This is a note to let you know that I've just added the patch titled
usb: gadget: udc: core: Offload usb_udc_vbus_handler processing
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-udc-core-offload-usb_udc_vbus_handler-processing.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 50966da807c81c5eb3bdfd392990fe0bba94d1ee Mon Sep 17 00:00:00 2001
From: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
Date: Fri, 9 Jun 2023 01:02:26 +0000
Subject: usb: gadget: udc: core: Offload usb_udc_vbus_handler processing
From: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
commit 50966da807c81c5eb3bdfd392990fe0bba94d1ee upstream.
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@xxxxxxxxxxxxxxx
Fixes: 1016fc0c096c ("USB: gadget: Fix obscure lockdep violation for udc_mutex")
Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Message-ID: <20230609010227.978661-1-badhri@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/udc/core.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -37,6 +37,9 @@ static 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;
@@ -679,7 +684,7 @@ int usb_gadget_connect(struct usb_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.
@@ -1059,6 +1064,13 @@ static void usb_udc_connect_control(stru
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
@@ -1067,6 +1079,14 @@ static void usb_udc_connect_control(stru
*
* 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)
{
@@ -1074,7 +1094,7 @@ void usb_udc_vbus_handler(struct usb_gad
if (udc) {
udc->vbus = status;
- usb_udc_connect_control(udc);
+ schedule_work(&udc->vbus_work);
}
}
EXPORT_SYMBOL_GPL(usb_udc_vbus_handler);
@@ -1301,6 +1321,7 @@ int usb_add_gadget(struct usb_gadget *ga
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)
@@ -1432,6 +1453,7 @@ void usb_del_gadget(struct usb_gadget *g
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);
@@ -1500,6 +1522,7 @@ static int gadget_bind_driver(struct 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);
@@ -1531,6 +1554,8 @@ static void gadget_unbind_driver(struct
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)
Patches currently in stable-queue which might be from badhri@xxxxxxxxxx are
queue-6.3/usb-gadget-udc-core-offload-usb_udc_vbus_handler-processing.patch
queue-6.3/usb-gadget-udc-core-prevent-soft_connect_store-race.patch
