[patch 036/181] device-dax/kmem: introduce dax_kmem_range()

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From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: device-dax/kmem: introduce dax_kmem_range()

Towards removing the mode specific @dax_kmem_res attribute from the
generic 'struct dev_dax', and preparing for multi-range support, teach the
driver to calculate the hotplug range from the device range.  The hotplug
range is the trivially calculated memory-block-size aligned version of the
device range.

Link: https://lkml.kernel.org/r/160106111109.30709.3173462396758431559.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Brice Goglin <Brice.Goglin@xxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jia He <justin.he@xxxxxxx>
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Hulk Robot <hulkci@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Jason Yan <yanaijie@xxxxxxxxxx>
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 drivers/dax/kmem.c |   40 +++++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 23 deletions(-)

--- a/drivers/dax/kmem.c~device-dax-kmem-introduce-dax_kmem_range
+++ a/drivers/dax/kmem.c
@@ -19,13 +19,20 @@ static const char *kmem_name;
 /* Set if any memory will remain added when the driver will be unloaded. */
 static bool any_hotremove_failed;
 
+static struct range dax_kmem_range(struct dev_dax *dev_dax)
+{
+	struct range range;
+
+	/* memory-block align the hotplug range */
+	range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes());
+	range.end = ALIGN_DOWN(dev_dax->range.end + 1, memory_block_size_bytes()) - 1;
+	return range;
+}
+
 int dev_dax_kmem_probe(struct device *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
-	struct range *range = &dev_dax->range;
-	resource_size_t kmem_start;
-	resource_size_t kmem_size;
-	resource_size_t kmem_end;
+	struct range range = dax_kmem_range(dev_dax);
 	struct resource *new_res;
 	const char *new_res_name;
 	int numa_node;
@@ -44,25 +51,14 @@ int dev_dax_kmem_probe(struct device *de
 		return -EINVAL;
 	}
 
-	/* Hotplug starting at the beginning of the next block: */
-	kmem_start = ALIGN(range->start, memory_block_size_bytes());
-
-	kmem_size = range_len(range);
-	/* Adjust the size down to compensate for moving up kmem_start: */
-	kmem_size -= kmem_start - range->start;
-	/* Align the size down to cover only complete blocks: */
-	kmem_size &= ~(memory_block_size_bytes() - 1);
-	kmem_end = kmem_start + kmem_size;
-
 	new_res_name = kstrdup(dev_name(dev), GFP_KERNEL);
 	if (!new_res_name)
 		return -ENOMEM;
 
 	/* Region is permanently reserved if hotremove fails. */
-	new_res = request_mem_region(kmem_start, kmem_size, new_res_name);
+	new_res = request_mem_region(range.start, range_len(&range), new_res_name);
 	if (!new_res) {
-		dev_warn(dev, "could not reserve region [%pa-%pa]\n",
-			 &kmem_start, &kmem_end);
+		dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end);
 		kfree(new_res_name);
 		return -EBUSY;
 	}
@@ -96,9 +92,8 @@ int dev_dax_kmem_probe(struct device *de
 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;
-	resource_size_t kmem_start = res->start;
-	resource_size_t kmem_size = resource_size(res);
 	const char *res_name = res->name;
 	int rc;
 
@@ -108,12 +103,11 @@ static int dev_dax_kmem_remove(struct de
 	 * there is no way to hotremove this memory until reboot because device
 	 * unbind will succeed even if we return failure.
 	 */
-	rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
+	rc = remove_memory(dev_dax->target_node, range.start, range_len(&range));
 	if (rc) {
 		any_hotremove_failed = true;
-		dev_err(dev,
-			"DAX region %pR cannot be hotremoved until the next reboot\n",
-			res);
+		dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n",
+				range.start, range.end);
 		return rc;
 	}
 
_




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