Merge "audio policy: fix preemtible capture race" into mnc-dr-dev

3 files changed, 41 insertions, 3 deletions

diff --git a/services/audiopolicy/common/managerdefinitions/include/AudioInputDescriptor.h b/services/audiopolicy/common/managerdefinitions/include/AudioInputDescriptor.h
index 18bcfdb..48d09ed 100644
--- a/services/audiopolicy/common/managerdefinitions/include/AudioInputDescriptor.h
+++ b/services/audiopolicy/common/managerdefinitions/include/AudioInputDescriptor.h
@@ -56,9 +56,21 @@ public:
             const struct audio_port_config *srcConfig = NULL) const;
     virtual sp<AudioPort> getAudioPort() const { return mProfile; }
     void toAudioPort(struct audio_port *port) const;
+    void setPreemptedSessions(const SortedVector<audio_session_t>& sessions);
+    SortedVector<audio_session_t> getPreemptedSessions() const;
+    bool hasPreemptedSession(audio_session_t session) const;
+    void clearPreemptedSessions();
 
 private:
     audio_port_handle_t           mId;
+    // Because a preemtible capture session can preempt another one, we end up in an endless loop
+    // situation were each session is allowed to restart after being preempted,
+    // thus preempting the other one which restarts and so on.
+    // To avoid this situation, we store which audio session was preempted when
+    // a particular input started and prevent preemption of this active input by this session.
+    // We also inherit sessions from the preempted input to avoid a 3 way preemption loop etc...
+    SortedVector<audio_session_t> mPreemptedSessions;
+
 };
 
 class AudioInputCollection :
diff --git a/services/audiopolicy/common/managerdefinitions/src/AudioInputDescriptor.cpp b/services/audiopolicy/common/managerdefinitions/src/AudioInputDescriptor.cpp
index 937160b..626fdae 100644
--- a/services/audiopolicy/common/managerdefinitions/src/AudioInputDescriptor.cpp
+++ b/services/audiopolicy/common/managerdefinitions/src/AudioInputDescriptor.cpp
@@ -93,6 +93,26 @@ void AudioInputDescriptor::toAudioPort(struct audio_port *port) const
     port->ext.mix.latency_class = AUDIO_LATENCY_NORMAL;
 }
 
+void AudioInputDescriptor::setPreemptedSessions(const SortedVector<audio_session_t>& sessions)
+{
+    mPreemptedSessions = sessions;
+}
+
+SortedVector<audio_session_t> AudioInputDescriptor::getPreemptedSessions() const
+{
+    return mPreemptedSessions;
+}
+
+bool AudioInputDescriptor::hasPreemptedSession(audio_session_t session) const
+{
+    return (mPreemptedSessions.indexOf(session) >= 0);
+}
+
+void AudioInputDescriptor::clearPreemptedSessions()
+{
+    mPreemptedSessions.clear();
+}
+
 status_t AudioInputDescriptor::dump(int fd)
 {
     const size_t SIZE = 256;
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index dfb477d..8419ed5 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -1485,10 +1485,15 @@ status_t AudioPolicyManager::startInput(audio_io_handle_t input,
             // If the already active input uses AUDIO_SOURCE_HOTWORD then it is closed,
             // otherwise the active input continues and the new input cannot be started.
             sp<AudioInputDescriptor> activeDesc = mInputs.valueFor(activeInput);
-            if (activeDesc->mInputSource == AUDIO_SOURCE_HOTWORD) {
+            if ((activeDesc->mInputSource == AUDIO_SOURCE_HOTWORD) &&
+                    !activeDesc->hasPreemptedSession(session)) {
                 ALOGW("startInput(%d) preempting low-priority input %d", input, activeInput);
-                stopInput(activeInput, activeDesc->mSessions.itemAt(0));
-                releaseInput(activeInput, activeDesc->mSessions.itemAt(0));
+                audio_session_t activeSession = activeDesc->mSessions.itemAt(0);
+                SortedVector<audio_session_t> sessions = activeDesc->getPreemptedSessions();
+                sessions.add(activeSession);
+                inputDesc->setPreemptedSessions(sessions);
+                stopInput(activeInput, activeSession);
+                releaseInput(activeInput, activeSession);
             } else {
                 ALOGE("startInput(%d) failed: other input %d already started", input, activeInput);
                 return INVALID_OPERATION;
@@ -1592,6 +1597,7 @@ status_t AudioPolicyManager::stopInput(audio_io_handle_t input,
         if (mInputs.activeInputsCount() == 0) {
             SoundTrigger::setCaptureState(false);
         }
+        inputDesc->clearPreemptedSessions();
     }
     return NO_ERROR;
 }