[PATCH v4] usb: gadget: udc: Handle gadget_connect failure during bind operation

[Krishna Kurapati]

In the event, gadget_connect call (which invokes pullup) fails,
propagate the error to udc bind operation which inturn sends the
error to configfs. The userspace can then retry enumeartion if
it chooses to.

Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
---
Changes in v4: Fixed mutex locking imbalance during connect_control
failure
Link to v3: https://lore.kernel.org/all/20230510075252.31023-3-quic_kriskura@xxxxxxxxxxx/

 drivers/usb/gadget/udc/core.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 7d49d8a0b00c..53af25a333a1 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1125,12 +1125,16 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
 /* ------------------------------------------------------------------------- */
 
 /* Acquire connect_lock before calling this function. */
-static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
+static int usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
 {
+	int ret;
+
 	if (udc->vbus)
-		usb_gadget_connect_locked(udc->gadget);
+		ret = usb_gadget_connect_locked(udc->gadget);
 	else
-		usb_gadget_disconnect_locked(udc->gadget);
+		ret = usb_gadget_disconnect_locked(udc->gadget);
+
+	return ret;
 }
 
 static void vbus_event_work(struct work_struct *work)
@@ -1604,12 +1608,23 @@ static int gadget_bind_driver(struct device *dev)
 	}
 	usb_gadget_enable_async_callbacks(udc);
 	udc->allow_connect = true;
-	usb_udc_connect_control_locked(udc);
+	ret = usb_udc_connect_control_locked(udc);
+	if (ret) {
+		mutex_unlock(&udc->connect_lock);
+		goto err_connect_control;
+	}
+
 	mutex_unlock(&udc->connect_lock);
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 	return 0;
 
+ err_connect_control:
+	usb_gadget_disable_async_callbacks(udc);
+	if (gadget->irq)
+		synchronize_irq(gadget->irq);
+	usb_gadget_udc_stop_locked(udc);
+
  err_start:
 	driver->unbind(udc->gadget);
 
-- 
2.42.0