On Wed, 5 May 2021 11:41:56 +0200
Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> wrote:
> The PM runtime get logic is currently broken, as it checks if
> ret is zero instead of checking if it is an error code,
> as reported by Dan Carpenter.
>
> While here, use the pm_runtime_resume_and_get() as added by:
> commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> added pm_runtime_resume_and_get() in order to automatically handle
> dev->power.usage_count decrement on errors. As a bonus, such function
> always return zero on success.
>
> It should also be noticed that a fail of pm_runtime_get_sync() would
> potentially result in a spurious runtime_suspend(), instead of
> using pm_runtime_put_noidle().
Irony here is that pm_runtime_resume_and_get() returns <= 0 so with that
function change, you can stick with if (ret) and still be correct.
So only one of the two changes is needed to fix the bug.
J
>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Reviewed-by: Daniele Alessandrelli <daniele.alessandrelli@xxxxxxxxx>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> ---
> drivers/media/i2c/imx334.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/i2c/imx334.c b/drivers/media/i2c/imx334.c
> index 047aa7658d21..23f28606e570 100644
> --- a/drivers/media/i2c/imx334.c
> +++ b/drivers/media/i2c/imx334.c
> @@ -717,9 +717,9 @@ static int imx334_set_stream(struct v4l2_subdev *sd, int enable)
> }
>
> if (enable) {
> - ret = pm_runtime_get_sync(imx334->dev);
> - if (ret)
> - goto error_power_off;
> + ret = pm_runtime_resume_and_get(imx334->dev);
> + if (ret < 0)
> + goto error_unlock;
>
> ret = imx334_start_streaming(imx334);
> if (ret)
> @@ -737,6 +737,7 @@ static int imx334_set_stream(struct v4l2_subdev *sd, int enable)
>
> error_power_off:
> pm_runtime_put(imx334->dev);
> +error_unlock:
> mutex_unlock(&imx334->mutex);
>
> return ret;
