From b445375f50a1a619b2d7518d32387d5ea77ceb70 Mon Sep 17 00:00:00 2001
From: Andy Hung <hunga@google.com>
Date: Mon, 8 Sep 2014 11:47:24 -0700
Subject: Fix potential deadlock between AudioPolicyService and AudioSystem

Bug: 17109761
Change-Id: I315c1c5066f62b05e1c13b04fae1272b5fbce977
---
 media/libmedia/AudioSystem.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to '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 @@ const sp<IAudioPolicyService>& AudioSystem::get_audio_policy_service()
         }
         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;
-- 
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