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 1.22 2007/05/08 02:31:42 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 #define cdevsw_ALLOCSTART (NUMCDEVSW/2)
53 static void cdev_terminate(struct cdev *dev);
55 MALLOC_DEFINE(M_DEVT, "cdev_t", "dev_t storage");
58 * SYSREF Integration - reference counting, allocation,
59 * sysid and syslink integration.
61 static struct sysref_class cdev_sysref_class = {
64 .proto = SYSREF_PROTO_DEV,
65 .offset = offsetof(struct cdev, si_sysref),
66 .objsize = sizeof(struct cdev),
70 .terminate = (sysref_terminate_func_t)cdev_terminate
75 * This is the number of hash-buckets. Experiements with 'real-life'
76 * udev_t's show that a prime halfway between two powers of two works
80 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
83 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
84 int dev_ref_debug = 0;
85 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, "");
88 * cdev_t and u_dev_t primitives. Note that the major number is always
89 * extracted from si_udev, not from si_devsw, because si_devsw is replaced
90 * when a device is destroyed.
97 return((dev->si_udev >> 8) & 0xff);
105 return(dev->si_udev & 0xffff00ff);
116 return ((i & 0xff) | (i >> 8));
120 * This is a bit complex because devices are always created relative to
121 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device
122 * backing a disk subsystem overlay), so we have to compare both the
123 * devsw and udev fields to locate the correct device.
125 * The device is created if it does not already exist. If SI_ADHOC is not
126 * set the device will be referenced (once) and SI_ADHOC will be set.
127 * The caller must explicitly add additional references to the device if
128 * the caller wishes to track additional references.
130 * NOTE: The passed ops vector must normally match the device. This is
131 * because the kernel may create shadow devices that are INVISIBLE TO
132 * USERLAND. For example, the block device backing a disk is created
133 * as a shadow underneath the user-visible disklabel management device.
134 * Sometimes a device ops vector can be overridden, such as by /dev/console.
135 * In this case and this case only we allow a match when the ops vector
136 * otherwise would not match.
140 hashdev(struct dev_ops *ops, int x, int y, int allow_intercept)
146 udev = makeudev(x, y);
147 hash = udev % DEVT_HASH;
148 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
149 if (si->si_udev == udev) {
150 if (si->si_ops == ops)
152 if (allow_intercept && (si->si_flags & SI_INTERCEPTED))
156 si = sysref_alloc(&cdev_sysref_class);
158 si->si_flags |= SI_HASHED | SI_ADHOC;
160 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
161 sysref_activate(&si->si_sysref);
164 if (ops != &dead_dev_ops)
167 kprintf("create dev %p %s(minor=%08x) refs=%d\n",
168 si, devtoname(si), uminor(si->si_udev),
169 si->si_sysref.refcnt);
175 * Convert a device pointer to a device number
182 return (dev->si_udev);
186 * Convert a device number to a device pointer. The device is referenced
187 * ad-hoc, meaning that the caller should call reference_dev() if it wishes
188 * to keep ahold of the returned structure long term.
190 * The returned device is associated with the currently installed cdevsw
191 * for the requested major number. NULL is returned if the major number
192 * has not been registered.
195 udev2dev(udev_t x, int b)
200 if (x == NOUDEV || b != 0)
202 ops = dev_ops_get(umajor(x), uminor(x));
205 dev = hashdev(ops, umajor(x), uminor(x), TRUE);
210 dev_is_good(cdev_t dev)
212 if (dev != NULL && dev->si_ops != &dead_dev_ops)
218 * Various user device number extraction and conversion routines
223 return(dev & 0xffff00ff);
229 return((dev & 0xff00) >> 8);
233 makeudev(int x, int y)
235 return ((x << 8) | y);
239 * Create an internal or external device.
241 * Device majors can be overloaded and used directly by the kernel without
242 * conflict, but userland will only see the particular device major that
243 * has been installed with dev_ops_add().
245 * This routine creates and returns an unreferenced ad-hoc entry for the
246 * device which will remain intact until the device is destroyed. If the
247 * caller intends to store the device pointer it must call reference_dev()
248 * to retain a real reference to the device.
250 * If an entry already exists, this function will set (or override)
251 * its cred requirements and name (XXX DEVFS interface).
254 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
255 int perms, const char *fmt, ...)
262 * compile the cdevsw and install the device
264 compile_dev_ops(ops);
265 dev = hashdev(ops, ops->head.maj, minor, FALSE);
268 * Set additional fields (XXX DEVFS interface goes here)
271 i = kvcprintf(fmt, NULL, dev->si_name, 32, ap);
272 dev->si_name[i] = '\0';
279 * This function is similar to make_dev() but no cred information or name
283 make_adhoc_dev(struct dev_ops *ops, int minor)
287 dev = hashdev(ops, ops->head.maj, minor, FALSE);
292 * This function is similar to make_dev() except the new device is created
293 * using an old device as a template.
296 make_sub_dev(cdev_t odev, int minor)
300 dev = hashdev(odev->si_ops, umajor(odev->si_udev), minor, FALSE);
303 * Copy cred requirements and name info XXX DEVFS.
305 if (dev->si_name[0] == 0 && odev->si_name[0])
306 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
311 * destroy_dev() removes the adhoc association for a device and revectors
312 * its ops to &dead_dev_ops.
314 * This routine releases the reference count associated with the ADHOC
315 * entry, plus releases the reference count held by the caller. What this
316 * means is that you should not call destroy_dev(make_dev(...)), because
317 * make_dev() does not bump the reference count (beyond what it needs to
318 * create the ad-hoc association). Any procedure that intends to destroy
319 * a device must have its own reference to it first.
322 destroy_dev(cdev_t dev)
328 if ((dev->si_flags & SI_ADHOC) == 0) {
333 kprintf("destroy dev %p %s(minor=%08x) refs=%d\n",
334 dev, devtoname(dev), uminor(dev->si_udev),
335 dev->si_sysref.refcnt);
337 if (dev->si_sysref.refcnt < 2) {
338 kprintf("destroy_dev(): too few references on device! "
339 "%p %s(minor=%08x) refs=%d\n",
340 dev, devtoname(dev), uminor(dev->si_udev),
341 dev->si_sysref.refcnt);
343 dev->si_flags &= ~SI_ADHOC;
344 if (dev->si_flags & SI_HASHED) {
345 hash = dev->si_udev % DEVT_HASH;
346 LIST_REMOVE(dev, si_hash);
347 dev->si_flags &= ~SI_HASHED;
351 * We have to release the ops reference before we replace the
352 * device switch with dead_dev_ops.
354 if (dead_dev_ops.d_strategy == NULL)
355 compile_dev_ops(&dead_dev_ops);
356 if (dev->si_ops && dev->si_ops != &dead_dev_ops)
357 dev_ops_release(dev->si_ops);
360 dev->si_ops = &dead_dev_ops;
361 sysref_put(&dev->si_sysref); /* release adhoc association */
362 release_dev(dev); /* release callers reference */
366 * Destroy all ad-hoc device associations associated with a domain within a
367 * device switch. Only the minor numbers are included in the mask/match
370 * Unlike the ops functions whos link structures do not contain
371 * any major bits, this function scans through the dev list via si_udev
372 * which is a 32 bit field that contains both major and minor bits.
373 * Because of this, we must mask the minor bits in the passed mask variable
374 * to allow -1 to be specified generically.
376 * The caller must not include any major bits in the match value.
379 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
386 for (i = 0; i < DEVT_HASH; ++i) {
387 ndev = LIST_FIRST(&dev_hash[i]);
388 while ((dev = ndev) != NULL) {
389 ndev = LIST_NEXT(dev, si_hash);
390 KKASSERT(dev->si_flags & SI_ADHOC);
391 if (dev->si_ops == ops &&
392 (dev->si_udev & mask) == match
402 * Add a reference to a device. Callers generally add their own references
403 * when they are going to store a device node in a variable for long periods
404 * of time, to prevent a disassociation from free()ing the node.
406 * Also note that a caller that intends to call destroy_dev() must first
407 * obtain a reference on the device. The ad-hoc reference you get with
408 * make_dev() and friends is NOT sufficient to be able to call destroy_dev().
411 reference_dev(cdev_t dev)
414 sysref_get(&dev->si_sysref);
416 kprintf("reference dev %p %s(minor=%08x) refs=%d\n",
417 dev, devtoname(dev), uminor(dev->si_udev),
418 dev->si_sysref.refcnt);
425 * release a reference on a device. The device will be terminated when the
426 * last reference has been released.
428 * NOTE: we must use si_udev to figure out the original (major, minor),
429 * because si_ops could already be pointing at dead_dev_ops.
432 release_dev(cdev_t dev)
436 sysref_put(&dev->si_sysref);
441 cdev_terminate(struct cdev *dev)
446 kprintf("release dev %p %s(minor=%08x) refs=%d\n",
447 dev, devtoname(dev), uminor(dev->si_udev),
448 dev->si_sysref.refcnt);
450 if (dev->si_flags & SI_ADHOC) {
451 kprintf("Warning: illegal final release on ADHOC"
452 " device %p(%s), the device was never"
454 dev, devtoname(dev));
457 if (dev->si_flags & SI_HASHED) {
458 kprintf("Warning: last release on device, no call"
459 " to destroy_dev() was made! dev %p(%s)\n",
460 dev, devtoname(dev));
465 if (SLIST_FIRST(&dev->si_hlist) != NULL) {
466 kprintf("Warning: last release on device, vnode"
467 " associations still exist! dev %p(%s)\n",
468 dev, devtoname(dev));
471 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
472 dev_ops_release(dev->si_ops);
476 sysref_put(&dev->si_sysref);
480 devtoname(cdev_t dev)
489 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
491 len = sizeof(dev->si_name);
492 if ((dname = dev_dname(dev)) != NULL)
493 ksnprintf(p, len, "#%s/", dname);
495 ksnprintf(p, len, "#%d/", major(dev));
499 if (mynor < 0 || mynor > 255)
500 ksnprintf(p, len, "%#x", (u_int)mynor);
502 ksnprintf(p, len, "%d", mynor);
504 return (dev->si_name);