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@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
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 2e10bba4468b..5c5001171dd3 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -392,6 +392,10 @@ 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)
@@ -415,6 +419,9 @@ 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)
@@ -436,6 +443,9 @@ 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)
{
@@ -754,6 +764,13 @@ 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 33adc8f8ab20..f10a5d57377e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1972,9 +1972,6 @@ 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);
--
2.5.1
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