[Public]
> -----Original Message-----
> From: Jan Beulich <jbeul...@suse.com>
> Sent: Monday, May 12, 2025 11:45 PM
> To: Penny, Zheng <penny.zh...@amd.com>
> Cc: Huang, Ray <ray.hu...@amd.com>; Andrew Cooper
> <andrew.coop...@citrix.com>; Anthony PERARD <anthony.per...@vates.tech>;
> Orzel, Michal <michal.or...@amd.com>; Julien Grall <jul...@xen.org>; Roger Pau
> Monné <roger....@citrix.com>; Stefano Stabellini <sstabell...@kernel.org>;
> xen-
> de...@lists.xenproject.org
> Subject: Re: [PATCH v4 02/15] xen/cpufreq: extract _PSD info from "struct
> xen_processor_performance"
>
> On 06.05.2025 09:22, Penny, Zheng wrote:
> >> -----Original Message-----
> >> From: Jan Beulich <jbeul...@suse.com>
> >> Sent: Monday, April 28, 2025 11:32 PM
> >>
> >> On 14.04.2025 09:40, Penny Zheng wrote:
> >>> --- a/xen/drivers/cpufreq/cpufreq.c
> >>> +++ b/xen/drivers/cpufreq/cpufreq.c
> >>> + {
> >>> + case XEN_PX_INIT:
> >>> + if ( shared_type )
> >>> + *shared_type = processor_pminfo[cpu]->perf.shared_type;
> >>> + if ( domain_info )
> >>> + *domain_info = processor_pminfo[cpu]->perf.domain_info;
> >>
> >> Does this need to be a structure copy? Can't you hand back just a
> >> pointer, with the function parameter being const struct xen_psd_package **?
> >>
> >
> > I've considered handing backing a pointer, then maybe we need to
> > allocate space for "struct xen_psd_package **domain_info =
> > xvzalloc(struct xen_psd_package *);", and XVFREE(xxx) it in each exit,
> especially cpufreq_add_cpu() has a lot exits, which could be a few code churn.
> > So I chose the struct copy to have the smallest change.
>
> I fear I don't see why such allocations (of space holding a single pointer)
> would be
> necessary. Afaict all you need is a local variable of the specific
> (pointer) type, the address of which you pass into here.
>
```
struct xen_psd_package *domain_info;
struct xen_psd_package **domain_info_ptr = &domain_info;
```
Oh, right, I could create a local variable to avoid nullptr initialization.
> Jan
