[PATCH] dax: Avoid extra kref_put() of dax_regions

[Ira Weiny]

In alloc_dax_region() sysfs attribute groups are created against the
parent object the dax_region is being created under.  A reference to the
dax_region was thus obtained for the lifetime of the parent device via
kobj_get() and released via dax_region_unregister().

The ownership of the dax_region was intended to be transferred to the
device dax device but this transfer is not necessary and could be
problematic if the sysfs entries are used after the dax device is
unwound but before the parent device is.

For the dax device the dax_region reference taken during creation in
devm_create_dev_dax() is sufficient to ensure the dax_region lifetime
for both the parent device and the dax device.

Remove the extraneous dax_region_put() from all call paths with this
pattern.

Not-Yet-Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
---
 drivers/dax/cxl.c       | 3 ---
 drivers/dax/hmem/hmem.c | 3 ---
 drivers/dax/pmem.c      | 7 +------
 3 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index ccdf8de85bd5..d3c3654842ba 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -31,9 +31,6 @@ static int cxl_dax_region_probe(struct device *dev)
 	dev_dax = devm_create_dev_dax(&data);
 	if (IS_ERR(dev_dax))
 		return PTR_ERR(dev_dax);
-
-	/* child dev_dax instances now own the lifetime of the dax_region */
-	dax_region_put(dax_region);
 	return 0;
 }
 
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index e5fe8b39fb94..d22d56964120 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -41,9 +41,6 @@ static int dax_hmem_probe(struct platform_device *pdev)
 	dev_dax = devm_create_dev_dax(&data);
 	if (IS_ERR(dev_dax))
 		return PTR_ERR(dev_dax);
-
-	/* child dev_dax instances now own the lifetime of the dax_region */
-	dax_region_put(dax_region);
 	return 0;
 }
 
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index f050ea78bb83..efbdaac51e5f 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -65,12 +65,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
 		.pgmap = &pgmap,
 		.size = range_len(&range),
 	};
-	dev_dax = devm_create_dev_dax(&data);
-
-	/* child dev_dax instances now own the lifetime of the dax_region */
-	dax_region_put(dax_region);
-
-	return dev_dax;
+	return devm_create_dev_dax(&data);
 }
 
 static int dax_pmem_probe(struct device *dev)
-- 
2.40.0