linux-kernel - Re: [PATCH v2-UPDATE2 3/4] resource: Add device-managed insert/remove

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Date:	Tue, 8 Mar 2016 14:44:28 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Toshi Kani <toshi.kani@....com>, 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 Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2-UPDATE2 3/4] resource: Add device-managed insert/remove_resource()

On Tue, Mar 8, 2016 at 2:23 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Tue, Mar 8, 2016 at 12:59 PM, Dan Williams <dan.j.williams@...el.com> wrote:
>>
>> Here's the usage patch from Toshi [1] (copied below).  It is indeed a
>> resource injected by nfit / nvdimm bus implementation.  We just happen
>> to support nfit and libnvdimm as modules.
>>
>> The goal of these patches is to use the ACPI NFIT data to create a
>> "Persistent Memory" rather than "reserved" resource.  This is for
>> platform-firmware implementations that use E820-Type2 rather than
>> E820-Type7 to describe pmem.
>
> So my worry is that there is likely exactly one or two of these kinds of sites.
>
> Why couldn't they just use insert_resource() and then remove it manually?

You mean instead of introducing a devm_insert_resource() as a helpful
first-class-citizen api, just arrange for the resource to be inserted
locally?  Sure.

I assume Toshi was looking to keep the devm semantics like the rest of
the nfit driver, but we can do that locally with devm_add_action() and
skip the new general purpose api.