2 * Parts Copyright (c) 1995 Terrence R. Lambert
3 * Copyright (c) 1995 Julian R. Elischer
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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
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
33 * $FreeBSD: src/sys/kern/kern_conf.c,v 1.73.2.3 2003/03/10 02:18:25 imp Exp $
34 * $DragonFly: src/sys/kern/kern_conf.c,v 1.23 2007/05/09 00:53:34 dillon Exp $
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>
44 #include <sys/vnode.h>
45 #include <sys/queue.h>
46 #include <sys/device.h>
47 #include <machine/stdarg.h>
49 #include <sys/sysref2.h>
51 static void cdev_terminate(struct cdev *dev);
53 MALLOC_DEFINE(M_DEVT, "cdev_t", "dev_t storage");
56 * SYSREF Integration - reference counting, allocation,
57 * sysid and syslink integration.
59 static struct sysref_class cdev_sysref_class = {
62 .proto = SYSREF_PROTO_DEV,
63 .offset = offsetof(struct cdev, si_sysref),
64 .objsize = sizeof(struct cdev),
68 .terminate = (sysref_terminate_func_t)cdev_terminate
73 * This is the number of hash-buckets. Experiements with 'real-life'
74 * udev_t's show that a prime halfway between two powers of two works
77 #define DEVT_HASH 128 /* must be power of 2 */
78 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
81 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
82 int dev_ref_debug = 0;
83 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, "");
86 * cdev_t and u_dev_t primitives. Note that the major number is always
87 * extracted from si_umajor, not from si_devsw, because si_devsw is replaced
88 * when a device is destroyed.
95 return(dev->si_umajor);
103 return(dev->si_uminor);
107 * Compatibility function with old udev_t format to convert the
108 * non-consecutive minor space into a consecutive minor space.
120 return ((y & 0xff) | (y >> 8));
124 * This is a bit complex because devices are always created relative to
125 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device
126 * backing a disk subsystem overlay), so we have to compare both the
127 * devsw and udev fields to locate the correct device.
129 * The device is created if it does not already exist. If SI_ADHOC is not
130 * set the device will be referenced (once) and SI_ADHOC will be set.
131 * The caller must explicitly add additional references to the device if
132 * the caller wishes to track additional references.
134 * NOTE: The passed ops vector must normally match the device. This is
135 * because the kernel may create shadow devices that are INVISIBLE TO
136 * USERLAND. For example, the block device backing a disk is created
137 * as a shadow underneath the user-visible disklabel management device.
138 * Sometimes a device ops vector can be overridden, such as by /dev/console.
139 * In this case and this case only we allow a match when the ops vector
140 * otherwise would not match.
144 __devthash(int x, int y)
146 return(((x << 2) ^ y) & (DEVT_HASH - 1));
151 hashdev(struct dev_ops *ops, int x, int y, int allow_intercept)
156 hash = __devthash(x, y);
157 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
158 if (si->si_umajor == x && si->si_uminor == y) {
159 if (si->si_ops == ops)
161 if (allow_intercept && (si->si_flags & SI_INTERCEPTED))
165 si = sysref_alloc(&cdev_sysref_class);
167 si->si_flags |= SI_HASHED | SI_ADHOC;
170 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
171 sysref_activate(&si->si_sysref);
174 if (ops != &dead_dev_ops)
177 kprintf("create dev %p %s(minor=%08x) refs=%d\n",
178 si, devtoname(si), y,
179 si->si_sysref.refcnt);
185 * Convert a device pointer to an old style device number. Return NOUDEV
186 * if the device is invalid or if the device (maj,min) cannot be converted
187 * to an old style udev_t.
194 if ((dev->si_umajor & 0xffffff00) ||
195 (dev->si_uminor & 0x0000ff00)) {
198 return((dev->si_umajor << 8) | dev->si_uminor);
202 * Convert a device number to a device pointer. The device is referenced
203 * ad-hoc, meaning that the caller should call reference_dev() if it wishes
204 * to keep ahold of the returned structure long term.
206 * The returned device is associated with the currently installed cdevsw
207 * for the requested major number. NULL is returned if the major number
208 * has not been registered.
211 udev2dev(udev_t x, int b)
216 if (x == NOUDEV || b != 0)
218 ops = dev_ops_get(umajor(x), uminor(x));
221 dev = hashdev(ops, umajor(x), uminor(x), TRUE);
226 dev_is_good(cdev_t dev)
228 if (dev != NULL && dev->si_ops != &dead_dev_ops)
234 * Various user device number extraction and conversion routines
241 return(dev & 0xffff00ff);
249 return((dev & 0xff00) >> 8);
253 makeudev(int x, int y)
255 if ((x & 0xffffff00) || (y & 0x0000ff00))
257 return ((x << 8) | y);
261 * Create an internal or external device.
263 * Device majors can be overloaded and used directly by the kernel without
264 * conflict, but userland will only see the particular device major that
265 * has been installed with dev_ops_add().
267 * This routine creates and returns an unreferenced ad-hoc entry for the
268 * device which will remain intact until the device is destroyed. If the
269 * caller intends to store the device pointer it must call reference_dev()
270 * to retain a real reference to the device.
272 * If an entry already exists, this function will set (or override)
273 * its cred requirements and name (XXX DEVFS interface).
276 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
277 int perms, const char *fmt, ...)
284 * compile the cdevsw and install the device
286 compile_dev_ops(ops);
287 dev = hashdev(ops, ops->head.maj, minor, FALSE);
290 * Set additional fields (XXX DEVFS interface goes here)
293 i = kvcprintf(fmt, NULL, dev->si_name, 32, ap);
294 dev->si_name[i] = '\0';
301 * This function is similar to make_dev() but no cred information or name
305 make_adhoc_dev(struct dev_ops *ops, int minor)
309 dev = hashdev(ops, ops->head.maj, minor, FALSE);
314 * This function is similar to make_dev() except the new device is created
315 * using an old device as a template.
318 make_sub_dev(cdev_t odev, int minor)
322 dev = hashdev(odev->si_ops, odev->si_umajor, minor, FALSE);
325 * Copy cred requirements and name info XXX DEVFS.
327 if (dev->si_name[0] == 0 && odev->si_name[0])
328 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
333 get_dev(int x, int y)
340 ops = dev_ops_get(x, y);
343 dev = hashdev(ops, x, y, TRUE);
348 * destroy_dev() removes the adhoc association for a device and revectors
349 * its ops to &dead_dev_ops.
351 * This routine releases the reference count associated with the ADHOC
352 * entry, plus releases the reference count held by the caller. What this
353 * means is that you should not call destroy_dev(make_dev(...)), because
354 * make_dev() does not bump the reference count (beyond what it needs to
355 * create the ad-hoc association). Any procedure that intends to destroy
356 * a device must have its own reference to it first.
359 destroy_dev(cdev_t dev)
365 if ((dev->si_flags & SI_ADHOC) == 0) {
370 kprintf("destroy dev %p %s(minor=%08x) refs=%d\n",
371 dev, devtoname(dev), dev->si_uminor,
372 dev->si_sysref.refcnt);
374 if (dev->si_sysref.refcnt < 2) {
375 kprintf("destroy_dev(): too few references on device! "
376 "%p %s(minor=%08x) refs=%d\n",
377 dev, devtoname(dev), dev->si_uminor,
378 dev->si_sysref.refcnt);
380 dev->si_flags &= ~SI_ADHOC;
381 if (dev->si_flags & SI_HASHED) {
382 hash = __devthash(dev->si_umajor, dev->si_uminor);
383 LIST_REMOVE(dev, si_hash);
384 dev->si_flags &= ~SI_HASHED;
388 * We have to release the ops reference before we replace the
389 * device switch with dead_dev_ops.
391 if (dead_dev_ops.d_strategy == NULL)
392 compile_dev_ops(&dead_dev_ops);
393 if (dev->si_ops && dev->si_ops != &dead_dev_ops)
394 dev_ops_release(dev->si_ops);
397 dev->si_ops = &dead_dev_ops;
398 sysref_put(&dev->si_sysref); /* release adhoc association */
399 release_dev(dev); /* release callers reference */
403 * Destroy all ad-hoc device associations associated with a domain within a
404 * device switch. Only the minor numbers are included in the mask/match
407 * Unlike the ops functions whos link structures do not contain
408 * any major bits, this function scans through the dev list via
409 * si_umajor/si_uminor.
411 * The caller must not include any major bits in the match value.
414 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
420 for (i = 0; i < DEVT_HASH; ++i) {
421 ndev = LIST_FIRST(&dev_hash[i]);
422 while ((dev = ndev) != NULL) {
423 ndev = LIST_NEXT(dev, si_hash);
424 KKASSERT(dev->si_flags & SI_ADHOC);
425 if (dev->si_ops == ops &&
426 ((u_int)dev->si_uminor & mask) == match
436 * Add a reference to a device. Callers generally add their own references
437 * when they are going to store a device node in a variable for long periods
438 * of time, to prevent a disassociation from free()ing the node.
440 * Also note that a caller that intends to call destroy_dev() must first
441 * obtain a reference on the device. The ad-hoc reference you get with
442 * make_dev() and friends is NOT sufficient to be able to call destroy_dev().
445 reference_dev(cdev_t dev)
448 sysref_get(&dev->si_sysref);
450 kprintf("reference dev %p %s(minor=%08x) refs=%d\n",
451 dev, devtoname(dev), dev->si_uminor,
452 dev->si_sysref.refcnt);
459 * release a reference on a device. The device will be terminated when the
460 * last reference has been released.
462 * NOTE: we must use si_umajor to figure out the original major number,
463 * because si_ops could already be pointing at dead_dev_ops.
466 release_dev(cdev_t dev)
470 sysref_put(&dev->si_sysref);
475 cdev_terminate(struct cdev *dev)
480 kprintf("release dev %p %s(minor=%08x) refs=%d\n",
481 dev, devtoname(dev), dev->si_uminor,
482 dev->si_sysref.refcnt);
484 if (dev->si_flags & SI_ADHOC) {
485 kprintf("Warning: illegal final release on ADHOC"
486 " device %p(%s), the device was never"
488 dev, devtoname(dev));
491 if (dev->si_flags & SI_HASHED) {
492 kprintf("Warning: last release on device, no call"
493 " to destroy_dev() was made! dev %p(%s)\n",
494 dev, devtoname(dev));
499 if (SLIST_FIRST(&dev->si_hlist) != NULL) {
500 kprintf("Warning: last release on device, vnode"
501 " associations still exist! dev %p(%s)\n",
502 dev, devtoname(dev));
505 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
506 dev_ops_release(dev->si_ops);
510 sysref_put(&dev->si_sysref);
514 devtoname(cdev_t dev)
523 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
525 len = sizeof(dev->si_name);
526 if ((dname = dev_dname(dev)) != NULL)
527 ksnprintf(p, len, "#%s/", dname);
529 ksnprintf(p, len, "#%d/", major(dev));
533 if (mynor < 0 || mynor > 255)
534 ksnprintf(p, len, "%#x", (u_int)mynor);
536 ksnprintf(p, len, "%d", mynor);
538 return (dev->si_name);