diff options
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem.c | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 440979f44a1a..6d64cff37fe2 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4246,6 +4246,30 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev, return obj; } +static bool discard_backing_storage(struct drm_i915_gem_object *obj) +{ + /* If we are the last user of the backing storage (be it shmemfs + * pages or stolen etc), we know that the pages are going to be + * immediately released. In this case, we can then skip copying + * back the contents from the GPU. + */ + + if (obj->madv != I915_MADV_WILLNEED) + return false; + + if (obj->base.filp == NULL) + return true; + + /* At first glance, this looks racy, but then again so would be + * userspace racing mmap against close. However, the first external + * reference to the filp can only be obtained through the + * i915_gem_mmap_ioctl() which safeguards us against the user + * acquiring such a reference whilst we are in the middle of + * freeing the object. + */ + return atomic_long_read(&obj->base.filp->f_count) == 1; +} + void i915_gem_free_object(struct drm_gem_object *gem_obj) { struct drm_i915_gem_object *obj = to_intel_bo(gem_obj); @@ -4284,7 +4308,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj) if (WARN_ON(obj->pages_pin_count)) obj->pages_pin_count = 0; - if (obj->madv != __I915_MADV_PURGED) + if (discard_backing_storage(obj)) obj->madv = I915_MADV_DONTNEED; i915_gem_object_put_pages(obj); i915_gem_object_free_mmap_offset(obj); |