Re: [PATCH net-next] stddef: don't include compiler_types.h in the uAPI header
From: Kees Cook <kees@kernel.org>
Date: 2025-08-26 02:54:45
On Wed, Aug 20, 2025 at 10:17:52AM -0700, Jakub Kicinski wrote:
I realized this include is to give kernel's __counted_by and friends precedence over the empty uAPI-facing defines.
Right.
Not sure this is the most fortunate approach, personally I'd rather wrap our empty user-space-facing defines under ifndef __KERNEL__. I think it'd be better from "include what you need" perspective. Perhaps stddef pulling in compiler annotations is expected, dunno...
I'm trying to leave the door open for userspace to start using these, if they defined them too.
quoted hunk ↗ jump to hunk
Would you be okay with: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? As you pointed out compiler_types.h is only included under stddef.h so the special handling in the installation script is easily avoided.
I think this should be fine, but something is itching at my mind that doing __KERNEL__ checks in uAPI is fragile. I can't substantiate this sensation, though. :P -- Kees Cook