On Tue, Mar 02, 2021 at 09:02:54AM +1100, Daniel Axtens wrote:
> Checkpatch does have one check that is relevant:
>
> CHECK: Macro argument reuse 'p' - possible side-effects?
> #36: FILE: arch/powerpc/include/asm/uaccess.h:482:
> +#define unsafe_get_user(x, p, e) do {
> \
> + if (unlikely(__get_user_nocheck((x), (p), sizeof(*(p)), false)))\
> + goto e; \
> +} while (0)
sizeof (of something other than a VLA) does not evaluate its operand.
The checkpatch warning is incorrect (well, it does say "possible" --
it just didn't find a possible problem here).
You can write
bla = sizeof *p++;
and p is *not* incremented.
Segher
