device-dax/kmem: replace release_resource() with release_mem_region()

Towards removing the mode specific @dax_kmem_res attribute from the
generic 'struct dev_dax', and preparing for multi-range support, change
the kmem driver to use the idiomatic release_mem_region() to pair with the
initial request_mem_region().  This also eliminates the need to open code
the release of the resource allocated by request_mem_region().

As there are no more dax_kmem_res users, delete this struct member.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jia He <justin.he@arm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hulk Robot <hulkci@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Yan <yanaijie@huawei.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/160106112239.30709.15909567572288425294.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/dax/dax-private.h

@@ -42,8 +42,6 @@ struct dax_region {
  * @dev - device core
  * @pgmap - pgmap for memmap setup / lifetime (driver owned)
  * @range: resource range for the instance
- * @dax_mem_res: physical address range of hotadded DAX memory
- * @dax_mem_name: name for hotadded DAX memory via add_memory_driver_managed()
  */
 struct dev_dax {
 	struct dax_region *region;
@@ -52,7 +50,6 @@ struct dev_dax {
 	struct device dev;
 	struct dev_pagemap *pgmap;
 	struct range range;
-	struct resource *dax_kmem_res;
 };
 
 static inline u64 range_len(struct range *range)

drivers/dax/kmem.c

@@ -33,7 +33,7 @@ int dev_dax_kmem_probe(struct device *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	struct range range = dax_kmem_range(dev_dax);
-	struct resource *new_res;
+	struct resource *res;
 	char *res_name;
 	int numa_node;
 	int rc;
@@ -56,8 +56,8 @@ int dev_dax_kmem_probe(struct device *dev)
 		return -ENOMEM;
 
 	/* Region is permanently reserved if hotremove fails. */
-	new_res = request_mem_region(range.start, range_len(&range), res_name);
-	if (!new_res) {
+	res = request_mem_region(range.start, range_len(&range), res_name);
+	if (!res) {
 		dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end);
 		kfree(res_name);
 		return -EBUSY;
@@ -69,23 +69,20 @@ int dev_dax_kmem_probe(struct device *dev)
 	 * inherit flags from the parent since it may set new flags
 	 * unknown to us that will break add_memory() below.
 	 */
-	new_res->flags = IORESOURCE_SYSTEM_RAM;
+	res->flags = IORESOURCE_SYSTEM_RAM;
 
 	/*
 	 * Ensure that future kexec'd kernels will not treat this as RAM
 	 * automatically.
 	 */
-	rc = add_memory_driver_managed(numa_node, new_res->start,
-				       resource_size(new_res), kmem_name);
+	rc = add_memory_driver_managed(numa_node, range.start, range_len(&range), kmem_name);
 	if (rc) {
-		release_resource(new_res);
-		kfree(new_res);
+		release_mem_region(range.start, range_len(&range));
 		kfree(res_name);
 		return rc;
 	}
 
 	dev_set_drvdata(dev, res_name);
-	dev_dax->dax_kmem_res = new_res;
 
 	return 0;
 }
@@ -95,7 +92,6 @@ static int dev_dax_kmem_remove(struct device *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	struct range range = dax_kmem_range(dev_dax);
-	struct resource *res = dev_dax->dax_kmem_res;
 	const char *res_name = dev_get_drvdata(dev);
 	int rc;
 
@@ -114,10 +110,8 @@ static int dev_dax_kmem_remove(struct device *dev)
 	}
 
 	/* Release and free dax resources */
-	release_resource(res);
-	kfree(res);
+	release_mem_region(range.start, range_len(&range));
 	kfree(res_name);
-	dev_dax->dax_kmem_res = NULL;
 
 	return 0;
 }