usb: sysfs: make locking interruptible

232275a USB: fix substandard locking for the sysfs files
introduced needed locking into sysfs operations on USB devices
It, however, uses uninterruptible sleep and if the error
handling is on extreme cases of sleep lengths of 10s of seconds
are possible. Unless we are removing the device we should use
interruptible sleep.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/device.h b/include/linux/device.h
index 6d6f1fe..2d0e6e5 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -958,6 +958,11 @@
 	mutex_lock(&dev->mutex);
 }
 
+static inline int device_lock_interruptible(struct device *dev)
+{
+	return mutex_lock_interruptible(&dev->mutex);
+}
+
 static inline int device_trylock(struct device *dev)
 {
 	return mutex_trylock(&dev->mutex);