[Intel-gfx] [PATCH v2 28/37] drm/i915: Allow i915 to manage the vma offset nodes instead of drm core

[Chris Wilson]

Quoting Matthew Auld (2019-06-27 21:56:24)
> +int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> +       struct drm_vma_offset_node *node;
> +       struct drm_file *priv = filp->private_data;
> +       struct drm_device *dev = priv->minor->dev;
> +       struct i915_mmap_offset *mmo;
> +       struct drm_gem_object *obj = NULL;
> +
> +       if (drm_dev_is_unplugged(dev))
> +               return -ENODEV;
> +
> +       drm_vma_offset_lock_lookup(dev->vma_offset_manager);
> +       node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
> +                                                 vma->vm_pgoff,
> +                                                 vma_pages(vma));
> +       if (likely(node)) {
> +               mmo = container_of(node, struct i915_mmap_offset,
> +                                  vma_node);
> +
> +               /* Take a ref for our mmap_offset and gem objects. The reference is cleaned

/*
 * Take

> +                * up when the vma is closed.
> +                *
> +                * Skip 0-refcnted objects as it is in the process of being destroyed
> +                * and will be invalid when the vma manager lock is released.
> +                */
> +               if (kref_get_unless_zero(&mmo->ref)) {
> +                       obj = &mmo->obj->base;
> +                       if (!kref_get_unless_zero(&obj->refcount))
> +                               obj = NULL;
> +               }
> +       }
> +       drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
> +
> +       if (!obj)
> +               return -EINVAL;

Please check the error paths for reference leaks.
-Chris