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 DB0A5C41513 for ; Wed, 16 Aug 2023 08:07:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242709AbjHPIGt (ORCPT ); Wed, 16 Aug 2023 04:06:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242752AbjHPIGg (ORCPT ); Wed, 16 Aug 2023 04:06:36 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CB7E9AB for ; Wed, 16 Aug 2023 01:06:34 -0700 (PDT) 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 3280F1063; Wed, 16 Aug 2023 01:07:15 -0700 (PDT) Received: from [10.162.40.18] (a077893.blr.arm.com [10.162.40.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DE5EA3F64C; Wed, 16 Aug 2023 01:06:31 -0700 (PDT) Message-ID: <435813e1-3e26-d125-d706-a2e3d8fd4e45@arm.com> Date: Wed, 16 Aug 2023 13:36:29 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before clk_put() Content-Language: en-US To: James Clark , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org Cc: Mike Leach , coresight@lists.linaro.org, linux-kernel@vger.kernel.org, Dan Carpenter References: <20230811062738.1066787-1-anshuman.khandual@arm.com> <07b0dabb-5409-9ba8-543f-aeecafe083e9@arm.com> <72960b11-9e35-a259-3ea6-bae91ff94838@arm.com> <32017de8-7b92-a88f-0bf6-da1dfe3a7f7d@arm.com> From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/11/23 15:44, James Clark wrote: > > > On 11/08/2023 10:22, Anshuman Khandual wrote: >> >> >> On 8/11/23 14:39, Suzuki K Poulose wrote: >>> On 11/08/2023 09:39, James Clark wrote: >>>> >>>> >>>> On 11/08/2023 07:27, Anshuman Khandual wrote: >>>>> This validates 'drvdata' and 'drvdata->pclk' clock before calling clk_put() >>>>> in etm4_remove_platform_dev(). The problem was detected using Smatch static >>>>> checker as reported. >>>>> >>>>> Cc: Suzuki K Poulose >>>>> Cc: Mike Leach >>>>> Cc: James Clark >>>>> Cc: coresight@lists.linaro.org >>>>> Cc: linux-arm-kernel@lists.infradead.org >>>>> Cc: linux-kernel@vger.kernel.org >>>>> Reported-by: Dan Carpenter >>>>> Closes: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/G4N6P4OXELPLLQSNU3GU2MR4LOLRXRMJ/ >>>>> Signed-off-by: Anshuman Khandual >>>>> --- >>>>> This applies on coresight-next >>>>> >>>>>   drivers/hwtracing/coresight/coresight-etm4x-core.c | 2 +- >>>>>   1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c >>>>> index 703b6fcbb6a5..eb412ce302cc 100644 >>>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c >>>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c >>>>> @@ -2269,7 +2269,7 @@ static int __exit etm4_remove_platform_dev(struct platform_device *pdev) >>>>>           etm4_remove_dev(drvdata); >>>>>       pm_runtime_disable(&pdev->dev); >>>>>   -    if (drvdata->pclk) >>>>> +    if (drvdata && drvdata->pclk && !IS_ERR(drvdata->pclk)) >>>>>           clk_put(drvdata->pclk); >>>>>         return 0; >>>> >>>> It could be !IS_ERR_OR_NULL(drvdata->pclk), but I wouldn't bother >>>> changing it at this point. >>> >>> +1, please could we have that. Someone else will run a code scanner and >>> send a patch later. Given this is straight and easy change, lets do it >>> in the first place. >> >> But we already have a drvdata->pclk validation check before IS_ERR(). >> Would not _OR_NULL be redundant ? > > I meant that it could be replaced with the single check: > > if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk)) > clk_put(drvdata->pclk); > > As Dan mentions it can't be an error pointer anyway, but leaving it like > this could just be considered defensive coding. Let's just go with the above change as you had suggested unless there is any particular objection. if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk)) clk_put(drvdata->pclk);