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freebsd-dev/sys/kern/kern_conf.c
Poul-Henning Kamp aa2f6ddc3f Reap more benefits from DEVFS: 
List devfs_dirents rather than vnodes off their shared struct cdev, this
saves a pointer field in the vnode at the expense of a field in the
devfs_dirent.  There are often 100 times more vnodes so this is bargain.
In addition it makes it harder for people to try to do stypid things like
"finding the vnode from cdev".

Since DEVFS handles all VCHR nodes now, we can do the vnode related
cleanup in devfs_reclaim() instead of in dev_rel() and vgonel().
Similarly, we can do the struct cdev related cleanup in dev_rel()
instead of devfs_reclaim().

	rename idestroy_dev() to destroy_devl() for consistency.

	Add LIST_ENTRY de_alias to struct devfs_dirent.
	Remove v_specnext from struct vnode.
	Change si_hlist to si_alist in struct cdev.
	String new devfs vnodes' devfs_dirent on si_alist when
	we create them and take them off in devfs_reclaim().

	Fix devfs_revoke() accordingly.  Also don't clear fields
	devfs_reclaim() will clear when called from vgone();

	Let devfs_reclaim() call dev_rel() instead of vgonel().

	Move the usecount tracking from dev_rel() to devfs_reclaim(),
	and let dev_rel() take a struct cdev argument instead of vnode.

	Destroy SI_CHEAPCLONE devices in dev_rel() (instead of
	devfs_reclaim()) when they are no longer used.   (This
	should maybe happen in devfs_close() instead.)
2005-02-22 15:51:07 +00:00

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/*-
* Copyright (c) 1999-2002 Poul-Henning Kamp
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/module.h>
#include <sys/malloc.h>
#include <sys/conf.h>
#include <sys/vnode.h>
#include <sys/queue.h>
#include <sys/poll.h>
#include <sys/ctype.h>
#include <sys/tty.h>
#include <machine/stdarg.h>
static MALLOC_DEFINE(M_DEVT, "cdev", "cdev storage");
/* Built at compile time from sys/conf/majors */
extern unsigned char reserved_majors[256];
/*
* This is the number of hash-buckets. Experiments with 'real-life'
* dev_t's show that a prime halfway between two powers of two works
* best.
*/
#define DEVT_HASH 83
static LIST_HEAD(, cdev) dev_hash[DEVT_HASH];
static struct mtx devmtx;
static void freedev(struct cdev *dev);
static struct cdev *newdev(int x, int y, struct cdev *);
static void destroy_devl(struct cdev *dev);
void
dev_lock(void)
{
if (!mtx_initialized(&devmtx))
mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
mtx_lock(&devmtx);
}
void
dev_unlock(void)
{
mtx_unlock(&devmtx);
}
void
dev_ref(struct cdev *dev)
{
mtx_assert(&devmtx, MA_OWNED);
dev->si_refcount++;
}
void
dev_rel(struct cdev *dev)
{
int flag = 0;
mtx_assert(&devmtx, MA_NOTOWNED);
dev_lock();
dev->si_refcount--;
KASSERT(dev->si_refcount >= 0,
("dev_rel(%s) gave negative count", devtoname(dev)));
if (dev->si_usecount == 0 &&
(dev->si_flags & SI_CHEAPCLONE) && (dev->si_flags & SI_NAMED))
if (dev->si_devsw == NULL && dev->si_refcount == 0) {
LIST_REMOVE(dev, si_list);
flag = 1;
}
dev_unlock();
if (flag)
freedev(dev);
}
struct cdevsw *
dev_refthread(struct cdev *dev)
{
struct cdevsw *csw;
mtx_assert(&devmtx, MA_NOTOWNED);
dev_lock();
csw = dev->si_devsw;
if (csw != NULL)
dev->si_threadcount++;
dev_unlock();
return (csw);
}
void
dev_relthread(struct cdev *dev)
{
mtx_assert(&devmtx, MA_NOTOWNED);
dev_lock();
dev->si_threadcount--;
dev_unlock();
}
int
nullop(void)
{
return (0);
}
int
eopnotsupp(void)
{
return (EOPNOTSUPP);
}
static int
enxio(void)
{
return (ENXIO);
}
static int
enodev(void)
{
return (ENODEV);
}
/* Define a dead_cdevsw for use when devices leave unexpectedly. */
#define dead_open (d_open_t *)enxio
#define dead_close (d_close_t *)enxio
#define dead_read (d_read_t *)enxio
#define dead_write (d_write_t *)enxio
#define dead_ioctl (d_ioctl_t *)enxio
#define dead_poll (d_poll_t *)enodev
#define dead_mmap (d_mmap_t *)enodev
static void
dead_strategy(struct bio *bp)
{
biofinish(bp, NULL, ENXIO);
}
#define dead_dump (dumper_t *)enxio
#define dead_kqfilter (d_kqfilter_t *)enxio
static struct cdevsw dead_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_NEEDGIANT, /* XXX: does dead_strategy need this ? */
.d_open = dead_open,
.d_close = dead_close,
.d_read = dead_read,
.d_write = dead_write,
.d_ioctl = dead_ioctl,
.d_poll = dead_poll,
.d_mmap = dead_mmap,
.d_strategy = dead_strategy,
.d_name = "dead",
.d_maj = 255,
.d_dump = dead_dump,
.d_kqfilter = dead_kqfilter
};
/* Default methods if driver does not specify method */
#define null_open (d_open_t *)nullop
#define null_close (d_close_t *)nullop
#define no_read (d_read_t *)enodev
#define no_write (d_write_t *)enodev
#define no_ioctl (d_ioctl_t *)enodev
#define no_mmap (d_mmap_t *)enodev
#define no_kqfilter (d_kqfilter_t *)enodev
static void
no_strategy(struct bio *bp)
{
biofinish(bp, NULL, ENODEV);
}
static int
no_poll(struct cdev *dev __unused, int events, struct thread *td __unused)
{
/*
* Return true for read/write. If the user asked for something
* special, return POLLNVAL, so that clients have a way of
* determining reliably whether or not the extended
* functionality is present without hard-coding knowledge
* of specific filesystem implementations.
* Stay in sync with vop_nopoll().
*/
if (events & ~POLLSTANDARD)
return (POLLNVAL);
return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
}
#define no_dump (dumper_t *)enodev
/*
* struct cdev * and u_dev_t primitives
*/
int
major(struct cdev *x)
{
if (x == NULL)
return NODEV;
return((x->si_udev >> 8) & 0xff);
}
int
minor(struct cdev *x)
{
if (x == NULL)
return NODEV;
return(x->si_udev & MAXMINOR);
}
int
dev2unit(struct cdev *x)
{
if (x == NULL)
return NODEV;
return (minor2unit(minor(x)));
}
int
minor2unit(int _minor)
{
KASSERT((_minor & ~MAXMINOR) == 0, ("Illegal minor %x", _minor));
return ((_minor & 0xff) | (_minor >> 8));
}
int
unit2minor(int unit)
{
KASSERT(unit <= 0xffffff, ("Invalid unit (%d) in unit2minor", unit));
return ((unit & 0xff) | ((unit << 8) & ~0xffff));
}
static struct cdev *
allocdev(void)
{
struct cdev *si;
si = malloc(sizeof *si, M_DEVT, M_USE_RESERVE | M_ZERO | M_WAITOK);
si->si_name = si->__si_namebuf;
LIST_INIT(&si->si_children);
LIST_INIT(&si->si_alist);
return (si);
}
static struct cdev *
newdev(int x, int y, struct cdev *si)
{
struct cdev *si2;
dev_t udev;
int hash;
mtx_assert(&devmtx, MA_OWNED);
if (x == umajor(NODEV) && y == uminor(NODEV))
panic("newdev of NODEV");
udev = (x << 8) | y;
hash = udev % DEVT_HASH;
LIST_FOREACH(si2, &dev_hash[hash], si_hash) {
if (si2->si_udev == udev) {
freedev(si);
return (si2);
}
}
si->si_udev = udev;
LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash);
return (si);
}
static void
freedev(struct cdev *dev)
{
free(dev, M_DEVT);
}
dev_t
dev2udev(struct cdev *x)
{
if (x == NULL)
return (NODEV);
return (x->si_udev);
}
struct cdev *
findcdev(dev_t udev)
{
struct cdev *si;
int hash;
mtx_assert(&devmtx, MA_NOTOWNED);
if (udev == NODEV)
return (NULL);
dev_lock();
hash = udev % DEVT_HASH;
LIST_FOREACH(si, &dev_hash[hash], si_hash) {
if (si->si_udev == udev)
break;
}
dev_unlock();
return (si);
}
int
uminor(dev_t dev)
{
return (dev & MAXMINOR);
}
int
umajor(dev_t dev)
{
return ((dev & ~MAXMINOR) >> 8);
}
static void
find_major(struct cdevsw *devsw)
{
int i;
for (i = NUMCDEVSW - 1; i > 0; i--)
if (reserved_majors[i] != i)
break;
KASSERT(i > 0, ("Out of major numbers (%s)", devsw->d_name));
devsw->d_maj = i;
reserved_majors[i] = i;
devsw->d_flags |= D_ALLOCMAJ;
}
static void
fini_cdevsw(struct cdevsw *devsw)
{
if (devsw->d_flags & D_ALLOCMAJ) {
reserved_majors[devsw->d_maj] = 0;
devsw->d_maj = MAJOR_AUTO;
devsw->d_flags &= ~D_ALLOCMAJ;
} else if (devsw->d_maj == 0)
devsw->d_maj = 256;
devsw->d_flags &= ~D_INIT;
}
static void
prep_cdevsw(struct cdevsw *devsw)
{
dev_lock();
if (devsw->d_version != D_VERSION_00) {
printf(
"WARNING: Device driver \"%s\" has wrong version %s\n",
devsw->d_name, "and is disabled. Recompile KLD module.");
devsw->d_open = dead_open;
devsw->d_close = dead_close;
devsw->d_read = dead_read;
devsw->d_write = dead_write;
devsw->d_ioctl = dead_ioctl;
devsw->d_poll = dead_poll;
devsw->d_mmap = dead_mmap;
devsw->d_strategy = dead_strategy;
devsw->d_dump = dead_dump;
devsw->d_kqfilter = dead_kqfilter;
}
if (devsw->d_flags & D_TTY) {
if (devsw->d_ioctl == NULL) devsw->d_ioctl = ttyioctl;
if (devsw->d_read == NULL) devsw->d_read = ttyread;
if (devsw->d_write == NULL) devsw->d_write = ttywrite;
if (devsw->d_kqfilter == NULL) devsw->d_kqfilter = ttykqfilter;
if (devsw->d_poll == NULL) devsw->d_poll = ttypoll;
}
if (devsw->d_open == NULL) devsw->d_open = null_open;
if (devsw->d_close == NULL) devsw->d_close = null_close;
if (devsw->d_read == NULL) devsw->d_read = no_read;
if (devsw->d_write == NULL) devsw->d_write = no_write;
if (devsw->d_ioctl == NULL) devsw->d_ioctl = no_ioctl;
if (devsw->d_poll == NULL) devsw->d_poll = no_poll;
if (devsw->d_mmap == NULL) devsw->d_mmap = no_mmap;
if (devsw->d_strategy == NULL) devsw->d_strategy = no_strategy;
if (devsw->d_dump == NULL) devsw->d_dump = no_dump;
if (devsw->d_kqfilter == NULL) devsw->d_kqfilter = no_kqfilter;
LIST_INIT(&devsw->d_devs);
devsw->d_flags |= D_INIT;
if (devsw->d_maj == MAJOR_AUTO) {
find_major(devsw);
} else {
if (devsw->d_maj == 256) /* XXX: tty_cons.c is magic */
devsw->d_maj = 0;
KASSERT(devsw->d_maj >= 0 && devsw->d_maj < 256,
("Invalid major (%d) in make_dev", devsw->d_maj));
if (reserved_majors[devsw->d_maj] != devsw->d_maj) {
printf("WARNING: driver \"%s\" used %s %d\n",
devsw->d_name, "unreserved major device number",
devsw->d_maj);
reserved_majors[devsw->d_maj] = devsw->d_maj;
}
}
dev_unlock();
}
struct cdev *
make_dev(struct cdevsw *devsw, int minornr, uid_t uid, gid_t gid, int perms, const char *fmt, ...)
{
struct cdev *dev;
va_list ap;
int i;
KASSERT((minornr & ~MAXMINOR) == 0,
("Invalid minor (0x%x) in make_dev", minornr));
if (!(devsw->d_flags & D_INIT))
prep_cdevsw(devsw);
dev = allocdev();
dev_lock();
dev = newdev(devsw->d_maj, minornr, dev);
if (dev->si_flags & SI_CHEAPCLONE &&
dev->si_flags & SI_NAMED &&
dev->si_devsw == devsw) {
/*
* This is allowed as it removes races and generally
* simplifies cloning devices.
* XXX: still ??
*/
dev_unlock();
return (dev);
}
KASSERT(!(dev->si_flags & SI_NAMED),
("make_dev() by driver %s on pre-existing device (maj=%d, min=%d, name=%s)",
devsw->d_name, major(dev), minor(dev), devtoname(dev)));
va_start(ap, fmt);
i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
if (i > (sizeof dev->__si_namebuf - 1)) {
printf("WARNING: Device name truncated! (%s)\n",
dev->__si_namebuf);
}
va_end(ap);
dev->si_devsw = devsw;
dev->si_uid = uid;
dev->si_gid = gid;
dev->si_mode = perms;
dev->si_flags |= SI_NAMED;
LIST_INSERT_HEAD(&devsw->d_devs, dev, si_list);
devfs_create(dev);
dev_unlock();
return (dev);
}
int
dev_named(struct cdev *pdev, const char *name)
{
struct cdev *cdev;
if (strcmp(devtoname(pdev), name) == 0)
return (1);
LIST_FOREACH(cdev, &pdev->si_children, si_siblings)
if (strcmp(devtoname(cdev), name) == 0)
return (1);
return (0);
}
void
dev_depends(struct cdev *pdev, struct cdev *cdev)
{
dev_lock();
cdev->si_parent = pdev;
cdev->si_flags |= SI_CHILD;
LIST_INSERT_HEAD(&pdev->si_children, cdev, si_siblings);
dev_unlock();
}
struct cdev *
make_dev_alias(struct cdev *pdev, const char *fmt, ...)
{
struct cdev *dev;
va_list ap;
int i;
dev = allocdev();
dev_lock();
dev->si_flags |= SI_ALIAS;
dev->si_flags |= SI_NAMED;
va_start(ap, fmt);
i = vsnrprintf(dev->__si_namebuf, sizeof dev->__si_namebuf, 32, fmt, ap);
if (i > (sizeof dev->__si_namebuf - 1)) {
printf("WARNING: Device name truncated! (%s)\n",
dev->__si_namebuf);
}
va_end(ap);
devfs_create(dev);
dev_unlock();
dev_depends(pdev, dev);
return (dev);
}
static void
destroy_devl(struct cdev *dev)
{
struct cdevsw *csw;
mtx_assert(&devmtx, MA_OWNED);
KASSERT(dev->si_flags & SI_NAMED,
("WARNING: Driver mistake: destroy_dev on %d/%d\n",
major(dev), minor(dev)));
devfs_destroy(dev);
/* Remove name marking */
dev->si_flags &= ~SI_NAMED;
/* If we are a child, remove us from the parents list */
if (dev->si_flags & SI_CHILD) {
LIST_REMOVE(dev, si_siblings);
dev->si_flags &= ~SI_CHILD;
}
/* Kill our children */
while (!LIST_EMPTY(&dev->si_children))
destroy_devl(LIST_FIRST(&dev->si_children));
/* Remove from clone list */
if (dev->si_flags & SI_CLONELIST) {
LIST_REMOVE(dev, si_clone);
dev->si_flags &= ~SI_CLONELIST;
}
csw = dev->si_devsw;
dev->si_devsw = NULL; /* already NULL for SI_ALIAS */
while (csw != NULL && csw->d_purge != NULL && dev->si_threadcount) {
printf("Purging %lu threads from %s\n",
dev->si_threadcount, devtoname(dev));
csw->d_purge(dev);
msleep(csw, &devmtx, PRIBIO, "devprg", hz/10);
}
if (csw != NULL && csw->d_purge != NULL)
printf("All threads purged from %s\n", devtoname(dev));
dev->si_drv1 = 0;
dev->si_drv2 = 0;
bzero(&dev->__si_u, sizeof(dev->__si_u));
if (!(dev->si_flags & SI_ALIAS)) {
/* Remove from cdevsw list */
LIST_REMOVE(dev, si_list);
/* If cdevsw has no struct cdev *'s, clean it */
if (LIST_EMPTY(&csw->d_devs))
fini_cdevsw(csw);
LIST_REMOVE(dev, si_hash);
}
dev->si_flags &= ~SI_ALIAS;
if (dev->si_refcount > 0) {
LIST_INSERT_HEAD(&dead_cdevsw.d_devs, dev, si_list);
} else {
freedev(dev);
}
}
void
destroy_dev(struct cdev *dev)
{
dev_lock();
destroy_devl(dev);
dev_unlock();
}
const char *
devtoname(struct cdev *dev)
{
char *p;
struct cdevsw *csw;
int mynor;
if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') {
p = dev->si_name;
sprintf(p, "#%d", major(dev));
p += strlen(p);
csw = dev_refthread(dev);
if (csw != NULL) {
sprintf(p, "(%s)", csw->d_name);
dev_relthread(dev);
}
p += strlen(p);
mynor = minor(dev);
if (mynor < 0 || mynor > 255)
sprintf(p, "/%#x", (u_int)mynor);
else
sprintf(p, "/%d", mynor);
}
return (dev->si_name);
}
int
dev_stdclone(char *name, char **namep, const char *stem, int *unit)
{
int u, i;
i = strlen(stem);
if (bcmp(stem, name, i) != 0)
return (0);
if (!isdigit(name[i]))
return (0);
u = 0;
if (name[i] == '0' && isdigit(name[i+1]))
return (0);
while (isdigit(name[i])) {
u *= 10;
u += name[i++] - '0';
}
if (u > 0xffffff)
return (0);
*unit = u;
if (namep)
*namep = &name[i];
if (name[i])
return (2);
return (1);
}
/*
* Helper functions for cloning device drivers.
*
* The objective here is to make it unnecessary for the device drivers to
* use rman or similar to manage their unit number space. Due to the way
* we do "on-demand" devices, using rman or other "private" methods
* will be very tricky to lock down properly once we lock down this file.
*
* Instead we give the drivers these routines which puts the struct cdev *'s
* that are to be managed on their own list, and gives the driver the ability
* to ask for the first free unit number or a given specified unit number.
*
* In addition these routines support paired devices (pty, nmdm and similar)
* by respecting a number of "flag" bits in the minor number.
*
*/
struct clonedevs {
LIST_HEAD(,cdev) head;
};
void
clone_setup(struct clonedevs **cdp)
{
*cdp = malloc(sizeof **cdp, M_DEVBUF, M_WAITOK | M_ZERO);
LIST_INIT(&(*cdp)->head);
}
int
clone_create(struct clonedevs **cdp, struct cdevsw *csw, int *up, struct cdev **dp, u_int extra)
{
struct clonedevs *cd;
struct cdev *dev, *ndev, *dl, *de;
int unit, low, u;
KASSERT(*cdp != NULL,
("clone_setup() not called in driver \"%s\"", csw->d_name));
KASSERT(!(extra & CLONE_UNITMASK),
("Illegal extra bits (0x%x) in clone_create", extra));
KASSERT(*up <= CLONE_UNITMASK,
("Too high unit (0x%x) in clone_create", *up));
if (csw->d_maj == MAJOR_AUTO)
find_major(csw);
/*
* Search the list for a lot of things in one go:
* A preexisting match is returned immediately.
* The lowest free unit number if we are passed -1, and the place
* in the list where we should insert that new element.
* The place to insert a specified unit number, if applicable
* the end of the list.
*/
unit = *up;
ndev = allocdev();
dev_lock();
low = extra;
de = dl = NULL;
cd = *cdp;
LIST_FOREACH(dev, &cd->head, si_clone) {
KASSERT(dev->si_flags & SI_CLONELIST,
("Dev %p(%s) should be on clonelist", dev, dev->si_name));
u = dev2unit(dev);
if (u == (unit | extra)) {
*dp = dev;
freedev(ndev);
dev_unlock();
return (0);
}
if (unit == -1 && u == low) {
low++;
de = dev;
continue;
}
if (u > (unit | extra)) {
dl = dev;
break;
}
}
if (unit == -1)
unit = low & CLONE_UNITMASK;
dev = newdev(csw->d_maj, unit2minor(unit | extra), ndev);
if (dev->si_flags & SI_CLONELIST) {
printf("dev %p (%s) is on clonelist\n", dev, dev->si_name);
printf("unit=%d\n", unit);
LIST_FOREACH(dev, &cd->head, si_clone) {
printf("\t%p %s\n", dev, dev->si_name);
}
panic("foo");
}
KASSERT(!(dev->si_flags & SI_CLONELIST),
("Dev %p(%s) should not be on clonelist", dev, dev->si_name));
if (dl != NULL)
LIST_INSERT_BEFORE(dl, dev, si_clone);
else if (de != NULL)
LIST_INSERT_AFTER(de, dev, si_clone);
else
LIST_INSERT_HEAD(&cd->head, dev, si_clone);
dev->si_flags |= SI_CLONELIST;
*up = unit;
dev_unlock();
return (1);
}
/*
* Kill everything still on the list. The driver should already have
* disposed of any softc hung of the struct cdev *'s at this time.
*/
void
clone_cleanup(struct clonedevs **cdp)
{
struct cdev *dev, *tdev;
struct clonedevs *cd;
cd = *cdp;
if (cd == NULL)
return;
dev_lock();
LIST_FOREACH_SAFE(dev, &cd->head, si_clone, tdev) {
KASSERT(dev->si_flags & SI_CLONELIST,
("Dev %p(%s) should be on clonelist", dev, dev->si_name));
KASSERT(dev->si_flags & SI_NAMED,
("Driver has goofed in cloning underways udev %x", dev->si_udev));
destroy_devl(dev);
}
dev_unlock();
free(cd, M_DEVBUF);
*cdp = NULL;
}
/*
* Helper sysctl for devname(3). We're given a struct cdev * and return
* the name, if any, registered by the device driver.
*/
static int
sysctl_devname(SYSCTL_HANDLER_ARGS)
{
int error;
dev_t ud;
struct cdev *dev;
error = SYSCTL_IN(req, &ud, sizeof (ud));
if (error)
return (error);
if (ud == NODEV)
return(EINVAL);
dev = findcdev(ud);
if (dev == NULL)
error = ENOENT;
else
error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
return (error);
}
SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
NULL, 0, sysctl_devname, "", "devname(3) handler");
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