Re: [PATCH] cpufreq: powernow-k8: Remove bogus smp_processor_id() usage

On Sat, 27 Oct 2012, Tejun Heo wrote:

Hello, Thomas.

On Sat, Oct 27, 2012 at 07:29:25PM +0200, Thomas Gleixner wrote:

quoted

This is fully preemptible non cpu bound context though the comment in the
code says:

	 * Must run on @pol->cpu.  cpufreq core is responsible for ensuring
	 * that we're bound to the current CPU and pol->cpu stays online.

The core only guarantees that pol->cpu stays online, but it has no way
to bind the thread and this needs to be fully preemptible context as
powernowk8_target_fn() calls functions which might sleep.

So the correct solution is to always go through work_on_cpu().

Yeah, that was stupid.  Rafael already has a patch queued.

  http://git.kernel.org/?p=linux/kernel/git/rafael/linux-pm.git;a=commit;h=e4df1cbcc1f329e53a1fff7450b2229e0addff20

Good. So more people noticed :)

      tglx