[PATCH v5 5/9] powerpc/mm/book3s64: Update tlb flush routines to take a page walk cache flush argument

[Michael Ellerman]

Segher Boessenkool <segher at kernel.crashing.org> writes:
> On Tue, May 18, 2021 at 07:45:14PM -0500, Segher Boessenkool wrote:
>> On Wed, May 19, 2021 at 10:26:22AM +1000, Michael Ellerman wrote:
>> > Guenter Roeck <linux at roeck-us.net> writes:
>> > > Ah, sorry. I wasn't aware that the following is valid C code
>> > >
>> > > void f1()
>> > > {
>> > >      return f2();
>> > >      ^^^^^^
>> > > }
>> > >
>> > > as long as f2() is void as well. Confusing, but we live and learn.
>> > 
>> > It might be valid, but it's still bad IMHO.
>> > 
>> > It's confusing to readers, and serves no useful purpose.
>> 
>> And it actually explicitly is undefined behaviour in C90 already
>> (3.6.6.4 in C90, 6.8.6.4 in C99 and later).

We use gnu89, which presumably does not make it UB.

> ... but there is a GCC extension that allows this by default:
> <https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wreturn-type>
>   For C only, warn about a 'return' statement with an expression in a
>   function whose return type is 'void', unless the expression type is
>   also 'void'.  As a GNU extension, the latter case is accepted
>   without a warning unless '-Wpedantic' is used.

There's no chance we'll ever enable -Wpedantic, so I guess it's allowed
for practical purposes. I guess clang must accept it too or we'd be
seeing warnings from it.

cheers