Re: [PATCH] mm/kasan: fix kasan_check_read() compiler warning

[Arnd Bergmann]

On Tue, Jul 9, 2019 at 8:46 PM Marco Elver <elver@xxxxxxxxxx> wrote:
>
> On Tue, 9 Jul 2019 at 20:36, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> >
> > The kasan_check_read() is marked 'inline', which usually includes
> > the 'always_inline' attribute. In some configuration, gcc decides that
> > it cannot inline this, causing a build failure:
> >
> > In file included from include/linux/compiler.h:257,
> >                  from arch/x86/include/asm/current.h:5,
> >                  from include/linux/sched.h:12,
> >                  from include/linux/ratelimit.h:6,
> >                  from fs/dcache.c:18:
> > include/linux/compiler.h: In function 'read_word_at_a_time':
> > include/linux/kasan-checks.h:31:20: error: inlining failed in call to always_inline 'kasan_check_read': function attribute mismatch
> >  static inline bool kasan_check_read(const volatile void *p, unsigned int size)
> >                     ^~~~~~~~~~~~~~~~
> > In file included from arch/x86/include/asm/current.h:5,
> >                  from include/linux/sched.h:12,
> >                  from include/linux/ratelimit.h:6,
> >                  from fs/dcache.c:18:
> > include/linux/compiler.h:280:2: note: called from here
> >   kasan_check_read(addr, 1);
> >   ^~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > While I have no idea why it does this, but changing the call to the
> > internal __kasan_check_read() fixes the issue.
>
> Thanks, this was fixed more generally in v5:
> http://lkml.kernel.org/r/20190708170706.174189-1-elver@xxxxxxxxxx

Ok, that looks like a better solution indeed. I tried something
similar at first but got it wrong.

      Arnd