driver core: Provide an wrapper around the mutex to do lockdep warnings

Instead of open-coding it in drivers that want to double check
that their functions are indeed holding the device lock.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

drivers/xen/xen-pciback/pci_stub.c

@@ -278,7 +278,7 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
 	/* Cleanup our device
 	 * (so it's ready for the next domain)
 	 */
-	lockdep_assert_held(&dev->dev.mutex);
+	device_lock_assert(&dev->dev);
 	__pci_reset_function_locked(dev);
 	pci_restore_state(dev);
 

include/linux/device.h

@@ -911,6 +911,11 @@ static inline void device_unlock(struct device *dev)
 	mutex_unlock(&dev->mutex);
 }
 
+static inline void device_lock_assert(struct device *dev)
+{
+	lockdep_assert_held(&dev->mutex);
+}
+
 void driver_init(void);
 
 /*