linux-kernel - Re: [PATCH] PM: runtime: Simplify __rpm_get

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Message-ID: <CAMuHMdUuPKyMDwAHvUxC_s-Cqv_aui=1+eHCMypkpQSmvz=uuQ@mail.gmail.com>
Date:   Tue, 24 Jan 2023 12:19:48 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] PM: runtime: Simplify __rpm_get_callback()

Hi Bjorn,

On Thu, Dec 15, 2022 at 7:23 PM Bjorn Helgaas <helgaas@...nel.org> wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
>
> Simplify __rpm_get_callback() slightly by returning as soon as the return
> value is known.  No functional change intended.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>

Thanks for your patch, which is now commit 650bdddb6b311705 ("PM:
runtime: Simplify __rpm_get_callback()") in pm/linux-next.

> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -20,8 +20,7 @@ typedef int (*pm_callback_t)(struct device *);
>
>  static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
>  {
> -       pm_callback_t cb;
> -       const struct dev_pm_ops *ops;
> +       const struct dev_pm_ops *ops = NULL;
>
>         if (dev->pm_domain)
>                 ops = &dev->pm_domain->ops;
> @@ -31,18 +30,14 @@ static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
>                 ops = dev->class->pm;
>         else if (dev->bus && dev->bus->pm)
>                 ops = dev->bus->pm;
> -       else
> -               ops = NULL;
>
>         if (ops)
> -               cb = *(pm_callback_t *)((void *)ops + cb_offset);
> -       else
> -               cb = NULL;
> +               return *(pm_callback_t *)((void *)ops + cb_offset);

This is a change in behavior in case the callback turns out to be NULL:
  - before, it would fall back to the driver-specific callback below,
  - after, it always returns NULL.

>
> -       if (!cb && dev->driver && dev->driver->pm)
> -               cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
> +       if (dev->driver && dev->driver->pm)
> +               return *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
>
> -       return cb;
> +       return NULL;
>  }

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