linux-kernel - Re: [PATCH v2 08/13] PCI/portdrv: Simplify PCIe feature permission checking

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Message-ID: <20180312142059.GA11186@wunner.de>
Date:   Mon, 12 Mar 2018 15:20:59 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Christoph Hellwig <hch@...radead.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Keith Busch <keith.busch@...el.com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Frederick Lawler <fred@...dlawl.com>
Subject: Re: [PATCH v2 08/13] PCI/portdrv: Simplify PCIe feature permission
 checking

On Mon, Mar 12, 2018 at 09:03:16AM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 12, 2018 at 01:04:02AM -0700, Christoph Hellwig wrote:
> > > +	 * We assume we can manage these PCIe features.  Some systems may
> > > +	 * reserve these for use by the platform itself, e.g., an ACPI BIOS
> > > +	 * may implement its own AER handling and use _OSC to prevent the
> > > +	 * OS from interfering.
> > > +	 */
> > > +	bridge->use_aer = 1;
> > > +	bridge->use_hotplug = 1;
> > > +	bridge->use_pme = 1;
> > 
> > If we start out with enabled maybe these should be disable_foo flags
> > instead?
> 
> I went back and forth on that.  "disable_foo" is nice because the
> default value is correct (zero means enabled).  But then you end up
> with things like:
> 
>   if (pcie_ports_native || !host->disable_hotplug)
> 
> where the "!host->disable_hotplug" is a double negative, and I have a
> really hard time reading that.

native_hotplug or, if you want it reversed, platform_hotplug
(or firmware_hotplug?) might improve readability.

Thanks,

Lukas