Re: [PATCH 1/2] ipu3-cio2: Unregister device nodes first, then release resources

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Bingbu,

On Mon, Oct 15, 2018 at 03:15:05PM +0800, Bing Bu Cao wrote:
> 
> On 10/10/2018 04:32 PM, Sakari Ailus wrote:
> > While there are issues related to object lifetime management, unregister
> > the media device first, followed immediately by other device nodes when
> > the driver is being unbound. Only then the resources needed by the driver
> > may be released. This is slightly safer.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  drivers/media/pci/intel/ipu3/ipu3-cio2.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.c b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > index 452eb9b42140..723022ef3662 100644
> > --- a/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > @@ -1846,12 +1846,12 @@ static void cio2_pci_remove(struct pci_dev *pci_dev)
> >  	struct cio2_device *cio2 = pci_get_drvdata(pci_dev);
> >  	unsigned int i;
> >  
> > +	media_device_unregister(&cio2->media_dev);
> >  	cio2_notifier_exit(cio2);
> > -	cio2_fbpt_exit_dummy(cio2);
> >  	for (i = 0; i < CIO2_QUEUES; i++)
> >  		cio2_queue_exit(cio2, &cio2->queue[i]);
> > +	cio2_fbpt_exit_dummy(cio2);
> Hi, Sakari,
> The fbpt dummy pages cleanup does not matter much before/after queues
> exit, right?

cio2_queue_exit() will unregister the video device and the video buffer
queue. Up to this point it's possible to open the video device and start
streaming on it. While this patch does not fully address the issue it makes
it a slightly lesser issue.

> >  	v4l2_device_unregister(&cio2->v4l2_dev);
> > -	media_device_unregister(&cio2->media_dev);
> >  	media_device_cleanup(&cio2->media_dev);
> >  	mutex_destroy(&cio2->lock);
> >  }
> 

-- 
Sakari Ailus
sakari.ailus@linux.intel.com