Adding support for setting thread stop state when a process stops.

This re-submission of this patch fixes a problem where the code sometimes caused a deadlock.  The Process::SetPrivateState method was locking the Process::m_private_state variable and then later calling ThreadList::DidStop, which locks the ThreadList mutex.  Other methods in ThreadList which were being called from other threads lock the ThreadList mutex and then call Process::GetPrivateState which locks the Process::m_private_state mutex.  To avoid deadlocks, Process::SetPrivateState now locks the ThreadList mutex before locking the Process::m_private_state mutex.

llvm-svn: 181609

lldb/include/lldb/Target/Thread.h

@@ -277,6 +277,10 @@ public:
     virtual void
     DidResume ();
 
+    // This notifies the thread when a private stop occurs.
+    virtual void
+    DidStop ();
+
     virtual void
     RefreshStateAfterStop() = 0;
 

lldb/include/lldb/Target/ThreadList.h

@@ -119,6 +119,9 @@ public:
     void
     DidResume ();
 
+    void
+    DidStop ();
+
     void
     DiscardThreadPlans();
 

lldb/source/Target/Process.cpp

@@ -1699,6 +1699,7 @@ Process::SetPrivateState (StateType new_state)
     if (log)
         log->Printf("Process::SetPrivateState (%s)", StateAsCString(new_state));
 
+    Mutex::Locker thread_locker(m_thread_list.GetMutex());
     Mutex::Locker locker(m_private_state.GetMutex());
 
     const StateType old_state = m_private_state.GetValueNoLock ();
@@ -1722,6 +1723,19 @@ Process::SetPrivateState (StateType new_state)
         m_private_state.SetValueNoLock (new_state);
         if (StateIsStoppedState(new_state, false))
         {
+            // Note, this currently assumes that all threads in the list
+            // stop when the process stops.  In the future we will want to
+            // support a debugging model where some threads continue to run
+            // while others are stopped.  When that happens we will either need
+            // a way for the thread list to identify which threads are stopping
+            // or create a special thread list containing only threads which
+            // actually stopped.
+            //
+            // The process plugin is responsible for managing the actual
+            // behavior of the threads and should have stopped any threads
+            // that are going to stop before we get here.
+            m_thread_list.DidStop();
+
             m_mod_id.BumpStopID();
             m_memory_cache.Clear();
             if (log)

lldb/source/Target/Thread.cpp

@@ -658,6 +658,12 @@ Thread::DidResume ()
     SetResumeSignal (LLDB_INVALID_SIGNAL_NUMBER);
 }
 
+void
+Thread::DidStop ()
+{
+    SetState (eStateStopped);
+}
+
 bool
 Thread::ShouldStop (Event* event_ptr)
 {

lldb/source/Target/ThreadList.cpp

@@ -11,6 +11,7 @@
 #include <algorithm>
 
 #include "lldb/Core/Log.h"
+#include "lldb/Core/State.h"
 #include "lldb/Target/RegisterContext.h"
 #include "lldb/Target/ThreadList.h"
 #include "lldb/Target/Thread.h"
@@ -643,6 +644,27 @@ ThreadList::DidResume ()
     }
 }
 
+void
+ThreadList::DidStop ()
+{
+    Mutex::Locker locker(GetMutex());
+    collection::iterator pos, end = m_threads.end();
+    for (pos = m_threads.begin(); pos != end; ++pos)
+    {
+        // Notify threads that the process just stopped.
+        // Note, this currently assumes that all threads in the list
+        // stop when the process stops.  In the future we will want to support
+        // a debugging model where some threads continue to run while others
+        // are stopped.  We either need to handle that somehow here or
+        // create a special thread list containing only threads which will
+        // stop in the code that calls this method (currently
+        // Process::SetPrivateState).
+        ThreadSP thread_sp(*pos);
+        if (StateIsRunningState(thread_sp->GetState()))
+            thread_sp->DidStop ();
+    }
+}
+
 ThreadSP
 ThreadList::GetSelectedThread ()
 {

lldb/test/functionalities/thread/state/TestThreadStates.py

@@ -14,14 +14,12 @@ class StopThreadsTestCase(TestBase):
 
     @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
     @dsym_test
-    @unittest2.expectedFailure("PR-15824") # thread states not properly maintained
     def test_state_after_breakpoint_with_dsym(self):
         """Test thread state after breakpoint."""
         self.buildDsym()
         self.thread_state_after_breakpoint_test()
 
     @dwarf_test
-    @unittest2.expectedFailure("PR-15824") # thread states not properly maintained
     def test_state_after_breakpoint_with_dwarf(self):
         """Test thread state after breakpoint."""
         self.buildDwarf()