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: Bhupesh Sharma <bhupesh.sharma@st.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/gadget/uvc_queue.c b/drivers/usb/gadget/uvc_queue.c
index d776adb..0cdf89d 100644 (file)
--- a/drivers/usb/gadget/uvc_queue.c
+++ b/drivers/usb/gadget/uvc_queue.c
@@ -543,11 +543,11 @@ done:
        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);