[PATCH 4.19 34/52] usb: roles: dont get/set_role() when usb_role_switch is unregistered

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit b787a3e781759026a6212736ef8e52cf83d1821a upstream.

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>
Link: https://lore.kernel.org/r/20240129093739.2371530-2-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/roles/class.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -19,6 +19,7 @@ struct usb_role_switch {
 	struct device dev;
 	struct mutex lock; /* device lock*/
 	enum usb_role role;
+	bool registered;
 
 	/* From descriptor */
 	struct device *usb2_port;
@@ -45,6 +46,9 @@ int usb_role_switch_set_role(struct usb_
 	if (IS_ERR_OR_NULL(sw))
 		return 0;
 
+	if (!sw->registered)
+		return -EOPNOTSUPP;
+
 	mutex_lock(&sw->lock);
 
 	ret = sw->set(sw->dev.parent, role);
@@ -68,7 +72,7 @@ enum usb_role usb_role_switch_get_role(s
 {
 	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);
@@ -276,6 +280,8 @@ usb_role_switch_register(struct device *
 		return ERR_PTR(ret);
 	}
 
+	sw->registered = true;
+
 	/* TODO: Symlinks for the host port and the device controller. */
 
 	return sw;
@@ -290,8 +296,10 @@ EXPORT_SYMBOL_GPL(usb_role_switch_regist
  */
 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);