greybus: Tear down devices in the reverse order

Normally, its a good practice to free resources in the reverse order in
which they are allocated, so that all the dependencies can be sorted out
properly.

This is true while creating/destroying devices as well. For example
consider this scenario (I faced a crash with control protocol due to
this). For a new module, we will first create a bundle+connection for
the control cport and then create other bundles/connections after
parsing manifest.

And while destroying interface on module hot unplug, we are removing the
devices in the order they are added. And so the bundle/connection for
the control cport are destroyed first. But, control cport was still
required while destroying other bundles/connections.

To solve this problem, lets destroy the resources in the reverse order
in which they are added.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/bundle.c

@@ -196,7 +196,7 @@ struct gb_bundle *gb_bundle_create(struct gb_interface *intf, u8 bundle_id,
 	}
 
 	spin_lock_irq(&gb_bundles_lock);
-	list_add_tail(&bundle->links, &intf->bundles);
+	list_add(&bundle->links, &intf->bundles);
 	spin_unlock_irq(&gb_bundles_lock);
 
 	return bundle;

drivers/staging/greybus/connection.c

@@ -213,8 +213,8 @@ struct gb_connection *gb_connection_create(struct gb_bundle *bundle,
 			 "protocol 0x%02hhx handler not found\n", protocol_id);
 
 	spin_lock_irq(&gb_connections_lock);
-	list_add_tail(&connection->hd_links, &hd->connections);
-	list_add_tail(&connection->bundle_links, &bundle->connections);
+	list_add(&connection->hd_links, &hd->connections);
+	list_add(&connection->bundle_links, &bundle->connections);
 	spin_unlock_irq(&gb_connections_lock);
 
 	atomic_set(&connection->op_cycle, 0);

drivers/staging/greybus/interface.c

@@ -122,7 +122,7 @@ static struct gb_interface *gb_interface_create(struct greybus_host_device *hd,
 	}
 
 	spin_lock_irq(&gb_interfaces_lock);
-	list_add_tail(&intf->links, &hd->interfaces);
+	list_add(&intf->links, &hd->interfaces);
 	spin_unlock_irq(&gb_interfaces_lock);
 
 	return intf;