kern_conf.c revision 111220 
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 111220 2003-02-21 19:00:48Z 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 *  Add a cdevsw entry
132 */
133
134int
135cdevsw_add(struct cdevsw *newentry)
136{
137
138	return (0);
139}
140
141/*
142 *  Remove a cdevsw entry
143 */
144
145int
146cdevsw_remove(struct cdevsw *oldentry)
147{
148
149	return 0;
150}
151
152/*
153 * dev_t and u_dev_t primitives
154 */
155
156int
157major(dev_t x)
158{
159	if (x == NODEV)
160		return NOUDEV;
161	return((x->si_udev >> 8) & 0xff);
162}
163
164int
165minor(dev_t x)
166{
167	if (x == NODEV)
168		return NOUDEV;
169	return(x->si_udev & 0xffff00ff);
170}
171
172int
173dev2unit(dev_t x)
174{
175	int i;
176
177	if (x == NODEV)
178		return NOUDEV;
179	i = minor(x);
180	return ((i & 0xff) | (i >> 8));
181}
182
183int
184unit2minor(int unit)
185{
186
187	KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
188	return ((unit & 0xff) | ((unit << 8) & ~0xffff));
189}
190
191static dev_t
192allocdev(void)
193{
194	static int stashed;
195	struct cdev *si;
196
197	if (LIST_FIRST(&dev_free)) {
198		si = LIST_FIRST(&dev_free);
199		LIST_REMOVE(si, si_hash);
200	} else if (stashed >= DEVT_STASH) {
201		MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
202		    M_USE_RESERVE | M_ZERO | M_WAITOK);
203	} else {
204		si = devt_stash + stashed++;
205		bzero(si, sizeof *si);
206		si->si_flags |= SI_STASHED;
207	}
208	si->__si_namebuf[0] = '\0';
209	si->si_name = si->__si_namebuf;
210	LIST_INIT(&si->si_children);
211	TAILQ_INIT(&si->si_snapshots);
212	return (si);
213}
214
215dev_t
216makedev(int x, int y)
217{
218	struct cdev *si;
219	udev_t	udev;
220	int hash;
221
222	if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
223		panic("makedev of NOUDEV");
224	udev = (x << 8) | y;
225	hash = udev % DEVT_HASH;
226	LIST_FOREACH(si, &dev_hash[hash], si_hash) {
227		if (si->si_udev == udev)
228			return (si);
229	}
230	si = allocdev();
231	si->si_udev = udev;
232	LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
233        return (si);
234}
235
236void
237freedev(dev_t dev)
238{
239
240	if (!free_devt)
241		return;
242	if (SLIST_FIRST(&dev->si_hlist))
243		return;
244	if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
245		return;
246	LIST_REMOVE(dev, si_hash);
247	if (dev->si_flags & SI_STASHED) {
248		bzero(dev, sizeof(*dev));
249		dev->si_flags |= SI_STASHED;
250		LIST_INSERT_HEAD(&dev_free, dev, si_hash);
251	} else {
252		FREE(dev, M_DEVT);
253	}
254}
255
256udev_t
257dev2udev(dev_t x)
258{
259	if (x == NODEV)
260		return NOUDEV;
261	return (x->si_udev);
262}
263
264dev_t
265udev2dev(udev_t x, int b)
266{
267
268	if (x == NOUDEV)
269		return (NODEV);
270	switch (b) {
271		case 0:
272			return makedev(umajor(x), uminor(x));
273		case 1:
274			return (NODEV);
275		default:
276			Debugger("udev2dev(...,X)");
277			return NODEV;
278	}
279}
280
281int
282uminor(udev_t dev)
283{
284	return(dev & 0xffff00ff);
285}
286
287int
288umajor(udev_t dev)
289{
290	return((dev & 0xff00) >> 8);
291}
292
293udev_t
294makeudev(int x, int y)
295{
296        return ((x << 8) | y);
297}
298
299dev_t
300make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
301{
302	dev_t	dev;
303	va_list ap;
304	int i;
305
306	KASSERT(umajor(makeudev(devsw->d_maj, minor)) == devsw->d_maj,
307	    ("Invalid minor (%d) in make_dev", minor));
308
309	if (!ready_for_devs) {
310		printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
311		       fmt);
312		/* XXX panic here once drivers are cleaned up */
313	}
314
315	dev = makedev(devsw->d_maj, minor);
316	if (dev->si_flags & SI_NAMED) {
317		printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
318		    dev->si_name);
319		panic("don't do that");
320		return (dev);
321	}
322	va_start(ap, fmt);
323	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
324	if (i > (sizeof dev->__si_namebuf - 1)) {
325		printf("WARNING: Device name truncated! (%s)",
326		    dev->__si_namebuf);
327	}
328	va_end(ap);
329	dev->si_devsw = devsw;
330	dev->si_uid = uid;
331	dev->si_gid = gid;
332	dev->si_mode = perms;
333	dev->si_flags |= SI_NAMED;
334
335	if (devfs_create_hook)
336		devfs_create_hook(dev);
337	return (dev);
338}
339
340int
341dev_named(dev_t pdev, const char *name)
342{
343	dev_t cdev;
344
345	if (strcmp(devtoname(pdev), name) == 0)
346		return (1);
347	LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
348		if (strcmp(devtoname(cdev), name) == 0)
349			return (1);
350	return (0);
351}
352
353void
354dev_depends(dev_t pdev, dev_t cdev)
355{
356
357	cdev->si_parent = pdev;
358	cdev->si_flags |= SI_CHILD;
359	LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
360}
361
362dev_t
363make_dev_alias(dev_t pdev, const char *fmt, ...)
364{
365	dev_t	dev;
366	va_list ap;
367	int i;
368
369	dev = allocdev();
370	dev->si_flags |= SI_ALIAS;
371	dev->si_flags |= SI_NAMED;
372	dev_depends(pdev, dev);
373	va_start(ap, fmt);
374	i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
375	if (i > (sizeof dev->__si_namebuf - 1)) {
376		printf("WARNING: Device name truncated! (%s)",
377		    dev->__si_namebuf);
378	}
379	va_end(ap);
380
381	if (devfs_create_hook)
382		devfs_create_hook(dev);
383	return (dev);
384}
385
386void
387revoke_and_destroy_dev(dev_t dev)
388{
389	struct vnode *vp;
390
391	GIANT_REQUIRED;
392
393	vp = SLIST_FIRST(&dev->si_hlist);
394	if (vp != NULL)
395		VOP_REVOKE(vp, REVOKEALL);
396	destroy_dev(dev);
397}
398
399void
400destroy_dev(dev_t dev)
401{
402
403	if (!(dev->si_flags & SI_NAMED)) {
404		printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
405		    major(dev), minor(dev));
406		panic("don't do that");
407		return;
408	}
409
410	if (devfs_destroy_hook)
411		devfs_destroy_hook(dev);
412	if (dev->si_flags & SI_CHILD) {
413		LIST_REMOVE(dev, si_siblings);
414		dev->si_flags &= ~SI_CHILD;
415	}
416	while (!LIST_EMPTY(&dev->si_children))
417		destroy_dev(LIST_FIRST(&dev->si_children));
418	dev->si_drv1 = 0;
419	dev->si_drv2 = 0;
420	dev->si_devsw = 0;
421	bzero(&dev->__si_u, sizeof(dev->__si_u));
422	dev->si_flags &= ~SI_NAMED;
423	dev->si_flags &= ~SI_ALIAS;
424	freedev(dev);
425}
426
427const char *
428devtoname(dev_t dev)
429{
430	char *p;
431	int mynor;
432
433	if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
434		p = dev->si_name;
435		if (devsw(dev))
436			sprintf(p, "#%s/", devsw(dev)->d_name);
437		else
438			sprintf(p, "#%d/", major(dev));
439		p += strlen(p);
440		mynor = minor(dev);
441		if (mynor < 0 || mynor > 255)
442			sprintf(p, "%#x", (u_int)mynor);
443		else
444			sprintf(p, "%d", mynor);
445	}
446	return (dev->si_name);
447}
448
449int
450dev_stdclone(char *name, char **namep, const char *stem, int *unit)
451{
452	int u, i;
453
454	i = strlen(stem);
455	if (bcmp(stem, name, i) != 0)
456		return (0);
457	if (!isdigit(name[i]))
458		return (0);
459	u = 0;
460	if (name[i] == '0' && isdigit(name[i+1]))
461		return (0);
462	while (isdigit(name[i])) {
463		u *= 10;
464		u += name[i++] - '0';
465	}
466	if (u > 0xffffff)
467		return (0);
468	*unit = u;
469	if (namep)
470		*namep = &name[i];
471	if (name[i])
472		return (2);
473	return (1);
474}
475
476/*
477 * Helper sysctl for devname(3).  We're given a {u}dev_t and return
478 * the name, if any, registered by the device driver.
479 */
480static int
481sysctl_devname(SYSCTL_HANDLER_ARGS)
482{
483	int error;
484	udev_t ud;
485	dev_t dev;
486
487	error = SYSCTL_IN(req, &ud, sizeof (ud));
488	if (error)
489		return (error);
490	if (ud == NOUDEV)
491		return(EINVAL);
492	dev = makedev(umajor(ud), uminor(ud));
493	if (dev->si_name[0] == '\0')
494		error = ENOENT;
495	else
496		error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
497	freedev(dev);
498	return (error);
499}
500
501SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
502	NULL, 0, sysctl_devname, "", "devname(3) handler");
503
504/*
505 * Set ready_for_devs; prior to this point, device creation is not allowed.
506 */
507static void
508dev_set_ready(void *junk)
509{
510	ready_for_devs = 1;
511}
512
513SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
514