On Wed, Dec 13, 2006 at 02:19:52PM -0800, H. Peter Anvin wrote:
> > void rdmsr_on_cpu(unsigned int cpu, unsigned long msr, unsigned long *lo,
> > unsigned long *hi)
> > {
> > cpumask_t oldmask;
> >
> > oldmask = current->cpus_allowed;
> > set_cpus_allowed(current, cpumask_of_cpu(cpu));
> >
> > rdmsr(msr, &lo, &hi);
> >
> > set_cpus_allowed(current, oldmask);
> > }
> >
>
> [The above doesn't work, by the way. This approach was discussed a long
> time ago, and vetoed due to the potential for deadlock.]
Can you explain this a little further? I'm fairly certain
there are places in the kernel already doing this (or similar).
In fact, I cut-n-pasted most of the above from similar code in the
powernow-k8 driver. What exactly can we deadlock on?
Dave
--
http://www.codemonkey.org.uk
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