On 2018-01-24 04:24 PM, Ville Syrjälä wrote: > On Wed, Jan 24, 2018 at 04:01:18PM -0500, Harry Wentland wrote: >> On 2018-01-24 01:37 PM, Ville Syrjala wrote: >>> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >>> >>> We use 32bit bitmasks to track planes/crtcs/encoders/connectors. >>> Naturally we can only do that if the index of those objects stays >>> below 32. Issue a warning whenever we exceed that limit, hopefully >>> prompting someone to fix the problem. >>> >>> Or should we just outright fail the object initializatio perhaps? >>> >> >> This would make sense in my opinion. index >= 32 looks like it would lead to completely undefined behavior when trying to attach objects to each other. > > I suppose. The counter argument is that this is basically the developer > shooting themselves in the foot intentionally, so it's a bit hard to > justify complicating the runtime error handling for this. > True, if this needs extensive runtime error handling a WARN_ON is probably better. > The connector case might be well justified though since the index there > comes from ida, and with MST connectors can come and go as they please. > So it might not be entirely impossible to overflow the bits there. > Right, I was trying to think of a real-life case where this might happen. MST is a good one (although still quite rare in the vast majority of cases). Harry >> >> Harry >> >>> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >>> --- >>> drivers/gpu/drm/drm_connector.c | 3 +++ >>> drivers/gpu/drm/drm_crtc.c | 3 +++ >>> drivers/gpu/drm/drm_encoder.c | 3 +++ >>> drivers/gpu/drm/drm_plane.c | 3 +++ >>> 4 files changed, 12 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c >>> index b85a7749709d..9278a81c5d54 100644 >>> --- a/drivers/gpu/drm/drm_connector.c >>> +++ b/drivers/gpu/drm/drm_connector.c >>> @@ -211,6 +211,9 @@ int drm_connector_init(struct drm_device *dev, >>> connector->index = ret; >>> ret = 0; >>> >>> + /* we have 32bit connector bitmasks */ >>> + WARN_ON(connector->index >= 32); >>> + >>> connector->connector_type = connector_type; >>> connector->connector_type_id = >>> ida_simple_get(connector_ida, 1, 0, GFP_KERNEL); >>> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c >>> index f0556e654116..e27ffa3561af 100644 >>> --- a/drivers/gpu/drm/drm_crtc.c >>> +++ b/drivers/gpu/drm/drm_crtc.c >>> @@ -318,6 +318,9 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc, >>> list_add_tail(&crtc->head, &config->crtc_list); >>> crtc->index = config->num_crtc++; >>> >>> + /* we have 32bit crtc bitmasks */ >>> + WARN_ON(crtc->index >= 32); >>> + >>> crtc->primary = primary; >>> crtc->cursor = cursor; >>> if (primary && !primary->possible_crtcs) >>> diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c >>> index 59e0ebe733f8..66d0cdd217fa 100644 >>> --- a/drivers/gpu/drm/drm_encoder.c >>> +++ b/drivers/gpu/drm/drm_encoder.c >>> @@ -136,6 +136,9 @@ int drm_encoder_init(struct drm_device *dev, >>> list_add_tail(&encoder->head, &dev->mode_config.encoder_list); >>> encoder->index = dev->mode_config.num_encoder++; >>> >>> + /* we have 32bit encoder bitmasks */ >>> + WARN_ON(encoder->index >= 32); >>> + >>> out_put: >>> if (ret) >>> drm_mode_object_unregister(dev, &encoder->base); >>> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c >>> index 2c90519576a3..0a8d807603c1 100644 >>> --- a/drivers/gpu/drm/drm_plane.c >>> +++ b/drivers/gpu/drm/drm_plane.c >>> @@ -242,6 +242,9 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane, >>> list_add_tail(&plane->head, &config->plane_list); >>> plane->index = config->num_total_plane++; >>> >>> + /* we have 32bit plane bitmasks */ >>> + WARN_ON(plane->index >= 32); >>> + >>> drm_object_attach_property(&plane->base, >>> config->plane_type_property, >>> plane->type); >>> > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
