Re: [Xen-devel] [PATCH v4 2/2] x86: add accessors for scratch cpu mask

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Feb 28, 2020 at 12:15:21PM +0100, Jan Beulich wrote:
> On 28.02.2020 11:31, Roger Pau Monné wrote:
> > On Fri, Feb 28, 2020 at 11:16:55AM +0100, Jan Beulich wrote:
> >> On 28.02.2020 10:33, Roger Pau Monne wrote:
> >>> +    /*
> >>> +     * Due to reentrancy scratch cpumask cannot be used in IRQ, #MC or 
> >>> #NMI
> >>> +     * context.
> >>> +     */
> >>> +    BUG_ON(in_irq() || in_mce_handler() || in_nmi_handler());
> >>> +
> >>> +    if ( use && unlikely(this_cpu(scratch_cpumask_use)) )
> >>> +    {
> >>> +        printk("scratch CPU mask already in use by %ps (%p)\n",
> >>> +               this_cpu(scratch_cpumask_use), 
> >>> this_cpu(scratch_cpumask_use));
> >>
> >> Why the raw %p as well? We don't do so elsewhere, I think. Yes,
> >> it's debugging code only, but I wonder anyway.
> > 
> > I use addr2line to find the offending line, and it's much easier to do
> > so if you have the address directly, rather than having to use nm in
> > order to figure out the address of the symbol and then add the offset.
> > 
> > Maybe I'm missing some other way to do this more easily?
> 
> In such a case we may want to consider making %ps (and %pS)
> print a hex presentation next to the decoded one, in debug
> builds at least. Andrew, thoughts? (There may be cases where
> this is not wanted, bit if we made this a debug mode only
> feature, I think it wouldn't do too much harm.)

If you agree to make %p[sS] print the address then I can drop this
and send a patch to that effect (likely next week).

Thanks, Roger.

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