Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Qinglang Miao]

在 2020/11/27 17:44, Krzysztof Kozlowski 写道:
> On Fri, Nov 27, 2020 at 05:44:46PM +0800, Qinglang Miao wrote:
> > pm_runtime_get_sync will increment pm usage counter even it
> > failed. Forgetting to putting operation will result in a
> > reference leak here.
> >
> > A new function pm_runtime_resume_and_get is introduced in
> > [0] to keep usage counter balanced. So We fix the reference
> > leak by replacing it with new funtion.
> >
> > [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")
>
> Do not put such dependencies into the commit message - it does not bring
> useful information to the history. Store it under '---' separator.
>
> > Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > Signed-off-by: Qinglang Miao <miaoqinglang@xxxxxxxxxx>
> > ---
> >   drivers/char/hw_random/exynos-trng.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
> > index 8e1fe3f8d..666246bc8 100644
> > --- a/drivers/char/hw_random/exynos-trng.c
> > +++ b/drivers/char/hw_random/exynos-trng.c
> > @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
> >   		return PTR_ERR(trng->mem);
> >   
> >   	pm_runtime_enable(&pdev->dev);
> > -	ret = pm_runtime_get_sync(&pdev->dev);
> > +	ret = pm_runtime_resume_and_get(&pdev->dev);
>
> This cannot be applied. Fix it by replacing err_clock label with this
> one. >
> Best regards,
> Krzysztof
>
> .
Hi Krzysztof,

I realize that there's a mistake in this patch through your reply.

There's two way to fix this one:
1) replace err_pm_get with err_clock label when pm_runtime_get_sync fails.
2) replace pm_runtime_get_sync with pm_runtime_resume_and_get and remove
redundant label(err_clock).

I take 2) on v2 for it makes codes more clearer in a way.

Thanks.

>