NetBSD-5.0.2/sys/kern/subr_devsw.c
/* $NetBSD: subr_devsw.c,v 1.22.8.1 2009/02/07 02:32:37 snj Exp $ */
/*-
* Copyright (c) 2001, 2002, 2007, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by MAEKAWA Masahide <gehenna@NetBSD.org>, and by Andrew Doran.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* Overview
*
* subr_devsw.c: registers device drivers by name and by major
* number, and provides wrapper methods for performing I/O and
* other tasks on device drivers, keying on the device number
* (dev_t).
*
* When the system is built, the config(8) command generates
* static tables of device drivers built into the kernel image
* along with their associated methods. These are recorded in
* the cdevsw0 and bdevsw0 tables. Drivers can also be added to
* and removed from the system dynamically.
*
* Allocation
*
* When the system initially boots only the statically allocated
* indexes (bdevsw0, cdevsw0) are used. If these overflow due to
* allocation, we allocate a fixed block of memory to hold the new,
* expanded index. This "fork" of the table is only ever performed
* once in order to guarantee that other threads may safely access
* the device tables:
*
* o Once a thread has a "reference" to the table via an earlier
* open() call, we know that the entry in the table must exist
* and so it is safe to access it.
*
* o Regardless of whether other threads see the old or new
* pointers, they will point to a correct device switch
* structure for the operation being performed.
*
* XXX Currently, the wrapper methods such as cdev_read() verify
* that a device driver does in fact exist before calling the
* associated driver method. This should be changed so that
* once the device is has been referenced by a vnode (opened),
* calling the other methods should be valid until that reference
* is dropped.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_devsw.c,v 1.22.8.1 2009/02/07 02:32:37 snj Exp $");
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/poll.h>
#include <sys/tty.h>
#include <sys/cpu.h>
#include <sys/buf.h>
#include <miscfs/specfs/specdev.h>
#ifdef DEVSW_DEBUG
#define DPRINTF(x) printf x
#else /* DEVSW_DEBUG */
#define DPRINTF(x)
#endif /* DEVSW_DEBUG */
#define MAXDEVSW 512 /* the maximum of major device number */
#define BDEVSW_SIZE (sizeof(struct bdevsw *))
#define CDEVSW_SIZE (sizeof(struct cdevsw *))
#define DEVSWCONV_SIZE (sizeof(struct devsw_conv))
extern const struct bdevsw **bdevsw, *bdevsw0[];
extern const struct cdevsw **cdevsw, *cdevsw0[];
extern struct devsw_conv *devsw_conv, devsw_conv0[];
extern const int sys_bdevsws, sys_cdevsws;
extern int max_bdevsws, max_cdevsws, max_devsw_convs;
static int bdevsw_attach(const struct bdevsw *, int *);
static int cdevsw_attach(const struct cdevsw *, int *);
static void devsw_detach_locked(const struct bdevsw *, const struct cdevsw *);
void
devsw_init(void)
{
KASSERT(sys_bdevsws < MAXDEVSW - 1);
KASSERT(sys_cdevsws < MAXDEVSW - 1);
}
int
devsw_attach(const char *devname, const struct bdevsw *bdev, int *bmajor,
const struct cdevsw *cdev, int *cmajor)
{
struct devsw_conv *conv;
char *name;
int error, i;
size_t len;
if (devname == NULL || cdev == NULL)
return (EINVAL);
mutex_enter(&specfs_lock);
for (i = 0 ; i < max_devsw_convs ; i++) {
conv = &devsw_conv[i];
if (conv->d_name == NULL || strcmp(devname, conv->d_name) != 0)
continue;
if (*bmajor < 0)
*bmajor = conv->d_bmajor;
if (*cmajor < 0)
*cmajor = conv->d_cmajor;
if (*bmajor != conv->d_bmajor || *cmajor != conv->d_cmajor) {
error = EINVAL;
goto fail;
}
if ((*bmajor >= 0 && bdev == NULL) || *cmajor < 0) {
error = EINVAL;
goto fail;
}
if ((*bmajor >= 0 && bdevsw[*bmajor] != NULL) ||
cdevsw[*cmajor] != NULL) {
error = EEXIST;
goto fail;
}
if (bdev != NULL)
bdevsw[*bmajor] = bdev;
cdevsw[*cmajor] = cdev;
mutex_exit(&specfs_lock);
return (0);
}
error = bdevsw_attach(bdev, bmajor);
if (error != 0)
goto fail;
error = cdevsw_attach(cdev, cmajor);
if (error != 0) {
devsw_detach_locked(bdev, NULL);
goto fail;
}
for (i = 0 ; i < max_devsw_convs ; i++) {
if (devsw_conv[i].d_name == NULL)
break;
}
if (i == max_devsw_convs) {
struct devsw_conv *newptr;
int old, new;
old = max_devsw_convs;
new = old + 1;
newptr = kmem_zalloc(new * DEVSWCONV_SIZE, KM_NOSLEEP);
if (newptr == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto fail;
}
newptr[old].d_name = NULL;
newptr[old].d_bmajor = -1;
newptr[old].d_cmajor = -1;
memcpy(newptr, devsw_conv, old * DEVSWCONV_SIZE);
if (devsw_conv != devsw_conv0)
kmem_free(devsw_conv, old * DEVSWCONV_SIZE);
devsw_conv = newptr;
max_devsw_convs = new;
}
len = strlen(devname) + 1;
name = kmem_alloc(len, KM_NOSLEEP);
if (name == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto fail;
}
strlcpy(name, devname, len);
devsw_conv[i].d_name = name;
devsw_conv[i].d_bmajor = *bmajor;
devsw_conv[i].d_cmajor = *cmajor;
mutex_exit(&specfs_lock);
return (0);
fail:
mutex_exit(&specfs_lock);
return (error);
}
static int
bdevsw_attach(const struct bdevsw *devsw, int *devmajor)
{
const struct bdevsw **newptr;
int bmajor, i;
KASSERT(mutex_owned(&specfs_lock));
if (devsw == NULL)
return (0);
if (*devmajor < 0) {
for (bmajor = sys_bdevsws ; bmajor < max_bdevsws ; bmajor++) {
if (bdevsw[bmajor] != NULL)
continue;
for (i = 0 ; i < max_devsw_convs ; i++) {
if (devsw_conv[i].d_bmajor == bmajor)
break;
}
if (i != max_devsw_convs)
continue;
break;
}
*devmajor = bmajor;
}
if (*devmajor >= MAXDEVSW) {
printf("bdevsw_attach: block majors exhausted");
return (ENOMEM);
}
if (*devmajor >= max_bdevsws) {
KASSERT(bdevsw == bdevsw0);
newptr = kmem_zalloc(MAXDEVSW * BDEVSW_SIZE, KM_NOSLEEP);
if (newptr == NULL)
return (ENOMEM);
memcpy(newptr, bdevsw, max_bdevsws * BDEVSW_SIZE);
bdevsw = newptr;
max_bdevsws = MAXDEVSW;
}
if (bdevsw[*devmajor] != NULL)
return (EEXIST);
bdevsw[*devmajor] = devsw;
return (0);
}
static int
cdevsw_attach(const struct cdevsw *devsw, int *devmajor)
{
const struct cdevsw **newptr;
int cmajor, i;
KASSERT(mutex_owned(&specfs_lock));
if (*devmajor < 0) {
for (cmajor = sys_cdevsws ; cmajor < max_cdevsws ; cmajor++) {
if (cdevsw[cmajor] != NULL)
continue;
for (i = 0 ; i < max_devsw_convs ; i++) {
if (devsw_conv[i].d_cmajor == cmajor)
break;
}
if (i != max_devsw_convs)
continue;
break;
}
*devmajor = cmajor;
}
if (*devmajor >= MAXDEVSW) {
printf("cdevsw_attach: character majors exhausted");
return (ENOMEM);
}
if (*devmajor >= max_cdevsws) {
KASSERT(cdevsw == cdevsw0);
newptr = kmem_zalloc(MAXDEVSW * CDEVSW_SIZE, KM_NOSLEEP);
if (newptr == NULL)
return (ENOMEM);
memcpy(newptr, cdevsw, max_cdevsws * CDEVSW_SIZE);
cdevsw = newptr;
max_cdevsws = MAXDEVSW;
}
if (cdevsw[*devmajor] != NULL)
return (EEXIST);
cdevsw[*devmajor] = devsw;
return (0);
}
static void
devsw_detach_locked(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
int i;
KASSERT(mutex_owned(&specfs_lock));
if (bdev != NULL) {
for (i = 0 ; i < max_bdevsws ; i++) {
if (bdevsw[i] != bdev)
continue;
bdevsw[i] = NULL;
break;
}
}
if (cdev != NULL) {
for (i = 0 ; i < max_cdevsws ; i++) {
if (cdevsw[i] != cdev)
continue;
cdevsw[i] = NULL;
break;
}
}
}
int
devsw_detach(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
mutex_enter(&specfs_lock);
devsw_detach_locked(bdev, cdev);
mutex_exit(&specfs_lock);
return 0;
}
/*
* Look up a block device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct bdevsw *
bdevsw_lookup(dev_t dev)
{
int bmajor;
if (dev == NODEV)
return (NULL);
bmajor = major(dev);
if (bmajor < 0 || bmajor >= max_bdevsws)
return (NULL);
return (bdevsw[bmajor]);
}
/*
* Look up a character device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct cdevsw *
cdevsw_lookup(dev_t dev)
{
int cmajor;
if (dev == NODEV)
return (NULL);
cmajor = major(dev);
if (cmajor < 0 || cmajor >= max_cdevsws)
return (NULL);
return (cdevsw[cmajor]);
}
/*
* Look up a block device by reference to its operations set.
*
* => Caller must ensure that the device is not detached, and therefore
* that the returned major is still valid when dereferenced.
*/
int
bdevsw_lookup_major(const struct bdevsw *bdev)
{
int bmajor;
for (bmajor = 0 ; bmajor < max_bdevsws ; bmajor++) {
if (bdevsw[bmajor] == bdev)
return (bmajor);
}
return (-1);
}
/*
* Look up a character device by reference to its operations set.
*
* => Caller must ensure that the device is not detached, and therefore
* that the returned major is still valid when dereferenced.
*/
int
cdevsw_lookup_major(const struct cdevsw *cdev)
{
int cmajor;
for (cmajor = 0 ; cmajor < max_cdevsws ; cmajor++) {
if (cdevsw[cmajor] == cdev)
return (cmajor);
}
return (-1);
}
/*
* Convert from block major number to name.
*
* => Caller must ensure that the device is not detached, and therefore
* that the name pointer is still valid when dereferenced.
*/
const char *
devsw_blk2name(int bmajor)
{
const char *name;
int cmajor, i;
name = NULL;
cmajor = -1;
mutex_enter(&specfs_lock);
if (bmajor < 0 || bmajor >= max_bdevsws || bdevsw[bmajor] == NULL) {
mutex_exit(&specfs_lock);
return (NULL);
}
for (i = 0 ; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_bmajor == bmajor) {
cmajor = devsw_conv[i].d_cmajor;
break;
}
}
if (cmajor >= 0 && cmajor < max_cdevsws && cdevsw[cmajor] != NULL)
name = devsw_conv[i].d_name;
mutex_exit(&specfs_lock);
return (name);
}
/*
* Convert from device name to block major number.
*
* => Caller must ensure that the device is not detached, and therefore
* that the major number is still valid when dereferenced.
*/
int
devsw_name2blk(const char *name, char *devname, size_t devnamelen)
{
struct devsw_conv *conv;
int bmajor, i;
if (name == NULL)
return (-1);
mutex_enter(&specfs_lock);
for (i = 0 ; i < max_devsw_convs ; i++) {
size_t len;
conv = &devsw_conv[i];
if (conv->d_name == NULL)
continue;
len = strlen(conv->d_name);
if (strncmp(conv->d_name, name, len) != 0)
continue;
if (*(name +len) && !isdigit(*(name + len)))
continue;
bmajor = conv->d_bmajor;
if (bmajor < 0 || bmajor >= max_bdevsws ||
bdevsw[bmajor] == NULL)
break;
if (devname != NULL) {
#ifdef DEVSW_DEBUG
if (strlen(conv->d_name) >= devnamelen)
printf("devsw_name2blk: too short buffer");
#endif /* DEVSW_DEBUG */
strncpy(devname, conv->d_name, devnamelen);
devname[devnamelen - 1] = '\0';
}
mutex_exit(&specfs_lock);
return (bmajor);
}
mutex_exit(&specfs_lock);
return (-1);
}
/*
* Convert from device name to char major number.
*
* => Caller must ensure that the device is not detached, and therefore
* that the major number is still valid when dereferenced.
*/
int
devsw_name2chr(const char *name, char *devname, size_t devnamelen)
{
struct devsw_conv *conv;
int cmajor, i;
if (name == NULL)
return (-1);
mutex_enter(&specfs_lock);
for (i = 0 ; i < max_devsw_convs ; i++) {
size_t len;
conv = &devsw_conv[i];
if (conv->d_name == NULL)
continue;
len = strlen(conv->d_name);
if (strncmp(conv->d_name, name, len) != 0)
continue;
if (*(name +len) && !isdigit(*(name + len)))
continue;
cmajor = conv->d_cmajor;
if (cmajor < 0 || cmajor >= max_cdevsws ||
cdevsw[cmajor] == NULL)
break;
if (devname != NULL) {
#ifdef DEVSW_DEBUG
if (strlen(conv->d_name) >= devnamelen)
printf("devsw_name2chr: too short buffer");
#endif /* DEVSW_DEBUG */
strncpy(devname, conv->d_name, devnamelen);
devname[devnamelen - 1] = '\0';
}
mutex_exit(&specfs_lock);
return (cmajor);
}
mutex_exit(&specfs_lock);
return (-1);
}
/*
* Convert from character dev_t to block dev_t.
*
* => Caller must ensure that the device is not detached, and therefore
* that the major number is still valid when dereferenced.
*/
dev_t
devsw_chr2blk(dev_t cdev)
{
int bmajor, cmajor, i;
dev_t rv;
cmajor = major(cdev);
bmajor = -1;
rv = NODEV;
mutex_enter(&specfs_lock);
if (cmajor < 0 || cmajor >= max_cdevsws || cdevsw[cmajor] == NULL) {
mutex_exit(&specfs_lock);
return (NODEV);
}
for (i = 0 ; i < max_devsw_convs ; i++) {
if (devsw_conv[i].d_cmajor == cmajor) {
bmajor = devsw_conv[i].d_bmajor;
break;
}
}
if (bmajor >= 0 && bmajor < max_bdevsws && bdevsw[bmajor] != NULL)
rv = makedev(bmajor, minor(cdev));
mutex_exit(&specfs_lock);
return (rv);
}
/*
* Convert from block dev_t to character dev_t.
*
* => Caller must ensure that the device is not detached, and therefore
* that the major number is still valid when dereferenced.
*/
dev_t
devsw_blk2chr(dev_t bdev)
{
int bmajor, cmajor, i;
dev_t rv;
bmajor = major(bdev);
cmajor = -1;
rv = NODEV;
mutex_enter(&specfs_lock);
if (bmajor < 0 || bmajor >= max_bdevsws || bdevsw[bmajor] == NULL) {
mutex_exit(&specfs_lock);
return (NODEV);
}
for (i = 0 ; i < max_devsw_convs ; i++) {
if (devsw_conv[i].d_bmajor == bmajor) {
cmajor = devsw_conv[i].d_cmajor;
break;
}
}
if (cmajor >= 0 && cmajor < max_cdevsws && cdevsw[cmajor] != NULL)
rv = makedev(cmajor, minor(bdev));
mutex_exit(&specfs_lock);
return (rv);
}
/*
* Device access methods.
*/
#define DEV_LOCK(d) \
if ((mpflag = (d->d_flag & D_MPSAFE)) == 0) { \
KERNEL_LOCK(1, NULL); \
}
#define DEV_UNLOCK(d) \
if (mpflag == 0) { \
KERNEL_UNLOCK_ONE(NULL); \
}
int
bdev_open(dev_t dev, int flag, int devtype, lwp_t *l)
{
const struct bdevsw *d;
int rv, mpflag;
/*
* For open we need to lock, in order to synchronize
* with attach/detach.
*/
mutex_enter(&specfs_lock);
d = bdevsw_lookup(dev);
mutex_exit(&specfs_lock);
if (d == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_open)(dev, flag, devtype, l);
DEV_UNLOCK(d);
return rv;
}
int
bdev_close(dev_t dev, int flag, int devtype, lwp_t *l)
{
const struct bdevsw *d;
int rv, mpflag;
if ((d = bdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_close)(dev, flag, devtype, l);
DEV_UNLOCK(d);
return rv;
}
void
bdev_strategy(struct buf *bp)
{
const struct bdevsw *d;
int mpflag;
if ((d = bdevsw_lookup(bp->b_dev)) == NULL)
panic("bdev_strategy");
DEV_LOCK(d);
(*d->d_strategy)(bp);
DEV_UNLOCK(d);
}
int
bdev_ioctl(dev_t dev, u_long cmd, void *data, int flag, lwp_t *l)
{
const struct bdevsw *d;
int rv, mpflag;
if ((d = bdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_ioctl)(dev, cmd, data, flag, l);
DEV_UNLOCK(d);
return rv;
}
int
bdev_dump(dev_t dev, daddr_t addr, void *data, size_t sz)
{
const struct bdevsw *d;
int rv;
/*
* Dump can be called without the device open. Since it can
* currently only be called with the system paused (and in a
* potentially unstable state), we don't perform any locking.
*/
if ((d = bdevsw_lookup(dev)) == NULL)
return ENXIO;
/* DEV_LOCK(d); */
rv = (*d->d_dump)(dev, addr, data, sz);
/* DEV_UNLOCK(d); */
return rv;
}
int
bdev_type(dev_t dev)
{
const struct bdevsw *d;
if ((d = bdevsw_lookup(dev)) == NULL)
return D_OTHER;
return d->d_flag & D_TYPEMASK;
}
int
cdev_open(dev_t dev, int flag, int devtype, lwp_t *l)
{
const struct cdevsw *d;
int rv, mpflag;
/*
* For open we need to lock, in order to synchronize
* with attach/detach.
*/
mutex_enter(&specfs_lock);
d = cdevsw_lookup(dev);
mutex_exit(&specfs_lock);
if (d == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_open)(dev, flag, devtype, l);
DEV_UNLOCK(d);
return rv;
}
int
cdev_close(dev_t dev, int flag, int devtype, lwp_t *l)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_close)(dev, flag, devtype, l);
DEV_UNLOCK(d);
return rv;
}
int
cdev_read(dev_t dev, struct uio *uio, int flag)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_read)(dev, uio, flag);
DEV_UNLOCK(d);
return rv;
}
int
cdev_write(dev_t dev, struct uio *uio, int flag)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_write)(dev, uio, flag);
DEV_UNLOCK(d);
return rv;
}
int
cdev_ioctl(dev_t dev, u_long cmd, void *data, int flag, lwp_t *l)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_ioctl)(dev, cmd, data, flag, l);
DEV_UNLOCK(d);
return rv;
}
void
cdev_stop(struct tty *tp, int flag)
{
const struct cdevsw *d;
int mpflag;
if ((d = cdevsw_lookup(tp->t_dev)) == NULL)
return;
DEV_LOCK(d);
(*d->d_stop)(tp, flag);
DEV_UNLOCK(d);
}
struct tty *
cdev_tty(dev_t dev)
{
const struct cdevsw *d;
if ((d = cdevsw_lookup(dev)) == NULL)
return NULL;
/* XXX Check if necessary. */
if (d->d_tty == NULL)
return NULL;
return (*d->d_tty)(dev);
}
int
cdev_poll(dev_t dev, int flag, lwp_t *l)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return POLLERR;
DEV_LOCK(d);
rv = (*d->d_poll)(dev, flag, l);
DEV_UNLOCK(d);
return rv;
}
paddr_t
cdev_mmap(dev_t dev, off_t off, int flag)
{
const struct cdevsw *d;
paddr_t rv;
int mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return (paddr_t)-1LL;
DEV_LOCK(d);
rv = (*d->d_mmap)(dev, off, flag);
DEV_UNLOCK(d);
return rv;
}
int
cdev_kqfilter(dev_t dev, struct knote *kn)
{
const struct cdevsw *d;
int rv, mpflag;
if ((d = cdevsw_lookup(dev)) == NULL)
return ENXIO;
DEV_LOCK(d);
rv = (*d->d_kqfilter)(dev, kn);
DEV_UNLOCK(d);
return rv;
}
int
cdev_type(dev_t dev)
{
const struct cdevsw *d;
if ((d = cdevsw_lookup(dev)) == NULL)
return D_OTHER;
return d->d_flag & D_TYPEMASK;
}