Re: [PATCH] coresight: etm4x: Ensure valid drvdata and clock before clk_put()

[Suzuki K Poulose]

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