[PATCH] acpica: fix -Wnull-pointer-arithmetic warnings

From: Qian Cai
Date: Tue Jul 16 2019 - 23:38:29 EST

Clang generate quite a few of those warnings.

drivers/acpi/scan.c:759:28: warning: arithmetic on a null pointer
treated as a cast from integer to pointer is a GNU extension
status = acpi_get_handle(ACPI_ROOT_OBJECT,
./include/acpi/actypes.h:458:56: note: expanded from macro
#define ACPI_ROOT_OBJECT ((acpi_handle) ACPI_TO_POINTER
./include/acpi/actypes.h:509:41: note: expanded from macro
#define ACPI_TO_POINTER(i) ACPI_ADD_PTR (void, (void *) 0,
(acpi_size) (i))
./include/acpi/actypes.h:503:84: note: expanded from macro
#define ACPI_ADD_PTR(t, a, b) ACPI_CAST_PTR (t,
(ACPI_CAST_PTR (u8, (a)) + (acpi_size)(b)))
./include/acpi/actypes.h:501:66: note: expanded from macro
#define ACPI_CAST_PTR(t, p) ((t *) (acpi_uintptr_t) (p))
This is because pointer arithmetic on a pointer not pointing to an array
is an undefined behavior. Fix it by doing an integer arithmetic

Signed-off-by: Qian Cai <cai@xxxxxx>
include/acpi/actypes.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index ad6892a24015..25b4a32da177 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -500,13 +500,13 @@ typedef u64 acpi_integer;

#define ACPI_CAST_PTR(t, p) ((t *) (acpi_uintptr_t) (p))
#define ACPI_CAST_INDIRECT_PTR(t, p) ((t **) (acpi_uintptr_t) (p))
-#define ACPI_ADD_PTR(t, a, b) ACPI_CAST_PTR (t, (ACPI_CAST_PTR (u8, (a)) + (acpi_size)(b)))
+#define ACPI_ADD_PTR(t, a, b) ACPI_CAST_PTR (t, (a) + (acpi_size)(b))
#define ACPI_SUB_PTR(t, a, b) ACPI_CAST_PTR (t, (ACPI_CAST_PTR (u8, (a)) - (acpi_size)(b)))
#define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))

/* Pointer/Integer type conversions */

-#define ACPI_TO_POINTER(i) ACPI_ADD_PTR (void, (void *) 0, (acpi_size) (i))
+#define ACPI_TO_POINTER(i) ACPI_ADD_PTR (void, 0, (acpi_size) (i))
#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
2.20.1 (Apple Git-117)