linux-kernel - Re: [PATCH 1/1] lib: devres: Add error information printing for __devm_ioremap

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Date:   Mon, 17 May 2021 09:04:15 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Zhen Lei <thunder.leizhen@...wei.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH 1/1] lib: devres: Add error information printing for __devm_ioremap_resource()

Hi Zhen,

On Wed, Apr 28, 2021 at 8:33 AM Zhen Lei <thunder.leizhen@...wei.com> wrote:
> 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.
>
> Fixes: 35bd8c07db2c ("devres: keep both device name and resource name in pretty name")
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>

Thanks for your patch, which is now commit 5c3e241f5246445d ("lib:
devres: Add error information printing for __devm_ioremap_resource()")
in driver-core-next.

> --- a/lib/devres.c
> +++ b/lib/devres.c
> @@ -157,8 +157,10 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,
>                                              dev_name(dev), res->name);
>         else
>                 pretty_name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
> -       if (!pretty_name)
> +       if (!pretty_name) {
> +               dev_err(dev, "can't generate pretty name for resource %pR\n", res);

If the above fails, it is due to a memory allocation failure, and the
memory allocation core will have already printed an error message.
So there is no need to print a second message.
Hence IMHO this commit should be reverted.

>                 return IOMEM_ERR_PTR(-ENOMEM);
> +       }
>
>         if (!devm_request_mem_region(dev, res->start, size, pretty_name)) {
>                 dev_err(dev, "can't request region for resource %pR\n", res);

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