Do not use peekIsCompleted in isQueueBlocked.

- This causes event tree update if virtual event is holding commands or
callbacks
- That causes race between other threads that may be updating the tree

Change-Id: Ic80a8b71ed1e1c1deab8af1bc64f8ce81c21de1b

runtime/command_queue/command_queue.cpp

@@ -164,7 +164,7 @@ bool CommandQueue::isQueueBlocked() {
     TakeOwnershipWrapper<CommandQueue> takeOwnershipWrapper(*this);
     //check if we have user event and if so, if it is in blocked state.
     if (this->virtualEvent) {
-        if (this->virtualEvent->peekIsCompleted()) {
+        if (this->virtualEvent->peekExecutionStatus() <= CL_COMPLETE) {
             UNRECOVERABLE_IF(this->virtualEvent == nullptr);
 
             if (this->virtualEvent->peekIsCompletedByTermination() == false) {

runtime/event/event.cpp

@@ -534,7 +534,11 @@ inline void Event::unblockEventBy(Event &event, uint32_t taskLevel, int32_t tran
     }
     DBG_LOG(EventsDebugEnable, "Event", this, "is unblocked by", &event);
 
-    this->taskLevel = taskLevel;
+    if (this->taskLevel == Event::eventNotReady) {
+        this->taskLevel = taskLevel;
+    } else {
+        this->taskLevel = std::max(this->taskLevel.load(), taskLevel);
+    }
 
     int32_t statusToPropagate = CL_SUBMITTED;
     if (peekIsCompletedByTermination(&blockerStatus)) {