SF: Remove display lookup in SurfaceTracing

Remove the strong reference to prevent a removed display from being
destroyed off the main thread. This is also a step in adding thread
annotations to display state accessors.

Also, clean up SurfaceTracing usage in the SurfaceFlinger class.

Bug: 123715322
Test: Tracing still works.
Change-Id: Iad174e7b42fbde96a46155c740838f6cd3966365
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index cd78c1a..b4ae8ed 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -169,19 +169,22 @@
 
 #pragma clang diagnostic pop
 
-class ConditionalLock {
-public:
-    ConditionalLock(Mutex& mutex, bool lock) : mMutex(mutex), mLocked(lock) {
-        if (lock) {
-            mMutex.lock();
-        }
+template <typename Mutex>
+struct ConditionalLockGuard {
+    ConditionalLockGuard(Mutex& mutex, bool lock) : mutex(mutex), lock(lock) {
+        if (lock) mutex.lock();
     }
-    ~ConditionalLock() { if (mLocked) mMutex.unlock(); }
-private:
-    Mutex& mMutex;
-    bool mLocked;
+
+    ~ConditionalLockGuard() {
+        if (lock) mutex.unlock();
+    }
+
+    Mutex& mutex;
+    const bool lock;
 };
 
+using ConditionalLock = ConditionalLockGuard<Mutex>;
+
 // TODO(b/141333600): Consolidate with HWC2::Display::Config::Builder::getDefaultDensity.
 constexpr float FALLBACK_DENSITY = ACONFIGURATION_DENSITY_TV / 160.f;
 
@@ -1948,8 +1951,15 @@
             // potentially trigger a display handoff.
             updateVrFlinger();
 
+            if (mTracingEnabledChanged) {
+                mTracingEnabled = mTracing.isEnabled();
+                mTracingEnabledChanged = false;
+            }
+
             bool refreshNeeded;
-            withTracingLock([&]() {
+            {
+                ConditionalLockGuard<std::mutex> lock(mTracingLock, mTracingEnabled);
+
                 refreshNeeded = handleMessageTransaction();
                 refreshNeeded |= handleMessageInvalidate();
                 if (mTracingEnabled) {
@@ -1959,7 +1969,7 @@
                         mTracing.notifyLocked("visibleRegionsDirty");
                     }
                 }
-            });
+            }
 
             // Layers need to get updated (in the previous line) before we can use them for
             // choosing the refresh rate.
@@ -3034,26 +3044,6 @@
     mDrawingState.traverse([&](Layer* layer) { layer->updateMirrorInfo(); });
 }
 
-void SurfaceFlinger::withTracingLock(std::function<void()> lockedOperation) {
-    if (mTracingEnabledChanged) {
-        mTracingEnabled = mTracing.isEnabled();
-        mTracingEnabledChanged = false;
-    }
-
-    // Synchronize with Tracing thread
-    std::unique_lock<std::mutex> lock;
-    if (mTracingEnabled) {
-        lock = std::unique_lock<std::mutex>(mDrawingStateLock);
-    }
-
-    lockedOperation();
-
-    // Synchronize with Tracing thread
-    if (mTracingEnabled) {
-        lock.unlock();
-    }
-}
-
 void SurfaceFlinger::commitOffscreenLayers() {
     for (Layer* offscreenLayer : mOffscreenLayers) {
         offscreenLayer->traverse(LayerVector::StateSet::Drawing, [](Layer* layer) {
@@ -4560,11 +4550,13 @@
     result.append("\n");
 }
 
-LayersProto SurfaceFlinger::dumpDrawingStateProto(
-        uint32_t traceFlags, const sp<const DisplayDevice>& displayDevice) const {
+LayersProto SurfaceFlinger::dumpDrawingStateProto(uint32_t traceFlags) const {
+    // If context is SurfaceTracing thread, mTracingLock blocks display transactions on main thread.
+    const auto display = getDefaultDisplayDeviceLocked();
+
     LayersProto layersProto;
     for (const sp<Layer>& layer : mDrawingState.layersSortedByZ) {
-        layer->writeToProto(layersProto, traceFlags, displayDevice);
+        layer->writeToProto(layersProto, traceFlags, display);
     }
 
     return layersProto;
@@ -4596,10 +4588,7 @@
 
 LayersProto SurfaceFlinger::dumpProtoFromMainThread(uint32_t traceFlags) {
     LayersProto layersProto;
-    postMessageSync(new LambdaMessage([&]() {
-        const auto& displayDevice = getDefaultDisplayDeviceLocked();
-        layersProto = dumpDrawingStateProto(traceFlags, displayDevice);
-    }));
+    postMessageSync(new LambdaMessage([&] { layersProto = dumpDrawingStateProto(traceFlags); }));
     return layersProto;
 }
 
@@ -5126,20 +5115,12 @@
                 n = data.readInt32();
                 if (n) {
                     ALOGD("LayerTracing enabled");
-                    Mutex::Autolock lock(mStateLock);
-                    mTracingEnabledChanged = true;
-                    mTracing.enable();
+                    mTracingEnabledChanged = mTracing.enable();
                     reply->writeInt32(NO_ERROR);
                 } else {
                     ALOGD("LayerTracing disabled");
-                    bool writeFile = false;
-                    {
-                        Mutex::Autolock lock(mStateLock);
-                        mTracingEnabledChanged = true;
-                        writeFile = mTracing.disable();
-                    }
-
-                    if (writeFile) {
+                    mTracingEnabledChanged = mTracing.disable();
+                    if (mTracingEnabledChanged) {
                         reply->writeInt32(mTracing.writeToFile());
                     } else {
                         reply->writeInt32(NO_ERROR);
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 72d1ffe..35212e5 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -931,8 +931,7 @@
     void dumpDisplayIdentificationData(std::string& result) const;
     void dumpRawDisplayIdentificationData(const DumpArgs&, std::string& result) const;
     void dumpWideColorInfo(std::string& result) const;
-    LayersProto dumpDrawingStateProto(uint32_t traceFlags = SurfaceTracing::TRACE_ALL,
-                                      const sp<const DisplayDevice>& displayDevice = nullptr) const;
+    LayersProto dumpDrawingStateProto(uint32_t traceFlags) const;
     void dumpOffscreenLayersProto(LayersProto& layersProto,
                                   uint32_t traceFlags = SurfaceTracing::TRACE_ALL) const;
     // Dumps state from HW Composer
@@ -940,7 +939,6 @@
     LayersProto dumpProtoFromMainThread(uint32_t traceFlags = SurfaceTracing::TRACE_ALL)
             EXCLUDES(mStateLock);
     void dumpOffscreenLayers(std::string& result) EXCLUDES(mStateLock);
-    void withTracingLock(std::function<void()> operation) REQUIRES(mStateLock);
 
     bool isLayerTripleBufferingDisabled() const {
         return this->mLayerTripleBufferingDisabled;
@@ -982,9 +980,6 @@
     SortedVector<sp<Layer>> mLayersPendingRemoval;
     bool mTraversalNeededMainThread = false;
 
-    // guards access to the mDrawing state if tracing is enabled.
-    mutable std::mutex mDrawingStateLock;
-
     // global color transform states
     Daltonizer mDaltonizer;
     float mGlobalSaturationFactor = 1.0f;
@@ -1059,10 +1054,13 @@
     bool mPropagateBackpressure = true;
     bool mPropagateBackpressureClientComposition = false;
     std::unique_ptr<SurfaceInterceptor> mInterceptor;
+
     SurfaceTracing mTracing{*this};
+    std::mutex mTracingLock;
     bool mTracingEnabled = false;
     bool mAddCompositionStateToTrace = false;
-    bool mTracingEnabledChanged GUARDED_BY(mStateLock) = false;
+    std::atomic<bool> mTracingEnabledChanged = false;
+
     const std::shared_ptr<TimeStats> mTimeStats;
     const std::unique_ptr<FrameTracer> mFrameTracer;
     bool mUseHwcVirtualDisplays = false;
diff --git a/services/surfaceflinger/SurfaceTracing.cpp b/services/surfaceflinger/SurfaceTracing.cpp
index f0b895d..d84ce69 100644
--- a/services/surfaceflinger/SurfaceTracing.cpp
+++ b/services/surfaceflinger/SurfaceTracing.cpp
@@ -33,7 +33,7 @@
 namespace android {
 
 SurfaceTracing::SurfaceTracing(SurfaceFlinger& flinger)
-      : mFlinger(flinger), mSfLock(flinger.mDrawingStateLock) {}
+      : mFlinger(flinger), mSfLock(flinger.mTracingLock) {}
 
 void SurfaceTracing::mainLoop() {
     bool enabled = addFirstEntry();
@@ -44,21 +44,19 @@
 }
 
 bool SurfaceTracing::addFirstEntry() {
-    const auto displayDevice = mFlinger.getDefaultDisplayDevice();
     LayersTraceProto entry;
     {
         std::scoped_lock lock(mSfLock);
-        entry = traceLayersLocked("tracing.enable", displayDevice);
+        entry = traceLayersLocked("tracing.enable");
     }
     return addTraceToBuffer(entry);
 }
 
 LayersTraceProto SurfaceTracing::traceWhenNotified() {
-    const auto displayDevice = mFlinger.getDefaultDisplayDevice();
     std::unique_lock<std::mutex> lock(mSfLock);
     mCanStartTrace.wait(lock);
     android::base::ScopedLockAssertion assumeLock(mSfLock);
-    LayersTraceProto entry = traceLayersLocked(mWhere, displayDevice);
+    LayersTraceProto entry = traceLayersLocked(mWhere);
     mTracingInProgress = false;
     mMissedTraceEntries = 0;
     lock.unlock();
@@ -126,15 +124,17 @@
     }
 }
 
-void SurfaceTracing::enable() {
+bool SurfaceTracing::enable() {
     std::scoped_lock lock(mTraceLock);
 
     if (mEnabled) {
-        return;
+        return false;
     }
+
     mBuffer.reset(mBufferSize);
     mEnabled = true;
     mThread = std::thread(&SurfaceTracing::mainLoop, this);
+    return true;
 }
 
 status_t SurfaceTracing::writeToFile() {
@@ -176,14 +176,13 @@
     mTraceFlags = flags;
 }
 
-LayersTraceProto SurfaceTracing::traceLayersLocked(const char* where,
-                                                   const sp<const DisplayDevice>& displayDevice) {
+LayersTraceProto SurfaceTracing::traceLayersLocked(const char* where) {
     ATRACE_CALL();
 
     LayersTraceProto entry;
     entry.set_elapsed_realtime_nanos(elapsedRealtimeNano());
     entry.set_where(where);
-    LayersProto layers(mFlinger.dumpDrawingStateProto(mTraceFlags, displayDevice));
+    LayersProto layers(mFlinger.dumpDrawingStateProto(mTraceFlags));
 
     if (flagIsSetLocked(SurfaceTracing::TRACE_EXTRA)) {
         mFlinger.dumpOffscreenLayersProto(layers);
diff --git a/services/surfaceflinger/SurfaceTracing.h b/services/surfaceflinger/SurfaceTracing.h
index e90fc4d..f208eb8 100644
--- a/services/surfaceflinger/SurfaceTracing.h
+++ b/services/surfaceflinger/SurfaceTracing.h
@@ -27,8 +27,6 @@
 #include <queue>
 #include <thread>
 
-#include "DisplayDevice.h"
-
 using namespace android::surfaceflinger;
 
 namespace android {
@@ -44,7 +42,7 @@
 class SurfaceTracing {
 public:
     explicit SurfaceTracing(SurfaceFlinger& flinger);
-    void enable();
+    bool enable();
     bool disable();
     status_t writeToFile();
     bool isEnabled() const;
@@ -92,9 +90,7 @@
     void mainLoop();
     bool addFirstEntry();
     LayersTraceProto traceWhenNotified();
-    LayersTraceProto traceLayersLocked(const char* where,
-                                       const sp<const DisplayDevice>& displayDevice)
-            REQUIRES(mSfLock);
+    LayersTraceProto traceLayersLocked(const char* where) REQUIRES(mSfLock);
 
     // Returns true if trace is enabled.
     bool addTraceToBuffer(LayersTraceProto& entry);