Re: [PATCH v1 2/3] PCI/sysfs: Use PM runtime class macro for auto cleanup in reset_method_store()

Rafael J. Wysocki
2025-09-26T14:37:03Z

On Fri, Sep 26, 2025 at 3:49 PM Jonathan Cameron
<jonathan.cameron@huawei.com> wrote:
>
> On Fri, 19 Sep 2025 18:38:42 +0200
> "Rafael J. Wysocki" <rafael@kernel.org> wrote:
>
> > From: Takashi Iwai <tiwai@suse.de>
> >
> > The newly introduced class macro can simplify the code.
> >
> > Also, add the proper error handling for the PM runtime get.
> >
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > [ rjw: Adjust subject and error handling ]
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> > drivers/pci/pci-sysfs.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > --- a/drivers/pci/pci-sysfs.c
> > +++ b/drivers/pci/pci-sysfs.c
> > @@ -1475,8 +1475,9 @@ static ssize_t reset_method_store(struct
> > return count;
> > }
> >
> > - pm_runtime_get_sync(dev);
> > - struct device *pmdev __free(pm_runtime_put) = dev;
> > + CLASS(pm_runtime_resume_and_get, pmdev)(dev);
> > + if (IS_ERR(pmdev))
> > + return -ENXIO;
> Hi Rafael,
>
> Why this approach rather than treating runtime pm state like a conditional
> lock (we use it much like one) and using ACQUIRE() / ACQUIRE_ERR()?

Mostly because devices are not locks.

> Ultimately that's a wrapper around the same infrastructure but
> perhaps neater as it removes need to have that explicit magic pmdev.

You'll need to have a magic pmdev or similar regardless IIUC.

Say there is

DEFINE_GUARD(pm_runtime_active, struct device *,
pm_runtime_get_sync(_T), pm_runtime_put(_T))
DEFINE_GUARD_COND(pm_runtime_active, _try, pm_runtime_resume_and_get(_T))

so the user of this will do

ACQUIRE(pm_runtime_active_try, pm)(dev);
if (ACQUIRE_ERR(pm_runtime_active_try, &pm))
return -ENXIO;

and there's a "magic" pm though pm is not a struct device pointer.

Maybe it's nicer. I guess people may be more used to dealing with int
error variables.

Let me try this and see how far I can get with this.

> +CC Dan as he can probably remember the discussions around ACQUIRE()
> vs the way you have here better than I can.
>
> In general great that you've done this. Was on my list too, but I didn't
> get around to actually spinning the patches! This is going to be
> very useful indeed.

Thanks!