linux-kernel - [RFC/RFT PATCH 4/6] uvcvideo: queue: Simplify spin-lock usage

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Message-Id: <2c5bcf7e4b2885071504cf61a99206aba9cb82b6.1515010476.git-series.kieran.bingham@ideasonboard.com>
Date:   Wed,  3 Jan 2018 20:32:54 +0000
From:   Kieran Bingham <kbingham@...nel.org>
To:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        laurent.pinchart@...asonboard.com
Cc:     Olivier BRAUN <olivier.braun@...reolabs.com>,
        kieran.bingham@...asonboard.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Guennadi Liakhovetski <g.liakhovetski@....de>,
        Hans Verkuil <hans.verkuil@...co.com>
Subject: [RFC/RFT PATCH 4/6] uvcvideo: queue: Simplify spin-lock usage

From: Kieran Bingham <kieran.bingham@...asonboard.com>

Both uvc_start_streaming(), and uvc_stop_streaming() are called from
userspace context. As such, they do not need to save the IRQ state, and
can use spin_lock_irq() and spin_unlock_irq() respectively.

Signed-off-by: Kieran Bingham <kieran.bingham@...asonboard.com>
---
 drivers/media/usb/uvc/uvc_queue.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 0711e3d9ff76..28dbdf8bb533 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -158,7 +158,6 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
 	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
-	unsigned long flags;
 	int ret;
 
 	queue->buf_used = 0;
@@ -167,9 +166,9 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	if (ret == 0)
 		return 0;
 
-	spin_lock_irqsave(&queue->irqlock, flags);
+	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
-	spin_unlock_irqrestore(&queue->irqlock, flags);
+	spin_unlock_irq(&queue->irqlock);
 
 	return ret;
 }
@@ -178,13 +177,12 @@ static void uvc_stop_streaming(struct vb2_queue *vq)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
 	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
-	unsigned long flags;
 
 	uvc_video_enable(stream, 0);
 
-	spin_lock_irqsave(&queue->irqlock, flags);
+	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
-	spin_unlock_irqrestore(&queue->irqlock, flags);
+	spin_unlock_irq(&queue->irqlock);
 }
 
 static const struct vb2_ops uvc_queue_qops = {
-- 
git-series 0.9.1