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