提交 2a6cc8a6 编写于 作者: M Masahiro Yamada 提交者: Linus Torvalds

linux/const.h: prefix include guard of uapi/linux/const.h with _UAPI

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@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 6f84f8d1
/* 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
......@@ -25,4 +25,4 @@
#define _BITUL(x) (_AC(1,UL) << (x))
#define _BITULL(x) (_AC(1,ULL) << (x))
#endif /* !(_LINUX_CONST_H) */
#endif /* _UAPI_LINUX_CONST_H */
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