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| author | Kevin Brodsky <kevin.brodsky@arm.com> | 2023-04-11 12:27:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-17 12:11:43 +0300 |
| commit | 6acc454e1b7781fb19a6e497d622abce61fd5d01 (patch) | |
| tree | 531b228ca3a38e8e47630987bd7184c14d7e3ec0 | |
| parent | f30c7c8d4db07a6cb1600fcec16ac1ff3d2dfef6 (diff) | |
| download | linux-6acc454e1b7781fb19a6e497d622abce61fd5d01.tar.xz | |
uapi/linux/const.h: prefer ISO-friendly __typeof__
[ Upstream commit 31088f6f7906253ef4577f6a9b84e2d42447dba0 ]
typeof is (still) a GNU extension, which means that it cannot be used when
building ISO C (e.g. -std=c99). It should therefore be avoided in uapi
headers in favour of the ISO-friendly __typeof__.
Unfortunately this issue could not be detected by
CONFIG_UAPI_HEADER_TEST=y as the __ALIGN_KERNEL() macro is not expanded in
any uapi header.
This matters from a userspace perspective, not a kernel one. uapi
headers and their contents are expected to be usable in a variety of
situations, and in particular when building ISO C applications (with
-std=c99 or similar).
This particular problem can be reproduced by trying to use the
__ALIGN_KERNEL macro directly in application code, say:
#include <linux/const.h>
int align(int x, int a)
{
return __KERNEL_ALIGN(x, a);
}
and trying to build that with -std=c99.
Link: https://lkml.kernel.org/r/20230411092747.3759032-1-kevin.brodsky@arm.com
Fixes: a79ff731a1b2 ("netfilter: xtables: make XT_ALIGN() usable in exported headers by exporting __ALIGN_KERNEL()")
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reported-by: Ruben Ayrapetyan <ruben.ayrapetyan@arm.com>
Tested-by: Ruben Ayrapetyan <ruben.ayrapetyan@arm.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Tested-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | include/uapi/linux/const.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/uapi/linux/const.h b/include/uapi/linux/const.h index 0bd39530b2e3..4ef7c87d1249 100644 --- a/include/uapi/linux/const.h +++ b/include/uapi/linux/const.h @@ -28,7 +28,7 @@ #define _BITUL(x) (_AC(1,UL) << (x)) #define _BITULL(x) (_AC(1,ULL) << (x)) -#define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1) +#define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (__typeof__(x))(a) - 1) #define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask)) #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) |