Re: [PATCH 1/3] mm/slub: Only define kmalloc_large_node_hook() for NUMA systems

Matthias Kaehlcke
2017-05-23T16:56:14Z

Hi David,

El Mon, May 22, 2017 at 06:35:23PM -0700 David Rientjes ha dit:

> On Mon, 22 May 2017, Andrew Morton wrote:
>
> > > > Is clang not inlining kmalloc_large_node_hook() for some reason? I don't
> > > > think this should ever warn on gcc.
> > >
> > > clang warns about unused static inline functions outside of header
> > > files, in difference to gcc.
> >
> > I wish it wouldn't. These patches just add clutter.
> >
>
> Matthias, what breaks if you do this?
>
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index de179993e039..e1895ce6fa1b 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -15,3 +15,8 @@
> * with any version that can compile the kernel
> */
> #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
> +
> +#ifdef inline
> +#undef inline
> +#define inline __attribute__((unused))
> +#endif

Thanks for the suggestion!

Nothing breaks and the warnings are silenced. It seems we could use
this if there is a stong opposition against having warnings on unused
static inline functions in .c files.

Still I am not convinced that gcc's behavior is preferable in this
case. True, it saves us from adding a bunch of __maybe_unused or
#ifdefs, on the other hand the warning is a useful tool to spot truly
unused code. So far about 50% of the warnings I looked into fall into
this category.