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

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Message-ID: <07b0dabb-5409-9ba8-543f-aeecafe083e9@arm.com>
Date:   Fri, 11 Aug 2023 09:39:40 +0100
From:   James Clark <james.clark@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        linux-arm-kernel@...ts.infradead.org, suzuki.poulose@....com
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 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.

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