linux-kernel - Re: [PATCH v4 1/9] i2c: riic: Introduce a separate variable for IRQ

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Message-ID: <CAMuHMdWJbdQybi6CBLQD1z1yF1t+C9LyowRnqAAnKV_=zs1Qjg@mail.gmail.com>
Date: Fri, 3 Jan 2025 11:47:58 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Chris Brandt <chris.brandt@...esas.com>, Andi Shyti <andi.shyti@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	Andy Shevchenko <andy.shevchenko@...il.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	linux-renesas-soc@...r.kernel.org, linux-i2c@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v4 1/9] i2c: riic: Introduce a separate variable for IRQ

Hi Prabhakar,

Thanks for your patch!

On Fri, Jan 3, 2025 at 10:19 AM Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Refactor the IRQ handling in riic_i2c_probe by introducing a local variable
> `irq` to store IRQ numbers instead of assigning them to `ret`. This change
> improves code readability and clarity.
>
> Remove explicit error handling after `platform_get_irq()` since
> `devm_request_irq()` already handles such errors.

Where does it handle such errors?
I only found the following check in request_threaded_irq():

        desc = irq_to_desc(irq);
        if (!desc)
                return -EINVAL;

Although irq_to_desc() takes an unsigned int, it should indeed catch
invalid (negative) interrupt numbers, but the code above would not
propagate the correct error code (e.g. -EPROBE_DEFER).

> Suggested-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>


> --- a/drivers/i2c/busses/i2c-riic.c
> +++ b/drivers/i2c/busses/i2c-riic.c
> @@ -464,11 +464,9 @@ static int riic_i2c_probe(struct platform_device *pdev)
>                 return ret;
>
>         for (i = 0; i < ARRAY_SIZE(riic_irqs); i++) {
> -               ret = platform_get_irq(pdev, riic_irqs[i].res_num);
> -               if (ret < 0)
> -                       return ret;
> +               int irq = platform_get_irq(pdev, riic_irqs[i].res_num);

So I think you need to keep a check for irq < 0.

>
> -               ret = devm_request_irq(dev, ret, riic_irqs[i].isr,
> +               ret = devm_request_irq(dev, irq, riic_irqs[i].isr,
>                                        0, riic_irqs[i].name, riic);
>                 if (ret) {
>                         dev_err(dev, "failed to request irq %s\n", riic_irqs[i].name);

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