linux-kernel - Re: [PATCH v2] driver core: Remove device link creation limitation

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Message-ID: <CAJZ5v0h5U60yCyaHeHVbWmwWDa4NBnuhgsV022nZm5HuGgV7ow@mail.gmail.com>
Date:   Mon, 29 Jul 2019 23:24:56 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Dmitry Osipenko <digetx@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Lukas Wunner <lukas@...ner.de>,
        Jon Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        Thierry Reding <thierry.reding@...il.com>
Subject: Re: [PATCH v2] driver core: Remove device link creation limitation

On Mon, Jul 29, 2019 at 10:47 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> Rafael,
>
> This is the fix you need. Or something link this.
>
> I had asked you to reject DL_FLAG_MANAGED as an input flag if you are
> marking it as internal (in the comments). But looks like you were also
> trying to check for "undefined" bit positions. However, the check
> isn't correct because DL_MANAGED_FLAGS doesn't include (rightfully so)
> DL_FLAG_PM_RUNTIME and DL_FLAG_RPM_ACTIVE .
>
> I tried to write a DL_FLAG_EXTERNAL to include all the external flags,
> but that felt like a maintenance headache that's not worth carrying. I
> think it's simpler to just error out when internal flags being passed
> in and ignore any undefined bit positions.

Well, IMO it is better to prevent people from passing unrecognized
flags to device_link_add() at all, even if that means some extra
effort when adding new flags.

I'll post an alternative fix shortly.