From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33543C4332F for ; Wed, 5 Jan 2022 10:48:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239491AbiAEKsu convert rfc822-to-8bit (ORCPT ); Wed, 5 Jan 2022 05:48:50 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:4344 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239492AbiAEKss (ORCPT ); Wed, 5 Jan 2022 05:48:48 -0500 Received: from fraeml744-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4JTR3r61jWz67kM8; Wed, 5 Jan 2022 18:46:16 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml744-chm.china.huawei.com (10.206.15.225) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Wed, 5 Jan 2022 11:48:45 +0100 Received: from localhost (10.47.83.118) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.20; Wed, 5 Jan 2022 10:48:44 +0000 Date: Wed, 5 Jan 2022 10:48:50 +0000 From: Jonathan Cameron To: Paul Cercueil CC: "Rafael J . Wysocki" , Ulf Hansson , Jonathan Cameron , "Lars-Peter Clausen" , Linus Walleij , "Arnd Bergmann" , Len Brown , Pavel Machek , , , , , , Subject: Re: [PATCH 3/8] PM: core: Add EXPORT[_GPL]_SIMPLE_DEV_PM_OPS macros Message-ID: <20220105104850.00006e98@Huawei.com> In-Reply-To: <06F85R.46PNU7YFWD631@crapouillou.net> References: <20220104214214.198843-1-paul@crapouillou.net> <20220104214214.198843-4-paul@crapouillou.net> <20220105100332.000001c1@Huawei.com> <06F85R.46PNU7YFWD631@crapouillou.net> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.29; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.47.83.118] X-ClientProxiedBy: lhreml704-chm.china.huawei.com (10.201.108.53) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Wed, 5 Jan 2022 10:15:36 +0000 Paul Cercueil wrote: > Hi Jonathan, > > Le mer., janv. 5 2022 at 10:03:32 +0000, Jonathan Cameron > a écrit : > > On Tue, 4 Jan 2022 21:42:09 +0000 > > Paul Cercueil wrote: > > > >> These macros are defined conditionally, according to CONFIG_PM: > >> - if CONFIG_PM is enabled, these macros resolve to > >> DEFINE_SIMPLE_DEV_PM_OPS(), and the dev_pm_ops symbol will be > >> exported. > >> > >> - if CONFIG_PM is disabled, these macros will result in a dummy > >> static > >> dev_pm_ops to be created with the __maybe_unused flag. The > >> dev_pm_ops > >> will then be discarded by the compiler, along with the provided > >> callback functions if they are not used anywhere else. > >> > >> In the second case, the symbol is not exported, which should be > >> perfectly fine - users of the symbol should all use the pm_ptr() or > >> pm_sleep_ptr() macro, so the dev_pm_ops marked as "extern" in the > >> client's code will never be accessed. > >> > >> Signed-off-by: Paul Cercueil > >> --- > >> include/linux/pm.h | 33 ++++++++++++++++++++++++++++++--- > >> 1 file changed, 30 insertions(+), 3 deletions(-) > >> > >> diff --git a/include/linux/pm.h b/include/linux/pm.h > >> index 389e600df233..a1ce29566aea 100644 > >> --- a/include/linux/pm.h > >> +++ b/include/linux/pm.h > >> @@ -8,6 +8,7 @@ > >> #ifndef _LINUX_PM_H > >> #define _LINUX_PM_H > >> > >> +#include > >> #include > >> #include > >> #include > >> @@ -357,14 +358,40 @@ struct dev_pm_ops { > >> #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) > >> #endif > >> > >> +#define _DEFINE_DEV_PM_OPS(name, \ > >> + suspend_fn, resume_fn, \ > >> + runtime_suspend_fn, runtime_resume_fn, idle_fn) \ > >> +const struct dev_pm_ops name = { \ > >> + SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \ > >> + RUNTIME_PM_OPS(runtime_suspend_fn, runtime_resume_fn, idle_fn) \ > >> +} > >> + > > > > one blank line probably enough. > > > >> + > >> /* > >> * Use this if you want to use the same suspend and resume > >> callbacks for suspend > >> * to RAM and hibernation. > >> */ > >> #define DEFINE_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \ > >> -const struct dev_pm_ops name = { \ > >> - SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \ > >> -} > >> + _DEFINE_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL) > >> + > >> +#ifdef CONFIG_PM > >> +#define _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, > >> runtime_suspend_fn, \ > >> + runtime_resume_fn, idle_fn, sec) \ > >> + _DEFINE_DEV_PM_OPS(name, suspend_fn, resume_fn, > >> runtime_suspend_fn, \ > >> + runtime_resume_fn, idle_fn); \ > >> + _EXPORT_SYMBOL(name, sec) > >> +#else > >> +#define _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, > >> runtime_suspend_fn, \ > >> + runtime_resume_fn, idle_fn, sec) \ > >> +static __maybe_unused _DEFINE_DEV_PM_OPS(__static_##name, > >> suspend_fn, \ > >> + resume_fn, runtime_suspend_fn, \ > >> + runtime_resume_fn, idle_fn) > >> +#endif > >> + > >> +#define EXPORT_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \ > >> + _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL, > >> "") > >> +#define EXPORT_GPL_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \ > >> + _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL, > >> "_gpl") > > > > So you can get away with these two cases because the > > SYSTEM_SLEEP_PM_OPS() all have > > pm_sleep_ptr() wrappers. However, _EXPORT_DEV_PM_OPS() could be used > > directly and > > would require __maybe_unused for the RUNTIME_PM_OPS() parameters > > which isn't ideal. > > I don't see why. On both cases (CONFIG_PM enabled/disabled) the > runtime-PM callbacks are referenced directly, so at no point do they > appear as unused; therefore __maybe_unused is not needed. Ah. I'd miss followed things through. Indeed the 'magic' __static_xxx_pm_ops structure maintains a reference that the compiler can then remove. On the plus side, turned out I'd not done a full set of tests with my own patch set and found one bug in that :) Acked-by: Jonathan Cameron > > Cheers, > -Paul > > > Maybe I'm missing some reason that isn't a problem though as easy to > > get lost in > > these macros. :) > > > > You could argue that the _ is meant to indicate that macro shouldn't > > be used directly > > but I'm not that optimistic. > > > > Jonathan > > > > > > > >> > >> /* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */ > >> #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \ > > > >