drm/nouveau: embed gem object in nouveau_bo

There is no reason to keep the gem object separately allocated. nouveau is
the last user of gem_obj->driver_private, so if we embed it, we can get
rid of 8bytes per gem-object.

The implementation follows the radeon driver. bo->gem is only valid, iff
the bo was created via the gem helpers _and_ iff the user holds a valid
gem reference. That is, as the gem object holds a reference to the
nouveau_bo. If you use nouveau_ref() to gain a bo reference, you are not
guaranteed to also hold a gem reference. The gem object might get
destroyed after the last user drops the gem-ref via
drm_gem_object_unreference(). Use drm_gem_object_reference() to gain a
gem-reference.

For debugging, we can use bo->gem.filp != NULL to test whether a gem-bo is
valid. However, this shouldn't be used for real functionality to avoid
gem-internal dependencies.

Note that the implementation follows the previous style. However, we no
longer can check for bo->gem != NULL to test for a valid gem object. This
wasn't done before, so we should be safe now.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 17 insertions, 19 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index f32b71238c03..6618318abf50 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -43,20 +43,17 @@ nouveau_gem_object_new(struct drm_gem_object *gem)
 void
 nouveau_gem_object_del(struct drm_gem_object *gem)
 {
-        struct nouveau_bo *nvbo = gem->driver_private;
+        struct nouveau_bo *nvbo = nouveau_gem_object(gem);
         struct ttm_buffer_object *bo = &nvbo->bo;
 
-        if (!nvbo)
-                return;
-        nvbo->gem = NULL;
-
         if (gem->import_attach)
                 drm_prime_gem_destroy(gem, nvbo->bo.sg);
 
-        ttm_bo_unref(&bo);
-
         drm_gem_object_release(gem);
-        kfree(gem);
+
+        /* reset filp so nouveau_bo_del_ttm() can test for it */
+        gem->filp = NULL;
+        ttm_bo_unref(&bo);
 }
 
 int
@@ -186,14 +183,15 @@ nouveau_gem_new(struct drm_device *dev, int size, int align, uint32_t domain,
         if (nv_device(drm->device)->card_type >= NV_50)
                 nvbo->valid_domains &= domain;
 
-        nvbo->gem = drm_gem_object_alloc(dev, nvbo->bo.mem.size);
-        if (!nvbo->gem) {
+        /* Initialize the embedded gem-object. We return a single gem-reference
+         * to the caller, instead of a normal nouveau_bo ttm reference. */
+        ret = drm_gem_object_init(dev, &nvbo->gem, nvbo->bo.mem.size);
+        if (ret) {
                 nouveau_bo_ref(NULL, pnvbo);
                 return -ENOMEM;
         }
 
-        nvbo->bo.persistent_swap_storage = nvbo->gem->filp;
-        nvbo->gem->driver_private = nvbo;
+        nvbo->bo.persistent_swap_storage = nvbo->gem.filp;
         return 0;
 }
 
@@ -250,15 +248,15 @@ nouveau_gem_ioctl_new(struct drm_device *dev, void *data,
         if (ret)
                 return ret;
 
-        ret = drm_gem_handle_create(file_priv, nvbo->gem, &req->info.handle);
+        ret = drm_gem_handle_create(file_priv, &nvbo->gem, &req->info.handle);
         if (ret == 0) {
-                ret = nouveau_gem_info(file_priv, nvbo->gem, &req->info);
+                ret = nouveau_gem_info(file_priv, &nvbo->gem, &req->info);
                 if (ret)
                         drm_gem_handle_delete(file_priv, req->info.handle);
         }
 
         /* drop reference from allocate - handle holds it now */
-        drm_gem_object_unreference_unlocked(nvbo->gem);
+        drm_gem_object_unreference_unlocked(&nvbo->gem);
         return ret;
 }
 
@@ -266,7 +264,7 @@ static int
 nouveau_gem_set_domain(struct drm_gem_object *gem, uint32_t read_domains,
                        uint32_t write_domains, uint32_t valid_domains)
 {
-        struct nouveau_bo *nvbo = gem->driver_private;
+        struct nouveau_bo *nvbo = nouveau_gem_object(gem);
         struct ttm_buffer_object *bo = &nvbo->bo;
         uint32_t domains = valid_domains & nvbo->valid_domains &
                 (write_domains ? write_domains : read_domains);
@@ -327,7 +325,7 @@ validate_fini_list(struct list_head *list, struct nouveau_fence *fence,
                 list_del(&nvbo->entry);
                 nvbo->reserved_by = NULL;
                 ttm_bo_unreserve_ticket(&nvbo->bo, ticket);
-                drm_gem_object_unreference_unlocked(nvbo->gem);
+                drm_gem_object_unreference_unlocked(&nvbo->gem);
         }
 }
 
@@ -376,7 +374,7 @@ retry:
                         validate_fini(op, NULL);
                         return -ENOENT;
                 }
-                nvbo = gem->driver_private;
+                nvbo = nouveau_gem_object(gem);
                 if (nvbo == res_bo) {
                         res_bo = NULL;
                         drm_gem_object_unreference_unlocked(gem);
@@ -478,7 +476,7 @@ validate_list(struct nouveau_channel *chan, struct nouveau_cli *cli,
                         return ret;
                 }
 
-                ret = nouveau_gem_set_domain(nvbo->gem, b->read_domains,
+                ret = nouveau_gem_set_domain(&nvbo->gem, b->read_domains,
                                              b->write_domains,
                                              b->valid_domains);
                 if (unlikely(ret)) {