Re: [Xen-devel] [PATCH v4 07/11] x86/intel_pstate: the main boby of the intel_pstate driver

["Wang, Wei W" <wei.w.wang@xxxxxxxxx>]

On 24/07/2015 21:54,  Jan Beulich wrote:
> >>> On 25.06.15 at 13:16, <wei.w.wang@xxxxxxxxx> wrote:
> > +int __init intel_pstate_init(void)
> > +{
> > +   int cpu, rc = 0;
> > +   const struct x86_cpu_id *id;
> > +   struct cpu_defaults *cpu_info;
> > +
> > +   id = x86_match_cpu(intel_pstate_cpu_ids);
> > +   if (!id)
> > +           return -ENODEV;
> > +
> > +   cpu_info = (struct cpu_defaults *)id->driver_data;
> > +
> > +   copy_pid_params(&cpu_info->pid_policy);
> > +   copy_cpu_funcs(&cpu_info->funcs);
> > +
> > +   if (intel_pstate_msrs_not_valid())
> > +           return -ENODEV;
> > +
> > +   all_cpu_data = xzalloc_array(struct cpudata *, NR_CPUS);
> > +   if (!all_cpu_data)
> > +           return -ENOMEM;
> > +
> > +   rc = cpufreq_register_driver(&intel_pstate_driver);
> > +   if (rc)
> > +           goto out;
> > +
> > +   return rc;
> > +out:
> > +   for_each_online_cpu(cpu) {
> > +           if (all_cpu_data[cpu]) {
> > +                   kill_timer(&all_cpu_data[cpu]->timer);
> > +                   xfree(all_cpu_data[cpu]);
> > +           }
> > +   }
> 
> I have a hard time seeing where in this function the setup happens that is
> being undone here (keeping in mind that the notifier registration inside
> cpufreq_register_driver() doesn't actually call the notifier function).
> 
> And then, looking at the diff between this and what Linux 4.2-rc3 has (which
> admittedly looks a little newer than what you sent, so I already subtract
> some of the delta), it is significantly larger than the source file itself. 
> That
> surely doesn't suggest a clone-with- minimal-delta. Yet as said before - 
> either
> you do that, or you accept us picking at things you inherited from Linux.

I think it's better to choose the latter - picking out things that are useful 
for us from Linux.
Can you please take a look this patch and summarize the comments? Thanks.

Best,
Wei

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