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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 AF11FC433DF for ; Wed, 22 Jul 2020 10:48:17 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 76E5E207BB for ; Wed, 22 Jul 2020 10:48:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="e9CUqXya" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76E5E207BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:References: To:From:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ZFArRCBGaUAVbY2SIEspSCndmBKMz5qPtDEjeqotNtE=; b=e9CUqXyaF1DQU9oLj2eILEPMz boqPSed18hrxR1KSUMI12aIruwCZMidkdWdjUCiVA6c/hJ8ku4dcFhkeUZajaUr/qG56ABki8PfGI I4N4JMAAxtBeG37VDgq51qMGPSWREd4sTTTeIPQhjKZ1mqIvYHzrOXc2gsWcwNYuNfwpJP4qLp9Gh /tBfhv1wz0ca/F5I813lRTYRHNc3jlwrejpkNK+bLoBKvHK6L6gqzyKFZrn1zGBFG3yIquFK3kEP7 HLln9rnW11ujHhPmNt4KI7pzTuIcMyQ9z0UE8SDfExiKZPn/HFuRkg3EOhhflDnkkSgI5Zbq9dSfu CtadxLb7w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jyCH3-0000vQ-Ve; Wed, 22 Jul 2020 10:46:58 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jyCH1-0000v1-Dv for linux-arm-kernel@lists.infradead.org; Wed, 22 Jul 2020 10:46:56 +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 55534101E; Wed, 22 Jul 2020 03:46:50 -0700 (PDT) Received: from [10.37.12.71] (unknown [10.37.12.71]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EA5FD3F66F; Wed, 22 Jul 2020 03:46:45 -0700 (PDT) Subject: Re: [PATCH v3 19/20] coresight: add try_get_module() in coresight_grab_device() From: Suzuki K Poulose To: tingwei@codeaurora.org, mathieu.poirier@linaro.org, alexander.shishkin@linux.intel.com References: <20200717054536.7052-1-tingwei@codeaurora.org> <20200717054536.7052-20-tingwei@codeaurora.org> <7ef8d427-23c9-10cd-b337-03ae75476a8c@arm.com> Message-ID: <34a3a704-293c-54ac-edfa-17715f419fa4@arm.com> Date: Wed, 22 Jul 2020 11:51:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <7ef8d427-23c9-10cd-b337-03ae75476a8c@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200722_064655_531225_8BEAF403 X-CRM114-Status: GOOD ( 16.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tsoni@codeaurora.org, saiprakash.ranjan@codeaurora.org, kim.phillips@arm.com, jinlmao@codeaurora.org, gregkh@linuxfoundation.org, coresight@lists.linaro.org, rdunlap@infradead.org, ykaukab@suse.de, linux@armlinux.org.uk, leo.yan@linaro.org, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/22/2020 11:49 AM, Suzuki K Poulose wrote: > Hi Tingwei, > > On 07/17/2020 06:45 AM, Tingwei Zhang wrote: >> When coresight device is in an active session, driver module of >> that device should not be removed. Use try_get_module() in >> coresight_grab_device() to prevent module to be unloaded. >> > > Is this really sufficient ? AFAIU, a device could be removed, but the > module may still be alive due to the refcount on the module. This > could imply that we have stale pointers in the _path_, which could > lead to corruption elsewhere. Should we do a get/put_device() instead ? Also, logically this refcount solution patch must be applied before the drivers are made modules to prevent breaking bisection failures. So, please re-order the patches in the series to take that into consideration. Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel