linux-kernel - Re: PM runtime auto-cleanup macros

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Message-ID: <CAJZ5v0htMKOcCoKts-B9BaE0VpS2oc9-cp=5VnNwS2Qe2iB+Kg@mail.gmail.com>
Date: Wed, 17 Sep 2025 20:58:36 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Takashi Iwai <tiwai@...e.de>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: PM runtime auto-cleanup macros

Hi,

Sorry for the delay.

On Thu, Sep 11, 2025 at 9:31 AM Takashi Iwai <tiwai@...e.de> wrote:
>
> On Wed, 10 Sep 2025 16:00:17 +0200,
> Takashi Iwai wrote:
> >
> > Hi,
> >
> > while I worked on the code cleanups in the drivers with the recent
> > auto-cleanup macros, I noticed that pm_runtime_get*() and _put*() can
> > be also managed with the auto-cleanup gracefully, too.  Actually we
> > already defined the __free(pm_runtime_put) in commit bfa4477751e9, and
> > there is a (single) user of it in pci-sysfs.c.
> >
> > Now I wanted to extend it to pm_runtime_put_autosuspend() as:
> >
> > DEFINE_FREE(pm_runtime_put_autosuspend, struct device *,
> >            if (_T) pm_runtime_put_autosuspend(_T))
> >
> > Then one can use it like
> >
> >       ret = pm_runtime_resume_and_get(dev);
> >       if (ret < 0)
> >               return ret;
> >       struct device *pmdev __free(pm_runtime_put_autosuspend) = dev;
> >
> > that is similar as done in pci-sysfs.c.  So far, so good.
> >
> > But, I find putting the line like above at each place a bit ugly.
> > So I'm wondering whether it'd be better to introduce some helper
> > macros, e.g.
> >
> > #define pm_runtime_auto_clean(dev, var) \
> >       struct device *var __free(pm_runtime_put) = (dev)
>
> It can be even simpler by assigning a temporary variable such as:
>
> #define pm_runtime_auto_clean(dev) \
>         struct device *__pm_runtime_var ## __LINE__ __free(pm_runtime_put) = (dev)

Well, if there's something like

struct device *pm_runtime_resume_and_get_dev(struct device *dev)
{
        int ret = pm_runtime_resume_and_get(dev);
        if (ret < 0)
                return ERR_PTR(ret);

        return dev;
}

It would be a matter of redefining the FREE to also take error
pointers into account and you could do

struct device *__dev __free(pm_runtim_put) = pm_runtime_resume_and_get_dev(dev);
if (IS_ERR(__dev))
        return PTR_ERR(__dev);