commit ccf37d7447b6ced5f08955e8d75b9c992052bf98
author Dominik Laskowski <domlaskowski@google.com> Fri Feb 01 16:47:58 2019 -0800
committer Dominik Laskowski <domlaskowski@google.com> Wed Feb 06 15:56:41 2019 -0800
tree f591310d70f18d6b019db59d8ba81c3553cd9006
parent 846c8337f0d48ce794cc745c92449ce97fcb1bc7

SF: Fix thread safety for scheduler callbacks

SurfaceFlinger::setRefreshRateTo, called from the Scheduler callbacks,
reads HWC and SF state without locking mStateLock, concurrently with
writes from the main thread. This CL registers ResetIdleTimerCallback
per EventThreadConnection, and locks mStateLock for connections used
off the main thread. Note that ExpiredTimerCallback locks mStateLock
unconditionally, since it is always called from the IdleTimer thread.

This CL also adds a thread annotation to setRefreshRateTo, and refactors
it accordingly.

Bug: 123715322
Test: libsurfaceflinger_unittest
Test: Boot with scheduler enabled
Change-Id: Id62c48ae22da38f292ffc18e8731a1c49a0a083c

services/surfaceflinger/Scheduler/Scheduler.h

diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index e77dc06..4abf027 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -37,7 +37,6 @@
 class Scheduler {
 public:
     using ExpiredIdleTimerCallback = std::function<void()>;
-    using ResetIdleTimerCallback = std::function<void()>;
 
     // Enum to indicate whether to start the transaction early, or at vsync time.
     enum class TransactionStart { EARLY, NORMAL };
@@ -72,12 +71,13 @@
     virtual ~Scheduler();
 
     /** Creates an EventThread connection. */
-    sp<ConnectionHandle> createConnection(
-            const char* connectionName, int64_t phaseOffsetNs, ResyncCallback resyncCallback,
-            impl::EventThread::InterceptVSyncsCallback interceptCallback);
+    sp<ConnectionHandle> createConnection(const char* connectionName, int64_t phaseOffsetNs,
+                                          ResyncCallback, ResetIdleTimerCallback,
+                                          impl::EventThread::InterceptVSyncsCallback);
 
     sp<IDisplayEventConnection> createDisplayEventConnection(const sp<ConnectionHandle>& handle,
-                                                             ResyncCallback resyncCallback);
+                                                             ResyncCallback,
+                                                             ResetIdleTimerCallback);
 
     // Getter methods.
     EventThread* getEventThread(const sp<ConnectionHandle>& handle);
@@ -116,8 +116,6 @@
     void incrementFrameCounter();
     // Callback that gets invoked once the idle timer expires.
     void setExpiredIdleTimerCallback(const ExpiredIdleTimerCallback& expiredTimerCallback);
-    // Callback that gets invoked once the idle timer is reset.
-    void setResetIdleTimerCallback(const ResetIdleTimerCallback& resetTimerCallback);
     // Returns relevant information about Scheduler for dumpsys purposes.
     std::string doDump();
 
@@ -127,6 +125,10 @@
             impl::EventThread::InterceptVSyncsCallback interceptCallback);
 
 private:
+    // Creates a connection on the given EventThread and forwards the given callbacks.
+    sp<EventThreadConnection> createConnectionInternal(EventThread*, ResyncCallback&&,
+                                                       ResetIdleTimerCallback&&);
+
     nsecs_t calculateAverage() const;
     void updateFrameSkipping(const int64_t skipCount);
     // Collects the statistical mean (average) and median between timestamp
@@ -184,7 +186,6 @@
 
     std::mutex mCallbackLock;
     ExpiredIdleTimerCallback mExpiredTimerCallback GUARDED_BY(mCallbackLock);
-    ResetIdleTimerCallback mResetTimerCallback GUARDED_BY(mCallbackLock);
 };
 
 } // namespace android