[Lldb-commits] [PATCH] Don't resume when creating new threads if there is a pending thread stop.

[Oleksiy Vyalov]

================
Comment at: source/Plugins/Process/Linux/NativeProcessLinux.cpp:2135
@@ -2135,8 +2134,3 @@
                 NotifyThreadCreateStopped (tid);
-                m_coordinator_up->RequestThreadResume (tid,
-                                                       [=](lldb::tid_t tid_to_resume, bool supress_signal)
-                                                       {
-                                                           std::static_pointer_cast<NativeThreadLinux> (new_thread_sp)->SetRunning ();
-                                                           return Resume (tid_to_resume, LLDB_INVALID_SIGNAL_NUMBER);
-                                                       },
-                                                       CoordinatorErrorHandler);
+                if (m_coordinator_up->IsPendingThreadStop())
+                {
----------------
It looks to me there might be a race  - if you'll be calling this method when TSC inside of ProcessEvent call between RequestStopOnAllRunningThreads() and  coordinator.SetPendingNotification() a thread might be mistakenly resumed. So, you may to synchronize  IsPendingThreadStop with ProcessEvent().

Can we make RequestThreadResume take additional boolean argument to check for pending stopped state  - so, effectively move this conditional logic into EventRequestResume?

================
Comment at: source/Plugins/Process/Linux/ThreadStateCoordinator.h:152
@@ +151,3 @@
+        bool
+        IsPendingThreadStop() {
+            return GetPendingThreadStopNotification();
----------------
This method should be synchronized - GetPendingThreadStopNotification() is used now only within TSC thread and that's why doesn't need synchronization. But if you're going to call it from another thread GetPendingThreadStopNotification should be protected by mutex.

http://reviews.llvm.org/D8906

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