commit b445375f50a1a619b2d7518d32387d5ea77ceb70
author Andy Hung <hunga@google.com> Mon Sep 08 11:47:24 2014 -0700
committer Andy Hung <hunga@google.com> Mon Sep 08 13:37:06 2014 -0700
tree 011f7b4e9ce5ee17d4265ed0fceebc484db3cee9
parent 2e97b01cecec65e690ac7da5df9433c52ff75bd8

Fix potential deadlock between AudioPolicyService and AudioSystem

Bug: 17109761
Change-Id: I315c1c5066f62b05e1c13b04fae1272b5fbce977

media/libmedia/AudioSystem.cpp

diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index 3486d21..1742fbe 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -582,9 +582,13 @@
         }
         binder->linkToDeath(gAudioPolicyServiceClient);
         gAudioPolicyService = interface_cast<IAudioPolicyService>(binder);
-        gAudioPolicyService->registerClient(gAudioPolicyServiceClient);
         gLock.unlock();
+        // Registering the client takes the AudioPolicyService lock.
+        // Don't hold the AudioSystem lock at the same time.
+        gAudioPolicyService->registerClient(gAudioPolicyServiceClient);
     } else {
+        // There exists a benign race condition where gAudioPolicyService
+        // is set, but gAudioPolicyServiceClient is not yet registered.
         gLock.unlock();
     }
     return gAudioPolicyService;