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/*
SSSD
Timer Watchdog routines
Copyright (C) Simo Sorce 2016
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "util/util.h"
#define WATCHDOG_DEF_INTERVAL 10
/* this is intentionally a global variable */
struct watchdog_ctx {
timer_t timerid;
struct timeval interval;
struct tevent_timer *te;
volatile int ticks;
} watchdog_ctx;
/* the watchdog is purposefully *not* handled by the tevent
* signal handler as it is meant to check if the daemon is
* still processing the event queue itself. A stuck process
* may not handle the event queue at all and thus not handle
* signals either */
static void watchdog_handler(int sig)
{
/* if 3 ticks passed by kills itself */
if (__sync_add_and_fetch(&watchdog_ctx.ticks, 1) > 3) {
DEBUG(SSSDBG_FATAL_FAILURE,
"Watchdog timer overflow, killing process!\n");
orderly_shutdown(1);
}
}
static void watchdog_reset(void)
{
__sync_and_and_fetch(&watchdog_ctx.ticks, 0);
}
static void watchdog_event_handler(struct tevent_context *ev,
struct tevent_timer *te,
struct timeval current_time,
void *private_data)
{
/* first thing reset the watchdog ticks */
watchdog_reset();
/* then set a new watchodg event */
watchdog_ctx.te = tevent_add_timer(ev, ev,
tevent_timeval_current_ofs(watchdog_ctx.interval.tv_sec, 0),
watchdog_event_handler, NULL);
/* if the function fails the watchdog will kill the
* process soon enough, so we just warn */
if (!watchdog_ctx.te) {
DEBUG(SSSDBG_FATAL_FAILURE,
"Failed to create a watchdog timer event!\n");
}
}
int setup_watchdog(struct tevent_context *ev, int interval)
{
struct sigevent sev;
struct itimerspec its;
int signum = SIGRTMIN;
int ret;
ZERO_STRUCT(sev);
CatchSignal(signum, watchdog_handler);
sev.sigev_notify = SIGEV_SIGNAL;
sev.sigev_signo = signum;
sev.sigev_value.sival_ptr = &watchdog_ctx.timerid;
errno = 0;
ret = timer_create(CLOCK_MONOTONIC, &sev, &watchdog_ctx.timerid);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_FATAL_FAILURE,
"Failed to create watchdog timer (%d) [%s]\n",
ret, strerror(ret));
return ret;
}
if (interval == 0) {
interval = WATCHDOG_DEF_INTERVAL;
}
watchdog_ctx.interval.tv_sec = interval;
watchdog_ctx.interval.tv_usec = 0;
/* Start the timer */
/* we give 1 second head start to the watchdog event */
its.it_value.tv_sec = interval + 1;
its.it_value.tv_nsec = 0;
its.it_interval.tv_sec = interval;
its.it_interval.tv_nsec = 0;
errno = 0;
ret = timer_settime(watchdog_ctx.timerid, 0, &its, NULL);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_FATAL_FAILURE,
"Failed to create watchdog timer (%d) [%s]\n",
ret, strerror(ret));
return ret;
}
/* Add the watchdog event and make it fire as fast as the timer */
watchdog_event_handler(ev, NULL, tevent_timeval_zero(), NULL);
return EOK;
}
void teardown_watchdog(void)
{
int ret;
/* Disarm the timer */
errno = 0;
ret = timer_delete(watchdog_ctx.timerid);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_FATAL_FAILURE,
"Failed to destroy watchdog timer (%d) [%s]\n",
ret, strerror(ret));
}
/* and kill the watchdog event */
talloc_free(watchdog_ctx.te);
}
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