linux-kernel - Re: [PATCH v6 07/10] hda: cs35l41: Add support for CS35L41 in HDA systems

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Date:   Sun, 30 Oct 2022 22:38:16 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Lucas Tanure <tanureal@...nsource.cirrus.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        patches@...nsource.cirrus.com,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 07/10] hda: cs35l41: Add support for CS35L41 in HDA
 systems

Sorry for resurrecting old thread...

On Thu, Jan 06, 2022 at 02:29:58PM +0200, Andy Shevchenko wrote:
> On Fri, Dec 17, 2021 at 5:45 PM Lucas Tanure
> <tanureal@...nsource.cirrus.com> wrote:
> >
> > Add support for CS35L41 using a new separated driver
> > that can be used in all upcoming designs

...

> > +       /* No devm_ version as CLSA0100, in no_acpi_dsd case, can't use devm version */
> 
> Can you elaborate why devm can't be used?
> 
> > +       cs35l41->reset_gpio = fwnode_gpiod_get_index(&adev->fwnode, "reset", cs35l41->index,
> 
> Please, do not dereference fwnode pointers.
> Also, why can't you use the device instead of fwnode?

We are doing "acpi_dev_put(adev);" a few lines above, so using adev in
the call to fwnode_gpiod_get_index() is technically use-after-free,
isn't it?

Also, why can't we do

	cs35l41->reset_gpio = gpiod_get_index(acpi_dev, "reset",
					      cs35l41->index,
					      GPIOD_OUT_LOW);

since acpi_dev is device structure corresponding to adev and we are
getting the rest of the properties from it?

I saw downthread that there was supposed to be a patch addressing
several issues raised by Andy, was it ever submitted?

Thanks.

-- 
Dmitry