linux-kernel - [PATCH] device-dax: don't set kobj parent during cdev init

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Date:   Fri, 10 Feb 2017 12:19:30 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        "Sajjan Vikas C" <vikas.cha.sajjan@....com>,
        Arnd Bergmann <arnd@...db.de>, Jan Kara <jack@...e.cz>
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-nvdimm@...ts.01.org, Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH] device-dax: don't set kobj parent during cdev init

I copied this code and per feedback from Greg Kroah-Hartman [1] the
cdev's kobject's parent should not be set to the related device.
This should have minor consequences but isn't doing what anyone
expects it to.

This patch then fixes device-dax so it doesn't make the same mistake.

[1] https://lkml.org/lkml/2017/2/10/370

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/dax/dax.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index ed758b7..24e53b7 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -699,13 +699,9 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 		goto err_inode;
 	}
 
-	/* device_initialize() so cdev can reference kobj parent */
-	device_initialize(dev);
-
 	cdev = &dax_dev->cdev;
 	cdev_init(cdev, &dax_fops);
 	cdev->owner = parent->driver->owner;
-	cdev->kobj.parent = &dev->kobj;
 	rc = cdev_add(&dax_dev->cdev, dev_t, 1);
 	if (rc)
 		goto err_cdev;
@@ -722,7 +718,7 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 	dev->groups = dax_attribute_groups;
 	dev->release = dax_dev_release;
 	dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
-	rc = device_add(dev);
+	rc = device_register(dev);
 	if (rc) {
 		put_device(dev);
 		return ERR_PTR(rc);
-- 
2.1.4