Possible deadlock in PCM audio Start() method...

media/audio/win/waveout_output_win.cc

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <windows.h>
 #include <mmsystem.h>
 #pragma comment(lib, "winmm.lib")
 
 #include "media/audio/win/waveout_output_win.h"
 
 #include "base/basictypes.h"
@@ skipping 134 matching lines @@
   if (state_ != PCMA_READY)
     return;
   callback_ = callback;
   state_ = PCMA_PLAYING;
   WAVEHDR* buffer = buffer_;
   for (int ix = 0; ix != kNumBuffers; ++ix) {
     QueueNextPacket(buffer);  // Read more data.
     buffer = GetNextBuffer(buffer);
   }
   buffer = buffer_;
-
-  // Send the buffers to the audio driver.
+  MMRESULT result = ::waveOutPause(waveout_);
+  if (result != MMSYSERR_NOERROR) {
+    HandleError(result);
+    return;
+  }
+  // Send the buffers to the audio driver. Note that the device is paused
+  // so we avoid entering the callback method while still here.
   for (int ix = 0; ix != kNumBuffers; ++ix) {
-    MMRESULT result = ::waveOutWrite(waveout_, buffer, sizeof(WAVEHDR));
+    result = ::waveOutWrite(waveout_, buffer, sizeof(WAVEHDR));
     if (result != MMSYSERR_NOERROR) {
       HandleError(result);
       break;
     }
     buffer = GetNextBuffer(buffer);
   }
+  result = ::waveOutRestart(waveout_);
+  if (result != MMSYSERR_NOERROR) {
+    HandleError(result);
+    return;
+  }
 }
 
 // Stopping is tricky. First, no buffer should be locked by the audio driver
 // or else the waveOutReset will deadlock and secondly, the callback should not
 // be inside the AudioSource's OnMoreData because waveOutReset() forcefully
 // kills the callback thread.
 void PCMWaveOutAudioOutputStream::Stop() {
   if (state_ != PCMA_PLAYING)
     return;
   state_ = PCMA_STOPPING;
@@ skipping 110 matching lines @@
     if (result != MMSYSERR_NOERROR)
       obj->HandleError(result);
 
   } else if (msg == WOM_CLOSE) {
     // We can be closed before calling Start, so it is possible to have a
     // null callback at this point.
     if (obj->callback_)
       obj->callback_->OnClose(obj);
   }
 }