linux-kernel - Re: [PATCH] media: sti: Fix reference count leaks

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Message-ID: <013fba3b-2451-855b-08d4-87682464b8bf@xs4all.nl>
Date:   Thu, 17 Sep 2020 13:40:31 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Jean-Christophe Trotin <jean-christophe.trotin@...com>
Cc:     wu000273@....edu, kjlu@....edu,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: sti: Fix reference count leaks

Hi Jean-Christophe,

I'll take this patch, but while reviewing it I noticed something else:

On 14/06/2020 05:31, wu000273@....edu wrote:
> From: Qiushi Wu <wu000273@....edu>
> 
> pm_runtime_get_sync() increments the runtime PM usage counter even
> when it returns an error code, causing incorrect ref count if
> pm_runtime_put_noidle() is not called in error handling paths.
> Thus call pm_runtime_put_noidle() if pm_runtime_get_sync() fails.
> 
> Signed-off-by: Qiushi Wu <wu000273@....edu>
> ---
>  drivers/media/platform/sti/hva/hva-hw.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/media/platform/sti/hva/hva-hw.c b/drivers/media/platform/sti/hva/hva-hw.c
> index 401aaafa1710..bb13348be083 100644
> --- a/drivers/media/platform/sti/hva/hva-hw.c
> +++ b/drivers/media/platform/sti/hva/hva-hw.c
> @@ -272,6 +272,7 @@ static unsigned long int hva_hw_get_ip_version(struct hva_dev *hva)
>  
>  	if (pm_runtime_get_sync(dev) < 0) {
>  		dev_err(dev, "%s     failed to get pm_runtime\n", HVA_PREFIX);
> +		pm_runtime_put_noidle(dev);
>  		mutex_unlock(&hva->protect_mutex);

This appears to be a spurious mutex_unlock() since I don't see a corresponding mutex_lock.

Jean-Christophe, can you check this and, if I am right, post a patch fixing this?

Regards,

	Hans

>  		return -EFAULT;
>  	}
> @@ -553,6 +554,7 @@ void hva_hw_dump_regs(struct hva_dev *hva, struct seq_file *s)
>  
>  	if (pm_runtime_get_sync(dev) < 0) {
>  		seq_puts(s, "Cannot wake up IP\n");
> +		pm_runtime_put_noidle(dev);
>  		mutex_unlock(&hva->protect_mutex);
>  		return;
>  	}
>