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 1.20 2006/12/23 00:35:03 swildner 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 #define cdevsw_ALLOCSTART (NUMCDEVSW/2)
51 MALLOC_DEFINE(M_DEVT, "cdev_t", "dev_t storage");
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
60 /* The number of cdev_t's we can create before malloc(9) kick in. */
63 static struct cdev devt_stash[DEVT_STASH];
64 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
65 static LIST_HEAD(, cdev) dev_free_list;
68 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
69 int dev_ref_debug = 0;
70 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, "");
73 * cdev_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.
82 return((x->si_udev >> 8) & 0xff);
90 return(x->si_udev & 0xffff00ff);
101 return ((i & 0xff) | (i >> 8));
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.
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.
115 * NOTE: The passed ops vector must normally match the device. This is
116 * because the kernel may create shadow devices that are INVISIBLE TO
117 * USERLAND. For example, the block device backing a disk is created
118 * as a shadow underneath the user-visible disklabel management device.
119 * Sometimes a device ops vector can be overridden, such as by /dev/console.
120 * In this case and this case only we allow a match when the ops vector
121 * otherwise would not match.
125 hashdev(struct dev_ops *ops, int x, int y, int allow_intercept)
132 udev = makeudev(x, y);
133 hash = udev % DEVT_HASH;
134 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
135 if (si->si_udev == udev) {
136 if (si->si_ops == ops)
138 if (allow_intercept && (si->si_flags & SI_INTERCEPTED))
142 if (stashed >= DEVT_STASH) {
143 MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
144 M_WAITOK|M_USE_RESERVE|M_ZERO);
145 } else if (LIST_FIRST(&dev_free_list)) {
146 si = LIST_FIRST(&dev_free_list);
147 LIST_REMOVE(si, si_hash);
149 si = devt_stash + stashed++;
150 si->si_flags |= SI_STASHED;
153 si->si_flags |= SI_HASHED | SI_ADHOC;
156 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
159 if (ops != &dead_dev_ops)
162 kprintf("create dev %p %s(minor=%08x) refs=%d\n",
163 si, devtoname(si), uminor(si->si_udev),
170 * Convert a device pointer to a device number
181 * Convert a device number to a device pointer. The device is referenced
182 * ad-hoc, meaning that the caller should call reference_dev() if it wishes
183 * to keep ahold of the returned structure long term.
185 * The returned device is associated with the currently installed cdevsw
186 * for the requested major number. NOCDEV is returned if the major number
187 * has not been registered.
190 udev2dev(udev_t x, int b)
195 if (x == NOUDEV || b != 0)
197 ops = dev_ops_get(umajor(x), uminor(x));
200 dev = hashdev(ops, umajor(x), uminor(x), TRUE);
205 dev_is_good(cdev_t dev)
207 if (dev != NOCDEV && dev->si_ops != &dead_dev_ops)
213 * Various user device number extraction and conversion routines
218 return(dev & 0xffff00ff);
224 return((dev & 0xff00) >> 8);
228 makeudev(int x, int y)
230 return ((x << 8) | y);
234 * Create an internal or external device.
236 * Device majors can be overloaded and used directly by the kernel without
237 * conflict, but userland will only see the particular device major that
238 * has been installed with dev_ops_add().
240 * This routine creates and returns an unreferenced ad-hoc entry for the
241 * device which will remain intact until the device is destroyed. If the
242 * caller intends to store the device pointer it must call reference_dev()
243 * to retain a real reference to the device.
245 * If an entry already exists, this function will set (or override)
246 * its cred requirements and name (XXX DEVFS interface).
249 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
250 int perms, const char *fmt, ...)
257 * compile the cdevsw and install the device
259 compile_dev_ops(ops);
260 dev = hashdev(ops, ops->head.maj, minor, FALSE);
263 * Set additional fields (XXX DEVFS interface goes here)
266 i = kvcprintf(fmt, NULL, dev->si_name, 32, ap);
267 dev->si_name[i] = '\0';
274 * This function is similar to make_dev() but no cred information or name
278 make_adhoc_dev(struct dev_ops *ops, int minor)
282 dev = hashdev(ops, ops->head.maj, minor, FALSE);
287 * This function is similar to make_dev() except the new device is created
288 * using an old device as a template.
291 make_sub_dev(cdev_t odev, int minor)
295 dev = hashdev(odev->si_ops, umajor(odev->si_udev), minor, FALSE);
298 * Copy cred requirements and name info XXX DEVFS.
300 if (dev->si_name[0] == 0 && odev->si_name[0])
301 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
306 * destroy_dev() removes the adhoc association for a device and revectors
307 * its ops to &dead_dev_ops.
309 * This routine releases the reference count associated with the ADHOC
310 * entry, plus releases the reference count held by the caller. What this
311 * means is that you should not call destroy_dev(make_dev(...)), because
312 * make_dev() does not bump the reference count (beyond what it needs to
313 * create the ad-hoc association). Any procedure that intends to destroy
314 * a device must have its own reference to it first.
317 destroy_dev(cdev_t dev)
323 if ((dev->si_flags & SI_ADHOC) == 0) {
328 kprintf("destroy dev %p %s(minor=%08x) refs=%d\n",
329 dev, devtoname(dev), uminor(dev->si_udev),
332 if (dev->si_refs < 2) {
333 kprintf("destroy_dev(): too few references on device! "
334 "%p %s(minor=%08x) refs=%d\n",
335 dev, devtoname(dev), uminor(dev->si_udev),
338 dev->si_flags &= ~SI_ADHOC;
339 if (dev->si_flags & SI_HASHED) {
340 hash = dev->si_udev % DEVT_HASH;
341 LIST_REMOVE(dev, si_hash);
342 dev->si_flags &= ~SI_HASHED;
346 * We have to release the ops reference before we replace the
347 * device switch with dead_dev_ops.
349 if (dead_dev_ops.d_strategy == NULL)
350 compile_dev_ops(&dead_dev_ops);
351 if (dev->si_ops && dev->si_ops != &dead_dev_ops)
352 dev_ops_release(dev->si_ops);
355 dev->si_ops = &dead_dev_ops;
356 --dev->si_refs; /* release adhoc association reference */
357 release_dev(dev); /* release callers reference */
361 * Destroy all ad-hoc device associations associated with a domain within a
362 * device switch. Only the minor numbers are included in the mask/match
365 * Unlike the ops functions whos link structures do not contain
366 * any major bits, this function scans through the dev list via si_udev
367 * which is a 32 bit field that contains both major and minor bits.
368 * Because of this, we must mask the minor bits in the passed mask variable
369 * to allow -1 to be specified generically.
371 * The caller must not include any major bits in the match value.
374 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
381 for (i = 0; i < DEVT_HASH; ++i) {
382 ndev = LIST_FIRST(&dev_hash[i]);
383 while ((dev = ndev) != NULL) {
384 ndev = LIST_NEXT(dev, si_hash);
385 KKASSERT(dev->si_flags & SI_ADHOC);
386 if (dev->si_ops == ops &&
387 (dev->si_udev & mask) == match
397 * Add a reference to a device. Callers generally add their own references
398 * when they are going to store a device node in a variable for long periods
399 * of time, to prevent a disassociation from free()ing the node.
401 * Also note that a caller that intends to call destroy_dev() must first
402 * obtain a reference on the device. The ad-hoc reference you get with
403 * make_dev() and friends is NOT sufficient to be able to call destroy_dev().
406 reference_dev(cdev_t dev)
411 kprintf("reference dev %p %s(minor=%08x) refs=%d\n",
412 dev, devtoname(dev), uminor(dev->si_udev),
420 * release a reference on a device. The device will be freed when the last
421 * reference has been released.
423 * NOTE: we must use si_udev to figure out the original (major, minor),
424 * because si_ops could already be pointing at dead_dev_ops.
427 release_dev(cdev_t dev)
432 KKASSERT(dev->si_refs > 0);
434 if (dev->si_refs <= 0) {
435 kprintf("Warning: extra release of dev %p(%s)\n",
436 dev, devtoname(dev));
437 free_devt = 0; /* prevent bad things from occuring */
442 kprintf("release dev %p %s(minor=%08x) refs=%d\n",
443 dev, devtoname(dev), uminor(dev->si_udev),
446 if (dev->si_refs == 0) {
447 if (dev->si_flags & SI_ADHOC) {
448 kprintf("Warning: illegal final release on ADHOC"
449 " device %p(%s), the device was never"
451 dev, devtoname(dev));
453 if (dev->si_flags & SI_HASHED) {
454 kprintf("Warning: last release on device, no call"
455 " to destroy_dev() was made! dev %p(%s)\n",
456 dev, devtoname(dev));
461 if (SLIST_FIRST(&dev->si_hlist) != NULL) {
462 kprintf("Warning: last release on device, vnode"
463 " associations still exist! dev %p(%s)\n",
464 dev, devtoname(dev));
465 free_devt = 0; /* prevent bad things from occuring */
467 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
468 dev_ops_release(dev->si_ops);
472 if (dev->si_flags & SI_STASHED) {
473 bzero(dev, sizeof(*dev));
474 LIST_INSERT_HEAD(&dev_free_list, dev, si_hash);
483 devtoname(cdev_t dev)
492 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
494 len = sizeof(dev->si_name);
495 if ((dname = dev_dname(dev)) != NULL)
496 ksnprintf(p, len, "#%s/", dname);
498 ksnprintf(p, len, "#%d/", major(dev));
502 if (mynor < 0 || mynor > 255)
503 ksnprintf(p, len, "%#x", (u_int)mynor);
505 ksnprintf(p, len, "%d", mynor);
507 return (dev->si_name);