linux-kernel - Re: [PATCH v3 2/6] of: dynamic: Refactor action prints to not use "%pOF" inside devtree

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Message-ID: <CAMuHMdW5PCHWb9o=6NSwEsFY8aGGNX17b7-mdaoszzAP-aUZyQ@mail.gmail.com>
Date:   Mon, 21 Aug 2023 13:52:01 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Frank Rowand <frowand.list@...il.com>,
        "Enrico Weigelt, metux IT consult" <info@...ux.net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Petr Mladek <pmladek@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/6] of: dynamic: Refactor action prints to not use
 "%pOF" inside devtree_lock

Hi Rob,

Thanks for the update!

On Fri, Aug 18, 2023 at 10:41 PM Rob Herring <robh@...nel.org> wrote:
> While originally it was fine to format strings using "%pOF" while
> holding devtree_lock, this now causes a deadlock.  Lockdep reports:
>
>     of_get_parent from of_fwnode_get_parent+0x18/0x24
>     ^^^^^^^^^^^^^
>     of_fwnode_get_parent from fwnode_count_parents+0xc/0x28
>     fwnode_count_parents from fwnode_full_name_string+0x18/0xac
>     fwnode_full_name_string from device_node_string+0x1a0/0x404
>     device_node_string from pointer+0x3c0/0x534
>     pointer from vsnprintf+0x248/0x36c
>     vsnprintf from vprintk_store+0x130/0x3b4
>
> Fix this by moving the printing in __of_changeset_entry_apply() outside
> the lock. As the only difference in the the multiple prints is the

scripts/checkpatch.pl says: WARNING: Possible repeated word: 'the'

> action name, use the existing "action_names" to refactor the prints into
> a single print.
>
> Fixes: a92eb7621b9fb2c2 ("lib/vsprintf: Make use of fwnode API to obtain node names and separators")
> Reported-by: Geert Uytterhoeven <geert+renesas@...der.be>
> Signed-off-by: Rob Herring <robh@...nel.org>
> ---
> v6 (v3 in this series):
>  - Add check on 'action' bounds. As action is only set in
>    of_changeset_action(), add the check there.
>  - Drop printing the changeset entry pointer

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds