util/u_queue: read fence->signalled locked with TSAN

When TSAN is enabled we use standard mutexes instead of futexes. With
futexes the fence->signalled is read using an atomic operation, to best
mimic this let's protect the read with a locked mutex.

This avoids TSAN reporting a race condition (false positive with
futexes) with Zink when accessing the pipeline cache.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28650>

src/util/u_queue.h

@@ -138,6 +138,7 @@ void util_queue_fence_signal(struct util_queue_fence *fence);
  * \warning The caller must ensure that no other thread may currently be
  *          waiting (or about to wait) on the fence.
  */
+#if !THREAD_SANITIZER
 static inline void
 util_queue_fence_reset(struct util_queue_fence *fence)
 {
@@ -150,6 +151,23 @@ util_queue_fence_is_signalled(struct util_queue_fence *fence)
 {
    return fence->signalled != 0;
 }
+#else
+static inline void
+util_queue_fence_reset(struct util_queue_fence *fence)
+{
+   assert(fence->signalled);
+   fence->signalled = 0;
+}
+
+static inline bool
+util_queue_fence_is_signalled(struct util_queue_fence *fence)
+{
+   mtx_lock(&fence->mutex);
+   bool signalled = fence->signalled != 0;
+   mtx_unlock(&fence->mutex);
+   return signalled;
+}
+#endif
 #endif
 
 void

tsan-blacklist.txt

@@ -1,2 +1 @@
-# Placeholder file, will be filled with surpressions for TSAN 
-
+# Placeholder file, will be filled with surpressions for TSAN