driver core: separate function to shutdown one device

Make a separate function for the part of device_shutdown() that does the
shutown for a single device.  This is in preparation for making device
shutdown asynchronous.

Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Tested-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240822202805.6379-3-stuart.w.hayes@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: stuartwhayes

drivers/base/core.c

@@ -4779,6 +4779,41 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
 }
 EXPORT_SYMBOL_GPL(device_change_owner);
 
+static void shutdown_one_device(struct device *dev)
+{
+	/* hold lock to avoid race with probe/release */
+	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
+		device_lock(dev->parent);
+	device_lock(dev);
+
+	/* Don't allow any more runtime suspends */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_barrier(dev);
+
+	if (dev->class && dev->class->shutdown_pre) {
+		if (initcall_debug)
+			dev_info(dev, "shutdown_pre\n");
+		dev->class->shutdown_pre(dev);
+	}
+	if (dev->bus && dev->bus->shutdown) {
+		if (initcall_debug)
+			dev_info(dev, "shutdown\n");
+		dev->bus->shutdown(dev);
+	} else if (dev->driver && dev->driver->shutdown) {
+		if (initcall_debug)
+			dev_info(dev, "shutdown\n");
+		dev->driver->shutdown(dev);
+	}
+
+	device_unlock(dev);
+	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
+		device_unlock(dev->parent);
+
+	put_device(dev);
+	if (dev->parent)
+		put_device(dev->parent);
+}
+
 /**
  * device_shutdown - call ->shutdown() on each device to shutdown.
  */
@@ -4815,36 +4850,7 @@ void device_shutdown(void)
 		list_del_init(&dev->kobj.entry);
 		spin_unlock(&devices_kset->list_lock);
 
-		/* hold lock to avoid race with probe/release */
-		if (parent && dev->bus && dev->bus->need_parent_lock)
-			device_lock(parent);
-		device_lock(dev);
-
-		/* Don't allow any more runtime suspends */
-		pm_runtime_get_noresume(dev);
-		pm_runtime_barrier(dev);
-
-		if (dev->class && dev->class->shutdown_pre) {
-			if (initcall_debug)
-				dev_info(dev, "shutdown_pre\n");
-			dev->class->shutdown_pre(dev);
-		}
-		if (dev->bus && dev->bus->shutdown) {
-			if (initcall_debug)
-				dev_info(dev, "shutdown\n");
-			dev->bus->shutdown(dev);
-		} else if (dev->driver && dev->driver->shutdown) {
-			if (initcall_debug)
-				dev_info(dev, "shutdown\n");
-			dev->driver->shutdown(dev);
-		}
-
-		device_unlock(dev);
-		if (parent && dev->bus && dev->bus->need_parent_lock)
-			device_unlock(parent);
-
-		put_device(dev);
-		put_device(parent);
+		shutdown_one_device(dev);
 
 		spin_lock(&devices_kset->list_lock);
 	}