[Lldb-commits] [lldb] 0ddcd20 - Don't hold the Target's ModuleListLock over running LoadScriptingResourceInTarget (#138216)

[via lldb-commits]

Author: jimingham
Date: 2025-05-02T11:51:21-07:00
New Revision: 0ddcd209ddc8956eb52d642937a4397c6b08449c

URL: https://github.com/llvm/llvm-project/commit/0ddcd209ddc8956eb52d642937a4397c6b08449c
DIFF: https://github.com/llvm/llvm-project/commit/0ddcd209ddc8956eb52d642937a4397c6b08449c.diff

LOG: Don't hold the Target's ModuleListLock over running LoadScriptingResourceInTarget (#138216)

That calls an unknown amount of Python code, and can do quite a bit of
work - especially if people do things like launch scripted processes in
this script affordance. Doing that while holding a major lock like the
ModuleList lock is asking for trouble.

I tried to make a test that would actually stall without this, but I
couldn't come up with anything that reliably failed. You always have to
get pretty unlucky.

Added: 
    

Modified: 
    lldb/source/Core/ModuleList.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Core/ModuleList.cpp b/lldb/source/Core/ModuleList.cpp
index 6052cc151744d..d5ddf6e846112 100644
--- a/lldb/source/Core/ModuleList.cpp
+++ b/lldb/source/Core/ModuleList.cpp
@@ -1046,8 +1046,14 @@ bool ModuleList::LoadScriptingResourcesInTarget(Target *target,
                                                 bool continue_on_error) {
   if (!target)
     return false;
-  std::lock_guard<std::recursive_mutex> guard(m_modules_mutex);
-  for (auto module : m_modules) {
+  m_modules_mutex.lock();
+  // Don't hold the module list mutex while loading the scripting resources,
+  // The initializer might do any amount of work, and having that happen while
+  // the module list is held is asking for A/B locking problems.
+  const ModuleList tmp_module_list(*this);
+  m_modules_mutex.unlock();
+
+  for (auto module : tmp_module_list.ModulesNoLocking()) {
     if (module) {
       Status error;
       if (!module->LoadScriptingResourceInTarget(target, error,