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 1.15 2006/09/10 01:26:39 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 #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.
117 hashdev(struct dev_ops *ops, int x, int y)
124 udev = makeudev(x, y);
125 hash = udev % DEVT_HASH;
126 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
127 if (si->si_ops == ops && si->si_udev == udev)
130 if (stashed >= DEVT_STASH) {
131 MALLOC(si, struct cdev *, sizeof(*si), M_DEVT,
132 M_WAITOK|M_USE_RESERVE|M_ZERO);
133 } else if (LIST_FIRST(&dev_free_list)) {
134 si = LIST_FIRST(&dev_free_list);
135 LIST_REMOVE(si, si_hash);
137 si = devt_stash + stashed++;
138 si->si_flags |= SI_STASHED;
141 si->si_flags |= SI_HASHED | SI_ADHOC;
144 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
147 if (ops != &dead_dev_ops)
150 printf("create dev %p %s(minor=%08x) refs=%d\n",
151 si, devtoname(si), uminor(si->si_udev),
158 * Convert a device pointer to a device number
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.
173 * The returned device is associated with the currently installed cdevsw
174 * for the requested major number. NOCDEV is returned if the major number
175 * has not been registered.
178 udev2dev(udev_t x, int b)
183 if (x == NOUDEV || b != 0)
185 ops = dev_ops_get(umajor(x), uminor(x));
188 dev = hashdev(ops, umajor(x), uminor(x));
193 dev_is_good(cdev_t dev)
195 if (dev != NOCDEV && dev->si_ops != &dead_dev_ops)
201 * Various user device number extraction and conversion routines
206 return(dev & 0xffff00ff);
212 return((dev & 0xff00) >> 8);
216 makeudev(int x, int y)
218 return ((x << 8) | y);
222 * Create an internal or external device.
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
226 * has been installed with dev_ops_add().
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.
233 * If an entry already exists, this function will set (or override)
234 * its cred requirements and name (XXX DEVFS interface).
237 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
238 int perms, const char *fmt, ...)
245 * compile the cdevsw and install the device
247 compile_dev_ops(ops);
248 dev = hashdev(ops, ops->head.maj, minor);
251 * Set additional fields (XXX DEVFS interface goes here)
254 i = kvprintf(fmt, NULL, dev->si_name, 32, ap);
255 dev->si_name[i] = '\0';
262 * This function is similar to make_dev() but no cred information or name
266 make_adhoc_dev(struct dev_ops *ops, int minor)
270 dev = hashdev(ops, ops->head.maj, minor);
275 * This function is similar to make_dev() except the new device is created
276 * using an old device as a template.
279 make_sub_dev(cdev_t odev, int minor)
283 dev = hashdev(odev->si_ops, umajor(odev->si_udev), minor);
286 * Copy cred requirements and name info XXX DEVFS.
288 if (dev->si_name[0] == 0 && odev->si_name[0])
289 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
294 * destroy_dev() removes the adhoc association for a device and revectors
295 * its ops to &dead_dev_ops.
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.
305 destroy_dev(cdev_t dev)
311 if ((dev->si_flags & SI_ADHOC) == 0) {
316 printf("destroy dev %p %s(minor=%08x) refs=%d\n",
317 dev, devtoname(dev), uminor(dev->si_udev),
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),
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;
334 * We have to release the ops reference before we replace the
335 * device switch with dead_dev_ops.
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);
343 dev->si_ops = &dead_dev_ops;
344 --dev->si_refs; /* release adhoc association reference */
345 release_dev(dev); /* release callers reference */
349 * Destroy all ad-hoc device associations associated with a domain within a
350 * device switch. Only the minor numbers are included in the mask/match
353 * Unlike the ops functions whos link structures do not contain
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.
359 * The caller must not include any major bits in the match value.
362 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
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);
374 if (dev->si_ops == ops &&
375 (dev->si_udev & mask) == match
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.
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().
394 reference_dev(cdev_t dev)
399 printf("reference dev %p %s(minor=%08x) refs=%d\n",
400 dev, devtoname(dev), uminor(dev->si_udev),
408 * release a reference on a device. The device will be freed when the last
409 * reference has been released.
411 * NOTE: we must use si_udev to figure out the original (major, minor),
412 * because si_ops could already be pointing at dead_dev_ops.
415 release_dev(cdev_t dev)
420 KKASSERT(dev->si_refs > 0);
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 */
430 printf("release dev %p %s(minor=%08x) refs=%d\n",
431 dev, devtoname(dev), uminor(dev->si_udev),
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"
439 dev, devtoname(dev));
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));
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 */
455 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
456 dev_ops_release(dev->si_ops);
460 if (dev->si_flags & SI_STASHED) {
461 bzero(dev, sizeof(*dev));
462 LIST_INSERT_HEAD(&dev_free_list, dev, si_hash);
471 devtoname(cdev_t dev)
480 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
482 len = sizeof(dev->si_name);
483 if ((dname = dev_dname(dev)) != NULL)
484 snprintf(p, len, "#%s/", dname);
486 snprintf(p, len, "#%d/", major(dev));
490 if (mynor < 0 || mynor > 255)
491 snprintf(p, len, "%#x", (u_int)mynor);
493 snprintf(p, len, "%d", mynor);
495 return (dev->si_name);