From ca39f7502425d437cbf83d29d99b43bd61342858 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 19 Jul 2022 11:18:15 +0200
Subject: [PATCH] md: fix mddev->kobj lifetime
Git-commit: ca39f7502425d437cbf83d29d99b43bd61342858
Patch-mainline: v6.0-rc1
References: jsc#PED-2766

Once a kobject is initialized, the containing object should not be
directly freed.  So delay initialization until it is added.  Also
remove the kobject_del call as the last put will remove the kobject as
well.  The explicitly delete isn't needed here, and dropping it will
simplify further fixes.

With this md_free now does not need to check that ->gendisk is non-NULL
as it is always set by the time that kobject_init is called on
mddev->kobj.

(Coly Li: rebase for Linux v5.14 based SUSE kernel)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/md.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -678,7 +678,6 @@ static void md_safemode_timeout(struct t
 
 void mddev_init(struct mddev *mddev)
 {
-	kobject_init(&mddev->kobj, &md_ktype);
 	mutex_init(&mddev->open_mutex);
 	mutex_init(&mddev->reconfig_mutex);
 	mutex_init(&mddev->bitmap_info.mutex);
@@ -5590,10 +5589,9 @@ static void md_free(struct kobject *ko)
 	if (mddev->sysfs_level)
 		sysfs_put(mddev->sysfs_level);
 
-	if (mddev->gendisk) {
-		del_gendisk(mddev->gendisk);
-		blk_cleanup_disk(mddev->gendisk);
-	}
+	del_gendisk(mddev->gendisk);
+	put_disk(mddev->gendisk);
+
 	percpu_ref_exit(&mddev->writes_pending);
 
 	bioset_exit(&mddev->bio_set);
@@ -5617,7 +5615,6 @@ static void mddev_delayed_delete(struct
 {
 	struct mddev *mddev = container_of(ws, struct mddev, del_work);
 
-	kobject_del(&mddev->kobj);
 	kobject_put(&mddev->kobj);
 }
 
@@ -5719,6 +5716,7 @@ int md_alloc(dev_t dev, char *name)
 	if (error)
 		goto out_cleanup_disk;
 
+	kobject_init(&mddev->kobj, &md_ktype);
 	error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");
 	if (error)
 		goto out_del_gendisk;