diff options
| -rw-r--r-- | Makefile.am | 1 | ||||
| -rw-r--r-- | src/util/util.h | 4 | ||||
| -rw-r--r-- | src/util/util_watchdog.c | 142 |
3 files changed, 147 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am index e2d2c38a..1559548d 100644 --- a/Makefile.am +++ b/Makefile.am @@ -867,6 +867,7 @@ libsss_util_la_SOURCES = \ src/util/well_known_sids.c \ src/util/string_utils.c \ src/util/become_user.c \ + src/util/util_watchdog.c \ $(NULL) libsss_util_la_CFLAGS = \ $(AM_CFLAGS) \ diff --git a/src/util/util.h b/src/util/util.h index 05ee8758..dd394514 100644 --- a/src/util/util.h +++ b/src/util/util.h @@ -587,4 +587,8 @@ int sss_unique_file(TALLOC_CTX *owner, */ int sss_unique_filename(TALLOC_CTX *owner, char *path_tmpl); +/* from util_watchdog.c */ +int setup_watchdog(struct tevent_context *ev, int interval); +void teardown_watchdog(void); + #endif /* __SSSD_UTIL_H__ */ diff --git a/src/util/util_watchdog.c b/src/util/util_watchdog.c new file mode 100644 index 00000000..9fef8427 --- /dev/null +++ b/src/util/util_watchdog.c @@ -0,0 +1,142 @@ +/* + 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 = { 0 }; + struct itimerspec its; + int signum = SIGRTMIN; + int ret; + + 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); +} + |