Re: [PATCH 4/8] x86/platform/uv: Setup UV functions for Hubless UV Systems

[Mike Travis]

On 9/11/2019 1:44 PM, Mike Travis wrote:
> On 9/10/2019 11:07 PM, Ingo Molnar wrote:
> > * Mike Travis <mike.travis@xxxxxxx> wrote:
> >
> > > +/* Initialize UV hubless systems */
> > > +static __init int uv_system_init_hubless(void)
> > > +{
> > > +    int rc;
> > > +
> > > +    /* Setup PCH NMI handler */
> > > +    uv_nmi_setup_hubless();
> > > +
> > > +    /* Init kernel/BIOS interface */
> > > +    rc = uv_bios_init();
> > > +
> > > +    return rc;
> > > +}
>
> This looks like an excessive cleanup error by me.  The original was:
>
> > +static __init int uv_system_init_hubless(void)
> > +{
> > +       int rc;
> > +
> > +       /* Setup PCH NMI handler */
> > +       uv_nmi_setup_hubless();
> > +
> > +       /* Init kernel/BIOS interface */
> > +       rc = uv_bios_init();
> > +
> > +       /* Create user access node if UVsystab available */
> > +       if (rc >= 0)
> > +               uv_setup_proc_files(1);
> > +
> > +       return rc;
> > +}
> > +
>
> Hubbed UV's do not have a non-UV BIOS, but hubless systems in theory 
> can.   So uv_bios_init can fail on hubless systems if it has some other 
> BIOS (unlikely but possible).  So I removed too much in this cleanup. 
> I'll send another patch set that puts this back.

I discovered the problem... In a rearrangement of the patches this 
change does happen but in a later patch [5/8]:

 /* Initialize UV hubless systems */
 static __init int uv_system_init_hubless(void)
 {
@@ -1468,6 +1555,10 @@ static __init int uv_system_init_hubless
        /* Init kernel/BIOS interface */
        rc = uv_bios_init();

+       /* Create user access node if UVsystab available */
+       if (rc >= 0)
+               uv_setup_proc_files(1);
+
        return rc;
 }

The mistake you saw [in patch 3/8] is very short lived... Hopefully no 
need for another patch set?

> Thanks,
> Mike
>
> > Am I the only one who immediately sees the trivial C transformation
> > through which this function could lose a local variable and become 4
> > lines shorter?
> >
> > And this function got two Reviewed-by tags...
> >
> > Thanks,
> >
> >     Ingo