It's racy, creating mmap offsets is a slowpath, so better to remove it to avoid drivers doing broken things.
The only user is i915, and it's ok there because everything (well almost) is protected by dev->struct_mutex in i915-gem.
While at it add a note in the create_mmap_offset kerneldoc that drivers must release it again. And then I also noticed that drm_gem_object_release entirely lacks kerneldoc.
Cc: David Herrmann dh.herrmann@gmail.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- drivers/gpu/drm/drm_gem.c | 17 +++++++++++++++++ drivers/gpu/drm/i915/i915_gem.c | 3 --- include/drm/drm_vma_manager.h | 15 +-------------- 3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 2e8c77e71e1f..74867edb8739 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -422,6 +422,10 @@ EXPORT_SYMBOL(drm_gem_handle_create); * @obj: obj in question * * This routine frees fake offsets allocated by drm_gem_create_mmap_offset(). + * + * Note that drm_gem_object_release() already calls this function, so drivers + * don't have to take care of releasing the mmap offset themselves when freeing + * the GEM object. */ void drm_gem_free_mmap_offset(struct drm_gem_object *obj) @@ -445,6 +449,9 @@ EXPORT_SYMBOL(drm_gem_free_mmap_offset); * This routine allocates and attaches a fake offset for @obj, in cases where * the virtual size differs from the physical size (ie. obj->size). Otherwise * just use drm_gem_create_mmap_offset(). + * + * This function is idempotent and handles an already allocated mmap offset + * transparently. Drivers do not need to check for this case. */ int drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size) @@ -466,6 +473,9 @@ EXPORT_SYMBOL(drm_gem_create_mmap_offset_size); * structures. * * This routine allocates and attaches a fake offset for @obj. + * + * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release + * the fake offset again. */ int drm_gem_create_mmap_offset(struct drm_gem_object *obj) { @@ -759,6 +769,13 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private) idr_destroy(&file_private->object_idr); }
+/** + * drm_gem_object_release - release GEM buffer object resources + * @obj: GEM buffer object + * + * This releases any structures and resources used by @obj and is the invers of + * drm_gem_object_init(). + */ void drm_gem_object_release(struct drm_gem_object *obj) { diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index c7a997aeb33f..3bc56166dd0d 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2031,9 +2031,6 @@ static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj) struct drm_i915_private *dev_priv = obj->base.dev->dev_private; int ret;
- if (drm_vma_node_has_offset(&obj->base.vma_node)) - return 0; - dev_priv->mm.shrinker_no_lock_stealing = true;
ret = drm_gem_create_mmap_offset(&obj->base); diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h index 2f63dd5e05eb..06ea8e077ec2 100644 --- a/include/drm/drm_vma_manager.h +++ b/include/drm/drm_vma_manager.h @@ -176,19 +176,6 @@ static inline unsigned long drm_vma_node_size(struct drm_vma_offset_node *node) }
/** - * drm_vma_node_has_offset() - Check whether node is added to offset manager - * @node: Node to be checked - * - * RETURNS: - * true iff the node was previously allocated an offset and added to - * an vma offset manager. - */ -static inline bool drm_vma_node_has_offset(struct drm_vma_offset_node *node) -{ - return drm_mm_node_allocated(&node->vm_node); -} - -/** * drm_vma_node_offset_addr() - Return sanitized offset for user-space mmaps * @node: Linked offset node * @@ -220,7 +207,7 @@ static inline __u64 drm_vma_node_offset_addr(struct drm_vma_offset_node *node) static inline void drm_vma_node_unmap(struct drm_vma_offset_node *node, struct address_space *file_mapping) { - if (drm_vma_node_has_offset(node)) + if (drm_mm_node_allocated(&node->vm_node)) unmap_mapping_range(file_mapping, drm_vma_node_offset_addr(node), drm_vma_node_size(node) << PAGE_SHIFT, 1);