drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks

Acquire the reservation lock directly in GEM pin callback. Same for
unpin. Prepares for further changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
nouveau accordingly by pushing locking out of the implementation. A
follow-up patch will fix locking for all GEM code at once.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # virtio-gpu
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240227113853.8464-7-tzimmermann@suse.de

drivers/gpu/drm/nouveau/nouveau_prime.c

@@ -86,21 +86,32 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 int nouveau_gem_prime_pin(struct drm_gem_object *obj)
 {
 	struct nouveau_bo *nvbo = nouveau_gem_object(obj);
+	struct ttm_buffer_object *bo = &nvbo->bo;
 	int ret;
 
-	/* pin buffer into GTT */
-	ret = nouveau_bo_pin(nvbo, NOUVEAU_GEM_DOMAIN_GART, false);
+	ret = ttm_bo_reserve(bo, false, false, NULL);
 	if (ret)
 		return -EINVAL;
+	/* pin buffer into GTT */
+	ret = nouveau_bo_pin_locked(nvbo, NOUVEAU_GEM_DOMAIN_GART, false);
+	if (ret)
+		ret = -EINVAL;
+	ttm_bo_unreserve(bo);
 
-	return 0;
+	return ret;
 }
 
 void nouveau_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct nouveau_bo *nvbo = nouveau_gem_object(obj);
+	struct ttm_buffer_object *bo = &nvbo->bo;
+	int ret;
 
-	nouveau_bo_unpin(nvbo);
+	ret = ttm_bo_reserve(bo, false, false, NULL);
+	if (ret)
+		return;
+	nouveau_bo_unpin_locked(nvbo);
+	ttm_bo_unreserve(bo);
 }
 
 struct dma_buf *nouveau_gem_prime_export(struct drm_gem_object *gobj,