Hi Bhupesh,
Thank you for the patch.
On Tuesday 13 March 2012 17:04:01 Bhupesh Sharma wrote:
> 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.
>
> A sample kernel crash log is given below (as observed on using 'g_webcam'
> with DWC designware 2.0 UDC):
>
> Kernel crash log:
> -----------------
[snip]
I don't think you need to include the complete crash report in the commit
message, the above description should be enough.
> Signed-off-by: Bhupesh Sharma <bhupesh.sha...@st.com>
Acked-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
This should probably go in through the USB tree. Could you please either send
a pull request or make sure the patch is picked up (after modifying the commit
message if you agree with my comment) ?
> ---
> drivers/usb/gadget/uvc_queue.c | 4 +---
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/gadget/uvc_queue.c b/drivers/usb/gadget/uvc_queue.c
> index d776adb..104ae9c 100644
> --- 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);
--
Regards,
Laurent Pinchart
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