linux-kernel - [PATCH v4 4/6] media: uvcvideo: queue: Simplify spin-lock usage

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Date:   Tue, 27 Mar 2018 17:46:01 +0100
From:   Kieran Bingham <kieran.bingham@...asonboard.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-media@...r.kernel.org
Cc:     Guennadi Liakhovetski <g.liakhovetski@....de>,
        Olivier BRAUN <olivier.braun@...reolabs.com>,
        Troy Kisky <troy.kisky@...ndarydevices.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Philipp Zabel <philipp.zabel@...il.com>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v4 4/6] media: uvcvideo: queue: Simplify spin-lock usage

Both uvc_start_streaming(), and uvc_stop_streaming() are called from
userspace context, with interrupts enabled. 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>

---

v4:
 - Rebase to v4.16 (linux-media/master)

 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 adcc4928fae4..698d9a5a5aae 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -169,7 +169,6 @@ 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;
@@ -178,9 +177,9 @@ 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;
 }
@@ -188,14 +187,13 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 static void uvc_stop_streaming(struct vb2_queue *vq)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-	unsigned long flags;
 
 	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
 		uvc_video_enable(uvc_queue_to_stream(queue), 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 = {
-- 
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