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31088f6f79
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: a79ff731a1 ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.