On Sun, Nov 04, 2007 at 09:18:32AM +0100, Franck Bui-Huu wrote:
> 1/ Its unconventional prototype is error prone: its prototype is
> the same as memset one but was documented by mips_ksym.c like the
> following:
>
> extern void *__bzero(void *__s, size_t __count);
>
> 2/ For the caller, it makes no difference to call memset instead
> since it has to setup the second parameter of __bzero to 0.
>
> 3/ It's not part of the Linux user access API, so no module can use
> it.
>
> 4/ It needs to be exported with EXPORT_SYMBOL and therefore consumes
> some extra bytes.
>
> 5/ It has only one user.
>
> Signed-off-by: Franck Bui-Huu <fbuihuu@xxxxxxxxx>
> ---
>
> I'm wondering if I'm missing something, because this function seems
> so ugly and useless in the first place, that I can't refrain to
> submit a patch to get rid of it.
Memset is almost always only ever invoked with a zero argument. So the
idea was to have something like this:
extern void *__memset(void *__s, int __c, size_t __count);
extern void *bzero(void *__s, size_t __count);
static inline void *memset(void *s, int c, size_t count)
{
if (__builtin_constant_p(c) && c == 0) {
bzero(s, count);
return s;
} else
return __memset(s, __c, count);
}
But that was never quite implemented like this as you noticed.
As for the differences in the return value, they're because of of
clear_user and __clear_user which return the number of bytes that could
_not_ be cleared in $a2. Memset being invoked through the normal C calling
conventions ignores this value while it's the actual result of interest for
__clear_user.
I hope that explains things a little.
Ralf
