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: 1016fc0c096c ("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 --- Changes since v1: - Address Alan Stern's comment on usb_udc_vbus_handler invocation from atomic context: * vbus_events_lock is now a spinlock and allocations in * usb_udc_vbus_handler are atomic now.
Changes since v2: - Addressing Alan Stern's comments: ** connect_lock is now held by callers of * usb_gadget_pullup_update_locked() and gadget_(un)bind_driver() does * notdirectly hold the lock.
** Both usb_gadget_(dis)connect() and usb_udc_vbus_handler() would * set/clear udc->vbus and invoke usb_gadget_pullup_update_locked.
** Add "unbinding" to prevent new connections after the gadget is being * unbound.
Changes since v3: ** Made a minor cleanup which I missed to do in v3 in * usb_udc_vbus_handler().
Changes since v4: - Addressing Alan Stern's comments: ** usb_udc_vbus_handler() now offloads invocation of usb_udc_connect_control() * from workqueue.
** Dropped vbus_events list as this was redundant. Updating to the * latest value is suffice
Changes since v5: - Addressing Alan Stern's comments: ** Squashed allow_connect logic to this patch. ** Fixed comment length to wrap at 76 ** Cancelling vbus_work in del_gadget()
Changes since v6: - Added reviewed by tag
Changes since v7: - None --- drivers/usb/gadget/udc/core.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 52e6d2e84e35..d2e4f78c53e3 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -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)
base-commit: d37537a1f7cf09e304fe7993cb5e732534a0fb22