[PATCH] drm: Fix writeback_job leak when state is check only or check failed

[Brian Starkey]

Hi James,

On Fri, Feb 22, 2019 at 07:39:55AM +0000, james qian wang (Arm Technology China) wrote:
> On Thu, Feb 21, 2019 at 02:56:56PM +0100, Maarten Lankhorst wrote:
> > Hey
> > 
> > Op 21-02-2019 om 12:14 schreef james qian wang (Arm Technology China):
> > > The writeback job will not be added to writeback queue if the state is
> > > check only or check failed, to avoid leak, need to cleanup writeback job
> > > in connector_destroy_state if the job existed.
> > >
> > > Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang at arm.com>
> > 
> > Is writeback_job in the conn_state set to null somewhere? I'm worried we might end up freeing writeback_job twice on success.
> > 
> > ~Maarten
> 
> Yes, the state->writeback_job need to be set to null once the job has been
> queued.
> Maybe we can refine the queue_job function and add this set NULL into
> it.
> 

Laurent has submitted patches for both of these issues, please check

[PATCH v5 12/19] drm: writeback: Cleanup job ownership handling when queuing job
[PATCH v5 13/19] drm: writeback: Fix leak of writeback job

Also note they will impact the komeda implementation

Thanks,
-Brian

> void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
> 			     struct drm_writeback_job **new_job)
> {
>         struct drm_writeback_job *job = *new_job;
> 	unsigned long flags;
> 
>         *new_job = NULL;
> 
> 	spin_lock_irqsave(&wb_connector->job_lock, flags);
> 	list_add_tail(&job->list_entry, &wb_connector->job_queue);
> 	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
> }
> 
> Thanks
> James
> 
> > 
> > >  drivers/gpu/drm/drm_atomic_state_helper.c |  4 ++++
> > >  drivers/gpu/drm/drm_writeback.c           | 21 ++++++++++++++++++---
> > >  2 files changed, 22 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
> > > index 4985384e51f6..6a8e414233de 100644
> > > --- a/drivers/gpu/drm/drm_atomic_state_helper.c
> > > +++ b/drivers/gpu/drm/drm_atomic_state_helper.c
> > > @@ -28,6 +28,7 @@
> > >  #include <drm/drm_crtc.h>
> > >  #include <drm/drm_plane.h>
> > >  #include <drm/drm_connector.h>
> > > +#include <drm/drm_writeback.h>
> > >  #include <drm/drm_atomic.h>
> > >  #include <drm/drm_device.h>
> > >  
> > > @@ -407,6 +408,9 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
> > >  void
> > >  __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
> > >  {
> > > +	if (state->writeback_job)
> > > +		drm_writeback_cleanup_job(state->writeback_job);
> > > +
> > >  	if (state->crtc)
> > >  		drm_connector_put(state->connector);
> > >  
> > > diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> > > index c20e6fe00cb3..486121150eaa 100644
> > > --- a/drivers/gpu/drm/drm_writeback.c
> > > +++ b/drivers/gpu/drm/drm_writeback.c
> > > @@ -268,6 +268,22 @@ void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
> > >  }
> > >  EXPORT_SYMBOL(drm_writeback_queue_job);
> > >  
> > > +/**
> > > + * drm_writeback_cleanup_job - cleanup a writeback job
> > > + * @job: The job to cleanup
> > > + */
> > > +void drm_writeback_cleanup_job(struct drm_writeback_job *job)
> > > +{
> > > +	if (job->fb)
> > > +		drm_framebuffer_put(job->fb);
> > > +
> > > +	if (job->out_fence)
> > > +		dma_fence_put(job->out_fence);
> > > +
> > > +	kfree(job);
> > > +}
> > > +EXPORT_SYMBOL(drm_writeback_cleanup_job);
> > > +
> > >  /*
> > >   * @cleanup_work: deferred cleanup of a writeback job
> > >   *
> > > @@ -280,11 +296,9 @@ static void cleanup_work(struct work_struct *work)
> > >  	struct drm_writeback_job *job = container_of(work,
> > >  						     struct drm_writeback_job,
> > >  						     cleanup_work);
> > > -	drm_framebuffer_put(job->fb);
> > > -	kfree(job);
> > > +	drm_writeback_cleanup_job(job);
> > >  }
> > >  
> > > -
> > >  /**
> > >   * drm_writeback_signal_completion - Signal the completion of a writeback job
> > >   * @wb_connector: The writeback connector whose job is complete
> > > @@ -319,6 +333,7 @@ drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector,
> > >  				dma_fence_set_error(job->out_fence, status);
> > >  			dma_fence_signal(job->out_fence);
> > >  			dma_fence_put(job->out_fence);
> > > +			job->out_fence = NULL;
> > >  		}
> > >  	}
> > >  	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
> >