[PATCH vkd3d 1/2] vkd3d: Delay adding a command queue to the blocked list until after the op is written.

[Conor McCarthy]

Otherwise the following sequence can occur:
1. A command queue is added to the blocked list during a Wait() call.
2. An unblocking Signal() occurs on the CPU in another thread, flushing the
   blocked ops, but as no op has been written, the queue is removed from the
   blocked list.
3. The blocked op is written.
3. Another op is queued and the queue is not re-added to the blocked
   list because this only happens for the first op.

World of Warcraft triggers this issue.

Signed-off-by: Conor McCarthy <cmccarthy at codeweavers.com>
---
 libs/vkd3d/command.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/libs/vkd3d/command.c b/libs/vkd3d/command.c
index d0782e5a..7452128c 100644
--- a/libs/vkd3d/command.c
+++ b/libs/vkd3d/command.c
@@ -6812,12 +6812,6 @@ static HRESULT STDMETHODCALLTYPE d3d12_command_queue_Wait(ID3D12CommandQueue *if
      * where multiple queues alias over the same physical queue, so effectively,
      * we need to manage out-of-order submits ourselves. */
 
-    if (!command_queue->ops_count)
-        hr = d3d12_device_add_blocked_command_queues(command_queue->device, &command_queue, 1);
-
-    if (FAILED(hr))
-        goto done;
-
     if (!(op = d3d12_command_queue_require_space_locked(command_queue)))
     {
         hr = E_OUTOFMEMORY;
@@ -6829,6 +6823,11 @@ static HRESULT STDMETHODCALLTYPE d3d12_command_queue_Wait(ID3D12CommandQueue *if
 
     d3d12_fence_incref(fence);
 
+    /* Add the queue to the blocked list after writing the op to ensure the queue isn't
+     * removed again in another thread because it has no ops. */
+    if (command_queue->ops_count == 1)
+        hr = d3d12_device_add_blocked_command_queues(command_queue->device, &command_queue, 1);
+
 done:
     vkd3d_mutex_unlock(&command_queue->op_mutex);
     return hr;
-- 
2.36.1