linux-kernel - [PATCH AUTOSEL 6.6 195/294] media: test-drivers: vivid: don't call schedule in loop

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Message-Id: <20250505225634.2688578-195-sashal@kernel.org>
Date: Mon,  5 May 2025 18:54:55 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Hans Verkuil <hverkuil@...all.nl>,
	"Artem S . Tashkinov" <aros@....com>,
	Nicolas Dufresne <nicolas.dufresne@...labora.com>,
	Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	mchehab@...nel.org,
	linux-media@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 195/294] media: test-drivers: vivid: don't call schedule in loop

From: Hans Verkuil <hverkuil@...all.nl>

[ Upstream commit e4740118b752005cbed339aec9a1d1c43620e0b9 ]

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@...all.nl>
Reported-by: Artem S. Tashkinov <aros@....com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219570
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/test-drivers/vivid/vivid-kthread-cap.c  | 11 ++++++++---
 drivers/media/test-drivers/vivid/vivid-kthread-out.c  | 11 ++++++++---
 .../media/test-drivers/vivid/vivid-kthread-touch.c    | 11 ++++++++---
 drivers/media/test-drivers/vivid/vivid-sdr-cap.c      | 11 ++++++++---
 4 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/media/test-drivers/vivid/vivid-kthread-cap.c b/drivers/media/test-drivers/vivid/vivid-kthread-cap.c
index 42048727d7ff3..b8cdffc9a1e9e 100644
--- a/drivers/media/test-drivers/vivid/vivid-kthread-cap.c
+++ b/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;
diff --git a/drivers/media/test-drivers/vivid/vivid-kthread-out.c b/drivers/media/test-drivers/vivid/vivid-kthread-out.c
index fac6208b51da8..015a7b166a1e6 100644
--- a/drivers/media/test-drivers/vivid/vivid-kthread-out.c
+++ b/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;
diff --git a/drivers/media/test-drivers/vivid/vivid-kthread-touch.c b/drivers/media/test-drivers/vivid/vivid-kthread-touch.c
index fa711ee36a3fb..c862689786b69 100644
--- a/drivers/media/test-drivers/vivid/vivid-kthread-touch.c
+++ b/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;
diff --git a/drivers/media/test-drivers/vivid/vivid-sdr-cap.c b/drivers/media/test-drivers/vivid/vivid-sdr-cap.c
index a81f26b769883..1dd59c710dae7 100644
--- a/drivers/media/test-drivers/vivid/vivid-sdr-cap.c
+++ b/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;
-- 
2.39.5