Re: [PATCH v2] selftests/ptrace/get_syscall_info: fix for MIPS n32

[Shuah Khan]

On 3/29/25 08:02, Maciej W. Rozycki wrote:
> On Sat, 29 Mar 2025, Dmitry V. Levin wrote:
>
> > > > +#if defined(_MIPS_SIM) && _MIPS_SIM == _MIPS_SIM_NABI32
> > > > +/*
> > > > + * MIPS N32 is the only architecture where __kernel_ulong_t
> > > > + * does not match the bitness of syscall arguments.
> > > > + */
> > > > +typedef unsigned long long kernel_ulong_t;
> > > > +#else
> > > > +typedef __kernel_ulong_t kernel_ulong_t;
> > > > +#endif
> > > > +
> > >
> > > What's the reason for adding these typedefs? checkpatch should
> > > have warned you about adding new typedefs.
> > >
> > > Also this introduces kernel_ulong_t in user-space test code.
> > > Something to avoid.
> >
> > There has to be a new type for this test, and the natural way to do this
> > is to use typedef.  The alternative would be to #define kernel_ulong_t
> > which is ugly.  By the way, there are quite a few typedefs in selftests,
> > and there seems to be given no rationale why adding new types in selftests
> > is a bad idea.

It causes problems down the road for maintenance. I would rather not
see these types of kernel typedefs added to user-space.

>   FWIW I agree, and I fail to see a reason why this would be a problem in a
> standalone test program where the typedef does not propagate anywhere.
>
>   The only potential issue I can identify would be a namespace clash, so
> perhaps the new type could have a name prefix specific to the test, but it
> doesn't appear to me a widespread practice across our selftests and then
> `kernel_' ought to be pretty safe against ISO C or POSIX, so perhaps let's
> leave the things alone?

Can't this be solved with ifdef?

thanks,
-- Shuah