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 #include <vfs/devfs/devfs.h>
54 static void cdev_terminate(struct cdev *dev);
56 MALLOC_DEFINE(M_DEVT, "cdev_t", "dev_t storage");
59 * SYSREF Integration - reference counting, allocation,
60 * sysid and syslink integration.
62 static struct sysref_class cdev_sysref_class = {
65 .proto = SYSREF_PROTO_DEV,
66 .offset = offsetof(struct cdev, si_sysref),
67 .objsize = sizeof(struct cdev),
71 .terminate = (sysref_terminate_func_t)cdev_terminate
76 * This is the number of hash-buckets. Experiements with 'real-life'
77 * udev_t's show that a prime halfway between two powers of two works
80 #define DEVT_HASH 128 /* must be power of 2 */
81 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
84 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
85 int dev_ref_debug = 0;
86 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, "");
89 * cdev_t and u_dev_t primitives. Note that the major number is always
90 * extracted from si_umajor, not from si_devsw, because si_devsw is replaced
91 * when a device is destroyed.
98 return(dev->si_umajor);
106 return(dev->si_uminor);
110 * Compatibility function with old udev_t format to convert the
111 * non-consecutive minor space into a consecutive minor space.
123 return ((y & 0xff) | (y >> 8));
127 * This is a bit complex because devices are always created relative to
128 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device
129 * backing a disk subsystem overlay), so we have to compare both the
130 * devsw and udev fields to locate the correct device.
132 * The device is created if it does not already exist. If SI_ADHOC is not
133 * set the device will be referenced (once) and SI_ADHOC will be set.
134 * The caller must explicitly add additional references to the device if
135 * the caller wishes to track additional references.
137 * NOTE: The passed ops vector must normally match the device. This is
138 * because the kernel may create shadow devices that are INVISIBLE TO
139 * USERLAND. For example, the block device backing a disk is created
140 * as a shadow underneath the user-visible disklabel management device.
141 * Sometimes a device ops vector can be overridden, such as by /dev/console.
142 * In this case and this case only we allow a match when the ops vector
143 * otherwise would not match.
147 __devthash(int x, int y)
149 return(((x << 2) ^ y) & (DEVT_HASH - 1));
154 hashdev(struct dev_ops *ops, int x, int y, int allow_intercept)
159 hash = __devthash(x, y);
160 LIST_FOREACH(si, &dev_hash[hash], si_hash) {
161 if (si->si_umajor == x && si->si_uminor == y) {
162 if (si->si_ops == ops)
164 if (allow_intercept && (si->si_flags & SI_INTERCEPTED))
168 si = sysref_alloc(&cdev_sysref_class);
170 si->si_flags |= SI_HASHED | SI_ADHOC;
174 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
175 sysref_activate(&si->si_sysref);
178 if (ops != &dead_dev_ops)
181 kprintf("create dev %p %s(minor=%08x) refs=%d\n",
182 si, devtoname(si), y,
183 si->si_sysref.refcnt);
189 * Convert a device pointer to an old style device number. Return NOUDEV
190 * if the device is invalid or if the device (maj,min) cannot be converted
191 * to an old style udev_t.
199 return (udev_t)dev->si_inode;
203 * Convert a device number to a device pointer. The device is referenced
204 * ad-hoc, meaning that the caller should call reference_dev() if it wishes
205 * to keep ahold of the returned structure long term.
207 * The returned device is associated with the currently installed cdevsw
208 * for the requested major number. NULL is returned if the major number
209 * has not been registered.
212 udev2dev(udev_t x, int b)
214 if (x == NOUDEV || b != 0)
217 return devfs_find_device_by_udev(x);
221 dev_is_good(cdev_t dev)
223 if (dev != NULL && dev->si_ops != &dead_dev_ops)
229 * Various user device number extraction and conversion routines
236 return(dev & 0xffff00ff);
244 return((dev & 0xff00) >> 8);
248 makeudev(int x, int y)
250 if ((x & 0xffffff00) || (y & 0x0000ff00))
252 return ((x << 8) | y);
256 * Create an internal or external device.
258 * Device majors can be overloaded and used directly by the kernel without
259 * conflict, but userland will only see the particular device major that
260 * has been installed with dev_ops_add().
262 * This routine creates and returns an unreferenced ad-hoc entry for the
263 * device which will remain intact until the device is destroyed. If the
264 * caller intends to store the device pointer it must call reference_dev()
265 * to retain a real reference to the device.
267 * If an entry already exists, this function will set (or override)
268 * its cred requirements and name (XXX DEVFS interface).
271 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
272 int perms, const char *fmt, ...)
277 char dev_name[PATH_MAX+1];
280 * compile the cdevsw and install the device
282 compile_dev_ops(ops);
285 * Set additional fields (XXX DEVFS interface goes here)
288 i = kvcprintf(fmt, NULL, dev_name, 32, ap);
293 if ((devfs_dev = devfs_find_device_by_name(dev_name)) != NULL) {
294 kprintf("make_dev: Device %s already exists, returning old dev without creating new node\n", dev_name);
299 devfs_dev = devfs_new_cdev(ops, minor);
300 memcpy(devfs_dev->si_name, dev_name, i+1);
302 devfs_debug(DEVFS_DEBUG_INFO, "make_dev called for %s\n", devfs_dev->si_name);
303 devfs_create_dev(devfs_dev, uid, gid, perms);
310 make_only_devfs_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
311 int perms, const char *fmt, ...)
319 * compile the cdevsw and install the device
321 compile_dev_ops(ops);
322 devfs_dev = devfs_new_cdev(ops, minor);
325 * Set additional fields (XXX DEVFS interface goes here)
328 i = kvcprintf(fmt, NULL, devfs_dev->si_name, 32, ap);
329 devfs_dev->si_name[i] = '\0';
333 devfs_create_dev(devfs_dev, uid, gid, perms);
340 make_only_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
341 int perms, const char *fmt, ...)
349 * compile the cdevsw and install the device
351 compile_dev_ops(ops);
352 devfs_dev = devfs_new_cdev(ops, minor);
353 devfs_dev->si_perms = perms;
354 devfs_dev->si_uid = uid;
355 devfs_dev->si_gid = gid;
358 * Set additional fields (XXX DEVFS interface goes here)
361 i = kvcprintf(fmt, NULL, devfs_dev->si_name, 32, ap);
362 devfs_dev->si_name[i] = '\0';
365 reference_dev(devfs_dev);
371 destroy_only_dev(cdev_t dev)
373 devfs_destroy_cdev(dev);
378 * This function is similar to make_dev() but no cred information or name
382 make_adhoc_dev(struct dev_ops *ops, int minor)
386 dev = hashdev(ops, ops->head.maj, minor, FALSE);
391 * This function is similar to make_dev() except the new device is created
392 * using an old device as a template.
395 make_sub_dev(cdev_t odev, int minor)
399 dev = hashdev(odev->si_ops, odev->si_umajor, minor, FALSE);
402 * Copy cred requirements and name info XXX DEVFS.
404 if (dev->si_name[0] == 0 && odev->si_name[0])
405 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name));
410 get_dev(int x, int y)
417 ops = dev_ops_get(x, y);
420 dev = hashdev(ops, x, y, TRUE);
425 * destroy_dev() removes the adhoc association for a device and revectors
426 * its ops to &dead_dev_ops.
428 * This routine releases the reference count associated with the ADHOC
429 * entry, plus releases the reference count held by the caller. What this
430 * means is that you should not call destroy_dev(make_dev(...)), because
431 * make_dev() does not bump the reference count (beyond what it needs to
432 * create the ad-hoc association). Any procedure that intends to destroy
433 * a device must have its own reference to it first.
436 destroy_dev(cdev_t dev)
443 devfs_debug(DEVFS_DEBUG_DEBUG, "destroy_dev called for %s\n", dev->si_name);
444 devfs_destroy_dev(dev);
448 if ((dev->si_flags & SI_ADHOC) == 0) {
453 kprintf("destroy dev %p %s(minor=%08x) refs=%d\n",
454 dev, devtoname(dev), dev->si_uminor,
455 dev->si_sysref.refcnt);
457 if (dev->si_sysref.refcnt < 2) {
458 kprintf("destroy_dev(): too few references on device! "
459 "%p %s(minor=%08x) refs=%d\n",
460 dev, devtoname(dev), dev->si_uminor,
461 dev->si_sysref.refcnt);
463 dev->si_flags &= ~SI_ADHOC;
464 if (dev->si_flags & SI_HASHED) {
465 hash = __devthash(dev->si_umajor, dev->si_uminor);
466 LIST_REMOVE(dev, si_hash);
467 dev->si_flags &= ~SI_HASHED;
471 * We have to release the ops reference before we replace the
472 * device switch with dead_dev_ops.
476 if (dead_dev_ops.d_strategy == NULL)
477 compile_dev_ops(&dead_dev_ops);
478 if (dev->si_ops && dev->si_ops != &dead_dev_ops)
479 dev_ops_release(dev->si_ops);
482 dev->si_ops = &dead_dev_ops;
483 sysref_put(&dev->si_sysref); /* release adhoc association */
485 release_dev(dev); /* release callers reference */
489 * Destroy all ad-hoc device associations associated with a domain within a
490 * device switch. Only the minor numbers are included in the mask/match
493 * Unlike the ops functions whos link structures do not contain
494 * any major bits, this function scans through the dev list via
495 * si_umajor/si_uminor.
497 * The caller must not include any major bits in the match value.
500 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match)
506 for (i = 0; i < DEVT_HASH; ++i) {
507 ndev = LIST_FIRST(&dev_hash[i]);
508 while ((dev = ndev) != NULL) {
509 ndev = LIST_NEXT(dev, si_hash);
510 if (dev->si_ops == ops &&
511 ((u_int)dev->si_uminor & mask) == match
513 KKASSERT(dev->si_flags & SI_ADHOC);
523 make_dev_alias(cdev_t target, const char *fmt, ...)
525 char name[PATH_MAX + 1];
530 i = kvcprintf(fmt, NULL, name, 32, ap);
534 devfs_make_alias(name, target);
541 * Add a reference to a device. Callers generally add their own references
542 * when they are going to store a device node in a variable for long periods
543 * of time, to prevent a disassociation from free()ing the node.
545 * Also note that a caller that intends to call destroy_dev() must first
546 * obtain a reference on the device. The ad-hoc reference you get with
547 * make_dev() and friends is NOT sufficient to be able to call destroy_dev().
550 reference_dev(cdev_t dev)
552 //kprintf("reference_dev\n");
555 sysref_get(&dev->si_sysref);
557 kprintf("reference dev %p %s(minor=%08x) refs=%d\n",
558 dev, devtoname(dev), dev->si_uminor,
559 dev->si_sysref.refcnt);
566 * release a reference on a device. The device will be terminated when the
567 * last reference has been released.
569 * NOTE: we must use si_umajor to figure out the original major number,
570 * because si_ops could already be pointing at dead_dev_ops.
573 release_dev(cdev_t dev)
575 //kprintf("release_dev\n");
579 sysref_put(&dev->si_sysref);
584 cdev_terminate(struct cdev *dev)
589 kprintf("release dev %p %s(minor=%08x) refs=%d\n",
590 dev, devtoname(dev), dev->si_uminor,
591 dev->si_sysref.refcnt);
593 if (dev->si_flags & SI_ADHOC) {
594 kprintf("Warning: illegal final release on ADHOC"
595 " device %p(%s), the device was never"
597 dev, devtoname(dev));
600 if (dev->si_flags & SI_HASHED) {
601 kprintf("Warning: last release on device, no call"
602 " to destroy_dev() was made! dev %p(%s)\n",
603 dev, devtoname(dev));
608 if (SLIST_FIRST(&dev->si_hlist) != NULL) {
609 kprintf("Warning: last release on device, vnode"
610 " associations still exist! dev %p(%s)\n",
611 dev, devtoname(dev));
614 if (dev->si_ops && dev->si_ops != &dead_dev_ops) {
615 dev_ops_release(dev->si_ops);
619 sysref_put(&dev->si_sysref);
623 devtoname(cdev_t dev)
632 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
634 len = sizeof(dev->si_name);
635 if ((dname = dev_dname(dev)) != NULL)
636 ksnprintf(p, len, "#%s/", dname);
638 ksnprintf(p, len, "#%d/", major(dev));
642 if (mynor < 0 || mynor > 255)
643 ksnprintf(p, len, "%#x", (u_int)mynor);
645 ksnprintf(p, len, "%d", mynor);
647 return (dev->si_name);