commit 35a395720a4d567e1aaf1749963088d9829ef8b8
author Drew Davenport <ddavenport@google.com> Thu Dec 19 13:54:39 2024 -0700
committer Drew Davenport <ddavenport@google.com> Fri Feb 21 10:51:42 2025 -0700
tree 45b50d8d4aafd43f451fd0920eb059cb525666f8
parent 6bfccb83af1656720d62bb3df7393e0f879e2be2

drm_hwcomposer: Use clang thread-safety analysis in VSyncWorker

See https://clang.llvm.org/docs/ThreadSafetyAnalysis.html for details.
Define thread annotation macros according to the example provided in the
documentation, and use these to annotate VSyncWorker members that can be
accessed from multiple threads.

Thread safety analysis does not yet work with std::unique_lock, so
disable the warnings when it is used.

Change-Id: I8b3b503fbaf0923588fbe3d0180f6fe6ec228350
Signed-off-by: Drew Davenport <ddavenport@google.com>

drm/VSyncWorker.h

diff --git a/drm/VSyncWorker.h b/drm/VSyncWorker.h
index c76dd14..5b97328 100644
--- a/drm/VSyncWorker.h
+++ b/drm/VSyncWorker.h
@@ -23,6 +23,7 @@
 #include <thread>
 
 #include "DrmDevice.h"
+#include "utils/thread_annotations.h"
 
 namespace android {
 
@@ -55,27 +56,26 @@
 
   void ThreadFn();
 
-  int64_t GetPhasedVSync(int64_t frame_ns, int64_t current) const;
+  int64_t GetPhasedVSync(int64_t frame_ns, int64_t current) const
+      REQUIRES(mutex_);
   int SyntheticWaitVBlank(int64_t *timestamp);
 
-  // Must hold the lock before calling these.
   void UpdateVSyncControl();
-  bool ShouldEnable() const;
+  bool ShouldEnable() const REQUIRES(mutex_);
 
   SharedFd drm_fd_;
   uint32_t high_crtc_ = 0;
 
-  bool enabled_ = false;
-  bool thread_exit_ = false;
-  int64_t last_timestamp_ = -1;
+  bool enabled_ GUARDED_BY(mutex_) = false;
+  bool thread_exit_ GUARDED_BY(mutex_) = false;
+  int64_t last_timestamp_ GUARDED_BY(mutex_) = -1;
 
   // Default to 60Hz refresh rate
   static constexpr uint32_t kDefaultVSPeriodNs = 16666666;
-  // Needs to be threadsafe.
-  uint32_t vsync_period_ns_ = kDefaultVSPeriodNs;
-  bool enable_vsync_timestamps_ = false;
-  uint32_t last_vsync_timestamp_ = 0;
-  std::optional<VsyncTimestampCallback> callback_;
+  uint32_t vsync_period_ns_ GUARDED_BY(mutex_) = kDefaultVSPeriodNs;
+  bool enable_vsync_timestamps_ GUARDED_BY(mutex_) = false;
+  uint32_t last_vsync_timestamp_ GUARDED_BY(mutex_) = 0;
+  std::optional<VsyncTimestampCallback> callback_ GUARDED_BY(mutex_);
 
   std::condition_variable cv_;
   std::thread vswt_;