Re: [PATCH v3 2/2] usb: roles: don't get/set_role() when usb_role_switch is unregistered

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Mon, Jan 29, 2024 at 05:37:39PM +0800, Xu Yang wrote:
> There is a possibility that usb_role_switch device is unregistered before
> the user put usb_role_switch. In this case, the user may still want to
> get/set_role() since the user can't sense the changes of usb_role_switch.
> 
> This will add a flag to show if usb_role_switch is already registered and
> avoid unwanted behaviors.
> 
> Fixes: fde0aa6c175a ("usb: common: Small class for USB role switches")
> cc: <stable@vger.kernel.org>
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Changes in v2:
>  - new patch during test patch 1
>  - add registered flag
> Changes in v3:
>  - add fix tag and stable list
> ---
>  drivers/usb/roles/class.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> index 2bad038fb9ad..70165dd86b5d 100644
> --- a/drivers/usb/roles/class.c
> +++ b/drivers/usb/roles/class.c
> @@ -23,6 +23,7 @@ struct usb_role_switch {
>  	struct mutex lock; /* device lock*/
>  	struct module *module; /* the module this device depends on */
>  	enum usb_role role;
> +	bool registered;
>  
>  	/* From descriptor */
>  	struct device *usb2_port;
> @@ -49,6 +50,9 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
>  	if (IS_ERR_OR_NULL(sw))
>  		return 0;
>  
> +	if (!sw->registered)
> +		return -EOPNOTSUPP;
> +
>  	mutex_lock(&sw->lock);
>  
>  	ret = sw->set(sw, role);
> @@ -74,7 +78,7 @@ enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
>  {
>  	enum usb_role role;
>  
> -	if (IS_ERR_OR_NULL(sw))
> +	if (IS_ERR_OR_NULL(sw) || !sw->registered)
>  		return USB_ROLE_NONE;
>  
>  	mutex_lock(&sw->lock);
> @@ -357,6 +361,8 @@ usb_role_switch_register(struct device *parent,
>  		return ERR_PTR(ret);
>  	}
>  
> +	sw->registered = true;
> +
>  	/* TODO: Symlinks for the host port and the device controller. */
>  
>  	return sw;
> @@ -371,8 +377,10 @@ EXPORT_SYMBOL_GPL(usb_role_switch_register);
>   */
>  void usb_role_switch_unregister(struct usb_role_switch *sw)
>  {
> -	if (!IS_ERR_OR_NULL(sw))
> +	if (!IS_ERR_OR_NULL(sw)) {
> +		sw->registered = false;
>  		device_unregister(&sw->dev);
> +	}
>  }
>  EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
>  
> -- 
> 2.34.1

-- 
heikki