Re: [PATCH 5/6] fix warning on test_ti_thread_flag()

Geert Uytterhoeven
2006-01-25T12:28:51Z

On Wed, 25 Jan 2006, Akinobu Mita wrote:
> If the arechitecture is
> - BITS_PER_LONG = 64
> - struct thread_info.flag 32 is bits
> - second argument of test_bit() was void *
>
> Then compiler print error message on test_ti_thread_flags()
> in include/linux/thread_info.h
>
> Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
> ---
> thread_info.h | 2 +-
> 1 files changed, 1 insertion(+), 1 deletion(-)
>
> Index: 2.6-git/include/linux/thread_info.h
> =================================> --- 2.6-git.orig/include/linux/thread_info.h 2006-01-25 19:07:12.000000000 +0900
> +++ 2.6-git/include/linux/thread_info.h 2006-01-25 19:14:26.000000000 +0900
> @@ -49,7 +49,7 @@
>
> static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
> {
> - return test_bit(flag,&ti->flags);
> + return test_bit(flag, (void *)&ti->flags);
> }

This is not safe. The bitops are defined to work on unsigned long only, so
flags should be changed to unsigned long instead, or you should use a
temporary.

Affected platforms:
- alpha: flags is unsigned int
- ia64, sh, x86_64: flags is __u32

The only affected 64-platforms are little endian, so it will silently work
after your change, though...

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds