commit 4d231dc0ee34380956c71cbe18a750e487a69601
author Eric Laurent <elaurent@google.com> Fri Mar 11 18:38:23 2016 -0800
committer Eric Laurent <elaurent@google.com> Mon Mar 14 15:50:19 2016 -0700
tree cee9e9b9ff4d3aa17bca9269622e9f40d470ff09
parent f56a02a5e7d1bfaeabf8b918e56bf49ea509bd42

audio: Fix race condition in AudioTrack underrun.

When audio flinger mixer removes an AudioTrack from the
active list in case of underrun, it is possible that the
client has written a full buffer just after the underrun detection and
is blocked waiting for more space to write. In this case, the client
will never detect the DISABLED flag and the track never be restarted.

Also implement missing DISABLE flag detection in server side audio tracks
(OutputTrack and PatchTrack).

bug: 27567768
Change-Id: I8d0753429d4113498258b1f61bd8ac5939a612f0

services/audioflinger/Threads.cpp

diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 96c5f59..f206e96 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -1113,7 +1113,7 @@
         status_t status;
         status = mPowerManager->updateWakeLockUids(mWakeLockToken, uids.size(), uids.array(),
                     true /* FIXME force oneway contrary to .aidl */);
-        ALOGV("acquireWakeLock_l() %s status %d", mThreadName, status);
+        ALOGV("updateWakeLockUids_l() %s status %d", mThreadName, status);
     }
 }
 
@@ -3961,7 +3961,7 @@
                     }
                     // indicate to client process that the track was disabled because of underrun;
                     // it will then automatically call start() when data is available
-                    android_atomic_or(CBLK_DISABLED, &track->mCblk->mFlags);
+                    track->disable();
                     // remove from active list, but state remains ACTIVE [confusing but true]
                     isActive = false;
                     break;
@@ -4322,7 +4322,7 @@
                     tracksToRemove->add(track);
                     // indicate to client process that the track was disabled because of underrun;
                     // it will then automatically call start() when data is available
-                    android_atomic_or(CBLK_DISABLED, &cblk->mFlags);
+                    track->disable();
                 // If one track is not ready, mark the mixer also not ready if:
                 //  - the mixer was ready during previous round OR
                 //  - no other track is ready
@@ -4869,7 +4869,7 @@
                     tracksToRemove->add(track);
                     // indicate to client process that the track was disabled because of underrun;
                     // it will then automatically call start() when data is available
-                    android_atomic_or(CBLK_DISABLED, &cblk->mFlags);
+                    track->disable();
                 } else if (last) {
                     ALOGW("pause because of UNDERRUN, framesReady = %zu,"
                             "minFrames = %u, mFormat = %#x",
@@ -5423,7 +5423,7 @@
                     tracksToRemove->add(track);
                     // indicate to client process that the track was disabled because of underrun;
                     // it will then automatically call start() when data is available
-                    android_atomic_or(CBLK_DISABLED, &cblk->mFlags);
+                    track->disable();
                 } else if (last){
                     mixerStatus = MIXER_TRACKS_ENABLED;
                 }