linux-kernel - Re: Re: [PATCH] [v2] media: venus: core: Fix runtime PM imbalance in venus

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Message-ID: <35c749cf.28af7.172ee1e4ac3.Coremail.dinghao.liu@zju.edu.cn>
Date:   Fri, 26 Jun 2020 08:54:22 +0800 (GMT+08:00)
From:   dinghao.liu@....edu.cn
To:     "Stanimir Varbanov" <stanimir.varbanov@...aro.org>
Cc:     kjlu@....edu, "Andy Gross" <agross@...nel.org>,
        "Bjorn Andersson" <bjorn.andersson@...aro.org>,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH] [v2] media: venus: core: Fix runtime PM imbalance
 in venus_probe


> Hi Dinghao,
> 
> On 6/24/20 9:30 AM, Dinghao Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter even
> > when it returns an error code. Thus a pairing decrement is needed on
> > the error handling path to keep the counter balanced. For other error
> > paths after this call, things are the same.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> > 
> > Changelog:
> > 
> > v2: - Add pm_runtime_get_noresume() on failure of
> >       pm_runtime_put_sync() to balance PM counter instead of
> >       releasing everything here.
> 
> You are adding pm_runtime_get_noresume in pm_runtime_put_sync error path
> but the patch description is referring to pm_runtime_get_sync. I'm confused.
> 

When pm_runtime_put_sync failed, the control flow will jump to 
err_dev_unregister, where has already been a pm_runtime_put_noidle. 
If we don't add an extra pm_runtime_get_noresume here, we will 
decrease PM usage counter twice. 

Anyway, this may seem a little strange. Do you have a better
strategy to reorder the labels? 

Regards,
Dinghao

> > ---
> >  drivers/media/platform/qcom/venus/core.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/qcom/venus/core.c b/drivers/media/platform/qcom/venus/core.c
> > index 203c6538044f..b0b932bf8c02 100644
> > --- a/drivers/media/platform/qcom/venus/core.c
> > +++ b/drivers/media/platform/qcom/venus/core.c
> > @@ -287,8 +287,10 @@ static int venus_probe(struct platform_device *pdev)
> >  		goto err_core_deinit;
> >  
> >  	ret = pm_runtime_put_sync(dev);
> > -	if (ret)
> > +	if (ret) {
> > +		pm_runtime_get_noresume(dev);
> >  		goto err_dev_unregister;
> > +	}
> >  
> >  	return 0;
> >  
> > @@ -299,6 +301,7 @@ static int venus_probe(struct platform_device *pdev)
> >  err_venus_shutdown:
> >  	venus_shutdown(core);
> >  err_runtime_disable:
> > +	pm_runtime_put_noidle(dev);
> >  	pm_runtime_set_suspended(dev);
> >  	pm_runtime_disable(dev);
> >  	hfi_destroy(core);
> > 
> 
> -- 
> regards,
> Stan