[PATCH v2 2/2] usb: gadget: uvc: refactor video cleanup into uvcg_video_deinit()

[Xu Yang <xu.yang_2@oss.nxp.com>]

From: Xu Yang <xu.yang_2@nxp.com>

kthread_destroy_worker() was never called during unbind, leaving the
UVCG kthread running after the gadget function is unbound. Also, if
uvcg_video_init() or uvc_register_video() fails during bind, async_wq
and kworker were not cleaned up, causing resource leaks.

Both issues require the same teardown sequence: cancel the pending work,
destroy the kworker, and destroy the workqueue. Consolidate this logic
into a new uvcg_video_deinit() helper and call it from both
uvc_function_unbind() and the v4l2_error path in uvc_function_bind().

In uvc_function_unbind(), uvcg_video_deinit() is placed after
video_unregister_device() to fix the ordering. Without this ordering,
tearing down the workers before unregistering the V4L2 device could lead
to use-after-free on video device resources still accessed by those
workers.

Fixes: f0bbfbd16b3b ("usb: gadget: uvc: rework to enqueue in pump worker from encoded queue")
Assisted-by: Claude:claude-sonnet-4.6
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
---
 drivers/usb/gadget/function/f_uvc.c     |  7 ++-----
 drivers/usb/gadget/function/uvc_video.c | 15 +++++++++++++++
 drivers/usb/gadget/function/uvc_video.h |  1 +
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index a4fb2790f4ff..fa2f9d0e4ce0 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -879,6 +879,7 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 	return 0;
 
 v4l2_error:
+	uvcg_video_deinit(&uvc->video);
 	v4l2_device_unregister(&uvc->v4l2_dev);
 error:
 	if (uvc->control_req) {
@@ -1028,11 +1029,6 @@ static void uvc_function_unbind(struct usb_configuration *c,
 		connected = uvc->func_connected;
 	}
 
-	kthread_cancel_work_sync(&video->hw_submit);
-
-	if (video->async_wq)
-		destroy_workqueue(video->async_wq);
-
 	/*
 	 * If we know we're connected via v4l2, then there should be a cleanup
 	 * of the device from userspace either via UVC_EVENT_DISCONNECT or
@@ -1048,6 +1044,7 @@ static void uvc_function_unbind(struct usb_configuration *c,
 
 	device_remove_file(&uvc->vdev.dev, &dev_attr_function_name);
 	video_unregister_device(&uvc->vdev);
+	uvcg_video_deinit(video);
 	v4l2_device_unregister(&uvc->v4l2_dev);
 
 	scoped_guard(mutex, &uvc->lock)
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index 9ba09118bb74..002afca9141e 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -841,3 +841,18 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
 	return uvcg_queue_init(&video->queue, uvc->v4l2_dev.dev->parent,
 			V4L2_BUF_TYPE_VIDEO_OUTPUT, &video->mutex);
 }
+
+void uvcg_video_deinit(struct uvc_video *video)
+{
+	kthread_cancel_work_sync(&video->hw_submit);
+
+	if (!IS_ERR_OR_NULL(video->kworker)) {
+		kthread_destroy_worker(video->kworker);
+		video->kworker = NULL;
+	}
+
+	if (video->async_wq) {
+		destroy_workqueue(video->async_wq);
+		video->async_wq = NULL;
+	}
+}
diff --git a/drivers/usb/gadget/function/uvc_video.h b/drivers/usb/gadget/function/uvc_video.h
index 8ef6259741f1..6c5481f107f9 100644
--- a/drivers/usb/gadget/function/uvc_video.h
+++ b/drivers/usb/gadget/function/uvc_video.h
@@ -18,5 +18,6 @@ int uvcg_video_enable(struct uvc_video *video);
 int uvcg_video_disable(struct uvc_video *video);
 
 int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc);
+void uvcg_video_deinit(struct uvc_video *video);
 
 #endif /* __UVC_VIDEO_H__ */

-- 
2.34.1