linux-kernel - Re: [PATCH v4 13/21] drivers/thermal/rcar_gen3_thermal: convert to use devm_request*_irq

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Date:   Mon, 10 Jul 2023 14:27:41 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Yangtao Li <frank.li@...o.com>
Cc:     Niklas Söderlund <niklas.soderlund@...natech.se>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-renesas-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 13/21] drivers/thermal/rcar_gen3_thermal: convert to
 use devm_request*_irq_probe()

On Mon, Jul 10, 2023 at 12:10 PM Yangtao Li <frank.li@...o.com> wrote:
> There are more than 700 calls to devm_request_threaded_irq method and
> more than 1000 calls to devm_request_irq method. Most drivers only
> request one interrupt resource, and these error messages are basically
> the same. If error messages are printed everywhere, more than 2000 lines
> of code can be saved by removing the msg in the driver.
>
> And tglx point out that:
>
>   If we actually look at the call sites of
>   devm_request_threaded_irq() then the vast majority of them print more or
>   less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
>
>      519 messages total (there are probably more)
>
>      352 unique messages
>
>      323 unique messages after lower casing
>
>          Those 323 are mostly just variants of the same patterns with
>          slight modifications in formatting and information provided.
>
>      186 of these messages do not deliver any useful information,
>          e.g. "no irq", "
>
>      The most useful one of all is: "could request wakeup irq: %d"
>
>   So there is certainly an argument to be made that this particular
>   function should print a well formatted and informative error message.
>
>   It's not a general allocator like kmalloc(). It's specialized and in the
>   vast majority of cases failing to request the interrupt causes the
>   device probe to fail. So having proper and consistent information why
>   the device cannot be used _is_ useful.
>
> So convert to use devm_request*_irq_probe() API, which ensure that all
> error handling branches print error information.
>
> In this way, when this function fails, the upper-layer functions can
> directly return an error code without missing debugging information.
> Otherwise, the error message will be printed redundantly or missing.
>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Krzysztof Kozlowski <krzk@...nel.org>
> Cc: "Uwe Kleine-König" <u.kleine-koenig@...gutronix.de>
> Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Cc: AngeloGioacchino Del Regno  <angelogioacchino.delregno@...labora.com>
> Signed-off-by: Yangtao Li <frank.li@...o.com>

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