[PATCH] media: i2c: ov5648: Plug runtime pm counter leak

[PATCH] media: i2c: ov5648: Plug runtime pm counter leak

[Pratyush Yadav]

When the stream is being enabled, the runtime pm usage counter is
incremented. Then if ov5648_sw_standby() fails, the function returns
error without decrementing the counter, leaking it.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---

Hi,

I spotted this when converting OV5640 driver to use runtime PM using
this driver as reference. I only have a very surface level understanding
of runtime PM system as of now so please review with that in mind.

This patch is only compile-tested since I don't have the hardware with
me.

 drivers/media/i2c/ov5648.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov5648.c b/drivers/media/i2c/ov5648.c
index 3ecb4a3e8773..6aa2c950f505 100644
--- a/drivers/media/i2c/ov5648.c
+++ b/drivers/media/i2c/ov5648.c
@@ -2143,8 +2143,12 @@ static int ov5648_s_stream(struct v4l2_subdev *subdev, int enable)
 	ret = ov5648_sw_standby(sensor, !enable);
 	mutex_unlock(&sensor->mutex);

-	if (ret)
+	if (ret) {
+		if (enable)
+			pm_runtime_put(sensor->dev);
+
 		return ret;
+	}

 	state->streaming = !!enable;

--
2.30.0

Re: [PATCH] media: i2c: ov5648: Plug runtime pm counter leak

[Sakari Ailus]

Hi Pratyush,

Thanks for the patch.

On Tue, May 11, 2021 at 06:14:37PM +0530, Pratyush Yadav wrote:
> When the stream is being enabled, the runtime pm usage counter is
> incremented. Then if ov5648_sw_standby() fails, the function returns
> error without decrementing the counter, leaking it.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
> 
> Hi,
> 
> I spotted this when converting OV5640 driver to use runtime PM using
> this driver as reference. I only have a very surface level understanding
> of runtime PM system as of now so please review with that in mind.
> 
> This patch is only compile-tested since I don't have the hardware with
> me.
> 
>  drivers/media/i2c/ov5648.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ov5648.c b/drivers/media/i2c/ov5648.c
> index 3ecb4a3e8773..6aa2c950f505 100644
> --- a/drivers/media/i2c/ov5648.c
> +++ b/drivers/media/i2c/ov5648.c
> @@ -2143,8 +2143,12 @@ static int ov5648_s_stream(struct v4l2_subdev *subdev, int enable)
>  	ret = ov5648_sw_standby(sensor, !enable);
>  	mutex_unlock(&sensor->mutex);
> 
> -	if (ret)
> +	if (ret) {
> +		if (enable)
> +			pm_runtime_put(sensor->dev);

The function powers the sensor off at the end if streaming was to be
disabled. You could do:

	if (ret || !enable)
		pm_runtime_put(sensor->dev);

> +
>  		return ret;
> +	}
> 
>  	state->streaming = !!enable;

state->streaming is assigned when not holding the lock. Could you address
that at the same time?

-- 
Kind regards,

Sakari Ailus