ACPI: fix memory hotplug range length handling

Address space descriptors contain _MIN, _MAX, and _LEN.  _MIN and _MAX are
the bounds within which the region can be moved (this is clarified in Table
6-38 of the ACPI 3.0 spec).  We should use _LEN to determine the size of
the region, not _MAX - _MIN + 1.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index d882bf87fa96..e0a95ba72371 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -74,7 +74,7 @@ struct acpi_memory_device {
         unsigned short caching; /* memory cache attribute */
         unsigned short write_protect;   /* memory read/write attribute */
         u64 start_addr;         /* Memory Range start physical addr */
-        u64 end_addr;           /* Memory Range end physical addr */
+        u64 length;             /* Memory Range length */
 };
 
 static int
@@ -97,12 +97,11 @@ acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
         if (ACPI_SUCCESS(status)) {
                 if (address64.resource_type == ACPI_MEMORY_RANGE) {
                         /* Populate the structure */
-                        mem_device->caching =
-                            address64.info.mem.caching;
+                        mem_device->caching = address64.info.mem.caching;
                         mem_device->write_protect =
                             address64.info.mem.write_protect;
                         mem_device->start_addr = address64.minimum;
-                        mem_device->end_addr = address64.maximum;
+                        mem_device->length = address64.address_length;
                 }
         }
 
@@ -199,8 +198,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
          * Tell the VM there is more memory here...
          * Note: Assume that this function returns zero on success
          */
-        result = add_memory(mem_device->start_addr,
-                            (mem_device->end_addr - mem_device->start_addr) + 1);
+        result = add_memory(mem_device->start_addr, mem_device->length);
         if (result) {
                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "\nadd_memory failed\n"));
                 mem_device->state = MEMORY_INVALID_STATE;
@@ -249,7 +247,7 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
 {
         int result;
         u64 start = mem_device->start_addr;
-        u64 len = mem_device->end_addr - start + 1;
+        u64 len = mem_device->length;
 
         ACPI_FUNCTION_TRACE("acpi_memory_disable_device");