linux-kernel - Re: [PATCH v8 1/6] software node: rename is_array to is

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Message-ID: <20191113080813.GO13374@dtor-ws>
Date:   Wed, 13 Nov 2019 00:08:13 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Bjørn Mork <bjorn@...k.no>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v8 1/6] software node: rename is_array to is_inline

On Wed, Nov 13, 2019 at 07:52:43AM +0100, Bjørn Mork wrote:
> Dmitry Torokhov <dmitry.torokhov@...il.com> writes:
> 
> > We do not need a special flag to know if we are dealing with an array,
> > as we can get that data from ratio between element length and the data
> > size, however we do need a flag to know whether the data is stored
> > directly inside property_entry or separately.
> 
> Doesn't a non-null prop->pointer tell you this?

No it does not because pointer is a part of a union.

> 
> And inverting the flag is unnecessarily risky IMHO. An all-zero prop
> might now result in dereferencing a NULL prop->pointer instead of using
> the empty prop->value.  Now I haven't looked at the code to see if this
> is a real problem.  But I believe it's better not having to do that
> anyway...

All-zero property is a terminator and thus we will not dereference
anything.

Thanks.

-- 
Dmitry