s390/cio: split subchannel registration

Split the subchannel registration in device_initialize and device_add
and move the initialization part inside the allocation function. With
this change we can use refcounting during the complete lifespan of a
subchannel which is important for devices where we do the actually
registration at a later time.
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/css.c

@@ -137,8 +137,21 @@ int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
 
 static void css_sch_todo(struct work_struct *work);
 
-static struct subchannel *
-css_alloc_subchannel(struct subchannel_id schid)
+static void css_subchannel_release(struct device *dev)
+{
+	struct subchannel *sch;
+
+	sch = to_subchannel(dev);
+	if (!cio_is_console(sch->schid)) {
+		/* Reset intparm to zeroes. */
+		sch->config.intparm = 0;
+		cio_commit_config(sch);
+		kfree(sch->lock);
+		kfree(sch);
+	}
+}
+
+static struct subchannel *css_alloc_subchannel(struct subchannel_id schid)
 {
 	struct subchannel *sch;
 	int ret;
@@ -152,24 +165,11 @@ css_alloc_subchannel(struct subchannel_id schid)
 		return ERR_PTR(ret);
 	}
 	INIT_WORK(&sch->todo_work, css_sch_todo);
+	sch->dev.release = &css_subchannel_release;
+	device_initialize(&sch->dev);
 	return sch;
 }
 
-static void
-css_subchannel_release(struct device *dev)
-{
-	struct subchannel *sch;
-
-	sch = to_subchannel(dev);
-	if (!cio_is_console(sch->schid)) {
-		/* Reset intparm to zeroes. */
-		sch->config.intparm = 0;
-		cio_commit_config(sch);
-		kfree(sch->lock);
-		kfree(sch);
-	}
-}
-
 static int css_sch_device_register(struct subchannel *sch)
 {
 	int ret;
@@ -177,7 +177,7 @@ static int css_sch_device_register(struct subchannel *sch)
 	mutex_lock(&sch->reg_mutex);
 	dev_set_name(&sch->dev, "0.%x.%04x", sch->schid.ssid,
 		     sch->schid.sch_no);
-	ret = device_register(&sch->dev);
+	ret = device_add(&sch->dev);
 	mutex_unlock(&sch->reg_mutex);
 	return ret;
 }
@@ -282,7 +282,6 @@ static int css_register_subchannel(struct subchannel *sch)
 	/* Initialize the subchannel structure */
 	sch->dev.parent = &channel_subsystems[0]->device;
 	sch->dev.bus = &css_bus_type;
-	sch->dev.release = &css_subchannel_release;
 	sch->dev.groups = default_subch_attr_groups;
 	/*
 	 * We don't want to generate uevents for I/O subchannels that don't