...G...PS. [ZBX-9867] fixed Zabbix daemon termination

(cherry picked from commit 857b9bea1fdb2e5f20642b10aeb8c4d5827615bb)

10 files changed, 67 insertions, 40 deletions

diff --git a/include/threads.h b/include/threads.h
index 5fa6c981c86..3d8fdd29a77 100644
--- a/include/threads.h
+++ b/include/threads.h
@@ -72,7 +72,7 @@
 
 	#define zbx_sleep(sec) sleep((sec))
 
-	#define zbx_thread_kill(h) kill(h, SIGTERM)
+	#define zbx_thread_kill(h) kill(h, SIGUSR2)
 	#define zbx_thread_kill_fatal(h) kill(h, SIGQUIT)
 #endif	/* _WINDOWS */
 
diff --git a/src/libs/zbxcrypto/tls.c b/src/libs/zbxcrypto/tls.c
index f4c367ac96d..3565f728857 100644
--- a/src/libs/zbxcrypto/tls.c
+++ b/src/libs/zbxcrypto/tls.c
@@ -2710,12 +2710,13 @@ void	zbx_tls_init_child(void)
 	zabbix_log(LOG_LEVEL_DEBUG, "In %s()", __func__);
 
 #ifndef _WINDOWS
-	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGTERM to */
+	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGQUIT to */
 	/* child processes which may be on their way to exit on their own - do not interrupt them, block signal */
-	/* SIGTERM and unblock it when TLS parameters are good and libraries are initialized. */
+	/* SIGQUIT and unblock it when TLS parameters are good and libraries are initialized. */
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGTERM);
 	sigaddset(&mask, SIGQUIT);
+	sigaddset(&mask, SIGUSR2);
 	sigprocmask(SIG_BLOCK, &mask, &orig_mask);
 
 	zbx_tls_library_init();		/* on Unix initialize crypto libraries in child processes */
@@ -2903,12 +2904,13 @@ void	zbx_tls_init_child(void)
 	zabbix_log(LOG_LEVEL_DEBUG, "In %s()", __func__);
 
 #ifndef _WINDOWS
-	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGTERM to */
+	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGQUIT to */
 	/* child processes which may be on their way to exit on their own - do not interrupt them, block signal */
-	/* SIGTERM and unblock it when TLS parameters are good and libraries are initialized. */
+	/* SIGQUIT and unblock it when TLS parameters are good and libraries are initialized. */
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGTERM);
 	sigaddset(&mask, SIGQUIT);
+	sigaddset(&mask, SIGUSR2);
 	sigprocmask(SIG_BLOCK, &mask, &orig_mask);
 
 	zbx_tls_library_init();		/* on Unix initialize crypto libraries in child processes */
@@ -3190,12 +3192,13 @@ void	zbx_tls_init_child(void)
 	zabbix_log(LOG_LEVEL_DEBUG, "In %s()", __func__);
 
 #ifndef _WINDOWS
-	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGTERM to */
+	/* Invalid TLS parameters will cause exit. Once one process exits the parent process will send SIGQUIT to */
 	/* child processes which may be on their way to exit on their own - do not interrupt them, block signal */
-	/* SIGTERM and unblock it when TLS parameters are good and libraries are initialized. */
+	/* SIGQUIT and unblock it when TLS parameters are good and libraries are initialized. */
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGTERM);
 	sigaddset(&mask, SIGQUIT);
+	sigaddset(&mask, SIGUSR2);
 	sigprocmask(SIG_BLOCK, &mask, &orig_mask);
 
 	zbx_tls_library_init();		/* on Unix initialize crypto libraries in child processes */
diff --git a/src/libs/zbxdbcache/dbcache.c b/src/libs/zbxdbcache/dbcache.c
index fad0476318d..b2850db0c53 100644
--- a/src/libs/zbxdbcache/dbcache.c
+++ b/src/libs/zbxdbcache/dbcache.c
@@ -3154,29 +3154,15 @@ void	zbx_log_sync_history_cache_progress(void)
  ******************************************************************************/
 void	zbx_sync_history_cache(int *values_num, int *triggers_num, int *more)
 {
-	sigset_t	orig_mask, mask;
-
 	zabbix_log(LOG_LEVEL_DEBUG, "In %s() history_num:%d", __func__, cache->history_num);
 
 	*values_num = 0;
 	*triggers_num = 0;
 
-	sigemptyset(&mask);
-	sigaddset(&mask, SIGTERM);
-	sigaddset(&mask, SIGINT);
-
-	if (0 > sigprocmask(SIG_BLOCK, &mask, &orig_mask))
-		zabbix_log(LOG_LEVEL_WARNING, "cannot set sigprocmask to block the user signal");
-
 	if (0 != (program_type & ZBX_PROGRAM_TYPE_SERVER))
 		sync_server_history(values_num, triggers_num, more);
 	else
 		sync_proxy_history(values_num, more);
-
-	if (0 > sigprocmask(SIG_SETMASK, &orig_mask, NULL))
-		zabbix_log(LOG_LEVEL_WARNING,"cannot restore sigprocmask");
-
-	zabbix_log(LOG_LEVEL_DEBUG, "End of %s()", __func__);
 }
 
 /******************************************************************************
diff --git a/src/libs/zbxdbupgrade/dbupgrade.c b/src/libs/zbxdbupgrade/dbupgrade.c
index b9f95c3dff3..f1ca923e9ad 100644
--- a/src/libs/zbxdbupgrade/dbupgrade.c
+++ b/src/libs/zbxdbupgrade/dbupgrade.c
@@ -933,9 +933,10 @@ int	DBcheck_version(void)
 			if (db_optional >= patches[i].version)
 				continue;
 
-			/* block SIGTERM, SIGINT to prevent interruption of statements that cause an implicit commit */
+			/* block signals to prevent interruption of statements that cause an implicit commit */
 			sigemptyset(&mask);
 			sigaddset(&mask, SIGTERM);
+			sigaddset(&mask, SIGUSR2);
 			sigaddset(&mask, SIGINT);
 			sigaddset(&mask, SIGQUIT);
 
diff --git a/src/libs/zbxlog/log.c b/src/libs/zbxlog/log.c
index b010a3646c7..fba23636495 100644
--- a/src/libs/zbxlog/log.c
+++ b/src/libs/zbxlog/log.c
@@ -232,9 +232,11 @@ static void	lock_log(void)
 {
 	sigset_t	mask;
 
+	/* block signals to prevent deadlock on log file mutex when signal handler attempts to lock log */
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGUSR1);
-	sigaddset(&mask, SIGTERM);	/* block SIGTERM, SIGINT to prevent deadlock on log file mutex */
+	sigaddset(&mask, SIGUSR2);
+	sigaddset(&mask, SIGTERM);
 	sigaddset(&mask, SIGINT);
 	sigaddset(&mask, SIGQUIT);
 
diff --git a/src/libs/zbxnix/fatal.c b/src/libs/zbxnix/fatal.c
index e77fb7f5dc9..eb862b4a4c2 100644
--- a/src/libs/zbxnix/fatal.c
+++ b/src/libs/zbxnix/fatal.c
@@ -62,6 +62,7 @@ const char	*get_signal_name(int sig)
 		case SIGTERM:	return "SIGTERM";
 		case SIGPIPE:	return "SIGPIPE";
 		case SIGUSR1:	return "SIGUSR1";
+		case SIGUSR2:	return "SIGUSR2";
 		default:	return "unknown";
 	}
 }
diff --git a/src/libs/zbxnix/sighandler.c b/src/libs/zbxnix/sighandler.c
index 26f1000310f..f666b122cb5 100644
--- a/src/libs/zbxnix/sighandler.c
+++ b/src/libs/zbxnix/sighandler.c
@@ -95,7 +95,7 @@ static void	alarm_signal_handler(int sig, siginfo_t *siginfo, void *context)
  *                                                                            *
  * Function: terminate_signal_handler                                         *
  *                                                                            *
- * Purpose: handle terminate signals: SIGQUIT, SIGINT, SIGTERM                *
+ * Purpose: handle terminate signals: SIGQUIT, SIGINT, SIGTERM, SIGUSR2       *
  *                                                                            *
  ******************************************************************************/
 static void	terminate_signal_handler(int sig, siginfo_t *siginfo, void *context)
@@ -104,24 +104,13 @@ static void	terminate_signal_handler(int sig, siginfo_t *siginfo, void *context)
 
 	if (!SIG_PARENT_PROCESS)
 	{
-		zabbix_log(sig_parent_pid == SIG_CHECKED_FIELD(siginfo, si_pid) || SIGINT == sig || SIGTERM == sig ?
-				LOG_LEVEL_DEBUG : LOG_LEVEL_WARNING,
-				"Got signal [signal:%d(%s),sender_pid:%d,sender_uid:%d,"
-				"reason:%d]. Exiting ...",
-				sig, get_signal_name(sig),
-				SIG_CHECKED_FIELD(siginfo, si_pid),
-				SIG_CHECKED_FIELD(siginfo, si_uid),
-				SIG_CHECKED_FIELD(siginfo, si_code));
-
-		/* ignore terminate signal in children - the parent */
-		/* process will send terminate signals instead      */
-		if (sig_parent_pid != SIG_CHECKED_FIELD(siginfo, si_pid))
-			return;
-
+		/* the parent process can either politely ask a child process to finish it's work and perform cleanup */
+		/* by sending SIGUSR2 or terminate child process immediately without cleanup by sending SIGQUIT       */
 		if (SIGQUIT == sig)
 			exit_with_failure();
 
-		sig_exiting = 1;
+		if (SIGUSR2 == sig)
+			sig_exiting = 1;
 	}
 	else
 	{
@@ -192,6 +181,7 @@ void	zbx_set_common_signal_handlers(void)
 	sigaction(SIGINT, &phan, NULL);
 	sigaction(SIGQUIT, &phan, NULL);
 	sigaction(SIGTERM, &phan, NULL);
+	sigaction(SIGUSR2, &phan, NULL);
 
 	phan.sa_sigaction = fatal_signal_handler;
 	sigaction(SIGILL, &phan, NULL);
diff --git a/src/libs/zbxsys/threads.c b/src/libs/zbxsys/threads.c
index dfbed362936..a4b75633003 100644
--- a/src/libs/zbxsys/threads.c
+++ b/src/libs/zbxsys/threads.c
@@ -57,9 +57,10 @@ void	zbx_child_fork(pid_t *pid)
 {
 	sigset_t	mask, orig_mask;
 
-	/* block SIGTERM, SIGINT and SIGCHLD during fork to avoid deadlock (we've seen one in __unregister_atfork()) */
+	/* block signals during fork to avoid deadlock (we've seen one in __unregister_atfork()) */
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGTERM);
+	sigaddset(&mask, SIGUSR2);
 	sigaddset(&mask, SIGINT);
 	sigaddset(&mask, SIGCHLD);
 	sigaddset(&mask, SIGQUIT);
diff --git a/src/zabbix_server/dbsyncer/dbsyncer.c b/src/zabbix_server/dbsyncer/dbsyncer.c
index ffb3a7d70eb..031cf17e7ca 100644
--- a/src/zabbix_server/dbsyncer/dbsyncer.c
+++ b/src/zabbix_server/dbsyncer/dbsyncer.c
@@ -31,6 +31,41 @@
 extern int		CONFIG_HISTSYNCER_FREQUENCY;
 extern unsigned char	process_type, program_type;
 extern int		server_num, process_num;
+static sigset_t		orig_mask;
+
+/******************************************************************************
+ *                                                                            *
+ * Function: block_signals                                                    *
+ *                                                                            *
+ * Purpose: block signals to avoid interruption                               *
+ *                                                                            *
+ ******************************************************************************/
+static	void	block_signals(void)
+{
+	sigset_t	mask;
+
+	sigemptyset(&mask);
+	sigaddset(&mask, SIGUSR1);
+	sigaddset(&mask, SIGUSR2);
+	sigaddset(&mask, SIGTERM);
+	sigaddset(&mask, SIGINT);
+
+	if (0 > sigprocmask(SIG_BLOCK, &mask, &orig_mask))
+		zabbix_log(LOG_LEVEL_WARNING, "cannot set sigprocmask to block the signal");
+}
+
+/******************************************************************************
+ *                                                                            *
+ * Function: unblock_signals                                                  *
+ *                                                                            *
+ * Purpose: unblock signals after blocking                                    *
+ *                                                                            *
+ ******************************************************************************/
+static	void	unblock_signals(void)
+{
+	if (0 > sigprocmask(SIG_SETMASK, &orig_mask, NULL))
+		zabbix_log(LOG_LEVEL_WARNING,"cannot restore sigprocmask");
+}
 
 /******************************************************************************
  *                                                                            *
@@ -67,7 +102,10 @@ ZBX_THREAD_ENTRY(dbsyncer_thread, args)
 
 	zbx_strcpy_alloc(&stats, &stats_alloc, &stats_offset, "started");
 
+	/* database APIs might not handle signals correctly and hang, block signals to avoid hanging */
+	block_signals();
 	DBconnect(ZBX_DB_CONNECT_NORMAL);
+	unblock_signals();
 
 	if (SUCCEED == zbx_is_export_enabled())
 	{
@@ -90,7 +128,11 @@ ZBX_THREAD_ENTRY(dbsyncer_thread, args)
 			zbx_log_sync_history_cache_progress();
 		}
 
+		/* database APIs might not handle signals correctly and hang, block signals to avoid hanging */
+		block_signals();
 		zbx_sync_history_cache(&values_num, &triggers_num, &more);
+		unblock_signals();
+
 		total_values_num += values_num;
 		total_triggers_num += triggers_num;
 		total_sec += zbx_time() - sec;
diff --git a/src/zabbix_server/poller/checks_snmp.c b/src/zabbix_server/poller/checks_snmp.c
index b9b8b62133e..b31e262bb38 100644
--- a/src/zabbix_server/poller/checks_snmp.c
+++ b/src/zabbix_server/poller/checks_snmp.c
@@ -2123,6 +2123,7 @@ void	zbx_init_snmp(void)
 
 	sigemptyset(&mask);
 	sigaddset(&mask, SIGTERM);
+	sigaddset(&mask, SIGUSR2);
 	sigaddset(&mask, SIGQUIT);
 	sigprocmask(SIG_BLOCK, &mask, &orig_mask);