linux-kernel - [PATCH v3 3/4] usb: gadget: uvc: disable stream when disconnected

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Date:   Wed,  9 Jan 2019 02:10:38 -0500
From:   Paul Elder <paul.elder@...asonboard.com>
To:     laurent.pinchart@...asonboard.com, kieran.bingham@...asonboard.com
Cc:     Paul Elder <paul.elder@...asonboard.com>, rogerq@...com,
        balbi@...nel.org, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 3/4] usb: gadget: uvc: disable stream when disconnected

If the streamon ioctl is issued while the stream is already on, then the
kernel BUGs. This happens at the BUG_ON in uvc_video_alloc_requests
within the call stack from the ioctl handler for VIDIOC_STREAMON.

This can also be triggered by starting the stream and then physically
disconnecting usb. To fix this, do the streamoff procedures on usb
disconnect. Since uvcg_video_enable is not interrupt-safe, add an
interrupt-safe version uvcg_video_cancel, and use that.

Signed-off-by: Paul Elder <paul.elder@...asonboard.com>
v2 Reviewed-by: Kieran Bingham <kieran.bingham@...asonboard.com>
---
Changes in v3:

- added interrupt-safe uvcg_video_cancel and used instead of the
  non-interrupt-save uvcg_video_enable 0

Changes in v2: Nothing

 drivers/usb/gadget/function/f_uvc.c     |  3 +++
 drivers/usb/gadget/function/uvc_video.c | 13 +++++++++++++
 drivers/usb/gadget/function/uvc_video.h |  2 ++
 3 files changed, 18 insertions(+)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index b407b10a95ed..4134117b5f81 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -369,9 +369,12 @@ uvc_function_disable(struct usb_function *f)
 {
 	struct uvc_device *uvc = to_uvc(f);
 	struct v4l2_event v4l2_event;
+	struct uvc_video *video = &uvc->video;
 
 	uvcg_info(f, "%s()\n", __func__);
 
+	uvcg_video_cancel(video, 1);
+
 	memset(&v4l2_event, 0, sizeof(v4l2_event));
 	v4l2_event.type = UVC_EVENT_DISCONNECT;
 	v4l2_event_queue(&uvc->vdev, &v4l2_event);
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index 5c042f380708..5f3ed9e0b5ad 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -348,6 +348,19 @@ int uvcg_video_pump(struct uvc_video *video)
 	return 0;
 }
 
+int uvcg_video_cancel(struct uvc_video *video, int disconnect)
+{
+	unsigned int i;
+
+	for (i = 0; i < UVC_NUM_REQUESTS; ++i)
+		if (video->req[i])
+			usb_ep_dequeue(video->ep, video->req[i]);
+
+	uvc_video_free_requests(video);
+	uvcg_queue_cancel(&video->queue, disconnect);
+	return 0;
+}
+
 /*
  * Enable or disable the video stream.
  */
diff --git a/drivers/usb/gadget/function/uvc_video.h b/drivers/usb/gadget/function/uvc_video.h
index 278dc52c7604..1f310fa58ce5 100644
--- a/drivers/usb/gadget/function/uvc_video.h
+++ b/drivers/usb/gadget/function/uvc_video.h
@@ -16,6 +16,8 @@ struct uvc_video;
 
 int uvcg_video_pump(struct uvc_video *video);
 
+int uvcg_video_cancel(struct uvc_video *video, int disconnect);
+
 int uvcg_video_enable(struct uvc_video *video, int enable);
 
 int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc);
-- 
2.20.1