watchdog.c revision 56f64d95763a799ba4475daf44d8e9f72a1bd474
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2012 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/watchdog.h>
#include "watchdog.h"
#include "log.h"
static int watchdog_fd = -1;
static usec_t watchdog_timeout = USEC_INFINITY;
static int update_timeout(void) {
int r;
if (watchdog_fd < 0)
return 0;
if (watchdog_timeout == USEC_INFINITY)
return 0;
else if (watchdog_timeout == 0) {
int flags;
flags = WDIOS_DISABLECARD;
r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
if (r < 0) {
log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
return -errno;
}
} else {
int sec, flags;
char buf[FORMAT_TIMESPAN_MAX];
sec = (int) ((watchdog_timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
if (r < 0) {
log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
return -errno;
}
watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout, 0));
flags = WDIOS_ENABLECARD;
r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
if (r < 0) {
log_warning_errno(errno, "Failed to enable hardware watchdog: %m");
return -errno;
}
r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
if (r < 0) {
log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
return -errno;
}
}
return 0;
}
static int open_watchdog(void) {
struct watchdog_info ident;
if (watchdog_fd >= 0)
return 0;
watchdog_fd = open("/dev/watchdog", O_WRONLY|O_CLOEXEC);
if (watchdog_fd < 0)
return -errno;
if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) >= 0)
log_info("Hardware watchdog '%s', version %x",
ident.identity,
ident.firmware_version);
return update_timeout();
}
int watchdog_set_timeout(usec_t *usec) {
int r;
watchdog_timeout = *usec;
/* If we didn't open the watchdog yet and didn't get any
* explicit timeout value set, don't do anything */
if (watchdog_fd < 0 && watchdog_timeout == USEC_INFINITY)
return 0;
if (watchdog_fd < 0)
r = open_watchdog();
else
r = update_timeout();
*usec = watchdog_timeout;
return r;
}
int watchdog_ping(void) {
int r;
if (watchdog_fd < 0) {
r = open_watchdog();
if (r < 0)
return r;
}
r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
if (r < 0) {
log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
return -errno;
}
return 0;
}
void watchdog_close(bool disarm) {
int r;
if (watchdog_fd < 0)
return;
if (disarm) {
int flags;
/* Explicitly disarm it */
flags = WDIOS_DISABLECARD;
r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
if (r < 0)
log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
/* To be sure, use magic close logic, too */
for (;;) {
static const char v = 'V';
if (write(watchdog_fd, &v, 1) > 0)
break;
if (errno != EINTR) {
log_error_errno(errno, "Failed to disarm watchdog timer: %m");
break;
}
}
}
watchdog_fd = safe_close(watchdog_fd);
}