X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=doc%2Fexamples%2Furcu-flavors%2Fqsbr.c;h=ca00933a1a88ba4640640c4b6cd2bd5cb3e36c7e;hb=81270292c23ff28aba1abd9a65f0624b657de82b;hp=1c50b8aedaf9b368309acc92e3b5bf840437f7a0;hpb=6df9f02d9de67572ab8bd34855eca233c16ced47;p=userspace-rcu.git

diff --git a/doc/examples/urcu-flavors/qsbr.c b/doc/examples/urcu-flavors/qsbr.c
index 1c50b8a..ca00933 100644
--- a/doc/examples/urcu-flavors/qsbr.c
+++ b/doc/examples/urcu-flavors/qsbr.c
@@ -1,27 +1,14 @@
-/*
- * Copyright (C) 2013  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
+// SPDX-FileCopyrightText: 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
 
+#include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <inttypes.h>
 
-#include <urcu-qsbr.h>		/* QSBR RCU flavor */
+#include <urcu/urcu-qsbr.h>	/* QSBR RCU flavor */
 #include <urcu/rculist.h>	/* List example */
 #include <urcu/compiler.h>	/* For CAA_ARRAY_SIZE */
 
@@ -45,7 +32,7 @@ int add_node(uint64_t v)
 {
 	struct mynode *node;
 
-	node = calloc(sizeof(*node), 1);
+	node = calloc(1, sizeof(*node));
 	if (!node)
 		return -1;
 	node->value = v;
@@ -61,7 +48,7 @@ void rcu_free_node(struct rcu_head *rh)
 	free(node);
 }
 
-int main(int argc, char **argv)
+int main(void)
 {
 	uint64_t values[] = { 42, 36, 24, };
 	unsigned int i;
@@ -72,7 +59,7 @@ int main(int argc, char **argv)
 	 * Each thread need using RCU read-side need to be explicitly
 	 * registered.
 	 */
-	rcu_register_thread();
+	urcu_qsbr_register_thread();
 
 	/*
 	 * Adding nodes to the linked-list. Safe against concurrent
@@ -84,21 +71,12 @@ int main(int argc, char **argv)
 			goto end;
 	}
 
-	/*
-	 * For all RCU flavors except QSBR, we need to explicitly mark
-	 * RCU read-side critical sections with rcu_read_lock() and
-	 * rcu_read_unlock(). They can be nested. Those are no-ops for
-	 * the QSBR flavor.
-	 */
-	rcu_read_lock();
-
 	/*
 	 * RCU traversal of the linked list.
 	 */
 	cds_list_for_each_entry_rcu(node, &mylist, node) {
 		printf("Value: %" PRIu64 "\n", node->value);
 	}
-	rcu_read_unlock();
 
 	/*
 	 * Removing nodes from linked list. Safe against concurrent RCU
@@ -106,7 +84,13 @@ int main(int argc, char **argv)
 	 */
 	cds_list_for_each_entry_safe(node, n, &mylist, node) {
 		cds_list_del_rcu(&node->node);
-		call_rcu(&node->rcu_head, rcu_free_node);
+		/*
+		 * call_rcu() will ensure that the handler
+		 * "rcu_free_node" is executed after a grace period.
+		 * call_rcu() can be called from RCU read-side critical
+		 * sections.
+		 */
+		urcu_qsbr_call_rcu(&node->rcu_head, rcu_free_node);
 	}
 
 	/*
@@ -115,27 +99,37 @@ int main(int argc, char **argv)
 	 * every online registered RCU threads in the program
 	 * periodically.
 	 */
-	rcu_quiescent_state();
+	urcu_qsbr_quiescent_state();
 
 	/*
 	 * For QSBR flavor, when a thread needs to be in a quiescent
 	 * state for a long period of time, we use rcu_thread_offline()
 	 * and rcu_thread_online().
 	 */
-	rcu_thread_offline();
+	urcu_qsbr_thread_offline();
 
 	sleep(1);
 
-	rcu_thread_online();
+	urcu_qsbr_thread_online();
+
+	/*
+	 * We can also wait for a quiescent state by calling
+	 * synchronize_rcu() rather than using call_rcu(). It is usually
+	 * a slower approach than call_rcu(), because the latter can
+	 * batch work. Moreover, call_rcu() can be called from a RCU
+	 * read-side critical section, but synchronize_rcu() ensures the
+	 * caller thread is offline, thus acting as a quiescent state.
+	 */
+	urcu_qsbr_synchronize_rcu();
 
 	/*
 	 * Waiting for previously called call_rcu handlers to complete
 	 * before program exits, or in library destructors, is a good
 	 * practice.
 	 */
-	rcu_barrier();
+	urcu_qsbr_barrier();
 
 end:
-	rcu_unregister_thread();
+	urcu_qsbr_unregister_thread();
 	return ret;
 }