Rename struct specinfo into struct cdev. Add a new typedef 'cdev_t' for cdev
[dragonfly.git] / sys / kern / kern_conf.c
CommitLineData
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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: src/sys/kern/kern_conf.c,v 1.73.2.3 2003/03/10 02:18:25 imp Exp $
0de08e6d 34 * $DragonFly: src/sys/kern/kern_conf.c,v 1.13 2006/09/09 19:07:28 dillon Exp $
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35 */
36
37#include <sys/param.h>
38#include <sys/kernel.h>
39#include <sys/sysctl.h>
40#include <sys/systm.h>
41#include <sys/module.h>
42#include <sys/malloc.h>
43#include <sys/conf.h>
44#include <sys/vnode.h>
45#include <sys/queue.h>
335dda38 46#include <sys/device.h>
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47#include <machine/stdarg.h>
48
49#define cdevsw_ALLOCSTART (NUMCDEVSW/2)
50
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51MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage");
52
53/*
54 * This is the number of hash-buckets. Experiements with 'real-life'
55 * udev_t's show that a prime halfway between two powers of two works
56 * best.
57 */
58#define DEVT_HASH 83
59
60/* The number of dev_t's we can create before malloc(9) kick in. */
61#define DEVT_STASH 50
62
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63static struct cdev devt_stash[DEVT_STASH];
64static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
65static LIST_HEAD(, cdev) dev_free_list;
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66
67static int free_devt;
68SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
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69int dev_ref_debug = 0;
70SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, "");
984263bc 71
984263bc 72/*
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73 * dev_t and u_dev_t primitives. Note that the major number is always
74 * extracted from si_udev, not from si_devsw, because si_devsw is replaced
75 * when a device is destroyed.
984263bc 76 */
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77int
78major(dev_t x)
79{
80 if (x == NODEV)
81 return NOUDEV;
82 return((x->si_udev >> 8) & 0xff);
83}
84
85int
86minor(dev_t x)
87{
88 if (x == NODEV)
89 return NOUDEV;
90 return(x->si_udev & 0xffff00ff);
91}
92
93int
94lminor(dev_t x)
95{
96 int i;
97
98 if (x == NODEV)
99 return NOUDEV;
100 i = minor(x);
101 return ((i & 0xff) | (i >> 8));
102}
103
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104/*
105 * This is a bit complex because devices are always created relative to
106 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device
107 * backing a disk subsystem overlay), so we have to compare both the
108 * devsw and udev fields to locate the correct device.
109 *
110 * The device is created if it does not already exist. If SI_ADHOC is not
111 * set the device will be referenced (once) and SI_ADHOC will be set.
112 * The caller must explicitly add additional references to the device if
113 * the caller wishes to track additional references.
114 */
115static
984263bc 116dev_t
fef8985e 117hashdev(struct dev_ops *ops, int x, int y)
984263bc 118{
0de08e6d 119 struct cdev *si;
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120 udev_t udev;
121 int hash;
122 static int stashed;
123
e4c9c0c8 124 udev = makeudev(x, y);
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125 hash = udev % DEVT_HASH;
126 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
fef8985e 127 if (si->si_ops == ops && si->si_udev == udev)
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128 return (si);
129 }
130 if (stashed >= DEVT_STASH) {
0de08e6d 131 MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
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132 M_WAITOK|M_USE_RESERVE|M_ZERO);
133 } else if (LIST_FIRST(&dev_free_list)) {
134 si = LIST_FIRST(&dev_free_list);
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135 LIST_REMOVE(si, si_hash);
136 } else {
137 si = devt_stash + stashed++;
138 si->si_flags |= SI_STASHED;
139 }
fef8985e 140 si->si_ops = ops;
e4c9c0c8 141 si->si_flags |= SI_HASHED | SI_ADHOC;
984263bc 142 si->si_udev = udev;
e4c9c0c8 143 si->si_refs = 1;
984263bc 144 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
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145
146 dev_dclone(si);
147 if (ops != &dead_dev_ops)
148 ++ops->head.refs;
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149 if (dev_ref_debug) {
150 printf("create dev %p %s(minor=%08x) refs=%d\n",
151 si, devtoname(si), uminor(si->si_udev),
152 si->si_refs);
984263bc 153 }
e4c9c0c8 154 return (si);
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155}
156
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157/*
158 * Convert a device pointer to a device number
159 */
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160udev_t
161dev2udev(dev_t x)
162{
163 if (x == NODEV)
164 return NOUDEV;
165 return (x->si_udev);
166}
167
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168/*
169 * Convert a device number to a device pointer. The device is referenced
170 * ad-hoc, meaning that the caller should call reference_dev() if it wishes
171 * to keep ahold of the returned structure long term.
172 *
173 * The returned device is associated with the currently installed cdevsw
174 * for the requested major number. NODEV is returned if the major number
175 * has not been registered.
176 */
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177dev_t
178udev2dev(udev_t x, int b)
179{
e4c9c0c8 180 dev_t dev;
fef8985e 181 struct dev_ops *ops;
984263bc 182
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183 if (x == NOUDEV || b != 0)
184 return(NODEV);
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185 ops = dev_ops_get(umajor(x), uminor(x));
186 if (ops == NULL)
e4c9c0c8 187 return(NODEV);
fef8985e 188 dev = hashdev(ops, umajor(x), uminor(x));
e4c9c0c8 189 return(dev);
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190}
191
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192int
193dev_is_good(dev_t dev)
194{
fef8985e 195 if (dev != NODEV && dev->si_ops != &dead_dev_ops)
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196 return(1);
197 return(0);
198}
199
200/*
201 * Various user device number extraction and conversion routines
202 */
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203int
204uminor(udev_t dev)
205{
206 return(dev & 0xffff00ff);
207}
208
209int
210umajor(udev_t dev)
211{
212 return((dev & 0xff00) >> 8);
213}
214
215udev_t
216makeudev(int x, int y)
217{
218 return ((x << 8) | y);
219}
220
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221/*
222 * Create an internal or external device.
223 *
224 * Device majors can be overloaded and used directly by the kernel without
225 * conflict, but userland will only see the particular device major that
fef8985e 226 * has been installed with dev_ops_add().
e4c9c0c8 227 *
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228 * This routine creates and returns an unreferenced ad-hoc entry for the
229 * device which will remain intact until the device is destroyed. If the
230 * caller intends to store the device pointer it must call reference_dev()
231 * to retain a real reference to the device.
232 *
233 * If an entry already exists, this function will set (or override)
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234 * its cred requirements and name (XXX DEVFS interface).
235 */
984263bc 236dev_t
fef8985e 237make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
e4c9c0c8 238 int perms, const char *fmt, ...)
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239{
240 dev_t dev;
e2565a42 241 __va_list ap;
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242 int i;
243
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244 /*
245 * compile the cdevsw and install the device
246 */
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247 compile_dev_ops(ops);
248 dev = hashdev(ops, ops->head.maj, minor);
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249
250 /*
251 * Set additional fields (XXX DEVFS interface goes here)
252 */
e2565a42 253 __va_start(ap, fmt);
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254 i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
255 dev->si_name[i] = '\0';
e2565a42 256 __va_end(ap);
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257
258 return (dev);
259}
260
217ff971 261/*
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262 * This function is similar to make_dev() but no cred information or name
263 * need be specified.
264 */
265dev_t
fef8985e 266make_adhoc_dev(struct dev_ops *ops, int minor)
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267{
268 dev_t dev;
269
fef8985e 270 dev = hashdev(ops, ops->head.maj, minor);
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271 return(dev);
272}
273
274/*
275 * This function is similar to make_dev() except the new device is created
276 * using an old device as a template.
277 */
278dev_t
279make_sub_dev(dev_t odev, int minor)
280{
281 dev_t dev;
282
fef8985e 283 dev = hashdev(odev->si_ops, umajor(odev->si_udev), minor);
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284
285 /*
286 * Copy cred requirements and name info XXX DEVFS.
287 */
288 if (dev->si_name[0] == 0 && odev->si_name[0])
289 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
290 return (dev);
291}
292
293/*
294 * destroy_dev() removes the adhoc association for a device and revectors
fef8985e 295 * its ops to &dead_dev_ops.
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296 *
297 * This routine releases the reference count associated with the ADHOC
298 * entry, plus releases the reference count held by the caller. What this
299 * means is that you should not call destroy_dev(make_dev(...)), because
300 * make_dev() does not bump the reference count (beyond what it needs to
301 * create the ad-hoc association). Any procedure that intends to destroy
302 * a device must have its own reference to it first.
217ff971 303 */
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304void
305destroy_dev(dev_t dev)
306{
e4c9c0c8 307 int hash;
217ff971 308
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309 if (dev == NODEV)
310 return;
311 if ((dev->si_flags & SI_ADHOC) == 0) {
312 release_dev(dev);
313 return;
314 }
315 if (dev_ref_debug) {
316 printf("destroy dev %p %s(minor=%08x) refs=%d\n",
317 dev, devtoname(dev), uminor(dev->si_udev),
318 dev->si_refs);
319 }
320 if (dev->si_refs < 2) {
321 printf("destroy_dev(): too few references on device! "
322 "%p %s(minor=%08x) refs=%d\n",
323 dev, devtoname(dev), uminor(dev->si_udev),
324 dev->si_refs);
325 }
326 dev->si_flags &= ~SI_ADHOC;
327 if (dev->si_flags & SI_HASHED) {
328 hash = dev->si_udev % DEVT_HASH;
329 LIST_REMOVE(dev, si_hash);
330 dev->si_flags &= ~SI_HASHED;
331 }
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332
333 /*
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334 * We have to release the ops reference before we replace the
335 * device switch with dead_dev_ops.
32beb3ff 336 */
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337 if (dead_dev_ops.d_strategy == NULL)
338 compile_dev_ops(&dead_dev_ops);
339 if (dev->si_ops && dev->si_ops != &dead_dev_ops)
340 dev_ops_release(dev->si_ops);
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341 dev->si_drv1 = NULL;
342 dev->si_drv2 = NULL;
fef8985e 343 dev->si_ops = &dead_dev_ops;
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344 --dev->si_refs; /* release adhoc association reference */
345 release_dev(dev); /* release callers reference */
346}
347
348/*
349 * Destroy all ad-hoc device associations associated with a domain within a
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350 * device switch. Only the minor numbers are included in the mask/match
351 * values.
352 *
fef8985e 353 * Unlike the ops functions whos link structures do not contain
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354 * any major bits, this function scans through the dev list via si_udev
355 * which is a 32 bit field that contains both major and minor bits.
356 * Because of this, we must mask the minor bits in the passed mask variable
357 * to allow -1 to be specified generically.
358 *
359 * The caller must not include any major bits in the match value.
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360 */
361void
fef8985e 362destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
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363{
364 int i;
365 dev_t dev;
366 dev_t ndev;
367
d969b138 368 mask = uminor(mask);
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369 for (i = 0; i < DEVT_HASH; ++i) {
370 ndev = LIST_FIRST(&dev_hash[i]);
371 while ((dev = ndev) != NULL) {
372 ndev = LIST_NEXT(dev, si_hash);
373 KKASSERT(dev->si_flags & SI_ADHOC);
fef8985e 374 if (dev->si_ops == ops &&
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375 (dev->si_udev & mask) == match
376 ) {
377 ++dev->si_refs;
378 destroy_dev(dev);
379 }
380 }
381 }
382}
383
384/*
385 * Add a reference to a device. Callers generally add their own references
386 * when they are going to store a device node in a variable for long periods
387 * of time, to prevent a disassociation from free()ing the node.
388 *
389 * Also note that a caller that intends to call destroy_dev() must first
390 * obtain a reference on the device. The ad-hoc reference you get with
391 * make_dev() and friends is NOT sufficient to be able to call destroy_dev().
392 */
393dev_t
394reference_dev(dev_t dev)
395{
396 if (dev != NODEV) {
397 ++dev->si_refs;
398 if (dev_ref_debug) {
399 printf("reference dev %p %s(minor=%08x) refs=%d\n",
400 dev, devtoname(dev), uminor(dev->si_udev),
401 dev->si_refs);
402 }
403 }
404 return(dev);
405}
406
407/*
408 * release a reference on a device. The device will be freed when the last
409 * reference has been released.
410 *
411 * NOTE: we must use si_udev to figure out the original (major, minor),
fef8985e 412 * because si_ops could already be pointing at dead_dev_ops.
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413 */
414void
415release_dev(dev_t dev)
416{
417 if (dev == NODEV)
418 return;
419 if (free_devt) {
420 KKASSERT(dev->si_refs > 0);
421 } else {
422 if (dev->si_refs <= 0) {
423 printf("Warning: extra release of dev %p(%s)\n",
424 dev, devtoname(dev));
425 free_devt = 0; /* prevent bad things from occuring */
426 }
427 }
428 --dev->si_refs;
429 if (dev_ref_debug) {
430 printf("release dev %p %s(minor=%08x) refs=%d\n",
431 dev, devtoname(dev), uminor(dev->si_udev),
432 dev->si_refs);
433 }
434 if (dev->si_refs == 0) {
435 if (dev->si_flags & SI_ADHOC) {
436 printf("Warning: illegal final release on ADHOC"
437 " device %p(%s), the device was never"
438 " destroyed!\n",
439 dev, devtoname(dev));
440 }
441 if (dev->si_flags & SI_HASHED) {
442 printf("Warning: last release on device, no call"
443 " to destroy_dev() was made! dev %p(%s)\n",
444 dev, devtoname(dev));
445 dev->si_refs = 3;
446 destroy_dev(dev);
447 dev->si_refs = 0;
448 }
449 if (SLIST_FIRST(&dev->si_hlist) != NULL) {
450 printf("Warning: last release on device, vnode"
451 " associations still exist! dev %p(%s)\n",
452 dev, devtoname(dev));
453 free_devt = 0; /* prevent bad things from occuring */
454 }
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455 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
456 dev_ops_release(dev->si_ops);
457 dev->si_ops = NULL;
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458 }
459 if (free_devt) {
460 if (dev->si_flags & SI_STASHED) {
461 bzero(dev, sizeof(*dev));
462 LIST_INSERT_HEAD(&dev_free_list, dev, si_hash);
463 } else {
464 FREE(dev, M_DEVT);
465 }
466 }
467 }
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468}
469
470const char *
471devtoname(dev_t dev)
472{
984263bc 473 int mynor;
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474 int len;
475 char *p;
476 const char *dname;
984263bc 477
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478 if (dev == NODEV)
479 return("#nodev");
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480 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
481 p = dev->si_name;
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482 len = sizeof(dev->si_name);
483 if ((dname = dev_dname(dev)) != NULL)
484 snprintf(p, len, "#%s/", dname);
984263bc 485 else
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486 snprintf(p, len, "#%d/", major(dev));
487 len -= strlen(p);
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488 p += strlen(p);
489 mynor = minor(dev);
490 if (mynor < 0 || mynor > 255)
335dda38 491 snprintf(p, len, "%#x", (u_int)mynor);
984263bc 492 else
335dda38 493 snprintf(p, len, "%d", mynor);
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494 }
495 return (dev->si_name);
496}
e4c9c0c8 497