[RFC PATCH 15/18] ring_buffer: Allow to exit the ring buffer benchmark immediately

[Petr Mladek]

It takes a while until the ring_buffer_benchmark module is removed
when the ring buffer hammer is running. It is because it takes
few seconds and kthread_should_terminate() is not being checked.

This patch adds the check for kthread termination into the producer.
It uses the existing kill_test flag to finish the kthreads as
cleanly as possible.

It disables printing the "ERROR" message when the kthread is going.

Also it makes sure that producer does not go into the 10sec sleep
when it is being killed.

Signed-off-by: Petr Mladek <pmladek at suse.cz>
---
 kernel/trace/ring_buffer_benchmark.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 2d276b892aea..4ecf7c4567e2 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -270,6 +270,9 @@ static void ring_buffer_producer(void)
 			try_to_freeze();
 		}
 
+		if (kthread_should_stop())
+			kill_test = 1;
+
 	} while (ktime_before(end_time, timeout) && !kill_test);
 	trace_printk("End ring buffer hammer\n");
 
@@ -291,7 +294,7 @@ static void ring_buffer_producer(void)
 	entries = ring_buffer_entries(buffer);
 	overruns = ring_buffer_overruns(buffer);
 
-	if (kill_test)
+	if (kill_test && !kthread_should_stop())
 		trace_printk("ERROR!\n");
 
 	if (!disable_reader) {
@@ -377,10 +380,8 @@ static void ring_buffer_producer_thread_init(void *arg)
 
 static void ring_buffer_producer_thread_func(void *arg)
 {
-	if (kill_test) {
-		set_kthread_iterant_int_sleep();
-		return;
-	}
+	if (kill_test)
+		goto test_killed;
 
 	ring_buffer_reset(buffer);
 
@@ -393,9 +394,16 @@ static void ring_buffer_producer_thread_func(void *arg)
 
 	ring_buffer_producer();
 
+	if (kill_test)
+		goto test_killed;
+
 	trace_printk("Sleeping for 10 secs\n");
 	set_current_state(TASK_INTERRUPTIBLE);
 	schedule_timeout(HZ * SLEEP_TIME);
+	return;
+
+test_killed:
+	set_kthread_iterant_int_sleep();
 }
 
 static int __init ring_buffer_benchmark_init(void)
-- 
1.8.5.6