Commit 50966da8 authored by Badhri Jagan Sridharan's avatar Badhri Jagan Sridharan Committed by Greg Kroah-Hartman
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usb: gadget: udc: core: Offload usb_udc_vbus_handler processing 



usb_udc_vbus_handler() can be invoked from interrupt context by irq
handlers of the gadget drivers, however, usb_udc_connect_control() has
to run in non-atomic context due to the following:
a. Some of the gadget driver implementations expect the ->pullup
   callback to be invoked in non-atomic context.
b. usb_gadget_disconnect() acquires udc_lock which is a mutex.

Hence offload invocation of usb_udc_connect_control()
to workqueue.

UDC should not be pulled up unless gadget driver is bound. The new flag
"allow_connect" is now set by gadget_bind_driver() and cleared by
gadget_unbind_driver(). This prevents work item to pull up the gadget
even if queued when the gadget driver is already unbound.

Cc: stable@vger.kernel.org
Fixes: 1016fc0c ("USB: gadget: Fix obscure lockdep violation for udc_mutex")
Signed-off-by: default avatarBadhri Jagan Sridharan <badhri@google.com>
Reviewed-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Message-ID: <20230609010227.978661-1-badhri@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 92c9c3ba

drivers/usb/gadget/udc/core.c

+27 −2
Original line number Diff line number Diff line
@@ -37,6 +37,9 @@ static const struct bus_type gadget_bus_type; 
 * @vbus: for udcs who care about vbus status, this value is real vbus status;

 * for udcs who do not care about vbus status, this value is always true

 * @started: the UDC's started state. True if the UDC had started.

 * @allow_connect: Indicates whether UDC is allowed to be pulled up.

 * Set/cleared by gadget_(un)bind_driver() after gadget driver is bound or

 * unbound.

 *

 * This represents the internal data structure which is used by the UDC-class

 * to hold information about udc driver and gadget together.
@@ -48,6 +51,8 @@ struct usb_udc { 
	struct list_head		list;

	bool				vbus;

	bool				started;

	bool				allow_connect;

	struct work_struct		vbus_work;

};



static struct class *udc_class;
@@ -706,7 +711,7 @@ int usb_gadget_connect(struct usb_gadget *gadget) 
		goto out;

	}



	if (gadget->deactivated) {

	if (gadget->deactivated || !gadget->udc->allow_connect) {

		/*

		 * If gadget is deactivated we only save new state.

		 * Gadget will be connected automatically after activation.
@@ -1086,6 +1091,13 @@ static void usb_udc_connect_control(struct usb_udc *udc) 
		usb_gadget_disconnect(udc->gadget);

}



static void vbus_event_work(struct work_struct *work)

{

	struct usb_udc *udc = container_of(work, struct usb_udc, vbus_work);



	usb_udc_connect_control(udc);

}



/**

 * usb_udc_vbus_handler - updates the udc core vbus status, and try to

 * connect or disconnect gadget
@@ -1094,6 +1106,14 @@ static void usb_udc_connect_control(struct usb_udc *udc) 
 *

 * The udc driver calls it when it wants to connect or disconnect gadget

 * according to vbus status.

 *

 * This function can be invoked from interrupt context by irq handlers of

 * the gadget drivers, however, usb_udc_connect_control() has to run in

 * non-atomic context due to the following:

 * a. Some of the gadget driver implementations expect the ->pullup

 * callback to be invoked in non-atomic context.

 * b. usb_gadget_disconnect() acquires udc_lock which is a mutex.

 * Hence offload invocation of usb_udc_connect_control() to workqueue.

 */

void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status)

{
@@ -1101,7 +1121,7 @@ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) 


	if (udc) {

		udc->vbus = status;

		usb_udc_connect_control(udc);

		schedule_work(&udc->vbus_work);

	}

}

EXPORT_SYMBOL_GPL(usb_udc_vbus_handler);
@@ -1328,6 +1348,7 @@ int usb_add_gadget(struct usb_gadget *gadget) 
	mutex_lock(&udc_lock);

	list_add_tail(&udc->list, &udc_list);

	mutex_unlock(&udc_lock);

	INIT_WORK(&udc->vbus_work, vbus_event_work);



	ret = device_add(&udc->dev);

	if (ret)
@@ -1459,6 +1480,7 @@ void usb_del_gadget(struct usb_gadget *gadget) 
	flush_work(&gadget->work);

	device_del(&gadget->dev);

	ida_free(&gadget_id_numbers, gadget->id_number);

	cancel_work_sync(&udc->vbus_work);

	device_unregister(&udc->dev);

}

EXPORT_SYMBOL_GPL(usb_del_gadget);
@@ -1527,6 +1549,7 @@ static int gadget_bind_driver(struct device *dev) 
	if (ret)

		goto err_start;

	usb_gadget_enable_async_callbacks(udc);

	udc->allow_connect = true;

	usb_udc_connect_control(udc);



	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
@@ -1558,6 +1581,8 @@ static void gadget_unbind_driver(struct device *dev) 


	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);



	udc->allow_connect = false;

	cancel_work_sync(&udc->vbus_work);

	usb_gadget_disconnect(gadget);

	usb_gadget_disable_async_callbacks(udc);

	if (gadget->irq)