linux-kernel - Re: [PATCH v2 4/4] ACPI: Change NFIT driver to insert new resource

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Date:	Thu, 03 Mar 2016 17:12:03 -0700
From:	Toshi Kani <toshi.kani@....com>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/4] ACPI: Change NFIT driver to insert new resource

On Thu, 2016-03-03 at 14:49 -0800, Dan Williams wrote:
> On Wed, Mar 2, 2016 at 2:50 PM, Toshi Kani <toshi.kani@....com> wrote:
 :
> > diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
> > index fb53db1..d97b53f 100644
> > --- a/drivers/acpi/nfit.c
> > +++ b/drivers/acpi/nfit.c
> > @@ -1571,6 +1571,30 @@ static int ars_status_process_records(struct
> > nvdimm_bus *nvdimm_bus,
> >         return 0;
> >  }
> > 
> > +static int acpi_nfit_insert_resource(struct acpi_nfit_desc *acpi_desc,
> > +               struct nd_region_desc *ndr_desc)
> > +{
> > +       struct resource *res, *nd_res = ndr_desc->res;
> > +       size_t size = nd_res->end - nd_res->start + 1;
> > +
> > +       /* No operation if the region is already registered as PMEM */
> > +       if (region_intersects(nd_res->start, size, IORESOURCE_MEM,
> > +                       IORES_DESC_PERSISTENT_MEMORY) ==
> > REGION_INTERSECTS)
> > +               return 0;
> > +
> > +       res = devm_kzalloc(acpi_desc->dev, sizeof(*res), GFP_KERNEL);
> 
> How about allocating this resource on the stack and then have
> devm_insert_resource handle the dynamic allocation (memdup) so we have
> one less failure point to handle in the driver.

I like the idea, but existing callers of insert_resource() allocate a
resource either statically or dynamically.  It may be contained by other
structure as well.  So, I think devm_insert_resource() should be consistent
with insert_resource() on this regard. 

Thanks,
-Toshi