Revert^17 "Thread suspension cleanup and deadlock fix"

This reverts commit c6371b52df0da31acc174a3526274417b7aac0a7.

Reason for revert: This seems to have two remaining issues:

1. The second DCHECK in WaitForFlipFunction is not completely guaranteed to hold, resulting in failures for 658-fp-read-barrier.
2. WaitForSuspendBarrier seems to time out occasionally, possibly spuriously so. We fail when the futex times out once. That's probably incompatible with the app freezer. We should retry a few times.

Change-Id: Ibd8909b31083fc29e6d4f1fcde003d08eb16fc0a

1 files changed, 3 insertions, 25 deletions

diff --git a/runtime/gc/task_processor.cc b/runtime/gc/task_processor.cc
index e56dbd17c3..494cf2bb79 100644
--- a/runtime/gc/task_processor.cc
+++ b/runtime/gc/task_processor.cc
@@ -103,31 +103,9 @@ bool TaskProcessor::IsRunning() const {
   return is_running_;
 }
 
-bool TaskProcessor::WaitForThread(Thread* self) {
-  // Waiting for too little time here may cause us to fail to get stack traces, since we can't
-  // safely do so without identifying a HeapTaskDaemon to avoid it. Waiting too long could
-  // conceivably deadlock if we somehow try to get a stack trace on the way to starting the
-  // HeapTaskDaemon. Under normal circumstances. this should terminate immediately, since
-  // HeapTaskDaemon should normally be running.
-  constexpr int kTotalWaitMillis = 100;
-  for (int i = 0; i < kTotalWaitMillis; ++i) {
-    if (is_running_) {
-      return true;
-    }
-    cond_.TimedWait(self, 1 /*msecs*/, 0 /*nsecs*/);
-  }
-  LOG(ERROR) << "No identifiable HeapTaskDaemon; unsafe to get thread stacks.";
-  return false;
-}
-
-bool TaskProcessor::IsRunningThread(Thread* t, bool wait) {
-  Thread* self = Thread::Current();
-  MutexLock mu(self, lock_);
-  if (wait && !WaitForThread(self)) {
-    // If Wait failed, either answer may be correct; in our case, true is safer.
-    return true;
-  }
-  return running_thread_ == t;
+Thread* TaskProcessor::GetRunningThread() const {
+  MutexLock mu(Thread::Current(), lock_);
+  return running_thread_;
 }
 
 void TaskProcessor::Stop(Thread* self) {