FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_conf.c
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
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/5.2/sys/kern/kern_conf.c 120560 2003-09-28 20:50:36Z phk $");
29
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/systm.h>
33 #include <sys/bio.h>
34 #include <sys/lock.h>
35 #include <sys/mutex.h>
36 #include <sys/sysctl.h>
37 #include <sys/module.h>
38 #include <sys/malloc.h>
39 #include <sys/conf.h>
40 #include <sys/vnode.h>
41 #include <sys/queue.h>
42 #include <sys/poll.h>
43 #include <sys/ctype.h>
44 #include <machine/stdarg.h>
45
46 static MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
47
48 /* Built at compile time from sys/conf/majors */
49 extern unsigned char reserved_majors[256];
50
51 /*
52 * This is the number of hash-buckets. Experiements with 'real-life'
53 * udev_t's show that a prime halfway between two powers of two works
54 * best.
55 */
56 #define DEVT_HASH 83
57
58 /* The number of dev_t's we can create before malloc(9) kick in. */
59 #define DEVT_STASH 50
60
61 static struct cdev devt_stash[DEVT_STASH];
62
63 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
64
65 static LIST_HEAD(, cdev) dev_free;
66
67 static int ready_for_devs;
68
69 static int free_devt;
70 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
71
72 int
73 nullop(void)
74 {
75
76 return (0);
77 }
78
79 int
80 eopnotsupp(void)
81 {
82
83 return (EOPNOTSUPP);
84 }
85
86 static int
87 enxio(void)
88 {
89 return (ENXIO);
90 }
91
92 static int
93 enodev(void)
94 {
95 return (ENODEV);
96 }
97
98 /* Define a dead_cdevsw for use when devices leave unexpectedly. */
99
100 #define dead_open (d_open_t *)enxio
101 #define dead_close (d_close_t *)enxio
102 #define dead_read (d_read_t *)enxio
103 #define dead_write (d_write_t *)enxio
104 #define dead_ioctl (d_ioctl_t *)enxio
105 #define dead_poll (d_poll_t *)enodev
106 #define dead_mmap (d_mmap_t *)enodev
107
108 static void
109 dead_strategy(struct bio *bp)
110 {
111
112 biofinish(bp, NULL, ENXIO);
113 }
114
115 #define dead_dump (dumper_t *)enxio
116 #define dead_kqfilter (d_kqfilter_t *)enxio
117
118 static struct cdevsw dead_cdevsw = {
119 .d_open = dead_open,
120 .d_close = dead_close,
121 .d_read = dead_read,
122 .d_write = dead_write,
123 .d_ioctl = dead_ioctl,
124 .d_poll = dead_poll,
125 .d_mmap = dead_mmap,
126 .d_strategy = dead_strategy,
127 .d_name = "dead",
128 .d_maj = 255,
129 .d_dump = dead_dump,
130 .d_kqfilter = dead_kqfilter
131 };
132
133 /* Default methods if driver does not specify method */
134
135 #define null_open (d_open_t *)nullop
136 #define null_close (d_close_t *)nullop
137 #define no_read (d_read_t *)enodev
138 #define no_write (d_write_t *)enodev
139 #define no_ioctl (d_ioctl_t *)enodev
140 #define no_mmap (d_mmap_t *)enodev
141
142 static int
143 no_kqfilter(dev_t dev __unused, struct knote *kn __unused)
144 {
145
146 return (1);
147 }
148
149 static void
150 no_strategy(struct bio *bp)
151 {
152
153 biofinish(bp, NULL, ENODEV);
154 }
155
156 static int
157 no_poll(dev_t dev __unused, int events, struct thread *td __unused)
158 {
159 /*
160 * Return true for read/write. If the user asked for something
161 * special, return POLLNVAL, so that clients have a way of
162 * determining reliably whether or not the extended
163 * functionality is present without hard-coding knowledge
164 * of specific filesystem implementations.
165 * Stay in sync with vop_nopoll().
166 */
167 if (events & ~POLLSTANDARD)
168 return (POLLNVAL);
169
170 return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
171 }
172
173 #define no_dump (dumper_t *)enodev
174
175 struct cdevsw *
176 devsw(dev_t dev)
177 {
178 if (dev->si_devsw)
179 return (dev->si_devsw);
180 return (&dead_cdevsw);
181 }
182
183 /*
184 * dev_t and u_dev_t primitives
185 */
186
187 int
188 major(dev_t x)
189 {
190 if (x == NODEV)
191 return NOUDEV;
192 return((x->si_udev >> 8) & 0xff);
193 }
194
195 int
196 minor(dev_t x)
197 {
198 if (x == NODEV)
199 return NOUDEV;
200 return(x->si_udev & 0xffff00ff);
201 }
202
203 int
204 dev2unit(dev_t x)
205 {
206 int i;
207
208 if (x == NODEV)
209 return NOUDEV;
210 i = minor(x);
211 return ((i & 0xff) | (i >> 8));
212 }
213
214 int
215 unit2minor(int unit)
216 {
217
218 KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
219 return ((unit & 0xff) | ((unit << 8) & ~0xffff));
220 }
221
222 static dev_t
223 allocdev(void)
224 {
225 static int stashed;
226 struct cdev *si;
227
228 if (LIST_FIRST(&dev_free)) {
229 si = LIST_FIRST(&dev_free);
230 LIST_REMOVE(si, si_hash);
231 } else if (stashed >= DEVT_STASH) {
232 MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
233 M_USE_RESERVE | M_ZERO | M_WAITOK);
234 } else {
235 si = devt_stash + stashed++;
236 bzero(si, sizeof *si);
237 si->si_flags |= SI_STASHED;
238 }
239 si->__si_namebuf[0] = '\0';
240 si->si_name = si->__si_namebuf;
241 LIST_INIT(&si->si_children);
242 TAILQ_INIT(&si->si_snapshots);
243 return (si);
244 }
245
246 dev_t
247 makedev(int x, int y)
248 {
249 struct cdev *si;
250 udev_t udev;
251 int hash;
252
253 if (x == umajor(NOUDEV) && y == uminor(NOUDEV))
254 panic("makedev of NOUDEV");
255 udev = (x << 8) | y;
256 hash = udev % DEVT_HASH;
257 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
258 if (si->si_udev == udev)
259 return (si);
260 }
261 si = allocdev();
262 si->si_udev = udev;
263 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
264 return (si);
265 }
266
267 void
268 freedev(dev_t dev)
269 {
270
271 if (!free_devt)
272 return;
273 if (SLIST_FIRST(&dev->si_hlist))
274 return;
275 if (dev->si_devsw || dev->si_drv1 || dev->si_drv2)
276 return;
277 LIST_REMOVE(dev, si_hash);
278 if (dev->si_flags & SI_STASHED) {
279 bzero(dev, sizeof(*dev));
280 dev->si_flags |= SI_STASHED;
281 LIST_INSERT_HEAD(&dev_free, dev, si_hash);
282 } else {
283 FREE(dev, M_DEVT);
284 }
285 }
286
287 udev_t
288 dev2udev(dev_t x)
289 {
290 if (x == NODEV)
291 return NOUDEV;
292 return (x->si_udev);
293 }
294
295 dev_t
296 udev2dev(udev_t x, int b)
297 {
298
299 if (x == NOUDEV)
300 return (NODEV);
301 switch (b) {
302 case 0:
303 return makedev(umajor(x), uminor(x));
304 case 1:
305 return (NODEV);
306 default:
307 Debugger("udev2dev(...,X)");
308 return NODEV;
309 }
310 }
311
312 int
313 uminor(udev_t dev)
314 {
315 return(dev & 0xffff00ff);
316 }
317
318 int
319 umajor(udev_t dev)
320 {
321 return((dev & 0xff00) >> 8);
322 }
323
324 udev_t
325 makeudev(int x, int y)
326 {
327 return ((x << 8) | y);
328 }
329
330 dev_t
331 make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
332 {
333 dev_t dev;
334 va_list ap;
335 int i;
336
337 KASSERT((minor & ~0xffff00ff) == 0,
338 ("Invalid minor (0x%x) in make_dev", minor));
339
340 if (devsw->d_open == NULL) devsw->d_open = null_open;
341 if (devsw->d_close == NULL) devsw->d_close = null_close;
342 if (devsw->d_read == NULL) devsw->d_read = no_read;
343 if (devsw->d_write == NULL) devsw->d_write = no_write;
344 if (devsw->d_ioctl == NULL) devsw->d_ioctl = no_ioctl;
345 if (devsw->d_poll == NULL) devsw->d_poll = no_poll;
346 if (devsw->d_mmap == NULL) devsw->d_mmap = no_mmap;
347 if (devsw->d_strategy == NULL) devsw->d_strategy = no_strategy;
348 if (devsw->d_dump == NULL) devsw->d_dump = no_dump;
349 if (devsw->d_kqfilter == NULL) devsw->d_kqfilter = no_kqfilter;
350
351 if (devsw->d_maj == MAJOR_AUTO) {
352 for (i = NUMCDEVSW - 1; i > 0; i--)
353 if (reserved_majors[i] != i)
354 break;
355 KASSERT(i > 0, ("Out of major numbers (%s)", devsw->d_name));
356 devsw->d_maj = i;
357 reserved_majors[i] = i;
358 } else {
359 if (devsw->d_maj == 256) /* XXX: tty_cons.c is magic */
360 devsw->d_maj = 0;
361 KASSERT(devsw->d_maj >= 0 && devsw->d_maj < 256,
362 ("Invalid major (%d) in make_dev", devsw->d_maj));
363 if (reserved_majors[devsw->d_maj] != devsw->d_maj) {
364 printf("WARNING: driver \"%s\" used %s %d\n",
365 devsw->d_name, "unreserved major device number",
366 devsw->d_maj);
367 reserved_majors[devsw->d_maj] = devsw->d_maj;
368 }
369 }
370
371 if (!ready_for_devs) {
372 printf("WARNING: Driver mistake: make_dev(%s) called before SI_SUB_DRIVERS\n",
373 fmt);
374 /* XXX panic here once drivers are cleaned up */
375 }
376
377 dev = makedev(devsw->d_maj, minor);
378 if (dev->si_flags & SI_CHEAPCLONE &&
379 dev->si_flags & SI_NAMED &&
380 dev->si_devsw == devsw) {
381 /*
382 * This is allowed as it removes races and generally
383 * simplifies cloning devices.
384 */
385 return (dev);
386 }
387 if (dev->si_flags & SI_NAMED) {
388 printf( "WARNING: Driver mistake: repeat make_dev(\"%s\")\n",
389 dev->si_name);
390 panic("don't do that");
391 }
392 va_start(ap, fmt);
393 i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
394 if (i > (sizeof dev->__si_namebuf - 1)) {
395 printf("WARNING: Device name truncated! (%s)",
396 dev->__si_namebuf);
397 }
398 va_end(ap);
399 dev->si_devsw = devsw;
400 dev->si_uid = uid;
401 dev->si_gid = gid;
402 dev->si_mode = perms;
403 dev->si_flags |= SI_NAMED;
404
405 devfs_create(dev);
406 return (dev);
407 }
408
409 int
410 dev_named(dev_t pdev, const char *name)
411 {
412 dev_t cdev;
413
414 if (strcmp(devtoname(pdev), name) == 0)
415 return (1);
416 LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
417 if (strcmp(devtoname(cdev), name) == 0)
418 return (1);
419 return (0);
420 }
421
422 void
423 dev_depends(dev_t pdev, dev_t cdev)
424 {
425
426 cdev->si_parent = pdev;
427 cdev->si_flags |= SI_CHILD;
428 LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
429 }
430
431 dev_t
432 make_dev_alias(dev_t pdev, const char *fmt, ...)
433 {
434 dev_t dev;
435 va_list ap;
436 int i;
437
438 dev = allocdev();
439 dev->si_flags |= SI_ALIAS;
440 dev->si_flags |= SI_NAMED;
441 dev_depends(pdev, dev);
442 va_start(ap, fmt);
443 i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
444 if (i > (sizeof dev->__si_namebuf - 1)) {
445 printf("WARNING: Device name truncated! (%s)",
446 dev->__si_namebuf);
447 }
448 va_end(ap);
449
450 devfs_create(dev);
451 return (dev);
452 }
453
454 void
455 destroy_dev(dev_t dev)
456 {
457
458 if (!(dev->si_flags & SI_NAMED)) {
459 printf( "WARNING: Driver mistake: destroy_dev on %d/%d\n",
460 major(dev), minor(dev));
461 panic("don't do that");
462 }
463
464 devfs_destroy(dev);
465 if (dev->si_flags & SI_CHILD) {
466 LIST_REMOVE(dev, si_siblings);
467 dev->si_flags &= ~SI_CHILD;
468 }
469 while (!LIST_EMPTY(&dev->si_children))
470 destroy_dev(LIST_FIRST(&dev->si_children));
471 dev->si_drv1 = 0;
472 dev->si_drv2 = 0;
473 dev->si_devsw = 0;
474 bzero(&dev->__si_u, sizeof(dev->__si_u));
475 dev->si_flags &= ~SI_NAMED;
476 dev->si_flags &= ~SI_ALIAS;
477 freedev(dev);
478 }
479
480 const char *
481 devtoname(dev_t dev)
482 {
483 char *p;
484 int mynor;
485
486 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
487 p = dev->si_name;
488 if (devsw(dev))
489 sprintf(p, "#%s/", devsw(dev)->d_name);
490 else
491 sprintf(p, "#%d/", major(dev));
492 p += strlen(p);
493 mynor = minor(dev);
494 if (mynor < 0 || mynor > 255)
495 sprintf(p, "%#x", (u_int)mynor);
496 else
497 sprintf(p, "%d", mynor);
498 }
499 return (dev->si_name);
500 }
501
502 int
503 dev_stdclone(char *name, char **namep, const char *stem, int *unit)
504 {
505 int u, i;
506
507 i = strlen(stem);
508 if (bcmp(stem, name, i) != 0)
509 return (0);
510 if (!isdigit(name[i]))
511 return (0);
512 u = 0;
513 if (name[i] == '' && isdigit(name[i+1]))
514 return (0);
515 while (isdigit(name[i])) {
516 u *= 10;
517 u += name[i++] - '';
518 }
519 if (u > 0xffffff)
520 return (0);
521 *unit = u;
522 if (namep)
523 *namep = &name[i];
524 if (name[i])
525 return (2);
526 return (1);
527 }
528
529 /*
530 * Helper sysctl for devname(3). We're given a {u}dev_t and return
531 * the name, if any, registered by the device driver.
532 */
533 static int
534 sysctl_devname(SYSCTL_HANDLER_ARGS)
535 {
536 int error;
537 udev_t ud;
538 dev_t dev;
539
540 error = SYSCTL_IN(req, &ud, sizeof (ud));
541 if (error)
542 return (error);
543 if (ud == NOUDEV)
544 return(EINVAL);
545 dev = makedev(umajor(ud), uminor(ud));
546 if (dev->si_name[0] == '\0')
547 error = ENOENT;
548 else
549 error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
550 freedev(dev);
551 return (error);
552 }
553
554 SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
555 NULL, 0, sysctl_devname, "", "devname(3) handler");
556
557 /*
558 * Set ready_for_devs; prior to this point, device creation is not allowed.
559 */
560 static void
561 dev_set_ready(void *junk)
562 {
563 ready_for_devs = 1;
564 }
565
566 SYSINIT(dev_ready, SI_SUB_DEVFS, SI_ORDER_FIRST, dev_set_ready, NULL);
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