Re: [PATCH] x86/mce: Fix build warning after MSR-interface switch

[Ingo Molnar]

* Jürgen Groß <jgross@xxxxxxxx> wrote:

> On 17.07.26 11:28, Ingo Molnar wrote:
> > 
> > * Juergen Gross <jgross@xxxxxxxx> wrote:
> > 
> > > The recent switch to 64-bit MSR interfaces introduced a build warning.
> > > 
> > > Fix it.
> > > 
> > > Fixes: cff219368bd0 ("x86/mce: Stop using 32-bit MSR interfaces")
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202607031726.ZOwu4snu-lkp@xxxxxxxxx/
> > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > > ---
> > > Said patch is in tip only right now, so this patch could either be added
> > > on top or be folded into the original patch.
> > > ---
> > >   arch/x86/kernel/cpu/mce/p5.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/x86/kernel/cpu/mce/p5.c b/arch/x86/kernel/cpu/mce/p5.c
> > > index eb99f384d747..3c2b6cc918b1 100644
> > > --- a/arch/x86/kernel/cpu/mce/p5.c
> > > +++ b/arch/x86/kernel/cpu/mce/p5.c
> > > @@ -44,7 +44,7 @@ noinstr void pentium_machine_check(struct pt_regs *regs)
> > >   /* Set up machine check reporting for processors with Intel style MCE: */
> > >   void intel_p5_mcheck_init(struct cpuinfo_x86 *c)
> > >   {
> > > -	u64 q;
> > > +	u64 __maybe_unused q;
> > 
> > Could we just fix the API to always assign 'q', instead of this
> > ugly & vague annotation?
> 
> q is always assigned. I believe the problem is that it is never read.

Indeed.

> OTOH this problem can be fixed easily after patch 31 of this series. I can send
> a V2 of patch 32 to just drop the assignment to q. This will be possible as
> rdmsrq() will be a function then, and not a macro requiring a variable being
> passed as parameter.

That's fine with me, as long as the build failure is only for this
i386 randconfig. If a new warning is generated for any of the
more prominent configs we'll have to make it go away for
the interim tree. (Because it's still not 100% clear whether
we'll be able to do patch 31 in this cycle.)

Thanks,

	Ingo