From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> commit 2a6cc8a6c0cb44baf7df2f64e5090aaf726002c3 upstream. Patch series "linux/const.h: cleanups of macros such as UL(), _BITUL(), BIT() etc", v3. ARM, ARM64, UniCore32 define UL() as a shorthand of _AC(..., UL). More architectures may introduce it in the future. UL() is arch-agnostic, and useful. So let's move it to include/linux/const.h Currently, <asm/memory.h> must be included to use UL(). It pulls in more bloats just for defining some bit macros. I posted V2 one year ago. The previous posts are: https://patchwork.kernel.org/patch/9498273/ https://patchwork.kernel.org/patch/9498275/ https://patchwork.kernel.org/patch/9498269/ https://patchwork.kernel.org/patch/9498271/ At that time, what blocked this series was a comment from David Howells: You need to be very careful doing this. Some userspace stuff depends on the guard macro names on the kernel header files. (https://patchwork.kernel.org/patch/9498275/) Looking at the code closer, I noticed this is not a problem. See the following line. https://github.com/torvalds/linux/blob/v4.16-rc2/scripts/headers_install.sh#L40 scripts/headers_install.sh rips off _UAPI prefix from guard macro names. I ran "make headers_install" and confirmed the result is what I expect. So, we can prefix the include guard of include/uapi/linux/const.h, and add a new include/linux/const.h. This patch (of 4): I am going to add include/linux/const.h for the kernel space. Add _UAPI to the include guard of include/uapi/linux/const.h to prepare for that. Please notice the guard name of the exported one will be kept as-is. So, this commit has no impact to the userspace even if some userspace stuff depends on the guard macro names. scripts/headers_install.sh processes exported headers by SED, and rips off "_UAPI" from guard macro names. #ifndef _UAPI_LINUX_CONST_H #define _UAPI_LINUX_CONST_H will be turned into #ifndef _LINUX_CONST_H #define _LINUX_CONST_H Link: http://lkml.kernel.org/r/1519301715-31798-2-git-send-email-yamada.masahiro@xxxxxxxxxxxxx Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Guan Xuetao <gxt@xxxxxxxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> [nd: resolve trivial conflict due to b732e14e6218b being backported before this] Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/uapi/linux/const.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/include/uapi/linux/const.h +++ b/include/uapi/linux/const.h @@ -1,8 +1,8 @@ /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ /* const.h: Macros for dealing with constants. */ -#ifndef _LINUX_CONST_H -#define _LINUX_CONST_H +#ifndef _UAPI_LINUX_CONST_H +#define _UAPI_LINUX_CONST_H /* Some constant macros are used in both assembler and * C code. Therefore we cannot annotate them always with @@ -30,4 +30,4 @@ #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) -#endif /* !(_LINUX_CONST_H) */ +#endif /* _UAPI_LINUX_CONST_H */
