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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE94FC56202 for ; Mon, 23 Nov 2020 12:59:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90754206D9 for ; Mon, 23 Nov 2020 12:59:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388139AbgKWM7Z (ORCPT ); Mon, 23 Nov 2020 07:59:25 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2138 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387524AbgKWMzN (ORCPT ); Mon, 23 Nov 2020 07:55:13 -0500 Received: from fraeml737-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4CfnBR6d03z67Gn6; Mon, 23 Nov 2020 20:53:03 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml737-chm.china.huawei.com (10.206.15.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 23 Nov 2020 13:55:05 +0100 Received: from [10.47.7.144] (10.47.7.144) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Mon, 23 Nov 2020 12:55:04 +0000 Subject: Re: [PATCH v2 1/3] genirq/affinity: Add irq_update_affinity_desc() To: Marc Zyngier CC: Thomas Gleixner , , , , , , , References: <87ft57r7v3.fsf@nanos.tec.linutronix.de> <78356caa-57a0-b807-fe52-8f12d36c1789@huawei.com> <874klmqu2r.fsf@nanos.tec.linutronix.de> <87lfexp6am.fsf@nanos.tec.linutronix.de> <3acb7fde-eae2-a223-9cfd-f409cc2abba6@huawei.com> <873615oy8a.fsf@nanos.tec.linutronix.de> <4aab9d3b-6ca6-01c5-f840-459f945c7577@huawei.com> <87sg91ik9e.wl-maz@kernel.org> From: John Garry Message-ID: <0edc9a11-0b92-537f-1790-6b4b6de4900d@huawei.com> Date: Mon, 23 Nov 2020 12:54:45 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <87sg91ik9e.wl-maz@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.7.144] X-ClientProxiedBy: lhreml748-chm.china.huawei.com (10.201.108.198) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, >>> Right, but if the driver is removed then the interrupts should be >>> deallocated, right? >>> >> >> When removing the driver we just call free_irq(), which removes the >> handler and disables the interrupt. >> >> But about the irq_desc, this is created when the mapping is created in >> irq_create_fwspec_mapping(), and I don't see this being torn down in >> the driver removal, so persistent in that regard. > > If the irq_descs are created via the platform_get_irq() calls in > platform_get_irqs_affinity(), I'd expect some equivalent helper to > tear things down as a result, calling irq_dispose_mapping() behind the > scenes. > So this looks lacking in the kernel AFAICS... So is there a reason for which irq dispose mapping is not a requirement for drivers when finished with the irq? because of shared interrupts? >> So for pci msi I can see that we free the irq_desc in >> pci_disable_msi() -> free_msi_irqs() -> msi_domain_free_irqs() ... >> >> So what I am missing here? > > I'm not sure the paths are strictly equivalent. On the PCI side, we > can have something that completely driver agnostic, as it is all > architectural. In your case, only the endpoint driver knows about what > happens, and needs to free things accordingly. > > Finally, there is the issue in your driver that everything is > requested using devm_request_irq, which cannot play nicely with an > explicit irq_desc teardown. You'll probably need to provide the > equivalent devm helpers for your driver to safely be taken down. > Yeah, so since we use the devm irq request method, we also need a devm dispose release method as we can't dispose the irq mapping in the remove() method, prior to the irq_free() in the later devm release method. But it looks like there is more to it than that, which I'm worried is far from non-trivial. For example, just calling irq_dispose_mapping() for removal and then plaform_get_irq()->acpi_get_irq() second time fails as it looks like more tidy-up is needed for removal... Cheers, John