linux-kernel - Re: [PATCH v2 1/3] PM: runtime: Add auto-cleanup macros for "resume and get" operations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87348eobnv.wl-tiwai@suse.de>
Date: Mon, 22 Sep 2025 15:32:36 +0200
From: Takashi Iwai <tiwai@...e.de>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Takashi Iwai <tiwai@...e.de>,
	Linux PM <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Bjorn Helgaas <helgaas@...nel.org>,
	Zhang Qilong <zhangqilong3@...wei.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v2 1/3] PM: runtime: Add auto-cleanup macros for "resume and get" operations

On Mon, 22 Sep 2025 14:50:32 +0200,
Rafael J. Wysocki wrote:
> 
> On Mon, Sep 22, 2025 at 10:38 AM Takashi Iwai <tiwai@...e.de> wrote:
> >
> > On Sat, 20 Sep 2025 12:54:58 +0200,
> > Rafael J. Wysocki wrote:
> > >
> > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > >
> > > It is generally useful to be able to automatically drop a device's
> > > runtime PM usage counter incremented by runtime PM operations that
> > > resume a device and bump up its usage counter [1].
> > >
> > > To that end, add DEFINE_CLASS() macros allowing pm_runtime_put()
> > > and pm_runtime_put_autosuspend() to be used for the auto-cleanup in
> > > those cases.
> > >
> > > Simply put, a piece of code like below:
> > >
> > >       pm_runtime_get_sync(dev);
> > >       .....
> > >       pm_runtime_put(dev);
> > >       return 0;
> > >
> > > can be transformed with CLASS() like:
> > >
> > >       CLASS(pm_runtime_get_active, pm)(dev);
> > >       if (IS_ERR(pm))
> > >               return PTR_ERR(pm);
> > >       .....
> > >       return 0;
> > >
> > > (note the new resume error handling).
> >
> > Do we still allow the code without the error check even using CLASS()?
> > Although the error check should be handled, it's not mandatory for
> > now.  That said, the above example could be still in a form like:
> >
> >         CLASS(pm_runtime_get_active, pm)(dev);
> >         .....
> >         return 0;
> >
> > while adding the proper error check is recommended?
> 
> I'd rather not encourage doing this.
> 
> While it may still produce working code in some cases, one needs to
> remember that in case of a runtime resume error it will be running
> without a runtime PM reference it has attempted to acquire.

Fair enough.  Then it'd be also good to mention that in the
description, too.


thanks,

Takashi