linux-kernel - Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before clk

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Message-ID: <72960b11-9e35-a259-3ea6-bae91ff94838@arm.com>
Date:   Fri, 11 Aug 2023 10:09:43 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     James Clark <james.clark@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Mike Leach <mike.leach@...aro.org>, coresight@...ts.linaro.org,
        linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before
 clk_put()

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@....com>
>> Cc: Mike Leach <mike.leach@...aro.org>
>> Cc: James Clark <james.clark@....com>
>> Cc: coresight@...ts.linaro.org
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
>> Closes: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/G4N6P4OXELPLLQSNU3GU2MR4LOLRXRMJ/
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....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.

Cheers
Suzuki

> 
> Reviewed-by: James Clark <james.clark@....com>