Messages in this thread | | | Date | Fri, 11 Aug 2023 11:14:10 +0100 | Subject | Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before clk_put() | From | James Clark <> |
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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 <suzuki.poulose@arm.com> >>>> Cc: Mike Leach <mike.leach@linaro.org> >>>> Cc: James Clark <james.clark@arm.com> >>>> Cc: coresight@lists.linaro.org >>>> Cc: linux-arm-kernel@lists.infradead.org >>>> Cc: linux-kernel@vger.kernel.org >>>> Reported-by: Dan Carpenter <dan.carpenter@linaro.org> >>>> Closes: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/G4N6P4OXELPLLQSNU3GU2MR4LOLRXRMJ/ >>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >>>> --- >>>> 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.
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