[PATCH v2] media: uvcvideo: Return queued buffers on start_streaming() failure

[PATCH v2] media: uvcvideo: Return queued buffers on start_streaming() failure

[Laurent Pinchart]

From: Michal Pecio <michal.pecio@gmail.com>

Return buffers if streaming fails to start due to uvc_pm_get() error.

This bug may be responsible for a warning I got running

    while :; do yavta -c3 /dev/video0; done

on an xHCI controller which failed under this workload.
I had no luck reproducing this warning again to confirm.

xhci_hcd 0000:09:00.0: HC died; cleaning up
usb 13-2: USB disconnect, device number 2
WARNING: CPU: 2 PID: 29386 at drivers/media/common/videobuf2/videobuf2-core.c:1803 vb2_start_streaming+0xac/0x120

Fixes: 7dd56c47784a ("media: uvcvideo: Remove stream->is_streaming field")
Cc: stable@vger.kernel.org
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patch.msgid.link/20251015133642.3dede646.michal.pecio@gmail.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
Changes since v1:

- Reorganize error path
---
 drivers/media/usb/uvc/uvc_queue.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 790184c9843d..e838c6c1893a 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -177,18 +177,20 @@ static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
 
 	ret = uvc_pm_get(stream->dev);
 	if (ret)
-		return ret;
+		goto err_buffers;
 
 	queue->buf_used = 0;
 
 	ret = uvc_video_start_streaming(stream);
-	if (ret == 0)
-		return 0;
+	if (ret)
+		goto err_pm;
 
+	return 0;
+
+err_pm:
 	uvc_pm_put(stream->dev);
-
+err_buffers:
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
-
 	return ret;
 }
 

base-commit: d363bdfa0ec6b19a4f40b572cec70430d5b13ad6
-- 
Regards,

Laurent Pinchart

Re: [PATCH v2] media: uvcvideo: Return queued buffers on start_streaming() failure

[Michal Pecio]

On Thu, 13 Nov 2025 23:40:56 +0200, Laurent Pinchart wrote:
> From: Michal Pecio <michal.pecio@gmail.com>
> 
> Return buffers if streaming fails to start due to uvc_pm_get() error.
> 
> This bug may be responsible for a warning I got running
> 
>     while :; do yavta -c3 /dev/video0; done
> 
> on an xHCI controller which failed under this workload.
> I had no luck reproducing this warning again to confirm.
> 
> xhci_hcd 0000:09:00.0: HC died; cleaning up
> usb 13-2: USB disconnect, device number 2
> WARNING: CPU: 2 PID: 29386 at drivers/media/common/videobuf2/videobuf2-core.c:1803 vb2_start_streaming+0xac/0x120
> 
> Fixes: 7dd56c47784a ("media: uvcvideo: Remove stream->is_streaming field")
> Cc: stable@vger.kernel.org
> Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Link: https://patch.msgid.link/20251015133642.3dede646.michal.pecio@gmail.com
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> Changes since v1:
> 
> - Reorganize error path

Look alright, thanks for taking the patch.