From: Conor McCarthy cmccarthy@codeweavers.com
Fixes a race condition where the descriptor is modified between getting its object and resetting the `next` index. The new object would never be written. While it is invalid for the app to write descriptors used by a command list which has been submitted to a queue, unused descriptors may be written. This change also supports writing descriptors in a worker thread. --- libs/vkd3d/resource.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/libs/vkd3d/resource.c b/libs/vkd3d/resource.c index abbdfbe20..0c9c911a2 100644 --- a/libs/vkd3d/resource.c +++ b/libs/vkd3d/resource.c @@ -2632,20 +2632,18 @@ void d3d12_desc_flush_vk_heap_updates_locked(struct d3d12_descriptor_heap *descr for (; i != UINT_MAX; i = next) { src = &descriptors[i]; - next = (int)src->next >> 1; + next = vkd3d_atomic_exchange(&src->next, 0); + next = (int)next >> 1;
+ /* A race exists here between updating src->next and getting the current object. The best + * we can do is get the object last, which may result in a harmless rewrite later. */ u.object = d3d12_desc_get_object_ref(src, device);
if (!u.object) - { - vkd3d_atomic_exchange(&src->next, 0); continue; - }
writes.held_refs[writes.held_ref_count++] = u.object; d3d12_desc_write_vk_heap(descriptor_heap, i, &writes, u.object, device); - - vkd3d_atomic_exchange(&src->next, 0); }
/* Avoid thunk calls wherever possible. */