media: test-drivers: vivid: don't call schedule in loop

[ Upstream commit e474011 ]

Artem reported that the CPU load was 100% when capturing from
vivid at low resolution with ffmpeg.

This was caused by:

while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
       !kthread_should_stop())
        schedule();

If there are no other processes running that can be scheduled,
then this is basically a busy-loop.

Change it to wait_event_interruptible_timeout() which doesn't
have that problem.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Reported-by: Artem S. Tashkinov <aros@gmx.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219570
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit a9b2bb8a4f25b0b85a541625c310f892271fd794)

Author: hverkuil

drivers/media/test-drivers/vivid/vivid-kthread-cap.c

@@ -765,9 +765,14 @@ static int vivid_thread_vid_cap(void *data)
 			next_jiffies_since_start = jiffies_since_start;
 
 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
-		while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
-		       !kthread_should_stop())
-			schedule();
+		if (!time_is_after_jiffies(cur_jiffies + wait_jiffies))
+			continue;
+
+		wait_queue_head_t wait;
+
+		init_waitqueue_head(&wait);
+		wait_event_interruptible_timeout(wait, kthread_should_stop(),
+					cur_jiffies + wait_jiffies - jiffies);
 	}
 	dprintk(dev, 1, "Video Capture Thread End\n");
 	return 0;

drivers/media/test-drivers/vivid/vivid-kthread-out.c

@@ -235,9 +235,14 @@ static int vivid_thread_vid_out(void *data)
 			next_jiffies_since_start = jiffies_since_start;
 
 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
-		while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
-		       !kthread_should_stop())
-			schedule();
+		if (!time_is_after_jiffies(cur_jiffies + wait_jiffies))
+			continue;
+
+		wait_queue_head_t wait;
+
+		init_waitqueue_head(&wait);
+		wait_event_interruptible_timeout(wait, kthread_should_stop(),
+					cur_jiffies + wait_jiffies - jiffies);
 	}
 	dprintk(dev, 1, "Video Output Thread End\n");
 	return 0;

drivers/media/test-drivers/vivid/vivid-kthread-touch.c

@@ -135,9 +135,14 @@ static int vivid_thread_touch_cap(void *data)
 			next_jiffies_since_start = jiffies_since_start;
 
 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
-		while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
-		       !kthread_should_stop())
-			schedule();
+		if (!time_is_after_jiffies(cur_jiffies + wait_jiffies))
+			continue;
+
+		wait_queue_head_t wait;
+
+		init_waitqueue_head(&wait);
+		wait_event_interruptible_timeout(wait, kthread_should_stop(),
+					cur_jiffies + wait_jiffies - jiffies);
 	}
 	dprintk(dev, 1, "Touch Capture Thread End\n");
 	return 0;

drivers/media/test-drivers/vivid/vivid-sdr-cap.c

@@ -206,9 +206,14 @@ static int vivid_thread_sdr_cap(void *data)
 			next_jiffies_since_start = jiffies_since_start;
 
 		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
-		while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
-		       !kthread_should_stop())
-			schedule();
+		if (!time_is_after_jiffies(cur_jiffies + wait_jiffies))
+			continue;
+
+		wait_queue_head_t wait;
+
+		init_waitqueue_head(&wait);
+		wait_event_interruptible_timeout(wait, kthread_should_stop(),
+					cur_jiffies + wait_jiffies - jiffies);
 	}
 	dprintk(dev, 1, "SDR Capture Thread End\n");
 	return 0;