audio policy: bind setMode() and setPhoneState() operations

No routing operation should be allowed between setMode() and setPhoneState()
when starting a call as the audio HAL relies on a precise sequence of mode change
and routing change to select the initial audio device for the call.

Bug: 24083591.

Change-Id: I2d5ef62c11cf7aedc2ec7ca5e5fadd7ac875afbc

1 files changed, 5 insertions, 1 deletions

diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
index 793c26a..ca365a5 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
@@ -76,10 +76,14 @@ status_t AudioPolicyService::setPhoneState(audio_mode_t state)
 
     ALOGV("setPhoneState()");
 
+    // acquire lock before calling setMode() so that setMode() + setPhoneState() are an atomic
+    // operation from policy manager standpoint (no other operation (e.g track start or stop)
+    // can be interleaved).
+    Mutex::Autolock _l(mLock);
+
     // TODO: check if it is more appropriate to do it in platform specific policy manager
     AudioSystem::setMode(state);
 
-    Mutex::Autolock _l(mLock);
     mAudioPolicyManager->setPhoneState(state);
     mPhoneState = state;
     return NO_ERROR;