ACPI / processor: use container_of instead of casting first structure member

Use container_of instead of casting first structure member to resolve
acpi_madt_local_apic/sapic/x2apic from acpi_subtable_header.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
[ rjw: Subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index e32321ce9a5c..ef58f46c8442 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -16,7 +16,7 @@ static int map_lapic_id(struct acpi_subtable_header *entry,
                  u32 acpi_id, int *apic_id)
 {
         struct acpi_madt_local_apic *lapic =
-                (struct acpi_madt_local_apic *)entry;
+                container_of(entry, struct acpi_madt_local_apic, header);
 
         if (!(lapic->lapic_flags & ACPI_MADT_ENABLED))
                 return -ENODEV;
@@ -32,7 +32,7 @@ static int map_x2apic_id(struct acpi_subtable_header *entry,
                          int device_declaration, u32 acpi_id, int *apic_id)
 {
         struct acpi_madt_local_x2apic *apic =
-                (struct acpi_madt_local_x2apic *)entry;
+                container_of(entry, struct acpi_madt_local_x2apic, header);
 
         if (!(apic->lapic_flags & ACPI_MADT_ENABLED))
                 return -ENODEV;
@@ -49,7 +49,7 @@ static int map_lsapic_id(struct acpi_subtable_header *entry,
                 int device_declaration, u32 acpi_id, int *apic_id)
 {
         struct acpi_madt_local_sapic *lsapic =
-                (struct acpi_madt_local_sapic *)entry;
+                container_of(entry, struct acpi_madt_local_sapic, header);
 
         if (!(lsapic->lapic_flags & ACPI_MADT_ENABLED))
                 return -ENODEV;