From d5ed6e88a9bea1879e41d7defaf1edea7c09f554 Mon Sep 17 00:00:00 2001 From: Glenn Kasten Date: Fri, 2 Nov 2012 13:05:14 -0700 Subject: [PATCH] Fix call to restoreTrack_l() without lock held Also document lock order Change-Id: I2c1f273a0a51fa79ee3dd766de8d23083e270051 --- include/media/AudioTrack.h | 7 +++++++ media/libmedia/AudioTrack.cpp | 6 ++++++ 2 files changed, 13 insertions(+) diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h index 529f74eaba..1a199993a2 100644 --- a/include/media/AudioTrack.h +++ b/include/media/AudioTrack.h @@ -481,6 +481,7 @@ protected: // body of AudioTrackThread::threadLoop() bool processAudioBuffer(const sp& thread); + // caller must hold lock on mLock for all _l methods status_t createTrack_l(audio_stream_type_t streamType, uint32_t sampleRate, audio_format_t format, @@ -535,7 +536,13 @@ protected: audio_output_flags_t mFlags; int mSessionId; int mAuxEffectId; + + // When locking both mLock and mCblk->lock, must lock in this order to avoid deadlock: + // 1. mLock + // 2. mCblk->lock + // It is OK to lock only mCblk->lock. mutable Mutex mLock; + status_t mRestoreStatus; bool mIsTimed; int mPreviousPriority; // before start() diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp index 5348646474..1f4f3d0607 100644 --- a/media/libmedia/AudioTrack.cpp +++ b/media/libmedia/AudioTrack.cpp @@ -1122,8 +1122,14 @@ TimedAudioTrack::TimedAudioTrack() { status_t TimedAudioTrack::allocateTimedBuffer(size_t size, sp* buffer) { + AutoMutex lock(mLock); status_t result = UNKNOWN_ERROR; + // acquire a strong reference on the IMemory and IAudioTrack so that they cannot be destroyed + // while we are accessing the cblk + sp audioTrack = mAudioTrack; + sp iMem = mCblkMemory; + // If the track is not invalid already, try to allocate a buffer. alloc // fails indicating that the server is dead, flag the track as invalid so // we can attempt to restore in just a bit. -- 2.11.0