Revert "driver core: shut down devices asynchronously"

This reverts commit 8064952c.

The series is being reverted before -rc1 as there are still reports of
lockups on shutdown, so it's not quite ready for "prime time."
Reported-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Link: https://lore.kernel.org/r/ZvMkkhyJrohaajuk@skv.local
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Jeffery <djeffery@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/base.h

@@ -10,7 +10,6 @@
  * shared outside of the drivers/base/ directory.
  *
  */
-#include <linux/async.h>
 #include <linux/notifier.h>
 
 /**
@@ -98,8 +97,6 @@ struct driver_private {
  *	the device; typically because it depends on another driver getting
  *	probed first.
  * @async_driver - pointer to device driver awaiting probe via async_probe
- * @shutdown_after - used during device shutdown to ensure correct shutdown
- *	ordering.
  * @device - pointer back to the struct device that this structure is
  * associated with.
  * @dead - This device is currently either in the process of or has been
@@ -117,7 +114,6 @@ struct device_private {
 	struct list_head deferred_probe;
 	const struct device_driver *async_driver;
 	char *deferred_probe_reason;
-	async_cookie_t shutdown_after;
 	struct device *device;
 	u8 dead:1;
 };

drivers/base/core.c

@@ -9,7 +9,6 @@
  */
 
 #include <linux/acpi.h>
-#include <linux/async.h>
 #include <linux/blkdev.h>
 #include <linux/cleanup.h>
 #include <linux/cpufreq.h>
@@ -3525,7 +3524,6 @@ static int device_private_init(struct device *dev)
 	klist_init(&dev->p->klist_children, klist_children_get,
 		   klist_children_put);
 	INIT_LIST_HEAD(&dev->p->deferred_probe);
-	dev->p->shutdown_after = 0;
 	return 0;
 }
 
@@ -4781,8 +4779,6 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
 }
 EXPORT_SYMBOL_GPL(device_change_owner);
 
-static ASYNC_DOMAIN(sd_domain);
-
 static void shutdown_one_device(struct device *dev)
 {
 	/* hold lock to avoid race with probe/release */
@@ -4818,34 +4814,12 @@ static void shutdown_one_device(struct device *dev)
 		put_device(dev->parent);
 }
 
-/**
- * shutdown_one_device_async
- * @data: the pointer to the struct device to be shutdown
- * @cookie: not used
- *
- * Shuts down one device, after waiting for shutdown_after to complete.
- * shutdown_after should be set to the cookie of the last child or consumer
- * of this device to be shutdown (if any), or to the cookie of the previous
- * device to be shut down for devices that don't enable asynchronous shutdown.
- */
-static void shutdown_one_device_async(void *data, async_cookie_t cookie)
-{
-	struct device *dev = data;
-
-	async_synchronize_cookie_domain(dev->p->shutdown_after + 1, &sd_domain);
-
-	shutdown_one_device(dev);
-}
-
 /**
  * device_shutdown - call ->shutdown() on each device to shutdown.
  */
 void device_shutdown(void)
 {
 	struct device *dev, *parent;
-	async_cookie_t cookie = 0;
-	struct device_link *link;
-	int idx;
 
 	wait_for_device_probe();
 	device_block_probing();
@@ -4876,37 +4850,11 @@ void device_shutdown(void)
 		list_del_init(&dev->kobj.entry);
 		spin_unlock(&devices_kset->list_lock);
 
-
-		/*
-		 * Set cookie for devices that will be shut down synchronously
-		 */
-		if (!dev->driver || !dev->driver->async_shutdown_enable)
-			dev->p->shutdown_after = cookie;
-
-		get_device(dev);
-		get_device(parent);
-
-		cookie = async_schedule_domain(shutdown_one_device_async,
-					       dev, &sd_domain);
-		/*
-		 * Ensure parent & suppliers wait for this device to shut down
-		 */
-		if (parent) {
-			parent->p->shutdown_after = cookie;
-			put_device(parent);
-		}
-
-		idx = device_links_read_lock();
-		list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
-				device_links_read_lock_held())
-			link->supplier->p->shutdown_after = cookie;
-		device_links_read_unlock(idx);
-		put_device(dev);
+		shutdown_one_device(dev);
 
 		spin_lock(&devices_kset->list_lock);
 	}
 	spin_unlock(&devices_kset->list_lock);
-	async_synchronize_full_domain(&sd_domain);
 }
 
 /*

include/linux/device/driver.h

@@ -56,7 +56,6 @@ enum probe_type {
  * @mod_name:	Used for built-in modules.
  * @suppress_bind_attrs: Disables bind/unbind via sysfs.
  * @probe_type:	Type of the probe (synchronous or asynchronous) to use.
- * @async_shutdown_enable: Enables devices to be shutdown asynchronously.
  * @of_match_table: The open firmware table.
  * @acpi_match_table: The ACPI match table.
  * @probe:	Called to query the existence of a specific device,
@@ -103,7 +102,6 @@ struct device_driver {
 
 	bool suppress_bind_attrs;	/* disables bind/unbind via sysfs */
 	enum probe_type probe_type;
-	bool async_shutdown_enable;
 
 	const struct of_device_id	*of_match_table;
 	const struct acpi_device_id	*acpi_match_table;