Date:   Thu, 9 Dec 2021 21:31:15 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     David Brazdil <dbrazdil@google.com>,
        Rob Herring <robh+dt@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Derek Kiernan <derek.kiernan@xilinx.com>,
        Dragan Cvetic <dragan.cvetic@xilinx.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Hans de Goede <hdegoede@redhat.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, Andrew Scull <ascull@google.com>,
        Will Deacon <will@kernel.org>
Subject: Re: [PATCH v2 2/2] misc: dice: Add driver to forward secrets to
 userspace
Message-ID: <YbJnk7elmP4kUZEH@kroah.com>
References: <20211209151123.3759999-1-dbrazdil@google.com>
 <20211209151123.3759999-3-dbrazdil@google.com>
 <YbIhaWC8b2DV5C7Y@kroah.com>
 <20211209193857.GA28088@duo.ucw.cz>
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On Thu, Dec 09, 2021 at 08:38:57PM +0100, Pavel Machek wrote:
> Hi!
> 
> > > +	memzero_explicit(kaddr, dice_rmem->size);
> > > +	devm_memunmap(dice_misc.this_device, kaddr);
> > 
> > Do you really need to call memzero_explicit()?  This isn't "local"
> > memory, if the compiler "optimizes away" a normal call, it would be
> > _VERY_ broken.
> 
> For clearing secrets, I believe memzero_explicit is nice
> documentation.

Only if it's really needed please.