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SubjectRE: [PATCH v2] acpica: fix -Wnull-pointer-arithmetic warnings
We've taken the change to ACPI_TO_POINTER.

-----Original Message-----
From: Qian Cai []
Sent: Thursday, July 18, 2019 12:49 PM
To: Wysocki, Rafael J <>
Cc: Moore, Robert <>; Schmauss, Erik <>;;;;;;;; Qian Cai <>
Subject: [PATCH v2] acpica: fix -Wnull-pointer-arithmetic warnings

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 [-Wnull-pointer-arithmetic]
status = acpi_get_handle(ACPI_ROOT_OBJECT,
./include/acpi/actypes.h:458:56: note: expanded from macro 'ACPI_ROOT_OBJECT'
#define ACPI_ROOT_OBJECT ((acpi_handle) ACPI_TO_POINTER
./include/acpi/actypes.h:509:41: note: expanded from macro 'ACPI_TO_POINTER'
#define ACPI_TO_POINTER(i) ACPI_ADD_PTR (void, (void *) 0,
(acpi_size) (i))
./include/acpi/actypes.h:503:84: note: expanded from macro 'ACPI_ADD_PTR'
#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 'ACPI_CAST_PTR'
#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 (C11 6.5.6, constraint 8). Fix it by just casting the corresponding pointers using ACPI_CAST_PTR() and skip the arithmetic. Also, fix a checkpatch warning together.

ERROR: Macros with complex values should be enclosed in parentheses
#45: FILE: include/acpi/actypes.h:509:
+#define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, i)

Signed-off-by: Qian Cai <>

v2: Use ACPI_CAST_PTR() in ACPI_TO_POINTER() directly without

include/acpi/actypes.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h index ad6892a24015..163181e2d884 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -506,7 +506,7 @@ typedef u64 acpi_integer;

/* Pointer/Integer type conversions */

-#define ACPI_TO_POINTER(i) ACPI_ADD_PTR (void, (void *) 0, (acpi_size) (i))
+#define ACPI_TO_POINTER(i) (ACPI_CAST_PTR (void, 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)
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