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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <syslog.h>
#include <unistd.h>
#include <linux/watchdog.h>
#include "errno-util.h"
#include "fd-util.h"
#include "log.h"
#include "string-util.h"
#include "time-util.h"
#include "watchdog.h"
static int watchdog_fd = -1;
static char *watchdog_device = NULL;
static usec_t watchdog_timeout = USEC_INFINITY;
static usec_t watchdog_last_ping = USEC_INFINITY;
static int update_timeout(void) {
if (watchdog_fd < 0)
return 0;
if (watchdog_timeout == USEC_INFINITY)
return 0;
if (watchdog_timeout == 0) {
int flags;
flags = WDIOS_DISABLECARD;
if (ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags) < 0)
return log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
} else {
char buf[FORMAT_TIMESPAN_MAX];
int sec, flags;
usec_t t;
t = DIV_ROUND_UP(watchdog_timeout, USEC_PER_SEC);
sec = (int) t >= INT_MAX ? INT_MAX : t; /* Saturate */
if (ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec) < 0)
return log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
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;
if (ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags) < 0) {
/* ENOTTY means the watchdog is always enabled so we're fine */
log_full(ERRNO_IS_NOT_SUPPORTED(errno) ? LOG_DEBUG : LOG_WARNING,
"Failed to enable hardware watchdog: %m");
if (!ERRNO_IS_NOT_SUPPORTED(errno))
return -errno;
}
if (ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0) < 0)
return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
watchdog_last_ping = now(clock_boottime_or_monotonic());
}
return 0;
}
static int open_watchdog(void) {
struct watchdog_info ident;
const char *fn;
if (watchdog_fd >= 0)
return 0;
fn = watchdog_device ?: "/dev/watchdog";
watchdog_fd = open(fn, O_WRONLY|O_CLOEXEC);
if (watchdog_fd < 0)
return log_debug_errno(errno, "Failed to open watchdog device %s: %m", fn);
if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) < 0)
log_debug_errno(errno, "Hardware watchdog %s does not support WDIOC_GETSUPPORT ioctl: %m", fn);
else
log_info("Using hardware watchdog '%s', version %x, device %s",
ident.identity,
ident.firmware_version,
fn);
return update_timeout();
}
int watchdog_set_device(char *path) {
int r;
r = free_and_strdup(&watchdog_device, path);
if (r < 0)
return r;
if (r > 0) /* watchdog_device changed */
watchdog_fd = safe_close(watchdog_fd);
return r;
}
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;
}
usec_t watchdog_runtime_wait(void) {
usec_t rtwait, ntime;
if (!timestamp_is_set(watchdog_timeout))
return USEC_INFINITY;
/* Sleep half the watchdog timeout since the last successful ping at most */
if (timestamp_is_set(watchdog_last_ping)) {
ntime = now(clock_boottime_or_monotonic());
assert(ntime >= watchdog_last_ping);
rtwait = usec_sub_unsigned(watchdog_last_ping + (watchdog_timeout / 2), ntime);
} else
rtwait = watchdog_timeout / 2;
return rtwait;
}
int watchdog_ping(void) {
usec_t ntime;
int r;
ntime = now(clock_boottime_or_monotonic());
/* Never ping earlier than watchdog_timeout/4 and try to ping
* by watchdog_timeout/2 plus scheduling latencies the latest */
if (timestamp_is_set(watchdog_last_ping)) {
assert(ntime >= watchdog_last_ping);
if ((ntime - watchdog_last_ping) < (watchdog_timeout / 4))
return 0;
}
if (watchdog_fd < 0) {
r = open_watchdog();
if (r < 0)
return r;
}
if (ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0) < 0)
return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
watchdog_last_ping = ntime;
return 0;
}
void watchdog_close(bool disarm) {
if (watchdog_fd < 0)
return;
if (disarm) {
int flags;
/* Explicitly disarm it */
flags = WDIOS_DISABLECARD;
if (ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags) < 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);
}
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