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subr_devsw.c
1386 lines (1166 loc) · 29.7 KB
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subr_devsw.c
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/* $NetBSD: subr_devsw.c,v 1.45 2022/03/28 12:41:17 riastradh 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 1.45 2022/03/28 12:41:17 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_dtrace.h"
#endif
#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 <sys/reboot.h>
#include <sys/sdt.h>
#include <sys/atomic.h>
#include <sys/localcount.h>
#include <sys/pserialize.h>
#include <sys/xcall.h>
#include <sys/device.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))
struct devswref {
struct localcount *dr_lc;
};
/* XXX bdevsw, cdevsw, max_bdevsws, and max_cdevsws should be volatile */
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 struct devswref *cdevswref;
static struct devswref *bdevswref;
static kcondvar_t devsw_cv;
static int bdevsw_attach(const struct bdevsw *, devmajor_t *);
static int cdevsw_attach(const struct cdevsw *, devmajor_t *);
static void devsw_detach_locked(const struct bdevsw *, const struct cdevsw *);
kmutex_t device_lock;
void (*biodone_vfs)(buf_t *) = (void *)nullop;
void
devsw_init(void)
{
KASSERT(sys_bdevsws < MAXDEVSW - 1);
KASSERT(sys_cdevsws < MAXDEVSW - 1);
mutex_init(&device_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&devsw_cv, "devsw");
}
int
devsw_attach(const char *devname,
const struct bdevsw *bdev, devmajor_t *bmajor,
const struct cdevsw *cdev, devmajor_t *cmajor)
{
struct devsw_conv *conv;
char *name;
int error, i;
if (devname == NULL || cdev == NULL)
return EINVAL;
mutex_enter(&device_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 out;
}
if ((*bmajor >= 0 && bdev == NULL) || *cmajor < 0) {
error = EINVAL;
goto out;
}
if ((*bmajor >= 0 && bdevsw[*bmajor] != NULL) ||
cdevsw[*cmajor] != NULL) {
error = EEXIST;
goto out;
}
break;
}
/*
* XXX This should allocate what it needs up front so we never
* need to flail around trying to unwind.
*/
error = bdevsw_attach(bdev, bmajor);
if (error != 0)
goto out;
error = cdevsw_attach(cdev, cmajor);
if (error != 0) {
devsw_detach_locked(bdev, NULL);
goto out;
}
/*
* If we already found a conv, we're done. Otherwise, find an
* empty slot or extend the table.
*/
if (i == max_devsw_convs)
goto out;
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_convs, new_convs;
old_convs = max_devsw_convs;
new_convs = old_convs + 1;
newptr = kmem_zalloc(new_convs * DEVSWCONV_SIZE, KM_NOSLEEP);
if (newptr == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto out;
}
newptr[old_convs].d_name = NULL;
newptr[old_convs].d_bmajor = -1;
newptr[old_convs].d_cmajor = -1;
memcpy(newptr, devsw_conv, old_convs * DEVSWCONV_SIZE);
if (devsw_conv != devsw_conv0)
kmem_free(devsw_conv, old_convs * DEVSWCONV_SIZE);
devsw_conv = newptr;
max_devsw_convs = new_convs;
}
name = kmem_strdupsize(devname, NULL, KM_NOSLEEP);
if (name == NULL) {
devsw_detach_locked(bdev, cdev);
error = ENOMEM;
goto out;
}
devsw_conv[i].d_name = name;
devsw_conv[i].d_bmajor = *bmajor;
devsw_conv[i].d_cmajor = *cmajor;
error = 0;
out:
mutex_exit(&device_lock);
return error;
}
static int
bdevsw_attach(const struct bdevsw *devsw, devmajor_t *devmajor)
{
const struct bdevsw **newbdevsw = NULL;
struct devswref *newbdevswref = NULL;
struct localcount *lc;
devmajor_t bmajor;
int i;
KASSERT(mutex_owned(&device_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("%s: block majors exhausted\n", __func__);
return ENOMEM;
}
if (bdevswref == NULL) {
newbdevswref = kmem_zalloc(MAXDEVSW * sizeof(newbdevswref[0]),
KM_NOSLEEP);
if (newbdevswref == NULL)
return ENOMEM;
atomic_store_release(&bdevswref, newbdevswref);
}
if (*devmajor >= max_bdevsws) {
KASSERT(bdevsw == bdevsw0);
newbdevsw = kmem_zalloc(MAXDEVSW * sizeof(newbdevsw[0]),
KM_NOSLEEP);
if (newbdevsw == NULL)
return ENOMEM;
memcpy(newbdevsw, bdevsw, max_bdevsws * sizeof(bdevsw[0]));
atomic_store_release(&bdevsw, newbdevsw);
atomic_store_release(&max_bdevsws, MAXDEVSW);
}
if (bdevsw[*devmajor] != NULL)
return EEXIST;
KASSERT(bdevswref[*devmajor].dr_lc == NULL);
lc = kmem_zalloc(sizeof(*lc), KM_SLEEP);
localcount_init(lc);
bdevswref[*devmajor].dr_lc = lc;
atomic_store_release(&bdevsw[*devmajor], devsw);
return 0;
}
static int
cdevsw_attach(const struct cdevsw *devsw, devmajor_t *devmajor)
{
const struct cdevsw **newcdevsw = NULL;
struct devswref *newcdevswref = NULL;
struct localcount *lc;
devmajor_t cmajor;
int i;
KASSERT(mutex_owned(&device_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("%s: character majors exhausted\n", __func__);
return ENOMEM;
}
if (cdevswref == NULL) {
newcdevswref = kmem_zalloc(MAXDEVSW * sizeof(newcdevswref[0]),
KM_NOSLEEP);
if (newcdevswref == NULL)
return ENOMEM;
atomic_store_release(&cdevswref, newcdevswref);
}
if (*devmajor >= max_cdevsws) {
KASSERT(cdevsw == cdevsw0);
newcdevsw = kmem_zalloc(MAXDEVSW * sizeof(newcdevsw[0]),
KM_NOSLEEP);
if (newcdevsw == NULL)
return ENOMEM;
memcpy(newcdevsw, cdevsw, max_cdevsws * sizeof(cdevsw[0]));
atomic_store_release(&cdevsw, newcdevsw);
atomic_store_release(&max_cdevsws, MAXDEVSW);
}
if (cdevsw[*devmajor] != NULL)
return EEXIST;
KASSERT(cdevswref[*devmajor].dr_lc == NULL);
lc = kmem_zalloc(sizeof(*lc), KM_SLEEP);
localcount_init(lc);
cdevswref[*devmajor].dr_lc = lc;
atomic_store_release(&cdevsw[*devmajor], devsw);
return 0;
}
static void
devsw_detach_locked(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
int bi, ci = -1/*XXXGCC*/;
KASSERT(mutex_owned(&device_lock));
/* Prevent new references. */
if (bdev != NULL) {
for (bi = 0; bi < max_bdevsws; bi++) {
if (bdevsw[bi] != bdev)
continue;
atomic_store_relaxed(&bdevsw[bi], NULL);
break;
}
KASSERT(bi < max_bdevsws);
}
if (cdev != NULL) {
for (ci = 0; ci < max_cdevsws; ci++) {
if (cdevsw[ci] != cdev)
continue;
atomic_store_relaxed(&cdevsw[ci], NULL);
break;
}
KASSERT(ci < max_cdevsws);
}
if (bdev == NULL && cdev == NULL) /* XXX possible? */
return;
/*
* Wait for all bdevsw_lookup_acquire, cdevsw_lookup_acquire
* calls to notice that the devsw is gone.
*
* XXX Despite the use of the pserialize_read_enter/exit API
* elsewhere in this file, we use xc_barrier here instead of
* pserialize_perform -- because devsw_init is too early for
* pserialize_create. Either pserialize_create should be made
* to work earlier, or it should be nixed altogether. Until
* that is fixed, xc_barrier will serve the same purpose.
*/
xc_barrier(0);
/*
* Wait for all references to drain. It is the caller's
* responsibility to ensure that at this point, there are no
* extant open instances and all new d_open calls will fail.
*
* Note that localcount_drain may release and reacquire
* device_lock.
*/
if (bdev != NULL) {
localcount_drain(bdevswref[bi].dr_lc,
&devsw_cv, &device_lock);
localcount_fini(bdevswref[bi].dr_lc);
kmem_free(bdevswref[bi].dr_lc, sizeof(*bdevswref[bi].dr_lc));
bdevswref[bi].dr_lc = NULL;
}
if (cdev != NULL) {
localcount_drain(cdevswref[ci].dr_lc,
&devsw_cv, &device_lock);
localcount_fini(cdevswref[ci].dr_lc);
kmem_free(cdevswref[ci].dr_lc, sizeof(*cdevswref[ci].dr_lc));
cdevswref[ci].dr_lc = NULL;
}
}
void
devsw_detach(const struct bdevsw *bdev, const struct cdevsw *cdev)
{
mutex_enter(&device_lock);
devsw_detach_locked(bdev, cdev);
mutex_exit(&device_lock);
}
/*
* Look up a block device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct bdevsw *
bdevsw_lookup(dev_t dev)
{
devmajor_t bmajor;
if (dev == NODEV)
return NULL;
bmajor = major(dev);
if (bmajor < 0 || bmajor >= atomic_load_relaxed(&max_bdevsws))
return NULL;
return atomic_load_consume(&bdevsw)[bmajor];
}
static const struct bdevsw *
bdevsw_lookup_acquire(dev_t dev, struct localcount **lcp)
{
devmajor_t bmajor;
const struct bdevsw *bdev = NULL, *const *curbdevsw;
struct devswref *curbdevswref;
int s;
if (dev == NODEV)
return NULL;
bmajor = major(dev);
if (bmajor < 0)
return NULL;
s = pserialize_read_enter();
/*
* max_bdevsws never goes down, so it is safe to rely on this
* condition without any locking for the array access below.
* Test sys_bdevsws first so we can avoid the memory barrier in
* that case.
*/
if (bmajor >= sys_bdevsws &&
bmajor >= atomic_load_acquire(&max_bdevsws))
goto out;
curbdevsw = atomic_load_consume(&bdevsw);
if ((bdev = atomic_load_consume(&curbdevsw[bmajor])) == NULL)
goto out;
curbdevswref = atomic_load_consume(&bdevswref);
if (curbdevswref == NULL) {
*lcp = NULL;
} else if ((*lcp = curbdevswref[bmajor].dr_lc) != NULL) {
localcount_acquire(*lcp);
}
out:
pserialize_read_exit(s);
return bdev;
}
static void
bdevsw_release(const struct bdevsw *bdev, struct localcount *lc)
{
if (lc == NULL)
return;
localcount_release(lc, &devsw_cv, &device_lock);
}
/*
* Look up a character device by number.
*
* => Caller must ensure that the device is attached.
*/
const struct cdevsw *
cdevsw_lookup(dev_t dev)
{
devmajor_t cmajor;
if (dev == NODEV)
return NULL;
cmajor = major(dev);
if (cmajor < 0 || cmajor >= atomic_load_relaxed(&max_cdevsws))
return NULL;
return atomic_load_consume(&cdevsw)[cmajor];
}
static const struct cdevsw *
cdevsw_lookup_acquire(dev_t dev, struct localcount **lcp)
{
devmajor_t cmajor;
const struct cdevsw *cdev = NULL, *const *curcdevsw;
struct devswref *curcdevswref;
int s;
if (dev == NODEV)
return NULL;
cmajor = major(dev);
if (cmajor < 0)
return NULL;
s = pserialize_read_enter();
/*
* max_cdevsws never goes down, so it is safe to rely on this
* condition without any locking for the array access below.
* Test sys_cdevsws first so we can avoid the memory barrier in
* that case.
*/
if (cmajor >= sys_cdevsws &&
cmajor >= atomic_load_acquire(&max_cdevsws))
goto out;
curcdevsw = atomic_load_consume(&cdevsw);
if ((cdev = atomic_load_consume(&curcdevsw[cmajor])) == NULL)
goto out;
curcdevswref = atomic_load_consume(&cdevswref);
if (curcdevswref == NULL) {
*lcp = NULL;
} else if ((*lcp = curcdevswref[cmajor].dr_lc) != NULL) {
localcount_acquire(*lcp);
}
out:
pserialize_read_exit(s);
return cdev;
}
static void
cdevsw_release(const struct cdevsw *cdev, struct localcount *lc)
{
if (lc == NULL)
return;
localcount_release(lc, &devsw_cv, &device_lock);
}
/*
* 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.
*/
devmajor_t
bdevsw_lookup_major(const struct bdevsw *bdev)
{
const struct bdevsw *const *curbdevsw;
devmajor_t bmajor, bmax;
bmax = atomic_load_acquire(&max_bdevsws);
curbdevsw = atomic_load_consume(&bdevsw);
for (bmajor = 0; bmajor < bmax; bmajor++) {
if (atomic_load_relaxed(&curbdevsw[bmajor]) == bdev)
return bmajor;
}
return NODEVMAJOR;
}
/*
* 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.
*/
devmajor_t
cdevsw_lookup_major(const struct cdevsw *cdev)
{
const struct cdevsw *const *curcdevsw;
devmajor_t cmajor, cmax;
cmax = atomic_load_acquire(&max_cdevsws);
curcdevsw = atomic_load_consume(&cdevsw);
for (cmajor = 0; cmajor < cmax; cmajor++) {
if (atomic_load_relaxed(&curcdevsw[cmajor]) == cdev)
return cmajor;
}
return NODEVMAJOR;
}
/*
* 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(devmajor_t bmajor)
{
const char *name;
devmajor_t cmajor;
int i;
name = NULL;
cmajor = -1;
mutex_enter(&device_lock);
if (bmajor < 0 || bmajor >= max_bdevsws || bdevsw[bmajor] == NULL) {
mutex_exit(&device_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(&device_lock);
return name;
}
/*
* Convert char major number to device driver name.
*/
const char *
cdevsw_getname(devmajor_t major)
{
const char *name;
int i;
name = NULL;
if (major < 0)
return NULL;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_cmajor == major) {
name = devsw_conv[i].d_name;
break;
}
}
mutex_exit(&device_lock);
return name;
}
/*
* Convert block major number to device driver name.
*/
const char *
bdevsw_getname(devmajor_t major)
{
const char *name;
int i;
name = NULL;
if (major < 0)
return NULL;
mutex_enter(&device_lock);
for (i = 0; i < max_devsw_convs; i++) {
if (devsw_conv[i].d_bmajor == major) {
name = devsw_conv[i].d_name;
break;
}
}
mutex_exit(&device_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.
*/
devmajor_t
devsw_name2blk(const char *name, char *devname, size_t devnamelen)
{
struct devsw_conv *conv;
devmajor_t bmajor;
int i;
if (name == NULL)
return NODEVMAJOR;
mutex_enter(&device_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] != '\0' && !isdigit((unsigned char)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("%s: too short buffer\n", __func__);
#endif /* DEVSW_DEBUG */
strncpy(devname, conv->d_name, devnamelen);
devname[devnamelen - 1] = '\0';
}
mutex_exit(&device_lock);
return bmajor;
}
mutex_exit(&device_lock);
return NODEVMAJOR;
}
/*
* 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.
*/
devmajor_t
devsw_name2chr(const char *name, char *devname, size_t devnamelen)
{
struct devsw_conv *conv;
devmajor_t cmajor;
int i;
if (name == NULL)
return NODEVMAJOR;
mutex_enter(&device_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] != '\0' && !isdigit((unsigned char)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("%s: too short buffer", __func__);
#endif /* DEVSW_DEBUG */
strncpy(devname, conv->d_name, devnamelen);
devname[devnamelen - 1] = '\0';
}
mutex_exit(&device_lock);
return cmajor;
}
mutex_exit(&device_lock);
return NODEVMAJOR;
}
/*
* 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)
{
devmajor_t bmajor, cmajor;
int i;
dev_t rv;
cmajor = major(cdev);
bmajor = NODEVMAJOR;
rv = NODEV;
mutex_enter(&device_lock);
if (cmajor < 0 || cmajor >= max_cdevsws || cdevsw[cmajor] == NULL) {
mutex_exit(&device_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(&device_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)
{
devmajor_t bmajor, cmajor;
int i;
dev_t rv;
bmajor = major(bdev);
cmajor = NODEVMAJOR;
rv = NODEV;
mutex_enter(&device_lock);
if (bmajor < 0 || bmajor >= max_bdevsws || bdevsw[bmajor] == NULL) {
mutex_exit(&device_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(&device_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;
struct localcount *lc;
device_t dv = NULL/*XXXGCC*/;
int unit, rv, mpflag;
d = bdevsw_lookup_acquire(dev, &lc);
if (d == NULL)
return ENXIO;
if (d->d_devtounit) {
/*
* If the device node corresponds to an autoconf device
* instance, acquire a reference to it so that during
* d_open, device_lookup is stable.
*
* XXX This should also arrange to instantiate cloning
* pseudo-devices if appropriate, but that requires
* reviewing them all to find and verify a common
* pattern.
*/
if ((unit = (*d->d_devtounit)(dev)) == -1)
return ENXIO;
if ((dv = device_lookup_acquire(d->d_cfdriver, unit)) == NULL)
return ENXIO;
}
DEV_LOCK(d);
rv = (*d->d_open)(dev, flag, devtype, l);
DEV_UNLOCK(d);
if (d->d_devtounit) {
device_release(dv);
}
bdevsw_release(d, lc);
return rv;
}
int
bdev_cancel(dev_t dev, int flag, int devtype, struct lwp *l)
{
const struct bdevsw *d;
int rv, mpflag;
if ((d = bdevsw_lookup(dev)) == NULL)
return ENXIO;
if (d->d_cancel == NULL)
return ENODEV;
DEV_LOCK(d);
rv = (*d->d_cancel)(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;
}
SDT_PROVIDER_DECLARE(io);
SDT_PROBE_DEFINE1(io, kernel, , start, "struct buf *"/*bp*/);
void
bdev_strategy(struct buf *bp)
{
const struct bdevsw *d;
int mpflag;
SDT_PROBE1(io, kernel, , start, bp);
if ((d = bdevsw_lookup(bp->b_dev)) == NULL) {
bp->b_error = ENXIO;
bp->b_resid = bp->b_bcount;
biodone_vfs(bp); /* biodone() iff vfs present */
return;
}
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);