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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jg58y-0001Ap-3x; Tue, 02 Jun 2020 11:31:44 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jg58v-00019z-Op; Tue, 02 Jun 2020 11:31:43 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B08A931B; Tue, 2 Jun 2020 04:31:37 -0700 (PDT) Received: from [10.37.12.87] (unknown [10.37.12.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 54B5E3F52E; Tue, 2 Jun 2020 04:31:27 -0700 (PDT) Subject: Re: [PATCH v8 4/8] PM / EM: add support for other devices than CPUs in Energy Model To: Daniel Lezcano , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-imx@nxp.com References: <20200527095854.21714-1-lukasz.luba@arm.com> <20200527095854.21714-5-lukasz.luba@arm.com> From: Lukasz Luba Message-ID: <7201e161-6952-6e28-4036-bd0f0353ec30@arm.com> Date: Tue, 2 Jun 2020 12:31:25 +0100 User-Agent: Mozilla/5.0 (X11; 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charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Daniel, On 6/1/20 10:44 PM, Daniel Lezcano wrote: > On 27/05/2020 11:58, Lukasz Luba wrote: >> Add support for other devices than CPUs. The registration function >> does not require a valid cpumask pointer and is ready to handle new >> devices. Some of the internal structures has been reorganized in order to >> keep consistent view (like removing per_cpu pd pointers). >> >> Signed-off-by: Lukasz Luba >> --- > > [ ... ] > >> } >> EXPORT_SYMBOL_GPL(em_register_perf_domain); >> + >> +/** >> + * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device >> + * @dev : Device for which the EM is registered >> + * >> + * Try to unregister the EM for the specified device (but not a CPU). >> + */ >> +void em_dev_unregister_perf_domain(struct device *dev) >> +{ >> + if (IS_ERR_OR_NULL(dev) || !dev->em_pd) >> + return; >> + >> + if (_is_cpu_device(dev)) >> + return; >> + >> + mutex_lock(&em_pd_mutex); > > Is the mutex really needed? I just wanted to align this unregister code with register. Since there is debugfs dir lookup and the device's EM existence checks I thought it wouldn't harm just to lock for a while and make sure the registration path is not used. These two paths shouldn't affect each other, but with modules loading/unloading I wanted to play safe. I can change it maybe to just dmb() and the end of the function if it's a big performance problem in this unloading path. What do you think? > > If this function is called that means there is no more user of the > em_pd, no? True, that EM users should already be unregistered i.e. thermal cooling. > >> + em_debug_remove_pd(dev); >> + >> + kfree(dev->em_pd->table); >> + kfree(dev->em_pd); >> + dev->em_pd = NULL; >> + mutex_unlock(&em_pd_mutex); >> +} >> +EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain); >> > > Thank you for reviewing this. Regards, Lukasz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel