From: Ondřej Surý <ondrej@isc.org>
Date: Tue, 4 Feb 2025 18:17:28 +0000 (+0100)
Subject: Explicitly create and shutdown the call_rcu_thread
X-Git-Tag: ondrej/lock-free-qpzone-reads-v1~36^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4917ffa61b83c4bb453c52516157d1bf0ba4d0d6;p=thirdparty%2Fbind9.git

Explicitly create and shutdown the call_rcu_thread

As the default_call_rcu_thread can't be forced to flush all the work
during the executable shutdown, create one call_rcu_thread explicitly
and assign it to the all created threads.

This allows this explicit call_rcu_thread to be unassociated from the
main thread and freed before the executable destructor exits.
---

diff --git a/lib/isc/Makefile.am b/lib/isc/Makefile.am
index 7cdca91b475..4359b517b7e 100644
--- a/lib/isc/Makefile.am
+++ b/lib/isc/Makefile.am
@@ -194,6 +194,7 @@ libisc_la_SOURCES =		\
 	symtab.c		\
 	syslog.c		\
 	thread.c		\
+	thread_p.h		\
 	tid.c			\
 	time.c			\
 	timer.c			\
diff --git a/lib/isc/lib.c b/lib/isc/lib.c
index 4553f4a3b50..db3918a5e22 100644
--- a/lib/isc/lib.c
+++ b/lib/isc/lib.c
@@ -29,6 +29,7 @@
 #include "mem_p.h"
 #include "mutex_p.h"
 #include "os_p.h"
+#include "thread_p.h"
 
 /***
  *** Functions
@@ -48,6 +49,7 @@ isc__lib_initialize(void) {
 	}
 
 	rcu_register_thread();
+	isc__thread_initialize();
 	isc__os_initialize();
 	isc__mutex_initialize();
 	isc__mem_initialize();
@@ -74,6 +76,7 @@ isc__lib_shutdown(void) {
 	isc__mem_shutdown();
 	isc__mutex_shutdown();
 	isc__os_shutdown();
+	isc__thread_shutdown();
 	/* should be after isc__mem_shutdown() which calls rcu_barrier() */
 	rcu_unregister_thread();
 }
diff --git a/lib/isc/thread.c b/lib/isc/thread.c
index ca0c1a219a1..8bc0e94ad48 100644
--- a/lib/isc/thread.c
+++ b/lib/isc/thread.c
@@ -38,10 +38,14 @@
 #include <isc/urcu.h>
 #include <isc/util.h>
 
+#include "thread_p.h"
+
 #ifndef THREAD_MINSTACKSIZE
 #define THREAD_MINSTACKSIZE (1024U * 1024)
 #endif /* ifndef THREAD_MINSTACKSIZE */
 
+static struct call_rcu_data *isc__thread_call_rcu_data = NULL;
+
 /*
  * We can't use isc_mem API here, because it's called too early and the
  * isc_mem_debugging flags can be changed later causing mismatch between flags
@@ -97,12 +101,16 @@ thread_run(void *wrap) {
 
 	rcu_register_thread();
 
+	set_thread_call_rcu_data(isc__thread_call_rcu_data);
+
 	void *ret = thread_body(wrap);
 
-	isc__iterated_hash_shutdown();
+	set_thread_call_rcu_data(NULL);
 
 	rcu_unregister_thread();
 
+	isc__iterated_hash_shutdown();
+
 	return ret;
 }
 
@@ -179,3 +187,15 @@ isc_thread_yield(void) {
 	pthread_yield_np();
 #endif /* if defined(HAVE_SCHED_YIELD) */
 }
+
+void
+isc__thread_initialize(void) {
+	isc__thread_call_rcu_data = create_call_rcu_data(0, -1);
+	set_thread_call_rcu_data(isc__thread_call_rcu_data);
+}
+
+void
+isc__thread_shutdown(void) {
+	set_thread_call_rcu_data(NULL);
+	call_rcu_data_free(isc__thread_call_rcu_data);
+}
diff --git a/lib/isc/thread_p.h b/lib/isc/thread_p.h
new file mode 100644
index 00000000000..6ed32cd984c
--- /dev/null
+++ b/lib/isc/thread_p.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#pragma once
+
+#include <isc/thread.h>
+
+/*! \file */
+
+void
+isc__thread_initialize(void);
+
+void
+isc__thread_shutdown(void);