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 E66C2C433F5 for ; Tue, 8 Mar 2022 13:20:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347102AbiCHNVf (ORCPT ); Tue, 8 Mar 2022 08:21:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233857AbiCHNVd (ORCPT ); Tue, 8 Mar 2022 08:21:33 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 845AE4968D; Tue, 8 Mar 2022 05:20:36 -0800 (PST) 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 CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , 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> From: Yicong Yang 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> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. >>> >>>> +} >>>> + >>> >>> >>> . >>> > > . >