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Commit 95faf82b authored by Bhupesh Sharma's avatar Bhupesh Sharma Committed by Mauro Carvalho Chehab
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[media] usb: gadget/uvc: Remove non-required locking from 'uvc_queue_next_buffer' routine 



This patch removes the non-required spinlock acquire/release calls on
'queue_irqlock' from 'uvc_queue_next_buffer' routine.

This routine is called from 'video->encode' function (which translates to either
'uvc_video_encode_bulk' or 'uvc_video_encode_isoc') in 'uvc_video.c'.
As, the 'video->encode' routines are called with 'queue_irqlock' already held,
so acquiring a 'queue_irqlock' again in 'uvc_queue_next_buffer' routine causes
a spin lock recursion.

Signed-off-by: default avatarBhupesh Sharma <bhupesh.sharma@st.com>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 7cfce77d

drivers/usb/gadget/uvc_queue.c

+1 −3
Original line number Diff line number Diff line
@@ -543,11 +543,11 @@ static int uvc_queue_enable(struct uvc_video_queue *queue, int enable) 
	return ret;

}



/* called with &queue_irqlock held.. */

static struct uvc_buffer *

uvc_queue_next_buffer(struct uvc_video_queue *queue, struct uvc_buffer *buf)

{

	struct uvc_buffer *nextbuf;

	unsigned long flags;



	if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&

	    buf->buf.length != buf->buf.bytesused) {
@@ -556,14 +556,12 @@ uvc_queue_next_buffer(struct uvc_video_queue *queue, struct uvc_buffer *buf) 
		return buf;

	}



	spin_lock_irqsave(&queue->irqlock, flags);

	list_del(&buf->queue);

	if (!list_empty(&queue->irqqueue))

		nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,

					   queue);

	else

		nextbuf = NULL;

	spin_unlock_irqrestore(&queue->irqlock, flags);



	buf->buf.sequence = queue->sequence++;

	do_gettimeofday(&buf->buf.timestamp);