linux-kernel - [PATCH 1/2] ring_buffer: Initialize completions statically in the benchmark

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <1436454561-29925-2-git-send-email-pmladek@suse.com>
Date:	Thu,  9 Jul 2015 17:09:20 +0200
From:	Petr Mladek <pmladek@...e.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Jiri Kosina <jkosina@...e.cz>, Ingo Molnar <mingo@...nel.org>,
	linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH 1/2] ring_buffer: Initialize completions statically in the benchmark

It looks strange to initialize the completions repeatedly.

This patch uses static initialization. It simplifies the code
and even helps to get rid of two memory barriers.

Signed-off-by: Petr Mladek <pmladek@...e.com>
---
 kernel/trace/ring_buffer_benchmark.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index a1503a027ee2..ccb1a0b95f64 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -24,8 +24,8 @@ struct rb_page {
 static int wakeup_interval = 100;
 
 static int reader_finish;
-static struct completion read_start;
-static struct completion read_done;
+static DECLARE_COMPLETION(read_start);
+static DECLARE_COMPLETION(read_done);
 
 static struct ring_buffer *buffer;
 static struct task_struct *producer;
@@ -270,11 +270,6 @@ static void ring_buffer_producer(void)
 	trace_printk("End ring buffer hammer\n");
 
 	if (consumer) {
-		/* Init both completions here to avoid races */
-		init_completion(&read_start);
-		init_completion(&read_done);
-		/* the completions must be visible before the finish var */
-		smp_wmb();
 		reader_finish = 1;
 		/* finish var visible before waking up the consumer */
 		smp_wmb();
@@ -389,13 +384,10 @@ static int ring_buffer_consumer_thread(void *arg)
 
 static int ring_buffer_producer_thread(void *arg)
 {
-	init_completion(&read_start);
-
 	while (!kthread_should_stop() && !kill_test) {
 		ring_buffer_reset(buffer);
 
 		if (consumer) {
-			smp_wmb();
 			wake_up_process(consumer);
 			wait_for_completion(&read_start);
 		}
-- 
1.8.5.6

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/