linux-kernel - Re: [PATCH] of/fdt: Remove duplicate check in early_init_dt_scan

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Message-ID: <CAL_JsqJ7eK3HB_E8OeSbs=xVLYrvOcXD9GxpKr2N4dXZWnBP+g@mail.gmail.com>
Date:   Mon, 17 Aug 2020 12:21:42 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Qi Zheng <arch0.zheng@...il.com>
Cc:     Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] of/fdt: Remove duplicate check in early_init_dt_scan_memory()

On Fri, Aug 14, 2020 at 4:57 PM Qi Zheng <arch0.zheng@...il.com> wrote:
>
> When the value of the first reg is not NULL, there will be
> two repeated checks. So modify it.

I prefer the way it was. I'm sure the compiler is smart enough to
throw out the 2nd check. Plus, 'linux,usable-memory' being present is
the exception, so usually 'reg' will be NULL.

> Signed-off-by: Qi Zheng <arch0.zheng@...il.com>
> ---
>  drivers/of/fdt.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 4602e467ca8b..f54412c00642 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1002,10 +1002,11 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
>                 return 0;
>
>         reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
> -       if (reg == NULL)
> +       if (reg == NULL) {
>                 reg = of_get_flat_dt_prop(node, "reg", &l);
> -       if (reg == NULL)
> -               return 0;
> +               if (reg == NULL)
> +                       return 0;
> +       }
>
>         endp = reg + (l / sizeof(__be32));
>         hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);
> --
> 2.25.1
>