commit 6abbffaa4528699ca66db7b5fa14f9b55c1fb68b
author Lloyd Pique <lpique@google.com> Tue Feb 13 18:51:55 2018 -0800
committer android-build-team Robot <android-build-team-robot@google.com> Wed Feb 14 21:40:13 2018 +0000
tree 3d6945598471401c0af7c73017b97588cf491e5c
parent 161088f574ca5f74b98369dbb391dc031fa0bed0

SF: Fix an EventThread deadlock

EventThread::removeDisplayEventConnection tried to acquire the mutex,
however the caller (eventThread::threadMain()) already had it.

The fix was to not acquire the mutex, since threadMain() was the only
caller.

Bug: 73256320
Test: Can toggle "Show taps" from dev options without lockup.
Change-Id: I855b19b3d0ac9e0ea05604cc7b077f4a5030a00b
(cherry picked from commit 9cbe4dad35ae986420a3dda164fb602ee6b48923)

services/surfaceflinger/EventThread.cpp

diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 90aab50..1f4f5a5 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -100,8 +100,7 @@
     return NO_ERROR;
 }
 
-void EventThread::removeDisplayEventConnection(const wp<EventThread::Connection>& connection) {
-    std::lock_guard<std::mutex> lock(mMutex);
+void EventThread::removeDisplayEventConnectionLocked(const wp<EventThread::Connection>& connection) {
     mDisplayEventConnections.remove(connection);
 }
 
@@ -195,7 +194,7 @@
                 // handle any other error on the pipe as fatal. the only
                 // reasonable thing to do is to clean-up this connection.
                 // The most common error we'll get here is -EPIPE.
-                removeDisplayEventConnection(signalConnections[i]);
+                removeDisplayEventConnectionLocked(signalConnections[i]);
             }
         }
     }

services/surfaceflinger/EventThread.h

diff --git a/services/surfaceflinger/EventThread.h b/services/surfaceflinger/EventThread.h
index 708806a..97f0a35 100644
--- a/services/surfaceflinger/EventThread.h
+++ b/services/surfaceflinger/EventThread.h
@@ -129,7 +129,7 @@
                                                            DisplayEventReceiver::Event* event)
             REQUIRES(mMutex);
 
-    void removeDisplayEventConnection(const wp<Connection>& connection);
+    void removeDisplayEventConnectionLocked(const wp<Connection>& connection) REQUIRES(mMutex);
     void enableVSyncLocked() REQUIRES(mMutex);
     void disableVSyncLocked() REQUIRES(mMutex);