linux-kernel - Re: [PATCH 1/1] x86: Use resource_set

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Message-ID: <7f0d376c-2d03-8e09-5d85-e53b0bce0cc5@linux.intel.com>
Date: Wed, 16 Apr 2025 15:18:56 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Andy Shevchenko <andy@...nel.org>
cc: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
    Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
    Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
    x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
    Bjorn Helgaas <bhelgaas@...gle.com>, linux-acpi@...r.kernel.org, 
    LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org
Subject: Re: [PATCH 1/1] x86: Use resource_set_{range,size}() helpers

On Wed, 16 Apr 2025, Andy Shevchenko wrote:

> On Wed, Apr 16, 2025 at 02:53:51PM +0300, Ilpo Järvinen wrote:
> > On Wed, 16 Apr 2025, Andy Shevchenko wrote:
> > > On Wed, Apr 16, 2025 at 01:13:18PM +0300, Ilpo Järvinen wrote:
> 
> > > > +			resource_set_range(res, 0xC0000, SZ_128K);
> > > >  			res->flags = IORESOURCE_MEM | IORESOURCE_ROM_SHADOW |
> > > >  				     IORESOURCE_PCI_FIXED;
> > > 
> > > I'm wondering why not DEFINE_RES_MEM() in such cases?
> > 
> > I guess you meant DEFINE_RES() as that seems to allow giving custom flags.
> > However, DEFINE_RES*() will overwrite ->name which seems something that 
> > ought to not be done here.
> 
> Okay, I haven't checked the initial state of name field here, so then
> DEFINE_RES_MEM_NAMED()?  Or don't we have one?

There's pre-existing res->name on it and your suggestion would have 
resulted in overwriting it with NULL. res->name seems to be filled earlier 
by PCI probe code.

> In any case I would rather see a one assignment for these cases than something
> hidden behind proposed conversions.

TBH, these DEFINE_RES*() helpers are doing hidden things such as 
blantantly overwriting ->name which I only realized after I had already 
converted to it as per your suggestion.

And yes, it is possible to pass the pre-existing res->name to 
DEFINE_RES_NAMED() if that what you insist, though it seems doing it for 
the sake of DEFINE_RES*() interface rather than this code wanting to 
really define the resource from scratch.

Given the hidden overwriting, please be careful on suggesting 
DEFINE_RES*() conversions as it's not as trivial as it seems.

> > I found one other case from the same file though which is truly defines
> > a resource from scratch.
> 
> 
> 

-- 
 i.