V4L2VDA: do not allocate input buffers in GPU child thread.

media/gpu/v4l2_video_decode_accelerator.cc

Index: media/gpu/v4l2_video_decode_accelerator.cc
diff --git a/media/gpu/v4l2_video_decode_accelerator.cc b/media/gpu/v4l2_video_decode_accelerator.cc
index 1d5cf8ee6cb11d9b4e7222f4b08d7089e7f2b47e..401aa1d1a94519eea914428b092029e6f084ae77 100644
--- a/media/gpu/v4l2_video_decode_accelerator.cc
+++ b/media/gpu/v4l2_video_decode_accelerator.cc
@@ -274,21 +274,10 @@ bool V4L2VideoDecodeAccelerator::Initialize(const Config& config,
   if (!SetupFormats())
     return false;
 
-  // Subscribe to the resolution change event.
-  struct v4l2_event_subscription sub;
-  memset(&sub, 0, sizeof(sub));
-  sub.type = V4L2_EVENT_SOURCE_CHANGE;
-  IOCTL_OR_ERROR_RETURN_FALSE(VIDIOC_SUBSCRIBE_EVENT, &sub);
-
   if (video_profile_ >= H264PROFILE_MIN && video_profile_ <= H264PROFILE_MAX) {
     decoder_h264_parser_.reset(new H264Parser());
   }
 
-  if (!CreateInputBuffers())
-    return false;
-
-  decoder_cmd_supported_ = IsDecoderCmdSupported();
-
   if (!decoder_thread_.Start()) {
     LOGF(ERROR) << "decoder thread failed to start";
     return false;
@@ -297,15 +286,36 @@ bool V4L2VideoDecodeAccelerator::Initialize(const Config& config,
   decoder_state_ = kInitialized;
   output_mode_ = config.output_mode;
 
-  // StartDevicePoll will NOTIFY_ERROR on failure, so IgnoreResult is fine here.
+  // InitializeTask will NOTIFY_ERROR on failure.
   decoder_thread_.task_runner()->PostTask(
-      FROM_HERE, base::Bind(base::IgnoreResult(
-                                &V4L2VideoDecodeAccelerator::StartDevicePoll),
+      FROM_HERE, base::Bind(&V4L2VideoDecodeAccelerator::InitializeTask,
                             base::Unretained(this)));
 
   return true;
 }
 
+void V4L2VideoDecodeAccelerator::InitializeTask() {
+  DVLOGF(3);
+  DCHECK(decoder_thread_.task_runner()->BelongsToCurrentThread());
+  DCHECK_EQ(decoder_state_, kUninitialized);

[kcwu, 2016/11/28 10:53:51]

You added line 286, then this DCHECK will fail.

[wuchengli, 2016/11/28 12:58:16]

Thanks for catching this.

+
+  // Subscribe to the resolution change event.
+  struct v4l2_event_subscription sub;
+  memset(&sub, 0, sizeof(sub));
+  sub.type = V4L2_EVENT_SOURCE_CHANGE;
+  IOCTL_OR_ERROR_RETURN(VIDIOC_SUBSCRIBE_EVENT, &sub);
+
+  if (!CreateInputBuffers()) {
+    NOTIFY_ERROR(PLATFORM_FAILURE);
+    return;
+  }
+
+  decoder_cmd_supported_ = IsDecoderCmdSupported();
+
+  if (!StartDevicePoll())
+    return;
+}
+
 void V4L2VideoDecodeAccelerator::Decode(
     const BitstreamBuffer& bitstream_buffer) {
   DVLOGF(1) << "input_id=" << bitstream_buffer.id()
@@ -2129,6 +2139,7 @@ gfx::Size V4L2VideoDecodeAccelerator::GetVisibleSize(
 
 bool V4L2VideoDecodeAccelerator::CreateInputBuffers() {
   DVLOGF(3);
+  DCHECK(decoder_thread_.task_runner()->BelongsToCurrentThread());
   // We always run this as we prepare to initialize.
   DCHECK_EQ(decoder_state_, kUninitialized);
   DCHECK(!input_streamon_);