uapi/linux/const.h: prefer ISO-friendly __typeof__

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/[email protected]
Fixes: a79ff731a1b2 ("netfilter: xtables: make XT_ALIGN() usable in exported headers by exporting __ALIGN_KERNEL()")
Signed-off-by: Kevin Brodsky <[email protected]>
Reported-by: Ruben Ayrapetyan <[email protected]>
Tested-by: Ruben Ayrapetyan <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Tested-by: Petr Vorel <[email protected]>
Reviewed-by: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions