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 smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4421CC433EF for ; Tue, 8 Mar 2022 13:20:44 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id C8E1C41795; Tue, 8 Mar 2022 13:20:43 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mvnvURI6QM5i; Tue, 8 Mar 2022 13:20:42 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 7BBE941794; Tue, 8 Mar 2022 13:20:42 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4A7A8C0012; Tue, 8 Mar 2022 13:20:42 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9AB04C000B for ; Tue, 8 Mar 2022 13:20:40 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 7512A84148 for ; Tue, 8 Mar 2022 13:20:40 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 37-Td-_BImlN for ; Tue, 8 Mar 2022 13:20:39 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by smtp1.osuosl.org (Postfix) with ESMTPS id BB44182965 for ; Tue, 8 Mar 2022 13:20:38 +0000 (UTC) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KCbW35fxwzBrbM; Tue, 8 Mar 2022 21:18:39 +0800 (CST) Received: from [10.67.102.169] (10.67.102.169) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 8 Mar 2022 21:20:34 +0800 Subject: Re: [PATCH v5 3/8] hisi_ptt: Register PMU device for PTT trace To: Jonathan Cameron References: <20220308084930.5142-1-yangyicong@hisilicon.com> <20220308084930.5142-4-yangyicong@hisilicon.com> <20220308102157.00003725@Huawei.com> <20220308120607.000064e6@Huawei.com> Message-ID: Date: Tue, 8 Mar 2022 21:20:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20220308120607.000064e6@Huawei.com> X-Originating-IP: [10.67.102.169] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected Cc: mark.rutland@arm.com, prime.zeng@huawei.com, alexander.shishkin@linux.intel.com, linux-pci@vger.kernel.org, linuxarm@huawei.com, yangyicong@hisilicon.com, will@kernel.org, daniel.thompson@linaro.org, peterz@infradead.org, mingo@redhat.com, helgaas@kernel.org, liuqi115@huawei.com, mike.leach@linaro.org, suzuki.poulose@arm.com, coresight@lists.linaro.org, acme@kernel.org, zhangshaokun@hisilicon.com, linux-arm-kernel@lists.infradead.org, song.bao.hua@hisilicon.com, mathieu.poirier@linaro.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, iommu@lists.linux-foundation.org, leo.yan@linaro.org, robin.murphy@arm.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Yicong Yang via iommu Reply-To: Yicong Yang Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2022/3/8 20:06, Jonathan Cameron wrote: > On Tue, 8 Mar 2022 19:13:08 +0800 > Yicong Yang wrote: > >> On 2022/3/8 18:21, Jonathan Cameron wrote: >>> On Tue, 8 Mar 2022 16:49:25 +0800 >>> Yicong Yang wrote: >>> >>>> Register PMU device of PTT trace, then users can use trace through perf >>>> command. The driver makes use of perf AUX trace and support following >>>> events to configure the trace: >>>> >>>> - filter: select Root port or Endpoint to trace >>>> - type: select the type of traced TLP headers >>>> - direction: select the direction of traced TLP headers >>>> - format: select the data format of the traced TLP headers >>>> >>>> This patch adds the PMU driver part of PTT trace. The perf command support >>>> of PTT trace is added in the following patch. >>>> >>>> Signed-off-by: Yicong Yang >>> >>> It seems to me that you ended up doing both suggestions for >>> how to clean up the remove order when it was meant to be >>> a question of picking one or the other. >>> >>> Otherwise this looks good to me - so with that tidied up >>> >> >> Hi Jonathan, >> >> Thanks for the comments. I'd like to illustrate the reason why I decide to >> manually unregister the PMU device. >> >> The DMA buffers are devm allocated when necessary. They're only allocated >> when user is going to use the PTT in the first time after the driver's probe, >> so when driver removal the buffers are released prior to the PMU device's >> unregistration. I think there's a race condition. >> >> IIUC, The PMU device(as the user interface) should be unregistered first then >> we're safe to free the DMA buffers. But unregister the PMU device by devm >> cannot keep that order. > > Ok. Please add a comment in the remove() giving this reasoning. > Sure will add a comment for the reason why we need this manual unregistration in remove(). > Jonathan > >> >> Thanks, >> Yicong >> >>> Reviewed-by: Jonathan Cameron >>> >>>> --- >>> >>>> + >>>> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt) >>>> +{ >>>> + u16 core_id, sicl_id; >>>> + char *pmu_name; >>>> + u32 reg; >>>> + >>>> + hisi_ptt->hisi_ptt_pmu = (struct pmu) { >>>> + .module = THIS_MODULE, >>>> + .capabilities = PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE, >>>> + .task_ctx_nr = perf_sw_context, >>>> + .attr_groups = hisi_ptt_pmu_groups, >>>> + .event_init = hisi_ptt_pmu_event_init, >>>> + .setup_aux = hisi_ptt_pmu_setup_aux, >>>> + .free_aux = hisi_ptt_pmu_free_aux, >>>> + .start = hisi_ptt_pmu_start, >>>> + .stop = hisi_ptt_pmu_stop, >>>> + .add = hisi_ptt_pmu_add, >>>> + .del = hisi_ptt_pmu_del, >>>> + }; >>>> + >>>> + reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION); >>>> + core_id = FIELD_GET(HISI_PTT_CORE_ID, reg); >>>> + sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg); >>>> + >>>> + pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u", >>>> + sicl_id, core_id); >>>> + if (!pmu_name) >>>> + return -ENOMEM; >>>> + >>>> + return perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1); >>> >>> As below, you can put back the devm cleanup that you had in v4 now you >>> have modified how the filter cleanup is done to also be devm managed. >>> >>>> +} >>>> + >>>> /* >>>> * The DMA of PTT trace can only use direct mapping, due to some >>>> * hardware restriction. Check whether there is an IOMMU or the >>>> @@ -303,15 +825,32 @@ static int hisi_ptt_probe(struct pci_dev *pdev, >>>> >>>> pci_set_master(pdev); >>>> >>>> + ret = hisi_ptt_register_irq(hisi_ptt); >>>> + if (ret) >>>> + return ret; >>>> + >>>> ret = hisi_ptt_init_ctrls(hisi_ptt); >>>> if (ret) { >>>> pci_err(pdev, "failed to init controls, ret = %d.\n", ret); >>>> return ret; >>>> } >>>> >>>> + ret = hisi_ptt_register_pmu(hisi_ptt); >>>> + if (ret) { >>>> + pci_err(pdev, "failed to register pmu device, ret = %d", ret); >>>> + return ret; >>>> + } >>>> + >>>> return 0; >>>> } >>>> >>>> +void hisi_ptt_remove(struct pci_dev *pdev) >>>> +{ >>>> + struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev); >>>> + >>>> + perf_pmu_unregister(&hisi_ptt->hisi_ptt_pmu); >>> >>> Now you have the filter cleanup occurring using a devm_add_action_or_reset() >>> there is no need to have a manual cleanup of this - you can >>> use the approach of a devm_add_action_or_reset like you had in v4. >>> >>> As it is the last call in the probe() order it will be the first one >>> called in the device managed cleanup. >>> >>>> +} >>>> + >>> >>> >>> . >>> > > . > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu