linux-kernel - Re: [PATCH v2 04/11] gpiolib: Clear the gpio_device's fwnode initialized flag before adding

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Message-ID: <Y9eyohkI7EKOlHSX@smile.fi.intel.com>
Date:   Mon, 30 Jan 2023 14:05:54 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Cristian Marussi <cristian.marussi@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Len Brown <lenb@...nel.org>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Tony Lindgren <tony@...mide.com>,
        Linux Kernel Functional Testing <lkft@...aro.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
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        Alexander Stein <alexander.stein@...tq-group.com>,
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        Martin Kepplinger <martin.kepplinger@...i.sm>,
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        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v2 04/11] gpiolib: Clear the gpio_device's fwnode
 initialized flag before adding

On Fri, Jan 27, 2023 at 11:33:38PM -0800, Saravana Kannan wrote:
> On Fri, Jan 27, 2023 at 1:27 AM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > On Thu, Jan 26, 2023 at 04:11:31PM -0800, Saravana Kannan wrote:

...

> > > +     /*
> > > +      * If fwnode doesn't belong to another device, it's safe to clear its
> > > +      * initialized flag.
> > > +      */
> > > +     if (!gdev->dev.fwnode->dev)
> > > +             fwnode_dev_initialized(gdev->dev.fwnode, false);
> >
> > Do not dereference fwnode in struct device. Use dev_fwnode() for that.
> >
> >         struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
> >
> >         if (!fwnode->dev)
> >                 fwnode_dev_initialized(fwnode, false);
> 
> Honestly, we should work towards NOT needing dev_fwnode().

Honestly, it's that We SHOULD go to avoid any direct dereference of fwnode from
the struct device. I explained you in the comment in the other patch.

> The
> function literally dereferences dev->fwnode or the one inside of_node.
> So my dereference is fine. The whole "fwnode might not be set for
> devices with of_node" is wrong and we should fix that instead of
> writing wrappers to work around it.
> 
> Also, for now I'm going to leave this as if for the same reasons as I
> mentioned in Patch 1.

Same.


-- 
With Best Regards,
Andy Shevchenko