[PATCH] ntdll: Increment num_busy_workers when queuing TP object.

[Paul Gofman]

Otherwise two consequative submits may have the same
num_busy_workers value if threadpool_worker_proc did not
have a chance to pick the work in between. A new thread is
not created in tp_submit() for the second submit and if the
first submit queues an (infinitely long) wait
the next submitted callback is not called for indefinite
time period.

Fixes hang on exit in Detroit Become Human.

Signed-off-by: Paul Gofman 
---
 dlls/ntdll/threadpool.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/threadpool.c b/dlls/ntdll/threadpool.c
index 451d441f572..84286fbee90 100644
--- a/dlls/ntdll/threadpool.c
+++ b/dlls/ntdll/threadpool.c
@@ -1375,7 +1375,6 @@ static NTSTATUS tp_new_worker_thread( struct threadpool *pool )
     {
         InterlockedIncrement( &pool->refcount );
         pool->num_workers++;
-        pool->num_busy_workers++;
         NtClose( thread );
     }
     return status;
@@ -2137,6 +2136,7 @@ static void tp_object_initialize( struct threadpool_object *object, struct threa

static void tp_object_prio_queue( struct threadpool_object *object )
 {
+    ++object->pool->num_busy_workers;
     list_add_tail( &object->pool->pools[object->priority], &object->pool_entry );
 }

@@ -2330,7 +2330,6 @@ static void CALLBACK threadpool_worker_proc( void *param )
     TRACE( "starting worker thread for pool %p\n", pool );

RtlEnterCriticalSection( &pool->cs );
-    pool->num_busy_workers--;
     for (;;)
     {
         while ((ptr = threadpool_get_next_item( pool )))
@@ -2360,7 +2359,6 @@ static void CALLBACK threadpool_worker_proc( void *param )
             /* Leave critical section and do the actual callback. */
             object->num_associated_callbacks++;
             object->num_running_callbacks++;
-            pool->num_busy_workers++;
             RtlLeaveCriticalSection( &pool->cs );

/* Initialize threadpool instance struct. */
@@ -2466,6 +2464,7 @@ static void CALLBACK threadpool_worker_proc( void *param )

skip_cleanup:
             RtlEnterCriticalSection( &pool->cs );
+            assert(pool->num_busy_workers);
             pool->num_busy_workers--;

/* Simple callbacks are automatically shutdown after execution. */