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

[Petr Mladek <pmladek@suse.com>]

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@suse.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