fix: openldap-servers upgrade hangs

Resolves: #664433
Upstream ITS: #6853

--- openldap-2.4.24.orig/servers/slapd/back-bdb/tools.c
+++ openldap-2.4.24/servers/slapd/back-bdb/tools.c
@@ -90,8 +90,10 @@
 #ifdef USE_TRICKLE
 static ldap_pvt_thread_mutex_t bdb_tool_trickle_mutex;
 static ldap_pvt_thread_cond_t bdb_tool_trickle_cond;
+static ldap_pvt_thread_cond_t bdb_tool_trickle_cond_end;
 
 static void * bdb_tool_trickle_task( void *ctx, void *ptr );
+static int bdb_tool_trickle_active;
 #endif
 
 static void * bdb_tool_index_task( void *ctx, void *ptr );
@@ -127,6 +129,7 @@
 #ifdef USE_TRICKLE
 			ldap_pvt_thread_mutex_init( &bdb_tool_trickle_mutex );
 			ldap_pvt_thread_cond_init( &bdb_tool_trickle_cond );
+			ldap_pvt_thread_cond_init( &bdb_tool_trickle_cond_end );
 			ldap_pvt_thread_pool_submit( &connection_pool, bdb_tool_trickle_task, bdb->bi_dbenv );
 #endif
 
@@ -159,7 +162,16 @@
 		slapd_shutdown = 1;
 #ifdef USE_TRICKLE
 		ldap_pvt_thread_mutex_lock( &bdb_tool_trickle_mutex );
+
+		/* trickle thread may not have started yet */
+		while ( !bdb_tool_trickle_active )
+			ldap_pvt_thread_cond_wait( &bdb_tool_trickle_cond_end,
+					&bdb_tool_trickle_mutex );
+
 		ldap_pvt_thread_cond_signal( &bdb_tool_trickle_cond );
+		while ( bdb_tool_trickle_active )
+			ldap_pvt_thread_cond_wait( &bdb_tool_trickle_cond_end,
+					&bdb_tool_trickle_mutex );
 		ldap_pvt_thread_mutex_unlock( &bdb_tool_trickle_mutex );
 #endif
 		ldap_pvt_thread_mutex_lock( &bdb_tool_index_mutex );
@@ -1249,6 +1261,8 @@
 	int wrote;
 
 	ldap_pvt_thread_mutex_lock( &bdb_tool_trickle_mutex );
+	bdb_tool_trickle_active = 1;
+	ldap_pvt_thread_cond_signal( &bdb_tool_trickle_cond_end );
 	while ( 1 ) {
 		ldap_pvt_thread_cond_wait( &bdb_tool_trickle_cond,
 			&bdb_tool_trickle_mutex );
@@ -1256,6 +1270,8 @@
 			break;
 		env->memp_trickle( env, 30, &wrote );
 	}
+	bdb_tool_trickle_active = 0;
+	ldap_pvt_thread_cond_signal( &bdb_tool_trickle_cond_end );
 	ldap_pvt_thread_mutex_unlock( &bdb_tool_trickle_mutex );
 
 	return NULL;