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usb: gadget: udc: core: Offload usb_udc_vbus_handler processing

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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: 1016fc0c09 ("USB: gadget: Fix obscure lockdep violation for udc_mutex")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Message-ID: <20230609010227.978661-1-badhri@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Badhri Jagan Sridharan 2023-06-09 01:02:26 +00:00 committed by Greg Kroah-Hartman
parent 92c9c3baad
commit 50966da807
1 changed files with 27 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/usb/gadget/udc/core.c
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@ -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)