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drm/gem/shmem: Extract drm_gem_shmem_release() from drm_gem_shmem_free()

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At the moment, the way that we currently free gem shmem objects is not
ideal for rust bindings. drm_gem_shmem_free() releases all of the
associated memory with a gem shmem object with kfree(), which means that
for us to correctly release a gem shmem object in rust we have to manually
drop all of the contents of our gem object structure in-place by hand
before finally calling drm_gem_shmem_free() to release the shmem resources
and the allocation for the gem object.

Since the only reason this is an issue is because of drm_gem_shmem_free()
calling kfree(), we can fix this by splitting drm_gem_shmem_free() out into
itself and drm_gem_shmem_release(), where drm_gem_shmem_release() releases
the various gem shmem resources without freeing the structure itself. With
this, we can safely re-acquire the KBox for the gem object's memory
allocation and let rust handle cleaning up all of the other struct members
automatically.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://lore.kernel.org/r/20250911230147.650077-3-lyude@redhat.com
This commit is contained in:
Lyude Paul
2025-09-11 18:57:39 -04:00
parent e3f4bdaf2c
commit c08c931060
2 changed files with 19 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/gpu/drm/drm_gem_shmem_helper.c
View File

@@ -175,13 +175,13 @@ struct drm_gem_shmem_object *drm_gem_shmem_create_with_mnt(struct drm_device *de
EXPORT_SYMBOL_GPL(drm_gem_shmem_create_with_mnt); EXPORT_SYMBOL_GPL(drm_gem_shmem_create_with_mnt);
/** /**
* drm_gem_shmem_free - Free resources associated with a shmem GEM object * drm_gem_shmem_release - Release resources associated with a shmem GEM object.
* @shmem: shmem GEM object to free * @shmem: shmem GEM object
* *
* This function cleans up the GEM object state and frees the memory used to * This function cleans up the GEM object state, but does not free the memory used to store the
* store the object itself. * object itself. This function is meant to be a dedicated helper for the Rust GEM bindings.
*/ */
void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) void drm_gem_shmem_release(struct drm_gem_shmem_object *shmem)
{ {
struct drm_gem_object *obj = &shmem->base; struct drm_gem_object *obj = &shmem->base;
@@ -208,6 +208,19 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
} }
drm_gem_object_release(obj); drm_gem_object_release(obj);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_release);
/**
* drm_gem_shmem_free - Free resources associated with a shmem GEM object
* @shmem: shmem GEM object to free
*
* This function cleans up the GEM object state and frees the memory used to
* store the object itself.
*/
void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
{
drm_gem_shmem_release(shmem);
kfree(shmem); kfree(shmem);
} }
EXPORT_SYMBOL_GPL(drm_gem_shmem_free); EXPORT_SYMBOL_GPL(drm_gem_shmem_free);

1
include/drm/drm_gem_shmem_helper.h
View File

@@ -112,6 +112,7 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
struct drm_gem_shmem_object *drm_gem_shmem_create_with_mnt(struct drm_device *dev, struct drm_gem_shmem_object *drm_gem_shmem_create_with_mnt(struct drm_device *dev,
size_t size, size_t size,
struct vfsmount *gemfs); struct vfsmount *gemfs);
void drm_gem_shmem_release(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem); void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem); void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem);