Re: [PATCH v3] drm: Warn if plane/crtc/encoder/connector index exceeds our 32bit bitmasks

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jan 25, 2018 at 10:12:52AM -0500, Harry Wentland wrote:
> On 2018-01-25 08:30 AM, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > 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.
> > 
> > For connectors the issue is a bit more complicated as they can
> > be created/destroyed at runtime due to MST. So the problem is no
> > longer a purely theoretical programmer error. As the connector
> > indexes are allocated via ida, we can simply limit the maximum
> > value the ida is allowed to hand out. The error handling is already
> > in place.
> > 
> > v2: Return an error to the caller (Harry)
> > v3: Print a debug message so that we know what happened (Maarten)
> > 
> > Cc: Harry Wentland <harry.wentland@amd.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> 
> Reviewed-by: Harry Wentland <harry.wentland@amd.com>

Thanks for the review. Pushed to drm-misc-next.

> 
> Harry
> 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_connector.c | 9 +++++++--
> >  drivers/gpu/drm/drm_crtc.c      | 4 ++++
> >  drivers/gpu/drm/drm_encoder.c   | 4 ++++
> >  drivers/gpu/drm/drm_plane.c     | 4 ++++
> >  4 files changed, 19 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index b85a7749709d..16b9c3810af2 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -205,9 +205,14 @@ int drm_connector_init(struct drm_device *dev,
> >  	connector->dev = dev;
> >  	connector->funcs = funcs;
> >  
> > -	ret = ida_simple_get(&config->connector_ida, 0, 0, GFP_KERNEL);
> > -	if (ret < 0)
> > +	/* connector index is used with 32bit bitmasks */
> > +	ret = ida_simple_get(&config->connector_ida, 0, 32, GFP_KERNEL);
> > +	if (ret < 0) {
> > +		DRM_DEBUG_KMS("Failed to allocate %s connector index: %d\n",
> > +			      drm_connector_enum_list[connector_type].name,
> > +			      ret);
> >  		goto out_put;
> > +	}
> >  	connector->index = ret;
> >  	ret = 0;
> >  
> > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> > index f0556e654116..5b4be382a1d7 100644
> > --- a/drivers/gpu/drm/drm_crtc.c
> > +++ b/drivers/gpu/drm/drm_crtc.c
> > @@ -282,6 +282,10 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
> >  	WARN_ON(primary && primary->type != DRM_PLANE_TYPE_PRIMARY);
> >  	WARN_ON(cursor && cursor->type != DRM_PLANE_TYPE_CURSOR);
> >  
> > +	/* crtc index is used with 32bit bitmasks */
> > +	if (WARN_ON(config->num_crtc >= 32))
> > +		return -EINVAL;
> > +
> >  	crtc->dev = dev;
> >  	crtc->funcs = funcs;
> >  
> > diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> > index 59e0ebe733f8..273e1c59c54a 100644
> > --- a/drivers/gpu/drm/drm_encoder.c
> > +++ b/drivers/gpu/drm/drm_encoder.c
> > @@ -110,6 +110,10 @@ int drm_encoder_init(struct drm_device *dev,
> >  {
> >  	int ret;
> >  
> > +	/* encoder index is used with 32bit bitmasks */
> > +	if (WARN_ON(dev->mode_config.num_encoder >= 32))
> > +		return -EINVAL;
> > +
> >  	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
> >  	if (ret)
> >  		return ret;
> > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> > index 2c90519576a3..22b54663b6e7 100644
> > --- a/drivers/gpu/drm/drm_plane.c
> > +++ b/drivers/gpu/drm/drm_plane.c
> > @@ -173,6 +173,10 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
> >  	unsigned int format_modifier_count = 0;
> >  	int ret;
> >  
> > +	/* plane index is used with 32bit bitmasks */
> > +	if (WARN_ON(config->num_total_plane >= 32))
> > +		return -EINVAL;
> > +
> >  	ret = drm_mode_object_add(dev, &plane->base, DRM_MODE_OBJECT_PLANE);
> >  	if (ret)
> >  		return ret;
> > 

-- 
Ville Syrjälä
Intel OTC
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