Message-ID: <CAMuHMdXx7h47cOg8AJysbS_ohT=SfRsXW+vRUh+KiOPEsXNfnA@mail.gmail.com>
Date:   Mon, 10 Jul 2023 14:25:24 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Yangtao Li <frank.li@...o.com>
Cc:     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-kernel@...r.kernel.org
Subject: Re: [PATCH v4 01/21] genirq/devres: Add devm_request_threaded_irq_probe()
 and devm_request_irq_probe()

Hi Yangtao,

On Mon, Jul 10, 2023 at 12:05 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 add devm_request_threaded_irq_probe() and devm_request_irq_probe(),
> 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>

Thanks for your patch!

> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -201,6 +201,21 @@ extern void free_percpu_nmi(unsigned int irq, void __percpu *percpu_dev_id);
>
>  struct device;
>
> +extern int __must_check
> +devm_request_threaded_irq_probe(struct device *dev, unsigned int irq,
> +                             irq_handler_t handler, irq_handler_t thread_fn,
> +                             unsigned long irqflags, const char *devname,
> +                             void *dev_id, const char *info);
> +
> +static inline int __must_check
> +devm_request_irq_probe(struct device *dev, unsigned int irq,
> +                      irq_handler_t handler, unsigned long irqflags,
> +                      const char *devname, void *dev_id, const char *info)
> +{
> +       return devm_request_threaded_irq_probe(dev, irq, handler, NULL, irqflags,
> +                                        devname, dev_id, info);
> +}
> +
>  extern int __must_check
>  devm_request_threaded_irq(struct device *dev, unsigned int irq,
>                           irq_handler_t handler, irq_handler_t thread_fn,
> diff --git a/kernel/irq/devres.c b/kernel/irq/devres.c
> index f6e5515ee077..43a40d6e2e0b 100644
> --- a/kernel/irq/devres.c
> +++ b/kernel/irq/devres.c
> @@ -79,6 +79,46 @@ int devm_request_threaded_irq(struct device *dev, unsigned int irq,
>  }
>  EXPORT_SYMBOL(devm_request_threaded_irq);
>
> +/**
> + *     devm_request_threaded_irq_probe - allocate an interrupt line for a managed device
> + *     @dev: device to request interrupt for
> + *     @irq: Interrupt line to allocate
> + *     @handler: Function to be called when the IRQ occurs
> + *     @thread_fn: function to be called in a threaded interrupt context. NULL
> + *                 for devices which handle everything in @handler
> + *     @irqflags: Interrupt type flags
> + *     @devname: An ascii name for the claiming device, dev_name(dev) if NULL
> + *     @dev_id: A cookie passed back to the handler function
> + *     @info: Optional additional error log
> + *
> + *     This is a variant of the devm_request_threaded_irq function.
> + *     It will print an error message by default when the request fails,
> + *     and the consumer can add a special error msg.
> + *
> + *     Except for the extra @dev argument, this function takes the

... extra @dev and @info arguments, ...

> + *     same arguments and performs the same function as
> + *     request_threaded_irq().  IRQs requested with this function will be

But probably you want to compare with devm_request_threaded_irq()
instead of with request_threaded_irq()?
I.e. "... extra @info argument..." above.

> + *     automatically freed on driver detach.
> + *
> + *     If an IRQ allocated with this function needs to be freed
> + *     separately, devm_free_irq() must be used.
> + */
> +int devm_request_threaded_irq_probe(struct device *dev, unsigned int irq,
> +                                   irq_handler_t handler, irq_handler_t thread_fn,
> +                                   unsigned long irqflags, const char *devname,
> +                                   void *dev_id, const char *info)
> +{
> +       int rc;
> +
> +       rc = devm_request_threaded_irq(dev, irq, handler, NULL, irqflags, devname, dev_id);
> +       if (rc)
> +               return dev_err_probe(dev, rc, "Failed to request %sinterrupt %u %s %s\n",
> +                                    thread_fn ? "threaded " : "", irq, devname ? : dev_name(dev),
> +                                    info ? : "");
> +       return 0;
> +}
> +EXPORT_SYMBOL(devm_request_threaded_irq_probe);
> +
>  /**
>   *     devm_request_any_context_irq - allocate an interrupt line for a managed device
>   *     @dev: device to request interrupt for

With the above fixed:
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

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