+ down(&ide_setting_sem);
+ spin_lock_irqsave(&ide_lock, flags);
+ /*
+ * ide_setting_sem protects the settings list
+ * ide_lock protects the use of settings
+ *
+ * so we need to hold both, ide_settings_sem because we want to
+ * modify the settings list, and ide_lock because we cannot take
+ * a setting out that is being used.
+ *
+ * OTOH both ide_{read,write}_setting are only ever used under
+ * ide_setting_sem.
+ */