From b9cb29076fbe196013f4e7f080395555d13e9586 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Thu, 10 Feb 2022 09:21:26 +0100
Subject: [PATCH] Log when starting and ending task exclusive mode

The task exclusive mode stops all processing (tasks and networking IO)
except the designated exclusive task events.  This has impact on the
operation of the server.  Add log messages indicating when we start the
exclusive mode, and when we end exclusive task mode.
---
 lib/isc/task.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/lib/isc/task.c b/lib/isc/task.c
index d0f9d9be38..666eb13fb2 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -25,6 +25,7 @@
 #include <isc/atomic.h>
 #include <isc/condition.h>
 #include <isc/event.h>
+#include <isc/log.h>
 #include <isc/magic.h>
 #include <isc/mem.h>
 #include <isc/once.h>
@@ -1107,8 +1108,20 @@ isc_task_beginexclusive(isc_task_t *task) {
 		return (ISC_R_LOCKBUSY);
 	}
 
+	if (isc_log_wouldlog(isc_lctx, ISC_LOG_DEBUG(1))) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_OTHER, ISC_LOG_DEBUG(1),
+			      "exclusive task mode: %s", "starting");
+	}
+
 	isc_nm_pause(manager->netmgr);
 
+	if (isc_log_wouldlog(isc_lctx, ISC_LOG_DEBUG(1))) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_OTHER, ISC_LOG_DEBUG(1),
+			      "exclusive task mode: %s", "started");
+	}
+
 	return (ISC_R_SUCCESS);
 }
 
@@ -1120,7 +1133,20 @@ isc_task_endexclusive(isc_task_t *task) {
 	REQUIRE(task->state == task_state_running);
 	manager = task->manager;
 
+	if (isc_log_wouldlog(isc_lctx, ISC_LOG_DEBUG(1))) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_OTHER, ISC_LOG_DEBUG(1),
+			      "exclusive task mode: %s", "ending");
+	}
+
 	isc_nm_resume(manager->netmgr);
+
+	if (isc_log_wouldlog(isc_lctx, ISC_LOG_DEBUG(1))) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_OTHER, ISC_LOG_DEBUG(1),
+			      "exclusive task mode: %s", "ended");
+	}
+
 	REQUIRE(atomic_compare_exchange_strong(&manager->exclusive_req,
 					       &(bool){ true }, false));
 }