freebsd-dev/sys/dev/null/null.c
Conrad Meyer 6b6e2954dd List-ify kernel dump device configuration
Allow users to specify multiple dump configurations in a prioritized list.
This enables fallback to secondary device(s) if primary dump fails.  E.g.,
one might configure a preference for netdump, but fallback to disk dump as a
second choice if netdump is unavailable.

This change does not list-ify netdump configuration, which is tracked
separately from ordinary disk dumps internally; only one netdump
configuration can be made at a time, for now.  It also does not implement
IPv6 netdump.

savecore(8) is already capable of scanning and iterating multiple devices
from /etc/fstab or passed on the command line.

This change doesn't update the rc or loader variables 'dumpdev' in any way;
it can still be set to configure a single dump device, and rc.d/savecore
still uses it as a single device.  Only dumpon(8) is updated to be able to
configure the more complicated configurations for now.

As part of revving the ABI, unify netdump and disk dump configuration ioctl
/ structure, and leave room for ipv6 netdump as a future possibility.
Backwards-compatibility ioctls are added to smooth ABI transition,
especially for developers who may not keep kernel and userspace perfectly
synced.

Reviewed by:	markj, scottl (earlier version)
Relnotes:	maybe
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D19996
2019-05-06 18:24:07 +00:00

219 lines
5.2 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
* Copyright (c) 2001-2004 Mark R. V. Murray
* Copyright (c) 2014 Eitan Adler
* 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
* in this position and unchanged.
* 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 AUTHORS ``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 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/systm.h>
#include <sys/conf.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/disk.h>
#include <sys/bus.h>
#include <sys/filio.h>
#include <machine/bus.h>
#include <machine/vmparam.h>
/* For use with destroy_dev(9). */
static struct cdev *full_dev;
static struct cdev *null_dev;
static struct cdev *zero_dev;
static d_write_t full_write;
static d_write_t null_write;
static d_ioctl_t null_ioctl;
static d_ioctl_t zero_ioctl;
static d_read_t zero_read;
static struct cdevsw full_cdevsw = {
.d_version = D_VERSION,
.d_read = zero_read,
.d_write = full_write,
.d_ioctl = zero_ioctl,
.d_name = "full",
};
static struct cdevsw null_cdevsw = {
.d_version = D_VERSION,
.d_read = (d_read_t *)nullop,
.d_write = null_write,
.d_ioctl = null_ioctl,
.d_name = "null",
};
static struct cdevsw zero_cdevsw = {
.d_version = D_VERSION,
.d_read = zero_read,
.d_write = null_write,
.d_ioctl = zero_ioctl,
.d_name = "zero",
.d_flags = D_MMAP_ANON,
};
/* ARGSUSED */
static int
full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused)
{
return (ENOSPC);
}
/* ARGSUSED */
static int
null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
{
uio->uio_resid = 0;
return (0);
}
/* ARGSUSED */
static int
null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
int flags __unused, struct thread *td)
{
struct diocskerneldump_arg kda;
int error;
error = 0;
switch (cmd) {
#ifdef COMPAT_FREEBSD11
case DIOCSKERNELDUMP_FREEBSD11:
gone_in(13, "FreeBSD 11.x ABI compat");
/* FALLTHROUGH */
#endif
#ifdef COMPAT_FREEBSD12
case DIOCSKERNELDUMP_FREEBSD12:
if (cmd == DIOCSKERNELDUMP_FREEBSD12)
gone_in(14, "FreeBSD 12.x ABI compat");
/* FALLTHROUGH */
#endif
case DIOCSKERNELDUMP:
bzero(&kda, sizeof(kda));
kda.kda_index = KDA_REMOVE_ALL;
error = dumper_remove(NULL, &kda);
break;
case FIONBIO:
break;
case FIOASYNC:
if (*(int *)data != 0)
error = EINVAL;
break;
default:
error = ENOIOCTL;
}
return (error);
}
/* ARGSUSED */
static int
zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
int flags __unused, struct thread *td)
{
int error;
error = 0;
switch (cmd) {
case FIONBIO:
break;
case FIOASYNC:
if (*(int *)data != 0)
error = EINVAL;
break;
default:
error = ENOIOCTL;
}
return (error);
}
/* ARGSUSED */
static int
zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
{
void *zbuf;
ssize_t len;
int error = 0;
KASSERT(uio->uio_rw == UIO_READ,
("Can't be in %s for write", __func__));
zbuf = __DECONST(void *, zero_region);
while (uio->uio_resid > 0 && error == 0) {
len = uio->uio_resid;
if (len > ZERO_REGION_SIZE)
len = ZERO_REGION_SIZE;
error = uiomove(zbuf, len, uio);
}
return (error);
}
/* ARGSUSED */
static int
null_modevent(module_t mod __unused, int type, void *data __unused)
{
switch(type) {
case MOD_LOAD:
if (bootverbose)
printf("null: <full device, null device, zero device>\n");
full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
NULL, UID_ROOT, GID_WHEEL, 0666, "full");
null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
NULL, UID_ROOT, GID_WHEEL, 0666, "null");
zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
break;
case MOD_UNLOAD:
destroy_dev(full_dev);
destroy_dev(null_dev);
destroy_dev(zero_dev);
break;
case MOD_SHUTDOWN:
break;
default:
return (EOPNOTSUPP);
}
return (0);
}
DEV_MODULE(null, null_modevent, NULL);
MODULE_VERSION(null, 1);