dax: Cleanup extra dax_region references

Now that free_dev_dax_id() internally manages the references it needs
the extra references taken by the dax_region drivers are not needed.

Reported-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/168577285161.1672036.8111253437794419696.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

Author: djbw

drivers/dax/bus.c

@@ -454,11 +454,10 @@ static void dax_region_free(struct kref *kref)
 	kfree(dax_region);
 }
 
-void dax_region_put(struct dax_region *dax_region)
+static void dax_region_put(struct dax_region *dax_region)
 {
 	kref_put(&dax_region->kref, dax_region_free);
 }
-EXPORT_SYMBOL_GPL(dax_region_put);
 
 /* a return value >= 0 indicates this invocation invalidated the id */
 static int __free_dev_dax_id(struct dev_dax *dev_dax)
@@ -641,7 +640,6 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 		return NULL;
 	}
 
-	kref_get(&dax_region->kref);
 	if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 		return NULL;
 	return dax_region;

drivers/dax/bus.h

@@ -9,7 +9,6 @@ struct dev_dax;
 struct resource;
 struct dax_device;
 struct dax_region;
-void dax_region_put(struct dax_region *dax_region);
 
 /* dax bus specific ioresource flags */
 #define IORESOURCE_DAX_STATIC BIT(0)

drivers/dax/cxl.c

@@ -13,7 +13,6 @@ static int cxl_dax_region_probe(struct device *dev)
 	struct cxl_region *cxlr = cxlr_dax->cxlr;
 	struct dax_region *dax_region;
 	struct dev_dax_data data;
-	struct dev_dax *dev_dax;
 
 	if (nid == NUMA_NO_NODE)
 		nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);
@@ -28,13 +27,8 @@ static int cxl_dax_region_probe(struct device *dev)
 		.id = -1,
 		.size = range_len(&cxlr_dax->hpa_range),
 	};
-	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;
+	return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
 }
 
 static struct cxl_driver cxl_dax_region_driver = {

drivers/dax/hmem/hmem.c

@@ -16,7 +16,6 @@ static int dax_hmem_probe(struct platform_device *pdev)
 	struct dax_region *dax_region;
 	struct memregion_info *mri;
 	struct dev_dax_data data;
-	struct dev_dax *dev_dax;
 
 	/*
 	 * @region_idle == true indicates that an administrative agent
@@ -38,13 +37,8 @@ static int dax_hmem_probe(struct platform_device *pdev)
 		.id = -1,
 		.size = region_idle ? 0 : range_len(&mri->range),
 	};
-	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;
+	return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
 }
 
 static struct platform_driver dax_hmem_driver = {

drivers/dax/pmem.c

@@ -13,7 +13,6 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
 	int rc, id, region_id;
 	resource_size_t offset;
 	struct nd_pfn_sb *pfn_sb;
-	struct dev_dax *dev_dax;
 	struct dev_dax_data data;
 	struct nd_namespace_io *nsio;
 	struct dax_region *dax_region;
@@ -65,12 +64,8 @@ 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)