[SYCL] Fix unsafe command usage (#5789)

Command may be destroyed by cleanup process in another thread

Signed-off-by: Tikhomirova, Kseniya <[email protected]>

Author: KseniyaTikhomirova

sycl/source/detail/scheduler/scheduler.cpp

@@ -291,18 +291,18 @@ void Scheduler::removeMemoryObject(detail::SYCLMemObjI *MemObj) {
 
 EventImplPtr Scheduler::addHostAccessor(Requirement *Req) {
   std::vector<Command *> AuxiliaryCmds;
-  Command *NewCmd = nullptr;
+  EventImplPtr NewCmdEvent = nullptr;
 
   {
     WriteLockT Lock(MGraphLock, std::defer_lock);
     acquireWriteLock(Lock);
 
-    NewCmd = MGraphBuilder.addHostAccessor(Req, AuxiliaryCmds);
+    Command *NewCmd = MGraphBuilder.addHostAccessor(Req, AuxiliaryCmds);
+    if (!NewCmd)
+      return nullptr;
+    NewCmdEvent = NewCmd->getEvent();
   }
 
-  if (!NewCmd)
-    return nullptr;
-
   std::vector<Command *> ToCleanUp;
   {
     ReadLockT ReadLock(MGraphLock);
@@ -315,14 +315,15 @@ EventImplPtr Scheduler::addHostAccessor(Requirement *Req) {
         throw runtime_error("Enqueue process failed.", PI_INVALID_OPERATION);
     }
 
-    Enqueued = GraphProcessor::enqueueCommand(NewCmd, Res, ToCleanUp);
-    if (!Enqueued && EnqueueResultT::SyclEnqueueFailed == Res.MResult)
-      throw runtime_error("Enqueue process failed.", PI_INVALID_OPERATION);
+    if (Command *NewCmd = static_cast<Command *>(NewCmdEvent->getCommand())) {
+      Enqueued = GraphProcessor::enqueueCommand(NewCmd, Res, ToCleanUp);
+      if (!Enqueued && EnqueueResultT::SyclEnqueueFailed == Res.MResult)
+        throw runtime_error("Enqueue process failed.", PI_INVALID_OPERATION);
+    }
   }
 
-  EventImplPtr NewEvent = NewCmd->getEvent();
   cleanupCommands(ToCleanUp);
-  return NewEvent;
+  return NewCmdEvent;
 }
 
 void Scheduler::releaseHostAccessor(Requirement *Req) {