Re: [PATCH v3 1/3] usb: gadget: uvc: prevent use of disabled endpoint

[Michael Grzeschik <mgr@pengutronix.de>]

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On Thu, Oct 05, 2023 at 11:08:12AM -0700, Avichal Rakesh wrote:
>Currently the set_alt callback immediately disables the endpoint and queues
>the v4l2 streamoff event. However, as the streamoff event is processed
>asynchronously, it is possible that the video_pump thread attempts to queue
>requests to an already disabled endpoint.
>
>This change moves disabling usb endpoint to the end of streamoff event
>callback. To be consistent with the actual streaming state, uvc->state
>is now toggled between CONNECTED and STREAMING from the v4l2 event
>callback only.
>
>Link: https://lore.kernel.org/20230615171558.GK741@pendragon.ideasonboard.com/
>Link: https://lore.kernel.org/20230531085544.253363-1-dan.scally@ideasonboard.com/
>Signed-off-by: Avichal Rakesh <arakesh@google.com>
>---
>v1 -> v2: Rebased to ToT and reworded commit message.
>v2 -> v3: Fix email threading goof-up
>
> drivers/usb/gadget/function/f_uvc.c    | 11 +++++------
> drivers/usb/gadget/function/f_uvc.h    |  2 +-
> drivers/usb/gadget/function/uvc.h      |  2 +-
> drivers/usb/gadget/function/uvc_v4l2.c | 21 ++++++++++++++++++---
> 4 files changed, 25 insertions(+), 11 deletions(-)
>
>diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
>index faa398109431..75c9f9a3f884 100644
>--- a/drivers/usb/gadget/function/f_uvc.c
>+++ b/drivers/usb/gadget/function/f_uvc.c
>@@ -263,10 +263,13 @@ uvc_function_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
> 	return 0;
> }
>
>-void uvc_function_setup_continue(struct uvc_device *uvc)
>+void uvc_function_setup_continue(struct uvc_device *uvc, int disable_ep)
> {
> 	struct usb_composite_dev *cdev = uvc->func.config->cdev;
>
>+	if (disable_ep && uvc->video.ep) {
>+		usb_ep_disable(uvc->video.ep);
>+	}

Could you drop the extra braces and add one spare line here.

> 	usb_composite_setup_continue(cdev);
> }
>
>@@ -337,15 +340,11 @@ uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
> 		if (uvc->state != UVC_STATE_STREAMING)
> 			return 0;
>
>-		if (uvc->video.ep)
>-			usb_ep_disable(uvc->video.ep);
>-
> 		memset(&v4l2_event, 0, sizeof(v4l2_event));
> 		v4l2_event.type = UVC_EVENT_STREAMOFF;
> 		v4l2_event_queue(&uvc->vdev, &v4l2_event);
>
>-		uvc->state = UVC_STATE_CONNECTED;
>-		return 0;
>+		return USB_GADGET_DELAYED_STATUS;
>
> 	case 1:
> 		if (uvc->state != UVC_STATE_CONNECTED)
>diff --git a/drivers/usb/gadget/function/f_uvc.h b/drivers/usb/gadget/function/f_uvc.h
>index 1db972d4beeb..e7f9f13f14dc 100644
>--- a/drivers/usb/gadget/function/f_uvc.h
>+++ b/drivers/usb/gadget/function/f_uvc.h
>@@ -11,7 +11,7 @@
>
> struct uvc_device;
>
>-void uvc_function_setup_continue(struct uvc_device *uvc);
>+void uvc_function_setup_continue(struct uvc_device *uvc, int disale_ep);
>
> void uvc_function_connect(struct uvc_device *uvc);
>
>diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
>index 6751de8b63ad..989bc6b4e93d 100644
>--- a/drivers/usb/gadget/function/uvc.h
>+++ b/drivers/usb/gadget/function/uvc.h
>@@ -177,7 +177,7 @@ struct uvc_file_handle {
>  * Functions
>  */
>
>-extern void uvc_function_setup_continue(struct uvc_device *uvc);
>+extern void uvc_function_setup_continue(struct uvc_device *uvc, int disable_ep);
> extern void uvc_function_connect(struct uvc_device *uvc);
> extern void uvc_function_disconnect(struct uvc_device *uvc);
>
>diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
>index 3f0a9795c0d4..3d3469883ed0 100644
>--- a/drivers/usb/gadget/function/uvc_v4l2.c
>+++ b/drivers/usb/gadget/function/uvc_v4l2.c
>@@ -451,7 +451,7 @@ uvc_v4l2_streamon(struct file *file, void *fh, enum v4l2_buf_type type)
> 	 * Complete the alternate setting selection setup phase now that
> 	 * userspace is ready to provide video frames.
> 	 */
>-	uvc_function_setup_continue(uvc);
>+	uvc_function_setup_continue(uvc, 0);
> 	uvc->state = UVC_STATE_STREAMING;
>
> 	return 0;
>@@ -463,11 +463,19 @@ uvc_v4l2_streamoff(struct file *file, void *fh, enum v4l2_buf_type type)
> 	struct video_device *vdev = video_devdata(file);
> 	struct uvc_device *uvc = video_get_drvdata(vdev);
> 	struct uvc_video *video = &uvc->video;
>+	int ret = 0;
>
> 	if (type != video->queue.queue.type)
> 		return -EINVAL;
>
>-	return uvcg_video_enable(video, 0);
>+	uvc->state = UVC_STATE_CONNECTED;
>+	ret = uvcg_video_enable(video, 0);
>+	if (ret < 0) {
>+		return ret;
>+	}

Please drop those extra braces.

>+
>+	uvc_function_setup_continue(uvc, 1);
>+	return 0;
> }
>
> static int
>@@ -500,6 +508,14 @@ uvc_v4l2_subscribe_event(struct v4l2_fh *fh,
> static void uvc_v4l2_disable(struct uvc_device *uvc)
> {
> 	uvc_function_disconnect(uvc);
>+	if (uvc->state == UVC_STATE_STREAMING) {
>+		/*
>+		 * Drop uvc->state to CONNECTED if it was streaming before.
>+		 * This ensures that the usb_requests are no longer queued
>+		 * to the controller.
>+		 */
>+		uvc->state = UVC_STATE_CONNECTED;
>+	}

Could you write the comment above the check
and also remove the extra braces.

> 	uvcg_video_enable(&uvc->video, 0);
> 	uvcg_free_buffers(&uvc->video.queue);
> 	uvc->func_connected = false;
>@@ -647,4 +663,3 @@ const struct v4l2_file_operations uvc_v4l2_fops = {
> 	.get_unmapped_area = uvcg_v4l2_get_unmapped_area,
> #endif
> };
>-
>--
>2.42.0.609.gbb76f46606-goog


With this you can add my:

Reviewed-by: <m.grzeschik@pengutronix.de>

Thanks

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