From 1591d785596e500b650a5a2a706bad1699b90f7f 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.

(cherry picked from commit b9cb29076fbe196013f4e7f080395555d13e9586)
---
 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));
 }