linux-kernel - Re: [PATCH v2 2/2] of: overlay: Fix cleanup order in of_overlay

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Date:   Mon, 4 Dec 2017 13:35:30 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Frank Rowand <frowand.list@...il.com>,
        Colin King <colin.king@...onical.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] of: overlay: Fix cleanup order in of_overlay_apply()

On Mon, Dec 4, 2017 at 9:47 AM, Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
> The special overlay mutex is taken first, hence it should be released
> last in the error path.
>
> Move "mutex_lock(&of_mutex)" up, as suggested by Frank, as
> free_overlay_changeset() should be called with that mutex held if any
> non-trivial cleanup is to be done.

Not holding the of_mutex for of_resolve_phandles is just wrong.
Without it, a node and new phandle could be added via of_attach_node
making the max phandle wrong.

Now, with the 2 mutexes adjacent, what is the point of even having the
of_overlay_mutex? Seems like we should just drop it.

I also don't think we really need to hold the mutex during post-apply
notifiers. It also seems like some steps could be moved outside the
mutex(es) like init_overlay_changeset().

Rob