor(udev_t dev)
233{
234	return(dev & 0xffff00ff);
235}
236
237int
238umajor(udev_t dev)
239{
240	return((dev & 0xff00) >> 8);
241}
242
243udev_t
244makeudev(int x, int y)
245{
246        return ((x << 8) | y);
247}
248
249dev_t
250make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
251{
252	dev_t	dev;
253	va_list ap;
254	int i;
255
256	KASSERT(umajor(makeudev(devsw->d_maj, minor)) == devsw->d_maj,
257	    ("Invalid minor (%d) in make_dev", minor));
258
259	if (!ready_for_devs) {
260		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
261		       fmt);
262		/* XXX panic here once drivers are cleaned up */
263	}
264
265	dev = makedev(devsw->d_maj, minor);
266	if (dev->si_flags & SI_NAMED) {
267		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
268		    dev->si_name);
269		panic("don't do that");
270		return (dev);
271	}
272	va_start(ap, fmt);
273	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
274	if (i > (sizeof dev->__si_namebuf - 1)) {
275		printf("WARNING: Device name truncated! (%s)",
276		    dev->__si_namebuf);
277	}
278	va_end(ap);
279	dev->si_devsw = devsw;
280	dev->si_uid = uid;
281	dev->si_gid = gid;
282	dev->si_mode = perms;
283	dev->si_flags |= SI_NAMED;
284
285	if (devfs_create_hook)
286		devfs_create_hook(dev);
287	return (dev);
288}
289
290int
291dev_named(dev_t pdev, const char *name)
292{
293	dev_t cdev;
294
295	if (strcmp(devtoname(pdev), name) == 0)
296		return (1);
297	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
298		if (strcmp(devtoname(cdev), name) == 0)
299			return (1);
300	return (0);
301}
302
303void
304dev_depends(dev_t pdev, dev_t cdev)
305{
306
307	cdev->si_parent = pdev;
308	cdev->si_flags |= SI_CHILD;
309	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
310}
311
312dev_t
313make_dev_alias(dev_t pdev, const char *fmt, ...)
314{
315	dev_t	dev;
316	va_list ap;
317	int i;
318
319	dev = allocdev();
320	dev->si_flags |= SI_ALIAS;
321	dev->si_flags |= SI_NAMED;
322	dev_depends(pdev, dev);
323	va_start(ap, fmt);
324	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
325	if (i > (sizeof dev->__si_namebuf - 1)) {
326		printf("WARNING: Device name truncated! (%s)",
327		    dev->__si_namebuf);
328	}
329	va_end(ap);
330
331	if (devfs_create_hook)
332		devfs_create_hook(dev);
333	return (dev);
334}
335
336void
337revoke_and_destroy_dev(dev_t dev)
338{
339	struct vnode *vp;
340
341	GIANT_REQUIRED;
342
343	vp = SLIST_FIRST(&dev->si_hlist);
344	if (vp != NULL)
345		VOP_REVOKE(vp, REVOKEALL);
346	destroy_dev(dev);
347}
348
349void
350destroy_dev(dev_t dev)
351{
352
353	if (!(dev->si_flags & SI_NAMED)) {
354		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
355		    major(dev), minor(dev));
356		panic("don't do that");
357		return;
358	}
359
360	if (devfs_destroy_hook)
361		devfs_destroy_hook(dev);
362	if (dev->si_flags & SI_CHILD) {
363		LIST_REMOVE(dev, si_siblings);
364		dev->si_flags &= ~SI_CHILD;
365	}
366	while (!LIST_EMPTY(&dev->si_children))
367		destroy_dev(LIST_FIRST(&dev->si_children));
368	dev->si_drv1 = 0;
369	dev->si_drv2 = 0;
370	dev->si_devsw = 0;
371	bzero(&dev->__si_u, sizeof(dev->__si_u));
372	dev->si_flags &= ~SI_NAMED;
373	dev->si_flags &= ~SI_ALIAS;
374	freedev(dev);
375}
376
377const char *
378devtoname(dev_t dev)
379{
380	char *p;
381	int mynor;
382
383	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
384		p = dev->si_name;
385		if (devsw(dev))
386			sprintf(p, "#%s/", devsw(dev)->d_name);
387		else
388			sprintf(p, "#%d/", major(dev));
389		p += strlen(p);
390		mynor = minor(dev);
391		if (mynor < 0 || mynor > 255)
392			sprintf(p, "%#x", (u_int)mynor);
393		else
394			sprintf(p, "%d", mynor);
395	}
396	return (dev->si_name);
397}
398
399int
400dev_stdclone(char *name, char **namep, const char *stem, int *unit)
401{
402	int u, i;
403
404	i = strlen(stem);
405	if (bcmp(stem, name, i) != 0)
406		return (0);
407	if (!isdigit(name[i]))
408		return (0);
409	u = 0;
410	if (name[i] == '0' && isdigit(name[i+1]))
411		return (0);
412	while (isdigit(name[i])) {
413		u *= 10;
414		u += name[i++] - '0';
415	}
416	if (u > 0xffffff)
417		return (0);
418	*unit = u;
419	if (namep)
420		*namep = &name[i];
421	if (name[i])
422		return (2);
423	return (1);
424}
425
426/*
427 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
428 * the name, if any, registered by the device driver.
429 */
430static int
431sysctl_devname(SYSCTL_HANDLER_ARGS)
432{
433	int error;
434	udev_t ud;
435	dev_t dev;
436
437	error = SYSCTL_IN(req, &ud, sizeof (ud));
438	if (error)
439		return (error);
440	if (ud == NOUDEV)
441		return(EINVAL);
442	dev = makedev(umajor(ud), uminor(ud));
443	if (dev->si_name[0] == '\0')
444		error = ENOENT;
445	else
446		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
447	freedev(dev);
448	return (error);
449}
450
451SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
452	NULL, 0, sysctl_devname, "", "devname(3) handler");
453
454/*
455 * Set ready_for_devs; prior to this point, device creation is not allowed.
456 */
457static void
458dev_set_ready(void *junk)
459{
460	ready_for_devs = 1;
461}
462
463SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
464