Re: [PATCH v3 2/5] thermal/drivers/armada: convert to use devm_request_threaded_irq_emsg()

Miquel Raynal
2023-07-04T08:46:19Z

Hi Yangtao,

frank.li@vivo.com wrote on Mon, 3 Jul 2023 17:04:51 +0800:

> There are more than 700 calls to the devm_request_threaded_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 1000 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.
>
> Let's use devm_request_threaded_irq_emsg(), 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@linutronix.de>
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
> drivers/thermal/armada_thermal.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> index 9f6dc4fc9112..a5e140643f00 100644
> --- a/drivers/thermal/armada_thermal.c
> +++ b/drivers/thermal/armada_thermal.c
> @@ -913,15 +913,12 @@ static int armada_thermal_probe(struct platform_device *pdev)
>
> /* The overheat interrupt feature is not mandatory */
> if (irq > 0) {
> - ret = devm_request_threaded_irq(&pdev->dev, irq,
> - armada_overheat_isr,
> - armada_overheat_isr_thread,
> - 0, NULL, priv);
> - if (ret) {
> - dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> - irq);
> + ret = devm_request_threaded_irq_emsg(&pdev->dev, irq,
> + armada_overheat_isr,
> + armada_overheat_isr_thread,
> + 0, NULL, priv, NULL);
> + if (ret)

I don't see a patch renaming this helper with s/emsg//, do you plan to
keep it like that? I bet nobody outside of this series will notice the
new helper and will continue to add error messages because it kind
of feels "right" to do so.

I would rather prefer returning to the original function name which
everybody knows/uses.

Anyhow, I'm fine with the idea of dropping custom error messages, so
whatever the final solution:

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks,
Miquèl