[Lldb-commits] [lldb] r169612 - /lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp

[Jim Ingham]

Author: jingham
Date: Fri Dec  7 11:42:15 2012
New Revision: 169612

URL: http://llvm.org/viewvc/llvm-project?rev=169612&view=rev
Log:
Take the Target API lock before letting the Python code start to work constructing threads, otherwise we will risk a lock-inversion deadlock between the thread list and the API mutex.

<rdar://problem/12554049>

Modified:
    lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp

Modified: lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp?rev=169612&r1=169611&r2=169612&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp (original)
+++ lldb/trunk/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp Fri Dec  7 11:42:15 2012
@@ -182,6 +182,12 @@
     
     LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
     
+    // First thing we have to do is get the API lock, and the run lock.  We're going to change the thread
+    // content of the process, and we're going to use python, which requires the API lock to do it.
+    // So get & hold that.  This is a recursive lock so we can grant it to any Python code called on the stack below us.
+    Target &target = m_process->GetTarget();
+    Mutex::Locker api_locker (target.GetAPIMutex());
+    
     if (log)
         log->Printf ("OperatingSystemPython::UpdateThreadList() fetching thread data from python for pid %" PRIu64, m_process->GetID());
 
@@ -251,6 +257,12 @@
     if (!m_interpreter || !m_python_object || !thread)
         return RegisterContextSP();
     
+    // First thing we have to do is get the API lock, and the run lock.  We're going to change the thread
+    // content of the process, and we're going to use python, which requires the API lock to do it.
+    // So get & hold that.  This is a recursive lock so we can grant it to any Python code called on the stack below us.
+    Target &target = m_process->GetTarget();
+    Mutex::Locker api_locker (target.GetAPIMutex());
+
     LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));
 
     if (reg_data_addr != LLDB_INVALID_ADDRESS)