commit 209500045607e6a7d363ee5c1010478a058c3e0a
author Dan Stoza <stoza@google.com> Thu Jun 18 14:56:58 2020 -0700
committer Dan Stoza <stoza@google.com> Thu Jun 18 14:56:58 2020 -0700
tree 0f685af3536ab1bcec5113a4f7d73857139bba89
parent dbc3025d05435657f35416eade5e20a066ff3751

SF: Guard Power HAL access with lock

Adds a lock around Power HAL access to prevent concurrent access from
multiple binder threads.

Bug: 158270361
Test: build, boot
Change-Id: I7262cdb8addf72ef0657f5b9394e1ba324e3e43f

services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp

diff --git a/services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp b/services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp
index 1d8179c..4b4c050 100644
--- a/services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp
+++ b/services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp
@@ -85,6 +85,7 @@
 
     const bool expectsExpensiveRendering = !mExpensiveDisplays.empty();
     if (mNotifiedExpensiveRendering != expectsExpensiveRendering) {
+        std::lock_guard lock(mPowerHalMutex);
         HalWrapper* const halWrapper = getPowerHal();
         if (halWrapper == nullptr) {
             return;
@@ -108,6 +109,7 @@
     }
 
     if (mSendUpdateImminent.load()) {
+        std::lock_guard lock(mPowerHalMutex);
         HalWrapper* const halWrapper = getPowerHal();
         if (halWrapper == nullptr) {
             return;

services/surfaceflinger/DisplayHardware/PowerAdvisor.h

diff --git a/services/surfaceflinger/DisplayHardware/PowerAdvisor.h b/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
index 34e63e7..95eb0e2 100644
--- a/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
+++ b/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
@@ -19,6 +19,8 @@
 #include <atomic>
 #include <unordered_set>
 
+#include <utils/Mutex.h>
+
 #include "../Scheduler/OneShotTimer.h"
 #include "DisplayIdentification.h"
 
@@ -56,10 +58,11 @@
     void notifyDisplayUpdateImminent() override;
 
 private:
-    HalWrapper* getPowerHal();
+    HalWrapper* getPowerHal() REQUIRES(mPowerHalMutex);
+    bool mReconnectPowerHal GUARDED_BY(mPowerHalMutex) = false;
+    std::mutex mPowerHalMutex;
 
     std::atomic_bool mBootFinished = false;
-    bool mReconnectPowerHal = false;
 
     std::unordered_set<DisplayId> mExpensiveDisplays;
     bool mNotifiedExpensiveRendering = false;