Re: [Xen-devel] [PATCH v3 07/11] x86/intel_pstate: changes in cpufreq_del_cpu for CPU offline

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

On 19/06/2015 17:44, Jan Beulich wrote:
> >>> On 11.06.15 at 10:28, <wei.w.wang@xxxxxxxxx> wrote:
> > cpufreq_cpu_policy is used in intel_pstate_set_pstate(), so we change
> > to NULL it after the call of cpufreq_driver->exit. Otherwise, a
> > calltrace will show up on your screen due to the reference of a NULL
> > pointer when you power down the system.
> 
> Apart from what was already said on this patch, I think it is placed too late 
> in
> this series (should precede patch 6) or, even better, not needed at all: 
> ->exit()
> gets passed the policy being cleaned up, so I don't follow why the driver
> needs to consult the per-CPU field to obtain it.

> Plus, if the patch is to be kept, the description suggesting this to be a
> problem at system shutdown only is wrong - it can equally well happen while
> offlining a CPU. Just saying that the pointer is still needed would be 
> sufficient.

It's needed. When unplugging a CPU, the intel_pstate driver sets it to run with 
the lowest P-state.

Best,
Wei

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel