kern_conf.c revision 75519 
1/*-
2 * Parts Copyright (c) 1995 Terrence R. Lambert
3 * Copyright (c) 1995 Julian R. Elischer
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *      This product includes software developed by Terrence R. Lambert.
17 * 4. The name Terrence R. Lambert may not be used to endorse or promote
18 *    products derived from this software without specific prior written
19 *    permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY Julian R. Elischer ``AS IS'' AND ANY
22 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: head/sys/kern/kern_conf.c 75519 2001-04-14 21:33:58Z brian $
34 */
35
36#include <sys/param.h>
37#include <sys/kernel.h>
38#include <sys/sysctl.h>
39#include <sys/systm.h>
40#include <sys/module.h>
41#include <sys/malloc.h>
42#include <sys/conf.h>
43#include <sys/vnode.h>
44#include <sys/queue.h>
45#include <sys/ctype.h>
46#include <machine/stdarg.h>
47
48#define cdevsw_ALLOCSTART	(NUMCDEVSW/2)
49
50struct cdevsw 	*cdevsw[NUMCDEVSW];
51
52static MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
53
54/*
55 * This is the number of hash-buckets.  Experiements with 'real-life'
56 * udev_t's show that a prime halfway between two powers of two works
57 * best.
58 */
59#define DEVT_HASH 83
60
61/* The number of dev_t's we can create before malloc(9) kick in.  */
62#define DEVT_STASH 50
63
64static struct specinfo devt_stash[DEVT_STASH];
65
66static LIST_HEAD(, specinfo) dev_hash[DEVT_HASH];
67
68static LIST_HEAD(, specinfo) dev_free;
69
70devfs_create_t *devfs_create_hook;
71devfs_destroy_t *devfs_destroy_hook;
72int devfs_present;
73
74static int free_devt;
75SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
76
77struct cdevsw *
78devsw(dev_t dev)
79{
80	if (dev->si_devsw)
81		return (dev->si_devsw);
82        return(cdevsw[major(dev)]);
83}
84
85/*
86 *  Add a cdevsw entry
87 */
88
89int
90cdevsw_add(struct cdevsw *newentry)
91{
92
93	if (newentry->d_maj < 0 || newentry->d_maj >= NUMCDEVSW) {
94		printf("%s: ERROR: driver has bogus cdevsw->d_maj = %d\n",
95		    newentry->d_name, newentry->d_maj);
96		return (EINVAL);
97	}
98
99	if (cdevsw[newentry->d_maj]) {
100		printf("WARNING: \"%s\" is usurping \"%s\"'s cdevsw[]\n",
101		    newentry->d_name, cdevsw[newentry->d_maj]->d_name);
102	}
103
104	cdevsw[newentry->d_maj] = newentry;
105
106	return (0);
107}
108
109/*
110 *  Remove a cdevsw entry
111 */
112
113int
114cdevsw_remove(struct cdevsw *oldentry)
115{
116	if (oldentry->d_maj < 0 || oldentry->d_maj >= NUMCDEVSW) {
117		printf("%s: ERROR: driver has bogus cdevsw->d_maj = %d\n",
118		    oldentry->d_name, oldentry->d_maj);
119		return EINVAL;
120	}
121
122	cdevsw[oldentry->d_maj] = NULL;
123
124	return 0;
125}
126
127/*
128 * dev_t and u_dev_t primitives
129 */
130
131int
132major(dev_t x)
133{
134	if (x == NODEV)
135		return NOUDEV;
136	return((x->si_udev >> 8) & 0xff);
137}
138
139int
140minor(dev_t x)
141{
142	if (x == NODEV)
143		return NOUDEV;
144	return(x->si_udev & 0xffff00ff);
145}
146
147int
148dev2unit(dev_t x)
149{
150	int i;
151
152	if (x == NODEV)
153		return NOUDEV;
154	i = minor(x);
155	return ((i & 0xff) | (i >> 8));
156}
157
158int
159unit2minor(int unit)
160{
161
162	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
163	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
164}
165
166static dev_t
167allocdev(void)
168{
169	static int stashed;
170	struct specinfo *si;
171
172	if (stashed >= DEVT_STASH) {
173		MALLOC(si, struct specinfo *, sizeof(*si), M_DEVT,
174		    M_USE_RESERVE | M_ZERO);
175	} else if (LIST_FIRST(&dev_free)) {
176		si = LIST_FIRST(&dev_free);
177		LIST_REMOVE(si, si_hash);
178	} else {
179		si = devt_stash + stashed++;
180		si->si_flags |= SI_STASHED;
181	}
182	LIST_INIT(&si->si_names);
183	TAILQ_INIT(&si->si_snapshots);
184	return (si);
185}
186
187dev_t
188makedev(int x, int y)
189{
190	struct specinfo *si;
191	udev_t	udev;
192	int hash;
193
194	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
195		panic("makedev of NOUDEV");
196	udev = (x << 8) | y;
197	hash = udev % DEVT_HASH;
198	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
199		if (si->si_udev == udev)
200			return (si);
201	}
202	si = allocdev();
203	si->si_udev = udev;
204	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
205        return (si);
206}
207
208void
209freedev(dev_t dev)
210{
211	dev_t adev;
212
213	if (!free_devt)
214		return;
215	if (SLIST_FIRST(&dev->si_hlist))
216		return;
217	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
218		return;
219	while (!LIST_EMPTY(&dev->si_names)) {
220		adev = LIST_FIRST(&dev->si_names);
221		adev->si_drv1 = NULL;
222		freedev(adev);
223	}
224	LIST_REMOVE(dev, si_hash);
225	if (dev->si_flags & SI_STASHED) {
226		bzero(dev, sizeof(*dev));
227		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
228	} else {
229		FREE(dev, M_DEVT);
230	}
231}
232
233udev_t
234dev2udev(dev_t x)
235{
236	if (x == NODEV)
237		return NOUDEV;
238	return (x->si_udev);
239}
240
241dev_t
242udev2dev(udev_t x, int b)
243{
244
245	if (x == NOUDEV)
246		return (NODEV);
247	switch (b) {
248		case 0:
249			return makedev(umajor(x), uminor(x));
250		case 1:
251			return (NODEV);
252		default:
253			Debugger("udev2dev(...,X)");
254			return NODEV;
255	}
256}
257
258int
259uminor(udev_t dev)
260{
261	return(dev & 0xffff00ff);
262}
263
264int
265umajor(udev_t dev)
266{
267	return((dev & 0xff00) >> 8);
268}
269
270udev_t
271makeudev(int x, int y)
272{
273        return ((x << 8) | y);
274}
275
276dev_t
277make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, char *fmt, ...)
278{
279	dev_t	dev;
280	va_list ap;
281	int i;
282
283	KASSERT(umajor(makeudev(devsw->d_maj, minor)) == devsw->d_maj,
284	    ("Invalid minor (%d) in make_dev", minor));
285
286	dev = makedev(devsw->d_maj, minor);
287	if (dev->si_flags & SI_NAMED) {
288		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
289		    dev->si_name);
290		return (dev);
291	}
292	va_start(ap, fmt);
293	i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
294	dev->si_name[i] = '\0';
295	va_end(ap);
296	dev->si_devsw = devsw;
297	dev->si_uid = uid;
298	dev->si_gid = gid;
299	dev->si_mode = perms;
300	dev->si_flags |= SI_NAMED;
301
302	if (devfs_create_hook)
303		devfs_create_hook(dev);
304	return (dev);
305}
306
307dev_t
308make_dev_alias(dev_t pdev, char *fmt, ...)
309{
310	dev_t	dev;
311	va_list ap;
312	int i;
313
314	dev = allocdev();
315	dev->si_flags |= SI_ALIAS;
316	dev->si_flags |= SI_NAMED;
317	dev->si_drv1 = pdev;
318	LIST_INSERT_HEAD(&pdev->si_names, dev, si_hash);
319
320	va_start(ap, fmt);
321	i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
322	dev->si_name[i] = '\0';
323	va_end(ap);
324
325	if (devfs_create_hook)
326		devfs_create_hook(dev);
327	return (dev);
328}
329
330void
331destroy_dev(dev_t dev)
332{
333
334	if (!(dev->si_flags & SI_NAMED)) {
335		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
336		    major(dev), minor(dev));
337		return;
338	}
339
340	if (devfs_destroy_hook)
341		devfs_destroy_hook(dev);
342	dev->si_drv1 = 0;
343	dev->si_drv2 = 0;
344	dev->si_devsw = 0;
345	dev->si_flags &= ~SI_NAMED;
346	dev->si_flags &= ~SI_ALIAS;
347	freedev(dev);
348}
349
350const char *
351devtoname(dev_t dev)
352{
353	char *p;
354	int mynor;
355
356	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
357		p = dev->si_name;
358		if (devsw(dev))
359			sprintf(p, "#%s/", devsw(dev)->d_name);
360		else
361			sprintf(p, "#%d/", major(dev));
362		p += strlen(p);
363		mynor = minor(dev);
364		if (mynor < 0 || mynor > 255)
365			sprintf(p, "%#x", (u_int)mynor);
366		else
367			sprintf(p, "%d", mynor);
368	}
369	return (dev->si_name);
370}
371
372int
373dev_stdclone(char *name, char **namep, char *stem, int *unit)
374{
375	int u, i;
376
377	i = strlen(stem);
378	if (bcmp(stem, name, i) != 0)
379		return (0);
380	if (!isdigit(name[i]))
381		return (0);
382	u = 0;
383	while (isdigit(name[i])) {
384		u *= 10;
385		u += name[i++] - '0';
386	}
387	*unit = u;
388	if (namep)
389		*namep = &name[i];
390	if (name[i])
391		return (2);
392	return (1);
393}
394
395/*
396 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
397 * the name, if any, registered by the device driver.
398 */
399static int
400sysctl_devname(SYSCTL_HANDLER_ARGS)
401{
402	int error;
403	udev_t ud;
404	dev_t dev;
405
406	error = SYSCTL_IN(req, &ud, sizeof (ud));
407	if (error)
408		return (error);
409	if (ud == NOUDEV)
410		return(EINVAL);
411	dev = makedev(umajor(ud), uminor(ud));
412	if (dev->si_name[0] == '\0')
413		error = ENOENT;
414	else
415		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
416	freedev(dev);
417	return (error);
418}
419
420SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
421	NULL, 0, sysctl_devname, "", "devname(3) handler");
422
423