kern_conf.c revision 110115 
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 110115 2003-01-30 19:22:27Z 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);
153	} else {
154		si = devt_stash + stashed++;
155		bzero(si, sizeof *si);
156		si->si_flags |= SI_STASHED;
157	}
158	LIST_INIT(&si->si_children);
159	TAILQ_INIT(&si->si_snapshots);
160	return (si);
161}
162
163dev_t
164makedev(int x, int y)
165{
166	struct cdev *si;
167	udev_t	udev;
168	int hash;
169
170	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
171		panic("makedev of NOUDEV");
172	udev = (x << 8) | y;
173	hash = udev % DEVT_HASH;
174	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
175		if (si->si_udev == udev)
176			return (si);
177	}
178	si = allocdev();
179	si->si_udev = udev;
180	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
181        return (si);
182}
183
184void
185freedev(dev_t dev)
186{
187
188	if (!free_devt)
189		return;
190	if (SLIST_FIRST(&dev->si_hlist))
191		return;
192	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
193		return;
194	LIST_REMOVE(dev, si_hash);
195	if (dev->si_flags & SI_STASHED) {
196		bzero(dev, sizeof(*dev));
197		dev->si_flags |= SI_STASHED;
198		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
199	} else {
200		FREE(dev, M_DEVT);
201	}
202}
203
204udev_t
205dev2udev(dev_t x)
206{
207	if (x == NODEV)
208		return NOUDEV;
209	return (x->si_udev);
210}
211
212dev_t
213udev2dev(udev_t x, int b)
214{
215
216	if (x == NOUDEV)
217		return (NODEV);
218	switch (b) {
219		case 0:
220			return makedev(umajor(x), uminor(x));
221		case 1:
222			return (NODEV);
223		default:
224			Debugger("udev2dev(...,X)");
225			return NODEV;
226	}
227}
228
229int
230uminor(udev_t dev)
231{
232	return(dev & 0xffff00ff);
233}
234
235int
236umajor(udev_t dev)
237{
238	return((dev & 0xff00) >> 8);
239}
240
241udev_t
242makeudev(int x, int y)
243{
244        return ((x << 8) | y);
245}
246
247dev_t
248make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
249{
250	dev_t	dev;
251	va_list ap;
252	int i;
253
254	KASSERT(umajor(makeudev(devsw->d_maj, minor)) == devsw->d_maj,
255	    ("Invalid minor (%d) in make_dev", minor));
256
257	if (!ready_for_devs) {
258		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
259		       fmt);
260		/* XXX panic here once drivers are cleaned up */
261	}
262
263	dev = makedev(devsw->d_maj, minor);
264	if (dev->si_flags & SI_NAMED) {
265		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
266		    dev->si_name);
267		panic("don't do that");
268		return (dev);
269	}
270	va_start(ap, fmt);
271	i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
272	dev->si_name[i] = '\0';
273	va_end(ap);
274	dev->si_devsw = devsw;
275	dev->si_uid = uid;
276	dev->si_gid = gid;
277	dev->si_mode = perms;
278	dev->si_flags |= SI_NAMED;
279
280	if (devfs_create_hook)
281		devfs_create_hook(dev);
282	return (dev);
283}
284
285int
286dev_named(dev_t pdev, const char *name)
287{
288	dev_t cdev;
289
290	if (strcmp(devtoname(pdev), name) == 0)
291		return (1);
292	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
293		if (strcmp(devtoname(cdev), name) == 0)
294			return (1);
295	return (0);
296}
297
298void
299dev_depends(dev_t pdev, dev_t cdev)
300{
301
302	cdev->si_parent = pdev;
303	cdev->si_flags |= SI_CHILD;
304	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
305}
306
307dev_t
308make_dev_alias(dev_t pdev, const 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_depends(pdev, dev);
318	va_start(ap, fmt);
319	i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
320	dev->si_name[i] = '\0';
321	va_end(ap);
322
323	if (devfs_create_hook)
324		devfs_create_hook(dev);
325	return (dev);
326}
327
328void
329revoke_and_destroy_dev(dev_t dev)
330{
331	struct vnode *vp;
332
333	GIANT_REQUIRED;
334
335	vp = SLIST_FIRST(&dev->si_hlist);
336	if (vp != NULL)
337		VOP_REVOKE(vp, REVOKEALL);
338	destroy_dev(dev);
339}
340
341void
342destroy_dev(dev_t dev)
343{
344
345	if (!(dev->si_flags & SI_NAMED)) {
346		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
347		    major(dev), minor(dev));
348		panic("don't do that");
349		return;
350	}
351
352	if (devfs_destroy_hook)
353		devfs_destroy_hook(dev);
354	if (dev->si_flags & SI_CHILD) {
355		LIST_REMOVE(dev, si_siblings);
356		dev->si_flags &= ~SI_CHILD;
357	}
358	while (!LIST_EMPTY(&dev->si_children))
359		destroy_dev(LIST_FIRST(&dev->si_children));
360	dev->si_drv1 = 0;
361	dev->si_drv2 = 0;
362	dev->si_devsw = 0;
363	bzero(&dev->__si_u, sizeof(dev->__si_u));
364	dev->si_flags &= ~SI_NAMED;
365	dev->si_flags &= ~SI_ALIAS;
366	freedev(dev);
367}
368
369const char *
370devtoname(dev_t dev)
371{
372	char *p;
373	int mynor;
374
375	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
376		p = dev->si_name;
377		if (devsw(dev))
378			sprintf(p, "#%s/", devsw(dev)->d_name);
379		else
380			sprintf(p, "#%d/", major(dev));
381		p += strlen(p);
382		mynor = minor(dev);
383		if (mynor < 0 || mynor > 255)
384			sprintf(p, "%#x", (u_int)mynor);
385		else
386			sprintf(p, "%d", mynor);
387	}
388	return (dev->si_name);
389}
390
391int
392dev_stdclone(char *name, char **namep, const char *stem, int *unit)
393{
394	int u, i;
395
396	i = strlen(stem);
397	if (bcmp(stem, name, i) != 0)
398		return (0);
399	if (!isdigit(name[i]))
400		return (0);
401	u = 0;
402	if (name[i] == '0' && isdigit(name[i+1]))
403		return (0);
404	while (isdigit(name[i])) {
405		u *= 10;
406		u += name[i++] - '0';
407	}
408	if (u > 0xffffff)
409		return (0);
410	*unit = u;
411	if (namep)
412		*namep = &name[i];
413	if (name[i])
414		return (2);
415	return (1);
416}
417
418/*
419 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
420 * the name, if any, registered by the device driver.
421 */
422static int
423sysctl_devname(SYSCTL_HANDLER_ARGS)
424{
425	int error;
426	udev_t ud;
427	dev_t dev;
428
429	error = SYSCTL_IN(req, &ud, sizeof (ud));
430	if (error)
431		return (error);
432	if (ud == NOUDEV)
433		return(EINVAL);
434	dev = makedev(umajor(ud), uminor(ud));
435	if (dev->si_name[0] == '\0')
436		error = ENOENT;
437	else
438		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
439	freedev(dev);
440	return (error);
441}
442
443SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
444	NULL, 0, sysctl_devname, "", "devname(3) handler");
445
446/*
447 * Set ready_for_devs; prior to this point, device creation is not allowed.
448 */
449static void
450dev_set_ready(void *junk)
451{
452	ready_for_devs = 1;
453}
454
455SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
456