drm/nouveau/gem: tie deferred unmapping of buffers to VMA fence completion

As VMAs are per-client, unlike buffers, this allows us to avoid referencing
foreign fences (those that belong to another client/driver) from the client
deferred work handler, and prevent some not-fun race conditions that can be
triggered when a fence stalls.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 2016d9e..300daee 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -115,25 +115,12 @@ nouveau_gem_object_delete_work(struct nouveau_cli_work *w)
 static void
 nouveau_gem_object_unmap(struct nouveau_bo *nvbo, struct nouveau_vma *vma)
 {
-       const bool mapped = nvbo->bo.mem.mem_type != TTM_PL_SYSTEM;
-       struct reservation_object *resv = nvbo->bo.resv;
-       struct reservation_object_list *fobj;
+       struct dma_fence *fence = vma->fence ? &vma->fence->base : NULL;
        struct nouveau_gem_object_unmap *work;
-       struct dma_fence *fence = NULL;
-
-       fobj = reservation_object_get_list(resv);
 
        list_del_init(&vma->head);
 
-       if (fobj && fobj->shared_count > 1)
-               ttm_bo_wait(&nvbo->bo, false, false);
-       else if (fobj && fobj->shared_count == 1)
-               fence = rcu_dereference_protected(fobj->shared[0],
-                                               reservation_object_held(resv));
-       else
-               fence = reservation_object_get_excl(nvbo->bo.resv);
-
-       if (!fence || !mapped) {
+       if (!fence) {
                nouveau_gem_object_delete(vma);
                return;
        }