drm/nvc0: reject the notifier_alloc ioctl

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_notifier.c

@@ -164,10 +164,15 @@ int
 nouveau_ioctl_notifier_alloc(struct drm_device *dev, void *data,
 			     struct drm_file *file_priv)
 {
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct drm_nouveau_notifierobj_alloc *na = data;
 	struct nouveau_channel *chan;
 	int ret;
 
+	/* completely unnecessary for these chipsets... */
+	if (unlikely(dev_priv->card_type >= NV_C0))
+		return -EINVAL;
+
 	chan = nouveau_channel_get(dev, file_priv, na->channel);
 	if (IS_ERR(chan))
 		return PTR_ERR(chan);