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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 AD60FC433DF for ; Thu, 16 Jul 2020 10:26:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 832F92064C for ; Thu, 16 Jul 2020 10:26:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727879AbgGPK03 (ORCPT ); Thu, 16 Jul 2020 06:26:29 -0400 Received: from foss.arm.com ([217.140.110.172]:52830 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726080AbgGPK02 (ORCPT ); Thu, 16 Jul 2020 06:26:28 -0400 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 315A91FB; Thu, 16 Jul 2020 03:26:28 -0700 (PDT) Received: from [10.57.35.46] (unknown [10.57.35.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BDA633F68F; Thu, 16 Jul 2020 03:26:26 -0700 (PDT) Subject: Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling To: Will Deacon , Qi Liu Cc: mark.rutland@arm.com, john.garry@huawei.com, linux-kernel@vger.kernel.org, linuxarm@huawei.com, zhangshaokun@hisilicon.com, wang.wanghaifeng@huawei.com, linux-arm-kernel@lists.infradead.org References: <1594891165-8228-1-git-send-email-liuqi115@huawei.com> <20200716094144.GC6771@willie-the-truck> From: Robin Murphy Message-ID: Date: Thu, 16 Jul 2020 11:26:25 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200716094144.GC6771@willie-the-truck> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-07-16 10:41, Will Deacon wrote: > On Thu, Jul 16, 2020 at 05:19:25PM +0800, Qi Liu wrote: >> Kernel panic will also happen when users try to unbind PMU drivers with >> device. This unbind issue could be solved by another patch latter. >> >> drivers/perf/arm_smmuv3_pmu.c | 1 + >> drivers/perf/fsl_imx8_ddr_perf.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_hha_pmu.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c | 1 + >> 5 files changed, 5 insertions(+) >> >> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c >> index 48e28ef..90caba56 100644 >> --- a/drivers/perf/arm_smmuv3_pmu.c >> +++ b/drivers/perf/arm_smmuv3_pmu.c >> @@ -742,6 +742,7 @@ static int smmu_pmu_probe(struct platform_device *pdev) >> platform_set_drvdata(pdev, smmu_pmu); >> >> smmu_pmu->pmu = (struct pmu) { >> + .module = THIS_MODULE, > > I thought platform_driver_register() did this automatically? For the platform device itself, yes, but this is for the PMU device - perf needs to take a reference to the module, otherwise the platform device can still be pulled out from under its feet. I can't remember if we ever discussed making perf_pmu_register() do the same trick as platform_device_register() and friends, but obviously it's a possibility. Robin.