Hi Ted,
(replying to an old thread)
On Wed, Jan 18, 2017 at 5:35 AM, Theodore Ts'o <tytso@xxxxxxx> wrote:
> On Tue, Dec 27, 2016 at 11:40:23PM +0100, Stephan Müller wrote:
>> The variable ip is defined to be a __u64 which is always 8 bytes on any
>> architecture. Thus, the check for sizeof(ip) > 4 will always be true.
>>
>> As the check happens in a hot code path, remove the branch.
>
> The fact that it's a hot code path means the compiler will optimize it
> out, so the fact that it's on the hot code path is irrelevant. The
> main issue is that on platforms with a 32-bit IP's, ip >> 32 will
> always be zero. It might be that we can just do this via
>
> #if BITS_PER_LONG == 32
> ...
> #else
> ...
> #endif
>
> I'm not sure that works for all platforms, though. More research is
> needed...
Is the intention for the test "sizeof(ip) > 4" to distinguish between
32-bit and 64-bit platforms?
As ip is __u64, while regs is a pointer, shouldn't the test be
"sizeof(regs) > 4"?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
