Em Wed, 5 May 2021 13:34:09 +0300
Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> escreveu:
> Hi Mauro,
>
> Thanks for the patch.
>
> On Wed, May 05, 2021 at 11:42:15AM +0200, Mauro Carvalho Chehab wrote:
> > The pm_runtime_get_sync() internally increments the
> > dev->power.usage_count without decrementing it, even on errors.
> >
> > There is a bug at ccs_pm_get_init(): when this function returns
> > an error, the stream is not started, and RPM usage_count
> > should not be incremented. However, if the calls to
> > v4l2_ctrl_handler_setup() return errors, it will be kept
> > incremented.
> >
> > At ccs_suspend() the best is to replace it by the new
> > pm_runtime_resume_and_get(), introduced by:
> > commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> > in order to properly decrement the usage counter automatically,
> > in the case of errors.
> >
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
>
> Could you add Fixes: line and Cc: stable?
Sure. See the fixes one enclosed.
> The patch that breaks this is 96e3a6b92f23a .
>
> It would be better to fix the bug first so the patch to the stable trees
> doesn't need special handling.
>
> > ---
> > drivers/media/i2c/ccs/ccs-core.c | 39 ++++++++++++++++++++------------
> > 1 file changed, 24 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
> > index b05f409014b2..04c3ab9e37b4 100644
> > --- a/drivers/media/i2c/ccs/ccs-core.c
> > +++ b/drivers/media/i2c/ccs/ccs-core.c
> > @@ -1880,21 +1880,33 @@ static int ccs_pm_get_init(struct ccs_sensor *sensor)
> > struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
> > int rval;
> >
> > + /*
> > + * It can't use pm_runtime_resume_and_get() here, as the driver
> > + * relies at the returned value to detect if the device was already
> > + * active or not.
> > + */
> > rval = pm_runtime_get_sync(&client->dev);
> > - if (rval < 0) {
> > - pm_runtime_put_noidle(&client->dev);
> > + if (rval < 0)
> > + goto error;
> >
> > - return rval;
> > - } else if (!rval) {
> > - rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->
> > - ctrl_handler);
> > - if (rval)
> > - return rval;
> > + /* Device was already active, so don't set controls */
> > + if (rval == 1)
> > + return 0;
> >
> > - return v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> > - }
> > + /* Restore V4L2 controls to the suspended device */
> > + rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->ctrl_handler);
> > + if (rval)
> > + goto error;
> >
> > + rval = v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
> > + if (rval)
> > + goto error;
> > +
> > + /* Keep PM runtime usage_count incremented on success */
> > return 0;
> > +error:
> > + pm_runtime_put_noidle(&client->dev);
>
> This needs to be pm_runtime_put() as the device has been successfully.
Ok.
>
> > + return rval;
> > }
> >
> > static int ccs_set_stream(struct v4l2_subdev *subdev, int enable)
> > @@ -3089,12 +3101,9 @@ static int __maybe_unused ccs_suspend(struct device *dev)
> > bool streaming = sensor->streaming;
> > int rval;
> >
> > - rval = pm_runtime_get_sync(dev);
> > - if (rval < 0) {
> > - pm_runtime_put_noidle(dev);
> > -
> > + rval = pm_runtime_resume_and_get(dev);
> > + if (rval < 0)
> > return rval;
> > - }
> >
> > if (sensor->streaming)
> > ccs_stop_streaming(sensor);
>
Thanks,
Mauro
---
[PATCH] media: i2c: ccs-core: fix pm_runtime_get_sync() usage count
The pm_runtime_get_sync() internally increments the
dev->power.usage_count without decrementing it, even on errors.
There is a bug at ccs_pm_get_init(): when this function returns
an error, the stream is not started, and RPM usage_count
should not be incremented. However, if the calls to
v4l2_ctrl_handler_setup() return errors, it will be kept
incremented.
At ccs_suspend() the best is to replace it by the new
pm_runtime_resume_and_get(), introduced by:
commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
in order to properly decrement the usage counter automatically,
in the case of errors.
Fixes: 96e3a6b92f23 ("media: smiapp: Avoid maintaining power state information")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c
index b05f409014b2..5ea471fefa3a 100644
--- a/drivers/media/i2c/ccs/ccs-core.c
+++ b/drivers/media/i2c/ccs/ccs-core.c
@@ -1880,21 +1880,33 @@ static int ccs_pm_get_init(struct ccs_sensor *sensor)
struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
int rval;
+ /*
+ * It can't use pm_runtime_resume_and_get() here, as the driver
+ * relies at the returned value to detect if the device was already
+ * active or not.
+ */
rval = pm_runtime_get_sync(&client->dev);
- if (rval < 0) {
- pm_runtime_put_noidle(&client->dev);
+ if (rval < 0)
+ goto error;
- return rval;
- } else if (!rval) {
- rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->
- ctrl_handler);
- if (rval)
- return rval;
+ /* Device was already active, so don't set controls */
+ if (rval == 1)
+ return 0;
- return v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
- }
+ /* Restore V4L2 controls to the suspended device */
+ rval = v4l2_ctrl_handler_setup(&sensor->pixel_array->ctrl_handler);
+ if (rval)
+ goto error;
+ rval = v4l2_ctrl_handler_setup(&sensor->src->ctrl_handler);
+ if (rval)
+ goto error;
+
+ /* Keep PM runtime usage_count incremented on success */
return 0;
+error:
+ pm_runtime_put(&client->dev);
+ return rval;
}
static int ccs_set_stream(struct v4l2_subdev *subdev, int enable)
