Messages in this thread | | | Date | Wed, 16 Aug 2023 13:36:29 +0530 | Subject | Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before clk_put() | From | Anshuman Khandual <> |
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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 <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.
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);
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