linux-kernel - [PATCH 3/9] media: uvcvideo: Keep streaming state in the file handle

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Message-Id: <20241126-uvc-granpower-ng-v1-3-6312bf26549c@chromium.org>
Date: Tue, 26 Nov 2024 16:18:53 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hdegoede@...hat.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Guennadi Liakhovetski <guennadi.liakhovetski@...el.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Mauro Carvalho Chehab <mchehab+samsung@...nel.org>, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH 3/9] media: uvcvideo: Keep streaming state in the file
 handle

Add a variable in the file handle state to figure out if a camera is in
the streaming state or not.
This variable will be used in the future for power management policies.

Now that we are at it, make use of guards to simplify the code.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_v4l2.c | 15 +++++++++++----
 drivers/media/usb/uvc/uvcvideo.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index b425306a3b8c..712a531e52f9 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -888,11 +888,17 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
 	if (!uvc_has_privileges(handle))
 		return -EBUSY;
 
-	mutex_lock(&stream->mutex);
+	guard(mutex)(&stream->mutex);
+
+	if (handle->is_streaming)
+		return 0;
+
 	ret = uvc_queue_streamon(&stream->queue, type);
-	mutex_unlock(&stream->mutex);
+	if (!ret)
+		handle->is_streaming = true;
 
 	return ret;
+
 }
 
 static int uvc_ioctl_streamoff(struct file *file, void *fh,
@@ -904,9 +910,10 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
 	if (!uvc_has_privileges(handle))
 		return -EBUSY;
 
-	mutex_lock(&stream->mutex);
+	guard(mutex)(&stream->mutex);
+
 	uvc_queue_streamoff(&stream->queue, type);
-	mutex_unlock(&stream->mutex);
+	handle->is_streaming = false;
 
 	return 0;
 }
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 2f8a9c48e32a..b63194a9c64e 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -613,6 +613,7 @@ struct uvc_fh {
 	struct uvc_streaming *stream;
 	enum uvc_handle_state state;
 	unsigned int pending_async_ctrls; /* Protected by ctrl_mutex. */
+	bool is_streaming;
 };
 
 struct uvc_driver {

-- 
2.47.0.338.g60cca15819-goog