dax: convert devm_create_dax_dev to PTR_ERR

For sub-division support we need access to the dax_dev created by
devm_create_dax_dev().
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dax/dax.c

@@ -558,8 +558,8 @@ static void unregister_dax_dev(void *dev)
 	device_unregister(dev);
 }
 
-int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
-		int count)
+struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
+		struct resource *res, int count)
 {
 	struct device *parent = dax_region->dev;
 	struct dax_dev *dax_dev;
@@ -570,7 +570,7 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
 
 	dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
 	if (!dax_dev)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	for (i = 0; i < count; i++) {
 		if (!IS_ALIGNED(res[i].start, dax_region->align)
@@ -632,10 +632,14 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
 	rc = device_add(dev);
 	if (rc) {
 		put_device(dev);
-		return rc;
+		return ERR_PTR(rc);
 	}
 
-	return devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
+	rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return dax_dev;
 
  err_cdev:
 	iput(dax_dev->inode);
@@ -646,7 +650,7 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
  err_id:
 	kfree(dax_dev);
 
-	return rc;
+	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_GPL(devm_create_dax_dev);
 

drivers/dax/dax.h

@@ -13,12 +13,13 @@
 #ifndef __DAX_H__
 #define __DAX_H__
 struct device;
+struct dax_dev;
 struct resource;
 struct dax_region;
 void dax_region_put(struct dax_region *dax_region);
 struct dax_region *alloc_dax_region(struct device *parent,
 		int region_id, struct resource *res, unsigned int align,
 		void *addr, unsigned long flags);
-int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
-		int count);
+struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
+		struct resource *res, int count);
 #endif /* __DAX_H__ */

drivers/dax/pmem.c

@@ -61,6 +61,7 @@ static int dax_pmem_probe(struct device *dev)
 	int rc;
 	void *addr;
 	struct resource res;
+	struct dax_dev *dax_dev;
 	struct nd_pfn_sb *pfn_sb;
 	struct dax_pmem *dax_pmem;
 	struct nd_region *nd_region;
@@ -123,12 +124,12 @@ static int dax_pmem_probe(struct device *dev)
 		return -ENOMEM;
 
 	/* TODO: support for subdividing a dax region... */
-	rc = devm_create_dax_dev(dax_region, &res, 1);
+	dax_dev = devm_create_dax_dev(dax_region, &res, 1);
 
 	/* child dax_dev instances now own the lifetime of the dax_region */
 	dax_region_put(dax_region);
 
-	return rc;
+	return PTR_ERR_OR_ZERO(dax_dev);
 }
 
 static struct nd_device_driver dax_pmem_driver = {