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Commit 8ea16e4b authored by Eric Laurent's avatar Eric Laurent
Browse files

audioflinger: fix race condition in SyncEvent callback 

Now that the SyncEvent callback is implemented by the
RecordTrack instead of the RecordThread, there is a possibility
that the callback is called after the track deletion.

SyncEvent callback now uses a weak pointer instead of
a raw pointer as cookie. This allows the callback implementer to
acquire a strong reference on the object pointed to by the cookie.

Bug: 13114128.
Change-Id: Id61b8f06044ed1e52c6f7e7c666cdede68340de2
parent 56df9ff3

services/audioflinger/AudioFlinger.cpp

+1 −1
Original line number Diff line number Diff line
@@ -2094,7 +2094,7 @@ sp<AudioFlinger::SyncEvent> AudioFlinger::createSyncEvent(AudioSystem::sync_even 
                                    int triggerSession,

                                    int listenerSession,

                                    sync_event_callback_t callBack,

                                    void *cookie)

                                    wp<RefBase> cookie)

{

    Mutex::Autolock _l(mLock);

services/audioflinger/AudioFlinger.h

+4 −4
Original line number Diff line number Diff line
@@ -253,7 +253,7 @@ public: 
                  int triggerSession,

                  int listenerSession,

                  sync_event_callback_t callBack,

                  void *cookie)

                  wp<RefBase> cookie)

        : mType(type), mTriggerSession(triggerSession), mListenerSession(listenerSession),

          mCallback(callBack), mCookie(cookie)

        {}
@@ -266,14 +266,14 @@ public: 
        AudioSystem::sync_event_t type() const { return mType; }

        int triggerSession() const { return mTriggerSession; }

        int listenerSession() const { return mListenerSession; }

        void *cookie() const { return mCookie; }

        wp<RefBase> cookie() const { return mCookie; }



    private:

          const AudioSystem::sync_event_t mType;

          const int mTriggerSession;

          const int mListenerSession;

          sync_event_callback_t mCallback;

          void * const mCookie;

          const wp<RefBase> mCookie;

          mutable Mutex mLock;

    };
@@ -281,7 +281,7 @@ public: 
                                        int triggerSession,

                                        int listenerSession,

                                        sync_event_callback_t callBack,

                                        void *cookie);

                                        wp<RefBase> cookie);



private:

    class AudioHwDevice;    // fwd declaration for findSuitableHwDev_l

services/audioflinger/Threads.cpp

+5 −2
Original line number Diff line number Diff line
@@ -5095,10 +5095,13 @@ void AudioFlinger::RecordThread::syncStartEventCallback(const wp<SyncEvent>& eve 
    sp<SyncEvent> strongEvent = event.promote();



    if (strongEvent != 0) {

        RecordTrack *recordTrack = (RecordTrack *)strongEvent->cookie();

        sp<RefBase> ptr = strongEvent->cookie().promote();

        if (ptr != 0) {

            RecordTrack *recordTrack = (RecordTrack *)ptr.get();

            recordTrack->handleSyncStartEvent(strongEvent);

        }

    }

}



bool AudioFlinger::RecordThread::stop(RecordThread::RecordTrack* recordTrack) {

    ALOGV("RecordThread::stop");