netdev - Re: [PATCH v3 1/2] pm: runtime: Simplify pm_runtime_get_if

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20240122181205.GA275751@bhelgaas>
Date: Mon, 22 Jan 2024 12:12:05 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rafael@...nel.org>,
	linux-pci@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	Jaroslav Kysela <perex@...ex.cz>,
	Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>,
	laurent.pinchart@...asonboard.com, David Airlie <airlied@...il.com>,
	Paul Elder <paul.elder@...asonboard.com>,
	linux-media@...r.kernel.org,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	intel-gfx@...ts.freedesktop.org,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Mark Brown <broonie@...nel.org>,
	Jacek Lawrynowicz <jacek.lawrynowicz@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	intel-xe@...ts.freedesktop.org,
	Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
	Alex Elder <elder@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-sound@...r.kernel.org, Takashi Iwai <tiwai@...e.com>,
	Daniel Vetter <daniel@...ll.ch>, netdev@...r.kernel.org
Subject: Re: [PATCH v3 1/2] pm: runtime: Simplify pm_runtime_get_if_active()
 usage

On Mon, Jan 22, 2024 at 01:41:21PM +0200, Sakari Ailus wrote:
> There are two ways to opportunistically increment a device's runtime PM
> usage count, calling either pm_runtime_get_if_active() or
> pm_runtime_get_if_in_use(). The former has an argument to tell whether to
> ignore the usage count or not, and the latter simply calls the former with
> ign_usage_count set to false. The other users that want to ignore the
> usage_count will have to explitly set that argument to true which is a bit
> cumbersome.

s/explitly/explicitly/

> To make this function more practical to use, remove the ign_usage_count
> argument from the function. The main implementation is renamed as
> pm_runtime_get_conditional().
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Reviewed-by: Alex Elder <elder@...aro.org> # drivers/net/ipa/ipa_smp2p.c
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Acked-by: Takashi Iwai <tiwai@...e.de> # sound/
> Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@...ux.intel.com> # drivers/accel/ivpu/
> Acked-by: Rodrigo Vivi <rodrigo.vivi@...el.com> # drivers/gpu/drm/i915/
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@...el.com>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com> # drivers/pci/

> -EXPORT_SYMBOL_GPL(pm_runtime_get_if_active);
> +EXPORT_SYMBOL_GPL(pm_runtime_get_conditional);

If pm_runtime_get_conditional() is exported, shouldn't it also be
documented in Documentation/power/runtime_pm.rst?

But I'm dubious about exporting it because
__intel_runtime_pm_get_if_active() is the only caller, and you end up
with the same pattern there that we have before this series in the PM
core.  Why can't intel_runtime_pm.c be updated to use
pm_runtime_get_if_active() or pm_runtime_get_if_in_use() directly, and
make pm_runtime_get_conditional() static?

> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -246,7 +246,7 @@ static intel_wakeref_t __intel_runtime_pm_get_if_active(struct intel_runtime_pm
>  		 * function, since the power state is undefined. This applies
>  		 * atm to the late/early system suspend/resume handlers.
>  		 */
> -		if (pm_runtime_get_if_active(rpm->kdev, ignore_usecount) <= 0)
> +		if (pm_runtime_get_conditional(rpm->kdev, ignore_usecount) <= 0)
>  			return 0;
>  	}

Bjorn