[Lldb-commits] [lldb] r361442 - [Target] Protect Processes' language runtimes map with a mutex

[Alex Langford via lldb-commits]

Author: xiaobai
Date: Wed May 22 16:01:18 2019
New Revision: 361442

URL: http://llvm.org/viewvc/llvm-project?rev=361442&view=rev
Log:
[Target] Protect Processes' language runtimes map with a mutex

Summary:
>From what I understand, it's possible for multiple threads to request
a specific language runtime (e.g. CPPLanguageRuntime). This leads to a data
race.

Reviewers: jingham, JDevlieghere, compnerd, clayborg

Differential Revision: https://reviews.llvm.org/D62169

Modified:
    lldb/trunk/include/lldb/Target/Process.h
    lldb/trunk/source/Target/Process.cpp

Modified: lldb/trunk/include/lldb/Target/Process.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Target/Process.h?rev=361442&r1=361441&r2=361442&view=diff
==============================================================================
--- lldb/trunk/include/lldb/Target/Process.h (original)
+++ lldb/trunk/include/lldb/Target/Process.h Wed May 22 16:01:18 2019
@@ -2701,6 +2701,7 @@ protected:
   bool m_should_detach; /// Should we detach if the process object goes away
                         /// with an explicit call to Kill or Detach?
   LanguageRuntimeCollection m_language_runtimes;
+  std::recursive_mutex m_language_runtimes_mutex;
   InstrumentationRuntimeCollection m_instrumentation_runtimes;
   std::unique_ptr<NextEventAction> m_next_event_action_up;
   std::vector<PreResumeCallbackAndBaton> m_pre_resume_actions;

Modified: lldb/trunk/source/Target/Process.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/Process.cpp?rev=361442&r1=361441&r2=361442&view=diff
==============================================================================
--- lldb/trunk/source/Target/Process.cpp (original)
+++ lldb/trunk/source/Target/Process.cpp Wed May 22 16:01:18 2019
@@ -660,7 +660,10 @@ void Process::Finalize() {
   m_image_tokens.clear();
   m_memory_cache.Clear();
   m_allocated_memory_cache.Clear();
-  m_language_runtimes.clear();
+  {
+    std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
+    m_language_runtimes.clear();
+  }
   m_instrumentation_runtimes.clear();
   m_next_event_action_up.reset();
   // Clear the last natural stop ID since it has a strong reference to this
@@ -1549,6 +1552,7 @@ LanguageRuntime *Process::GetLanguageRun
   if (m_finalizing)
     return nullptr;
 
+  std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
   LanguageRuntimeCollection::iterator pos;
   pos = m_language_runtimes.find(language);
   if (pos == m_language_runtimes.end() || (retry_if_null && !(*pos).second)) {
@@ -1562,6 +1566,7 @@ LanguageRuntime *Process::GetLanguageRun
 }
 
 CPPLanguageRuntime *Process::GetCPPLanguageRuntime(bool retry_if_null) {
+  std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
   LanguageRuntime *runtime =
       GetLanguageRuntime(eLanguageTypeC_plus_plus, retry_if_null);
   if (runtime != nullptr &&
@@ -1571,6 +1576,7 @@ CPPLanguageRuntime *Process::GetCPPLangu
 }
 
 ObjCLanguageRuntime *Process::GetObjCLanguageRuntime(bool retry_if_null) {
+  std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
   LanguageRuntime *runtime =
       GetLanguageRuntime(eLanguageTypeObjC, retry_if_null);
   if (runtime != nullptr && runtime->GetLanguageType() == eLanguageTypeObjC)
@@ -5604,7 +5610,10 @@ void Process::DidExec() {
   m_jit_loaders_up.reset();
   m_image_tokens.clear();
   m_allocated_memory_cache.Clear();
-  m_language_runtimes.clear();
+  {
+    std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
+    m_language_runtimes.clear();
+  }
   m_instrumentation_runtimes.clear();
   m_thread_list.DiscardThreadPlans();
   m_memory_cache.Clear(true);
@@ -5673,14 +5682,17 @@ void Process::ModulesDidLoad(ModuleList
   // Iterate over a copy of this language runtime list in case the language
   // runtime ModulesDidLoad somehow causes the language runtime to be
   // unloaded.
-  LanguageRuntimeCollection language_runtimes(m_language_runtimes);
-  for (const auto &pair : language_runtimes) {
-    // We must check language_runtime_sp to make sure it is not nullptr as we
-    // might cache the fact that we didn't have a language runtime for a
-    // language.
-    LanguageRuntimeSP language_runtime_sp = pair.second;
-    if (language_runtime_sp)
-      language_runtime_sp->ModulesDidLoad(module_list);
+  {
+    std::lock_guard<std::recursive_mutex> guard(m_language_runtimes_mutex);
+    LanguageRuntimeCollection language_runtimes(m_language_runtimes);
+    for (const auto &pair : language_runtimes) {
+      // We must check language_runtime_sp to make sure it is not nullptr as we
+      // might cache the fact that we didn't have a language runtime for a
+      // language.
+      LanguageRuntimeSP language_runtime_sp = pair.second;
+      if (language_runtime_sp)
+        language_runtime_sp->ModulesDidLoad(module_list);
+    }
   }
 
   // If we don't have an operating system plug-in, try to load one since