The uAPI stddef header includes compiler_types.h, a kernel-only
header, to make sure that kernel definitions of annotations
like __counted_by() take precedence.

There is a hack in scripts/headers_install.sh which strips includes
of compiler.h and compiler_types.h when installing uAPI headers.
While explicit handling makes sense for compiler.h, which is included
all over the uAPI, compiler_types.h is only included by stddef.h
(within the uAPI, obviously it's included in kernel code a lot).

Remove the stripping from scripts/headers_install.sh and wrap
the include of compiler_types.h in #ifdef __KERNEL__ instead.
This should be equivalent functionally, but is easier to understand
to a casual reader of the code. It also makes it easier to work
with kernel headers directly from under tools/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - remove the hack from scripts/headers_install.sh
 - wrap in __KERNEL__ instead of removing
v1: https://lore.kernel.org/20250818181848.799566-1-kuba@kernel.org

CC: dhowells@redhat.com
CC: kees@kernel.org
CC: gustavoars@kernel.org
CC: aleksander.lobakin@intel.com
CC: tstruk@gigaio.com
---
 scripts/headers_install.sh  | 2 +-
 include/uapi/linux/stddef.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
index 6bbccb43f7e7..4c20c62c4faf 100755
--- a/scripts/headers_install.sh
+++ b/scripts/headers_install.sh
@@ -32,7 +32,7 @@ fi
 sed -E -e '
 	s/([[:space:](])(__user|__force|__iomem)[[:space:]]/\1/g
 	s/__attribute_const__([[:space:]]|$)/\1/g
-	s@^#include <linux/compiler(|_types).h>@@
+	s@^#include <linux/compiler.h>@@
 	s/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g
 	s/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g
 	s@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @
diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h
index b87df1b485c2..9a28f7d9a334 100644
--- a/include/uapi/linux/stddef.h
+++ b/include/uapi/linux/stddef.h
@@ -2,7 +2,9 @@
 #ifndef _UAPI_LINUX_STDDEF_H
 #define _UAPI_LINUX_STDDEF_H
 
+#ifdef __KERNEL__
 #include <linux/compiler_types.h>
+#endif
 
 #ifndef __always_inline
 #define __always_inline inline
-- 
2.51.0

On Mon, Aug 25, 2025 at 01:18:28PM -0700, Jakub Kicinski wrote:
> The uAPI stddef header includes compiler_types.h, a kernel-only
> header, to make sure that kernel definitions of annotations
> like __counted_by() take precedence.
> 
> There is a hack in scripts/headers_install.sh which strips includes
> of compiler.h and compiler_types.h when installing uAPI headers.
> While explicit handling makes sense for compiler.h, which is included
> all over the uAPI, compiler_types.h is only included by stddef.h
> (within the uAPI, obviously it's included in kernel code a lot).
> 
> Remove the stripping from scripts/headers_install.sh and wrap
> the include of compiler_types.h in #ifdef __KERNEL__ instead.
> This should be equivalent functionally, but is easier to understand
> to a casual reader of the code. It also makes it easier to work
> with kernel headers directly from under tools/
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> v2:
>  - remove the hack from scripts/headers_install.sh
>  - wrap in __KERNEL__ instead of removing
> v1: https://lore.kernel.org/20250818181848.799566-1-kuba@kernel.org

Reviewed-by: Simon Horman <horms@kernel.org>