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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;
static usec_t watchdog_timeout; /* USEC_INFINITY → don't change timeout */
static usec_t watchdog_last_ping = USEC_INFINITY;
static int watchdog_set_enable(bool enable) {
int flags = enable ? WDIOS_ENABLECARD : WDIOS_DISABLECARD;
int r;
assert(watchdog_fd >= 0);
r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
if (r < 0) {
if (!enable)
return log_warning_errno(errno, "Failed to disable hardware watchdog, ignoring: %m");
/* ENOTTY means the watchdog is always enabled so we're fine */
log_full_errno(ERRNO_IS_NOT_SUPPORTED(errno) ? LOG_DEBUG : LOG_WARNING, errno,
"Failed to enable hardware watchdog, ignoring: %m");
if (!ERRNO_IS_NOT_SUPPORTED(errno))
return -errno;
}
return 0;
}
static int watchdog_get_timeout(void) {
int sec = 0;
assert(watchdog_fd > 0);
if (ioctl(watchdog_fd, WDIOC_GETTIMEOUT, &sec) < 0)
return -errno;
assert(sec > 0);
watchdog_timeout = sec * USEC_PER_SEC;
return 0;
}
static int watchdog_set_timeout(void) {
usec_t t;
int sec;
assert(watchdog_fd >= 0);
assert(timestamp_is_set(watchdog_timeout));
t = DIV_ROUND_UP(watchdog_timeout, USEC_PER_SEC);
sec = MIN(t, (usec_t) INT_MAX); /* Saturate */
if (ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec) < 0)
return -errno;
assert(sec > 0);/* buggy driver ? */
watchdog_timeout = sec * USEC_PER_SEC;
return 0;
}
static int watchdog_ping_now(void) {
assert(watchdog_fd >= 0);
if (ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0) < 0)
return log_warning_errno(errno, "Failed to ping hardware watchdog, ignoring: %m");
watchdog_last_ping = now(clock_boottime_or_monotonic());
return 0;
}
static int update_timeout(void) {
int r;
if (watchdog_fd < 0)
return 0;
if (watchdog_timeout == 0)
return watchdog_set_enable(false);
if (watchdog_timeout != USEC_INFINITY) {
r = watchdog_set_timeout();
if (r < 0) {
if (!ERRNO_IS_NOT_SUPPORTED(r))
return log_warning_errno(r, "Failed to set timeout to %s, ignoring: %m",
FORMAT_TIMESPAN(watchdog_timeout, 0));
log_info("Modifying watchdog timeout is not supported, reusing the programmed timeout.");
watchdog_timeout = USEC_INFINITY;
}
}
if (watchdog_timeout == USEC_INFINITY) {
r = watchdog_get_timeout();
if (r < 0)
return log_warning_errno(errno, "Failed to query watchdog HW timeout, ignoring: %m");
}
r = watchdog_set_enable(true);
if (r < 0)
return r;
log_info("Watchdog running with a timeout of %s.", FORMAT_TIMESPAN(watchdog_timeout, 0));
return watchdog_ping_now();
}
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, ignoring: %m", fn);
if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) < 0)
log_debug_errno(errno, "Hardware watchdog %s does not support WDIOC_GETSUPPORT ioctl, ignoring: %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(const 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_setup(usec_t timeout) {
/* Let's shortcut duplicated requests */
if (watchdog_fd >= 0 && watchdog_timeout == timeout)
return 0;
/* Initialize the watchdog timeout with the caller value. This value is
* going to be updated by update_timeout() with the closest value
* supported by the driver */
watchdog_timeout = timeout;
if (watchdog_fd < 0)
return open_watchdog();
return update_timeout();
}
usec_t watchdog_runtime_wait(void) {
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)) {
usec_t ntime = now(clock_boottime_or_monotonic());
assert(ntime >= watchdog_last_ping);
return usec_sub_unsigned(watchdog_last_ping + (watchdog_timeout / 2), ntime);
}
return watchdog_timeout / 2;
}
int watchdog_ping(void) {
usec_t ntime;
if (watchdog_timeout == 0)
return 0;
if (watchdog_fd < 0)
/* open_watchdog() will automatically ping the device for us if necessary */
return open_watchdog();
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;
}
return watchdog_ping_now();
}
void watchdog_close(bool disarm) {
if (watchdog_fd < 0)
return;
if (disarm) {
(void) watchdog_set_enable(false);
/* 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_warning_errno(errno, "Failed to disarm watchdog timer, ignoring: %m");
break;
}
}
}
watchdog_fd = safe_close(watchdog_fd);
/* Once closed, pinging the device becomes a NOP and we request a new
* call to watchdog_setup() to open the device again. */
watchdog_timeout = 0;
}
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