Re: [PATCH v2 1/2] usb: gadget: uvc: replace mutex lock/unlock with scoped_guard in uvc_function_bind()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] usb: uvc: architectural violation by mixing goto with scoped_guard cleanup
--

commit 7b1d83604fdc69bbda123c4e57da835730d015cb
Author: Xu Yang <xu.yang_2@nxp.com>

usb: gadget: uvc: replace mutex lock/unlock with scoped_guard in uvc_function_bind()

This patch replaces manual mutex locking and unlocking with scoped_guard()
to resolve a label fallthrough bug on failure paths.

> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
> index d1bf3ea751973..a4fb2790f4ffe 100644
> --- a/drivers/usb/gadget/function/f_uvc.c
> +++ b/drivers/usb/gadget/function/f_uvc.c
[ ... ]
> @@ -809,50 +803,50 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
[ ... ]
>  	/* Copy descriptors */
> -	f->fs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_FULL);
> -	if (IS_ERR(f->fs_descriptors)) {
> -		ret = PTR_ERR(f->fs_descriptors);
> -		f->fs_descriptors = NULL;
> -		goto error_unlock;
> -	}
> +	scoped_guard(mutex, &opts->lock) {
> +		f->fs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_FULL);
> +		if (IS_ERR(f->fs_descriptors)) {
> +			ret = PTR_ERR(f->fs_descriptors);
> +			f->fs_descriptors = NULL;
> +			goto error;
> +		}

[Severity: Low]
Does this code violate the kernel cleanup subsystem guidelines?

The documentation in include/linux/cleanup.h explicitly states that usage
of "goto" and scope-based cleanup helpers should never be mixed in the same
function to avoid confusing ownership semantics.

Here we jump out of the scoped_guard block to the legacy error label. While
this correctly releases the mutex lock and doesn't appear to cause a
functional issue, would it be better to convert the rest of the resources
in uvc_function_bind() to scope-based cleanup, or use manual locking if
goto error handling must be retained?

[ ... ]
> @@ -884,8 +878,6 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
>  
>  	return 0;
>  
> -error_unlock:
> -	mutex_unlock(&opts->lock);
>  v4l2_error:
>  	v4l2_device_unregister(&uvc->v4l2_dev);
>  error:

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260923-usb-uvc-fixes-v2-0-844e04a4a4b7@nxp.com?part=1