linux-kernel - Re: [PATCH] clk: renesas: rcar-usb2-clock-sel: Fix error handling in rcar_usb2_clock_sel

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Date:   Mon, 12 Apr 2021 11:02:17 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Dinghao Liu <dinghao.liu@....edu.cn>
Cc:     Kangjie Lu <kjlu@....edu>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: renesas: rcar-usb2-clock-sel: Fix error handling in rcar_usb2_clock_sel_probe

Hi Dinghao,

On Mon, Apr 12, 2021 at 9:51 AM Dinghao Liu <dinghao.liu@....edu.cn> wrote:
> When clk_get_rate() fails, a pairing PM usage counter decrement
> and disable is required to prevent refcount leak. It's the same
> for the subsequent error paths. When of_clk_add_hw_provider()
> fails, we need to unregister clk_hw.
>
> Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>

Thanks for your patch, which looks correct to me.

> --- a/drivers/clk/renesas/rcar-usb2-clock-sel.c
> +++ b/drivers/clk/renesas/rcar-usb2-clock-sel.c
> @@ -180,7 +180,8 @@ static int rcar_usb2_clock_sel_probe(struct platform_device *pdev)
>
>         if (!priv->extal && !priv->xtal) {
>                 dev_err(dev, "This driver needs usb_extal or usb_xtal\n");
> -               return -ENOENT;
> +               ret = -ENOENT;
> +               goto pm_put;
>         }

As the code above doesn't rely on the device being powered yet, you
could move the pm_runtime_{enable,get_sync}() calls below the clock
checks instead.

>
>         platform_set_drvdata(pdev, priv);
> @@ -194,10 +195,23 @@ static int rcar_usb2_clock_sel_probe(struct platform_device *pdev)
>         priv->hw.init = &init;
>
>         clk = clk_register(NULL, &priv->hw);
> -       if (IS_ERR(clk))
> -               return PTR_ERR(clk);
> +       if (IS_ERR(clk)) {
> +               ret = PTR_ERR(clk);
> +               goto pm_put;
> +       }
> +
> +       ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &priv->hw);
> +       if (ret)
> +               goto clk_unregister;
> +
> +       return 0;
>
> -       return of_clk_add_hw_provider(np, of_clk_hw_simple_get, &priv->hw);
> +clk_unregister:
> +       clk_hw_unregister(&priv->hw);

The error path can be simplified by replacing the call to clk_register()
by a call to devm_clk_register(), to match the style of the other
initialization steps.

> +pm_put:
> +       pm_runtime_put(dev);
> +       pm_runtime_disable(dev);
> +       return ret;

This part has to stay, of course.

>  }

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