| Message ID | 20180226214516.11559-6-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Laurent, On 26/02/18 21:45, Laurent Pinchart wrote: > The DRM pipeline handling code uses the entity's pipe list head to check > whether the entity is already included in a pipeline. This method is a > bit fragile in the sense that it uses list_empty() on a list_head that > is a list member. Replace it by a simpler check for the entity pipe > pointer. Yes, excellent. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> > --- > drivers/media/platform/vsp1/vsp1_drm.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/platform/vsp1/vsp1_drm.c b/drivers/media/platform/vsp1/vsp1_drm.c > index a7ad85ab0b08..e210917fdc3f 100644 > --- a/drivers/media/platform/vsp1/vsp1_drm.c > +++ b/drivers/media/platform/vsp1/vsp1_drm.c > @@ -119,9 +119,9 @@ int vsp1_du_setup_lif(struct device *dev, unsigned int pipe_index, > * Remove the RPF from the pipe and the list of BRU > * inputs. > */ > - WARN_ON(list_empty(&rpf->entity.list_pipe)); > + WARN_ON(!rpf->entity.pipe); Does this WARN_ON() have much value any more ? I think it could probably be removed... unless there is a race between potential calls through vsp1_du_atomic_flush() and vsp1_du_setup_lif() - but I would be very surprised if that wasn't protected at the DRM levels. (Removing it if chosen doesn't need to be in this patch though) > rpf->entity.pipe = NULL; > - list_del_init(&rpf->entity.list_pipe); > + list_del(&rpf->entity.list_pipe); > pipe->inputs[i] = NULL; > > bru->inputs[rpf->bru_input].rpf = NULL; > @@ -537,7 +537,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned int pipe_index) > continue; > } > > - if (list_empty(&rpf->entity.list_pipe)) { > + if (!rpf->entity.pipe) { > rpf->entity.pipe = pipe; > list_add_tail(&rpf->entity.list_pipe, &pipe->entities); > } > @@ -566,7 +566,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned int pipe_index) > VI6_DPR_NODE_UNUSED); > > entity->pipe = NULL; > - list_del_init(&entity->list_pipe); > + list_del(&entity->list_pipe); > > continue; > } >
Hi Kieran, On Wednesday, 28 March 2018 17:10:10 EEST Kieran Bingham wrote: > On 26/02/18 21:45, Laurent Pinchart wrote: > > The DRM pipeline handling code uses the entity's pipe list head to check > > whether the entity is already included in a pipeline. This method is a > > bit fragile in the sense that it uses list_empty() on a list_head that > > is a list member. Replace it by a simpler check for the entity pipe > > pointer. > > Yes, excellent. > > > Signed-off-by: Laurent Pinchart > > <laurent.pinchart+renesas@ideasonboard.com> > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> > > > --- > > > > drivers/media/platform/vsp1/vsp1_drm.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/media/platform/vsp1/vsp1_drm.c > > b/drivers/media/platform/vsp1/vsp1_drm.c index a7ad85ab0b08..e210917fdc3f > > 100644 > > --- a/drivers/media/platform/vsp1/vsp1_drm.c > > +++ b/drivers/media/platform/vsp1/vsp1_drm.c > > @@ -119,9 +119,9 @@ int vsp1_du_setup_lif(struct device *dev, unsigned int > > pipe_index,> > > * Remove the RPF from the pipe and the list of BRU > > * inputs. > > */ > > > > - WARN_ON(list_empty(&rpf->entity.list_pipe)); > > + WARN_ON(!rpf->entity.pipe); > > Does this WARN_ON() have much value any more ? > > I think it could probably be removed... unless there is a race between > potential calls through vsp1_du_atomic_flush() and vsp1_du_setup_lif() - > but I would be very surprised if that wasn't protected at the DRM levels. It should indeed be protected at the DRM level. The purpose of the WARN_ON() is twofold, it catches both bugs in the VSP1 driver (but I don't expect any bug here, so from that point of view the WARN_ON isn't needed), but also misbehaviours in the callers. There hasn't been any so far though, so maybe we could indeed remove the WARN_ON(). It just makes me feel a bit safer but probably not in any rational way :-) > (Removing it if chosen doesn't need to be in this patch though) > > > rpf->entity.pipe = NULL; > > > > - list_del_init(&rpf->entity.list_pipe); > > + list_del(&rpf->entity.list_pipe); > > > > pipe->inputs[i] = NULL; > > > > bru->inputs[rpf->bru_input].rpf = NULL; > > > > @@ -537,7 +537,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned > > int pipe_index)> > > continue; > > > > } > > > > - if (list_empty(&rpf->entity.list_pipe)) { > > + if (!rpf->entity.pipe) { > > > > rpf->entity.pipe = pipe; > > list_add_tail(&rpf->entity.list_pipe, &pipe->entities); > > > > } > > > > @@ -566,7 +566,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned > > int pipe_index)> > > VI6_DPR_NODE_UNUSED); > > > > entity->pipe = NULL; > > > > - list_del_init(&entity->list_pipe); > > + list_del(&entity->list_pipe); > > > > continue; > > > > }
diff --git a/drivers/media/platform/vsp1/vsp1_drm.c b/drivers/media/platform/vsp1/vsp1_drm.c index a7ad85ab0b08..e210917fdc3f 100644 --- a/drivers/media/platform/vsp1/vsp1_drm.c +++ b/drivers/media/platform/vsp1/vsp1_drm.c @@ -119,9 +119,9 @@ int vsp1_du_setup_lif(struct device *dev, unsigned int pipe_index, * Remove the RPF from the pipe and the list of BRU * inputs. */ - WARN_ON(list_empty(&rpf->entity.list_pipe)); + WARN_ON(!rpf->entity.pipe); rpf->entity.pipe = NULL; - list_del_init(&rpf->entity.list_pipe); + list_del(&rpf->entity.list_pipe); pipe->inputs[i] = NULL; bru->inputs[rpf->bru_input].rpf = NULL; @@ -537,7 +537,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned int pipe_index) continue; } - if (list_empty(&rpf->entity.list_pipe)) { + if (!rpf->entity.pipe) { rpf->entity.pipe = pipe; list_add_tail(&rpf->entity.list_pipe, &pipe->entities); } @@ -566,7 +566,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned int pipe_index) VI6_DPR_NODE_UNUSED); entity->pipe = NULL; - list_del_init(&entity->list_pipe); + list_del(&entity->list_pipe); continue; }
The DRM pipeline handling code uses the entity's pipe list head to check whether the entity is already included in a pipeline. This method is a bit fragile in the sense that it uses list_empty() on a list_head that is a list member. Replace it by a simpler check for the entity pipe pointer. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> --- drivers/media/platform/vsp1/vsp1_drm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)