Re: latest -git: WARNING: at arch/x86/kernel/ipi.c:123 send_IPI_mask_bitmask+0xc3/0xe0()

[Andi Kleen <andi@firstfloor.org>]

> We still need the equivalent functionality, though.  The midlayer 
> (msr_on_cpu) may be pointless, but that doesn't change the fact that 
> putting this functionality in the lower layer (smp_call_function_single) 
> makes more sense.

Assuming you can actually have interrupts enabled at these point
and be otherwise ready to do call_function_simple (e.g. cpu hotplug
locking etc.) 

For a lot of MSR accesses in more complicated subsystems like cpufreq 
that requires complications.  I would think for many circumstances it's 
better to simply set affinity of the thread before at a higher level.

In hindsight I think it was my mistake to ever merge that.
I admit I never liked it, but just merged it because I wasn't able
to come up with a strong enough counter argument back then.

-Andi