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

1 files changed, 14 insertions, 0 deletions

diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
index 93fd93a71de..01ee7e482d1 100644
--- a/lldb/source/Target/Process.cpp
+++ b/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)