Author: Vincent Belliard Date: 2024-04-12T10:48:41-04:00 New Revision: 5752e3196bc52fdac70e3650abc703570ff6209b
URL: https://github.com/llvm/llvm-project/commit/5752e3196bc52fdac70e3650abc703570ff6209b DIFF: https://github.com/llvm/llvm-project/commit/5752e3196bc52fdac70e3650abc703570ff6209b.diff LOG: [lldb] fix dead lock in TypeCategoryMap.cpp (#87540) FormatManager::GetCategoryForLanguage and FormatManager::GetCategory(can_create = true) can be called concurrently and they both take the TypeCategory::m_map_mutex and the FormatManager::m_language_categories_mutex but in reverse order. On one thread, GetCategoryForLanguage takes m_language_categories_mutex and then ends calling TypeCategoryMap::Get which takes m_map_mutex On another thread GetCategory calls TypeCategoryMap::Add which takes m_map_mutex and then calls FormatManager::Changed() which takes m_language_categories_mutex If both threads are running concurrently, we have a dead lock. The patch releases the m_map_mutex before calling Changed which avoids the dead lock. --------- Co-authored-by: Vincent Belliard <v-bu...@github.com> Added: Modified: lldb/source/DataFormatters/TypeCategoryMap.cpp Removed: ################################################################################ diff --git a/lldb/source/DataFormatters/TypeCategoryMap.cpp b/lldb/source/DataFormatters/TypeCategoryMap.cpp index fd76bab95826af..ce2cf369b5be53 100644 --- a/lldb/source/DataFormatters/TypeCategoryMap.cpp +++ b/lldb/source/DataFormatters/TypeCategoryMap.cpp @@ -25,19 +25,31 @@ TypeCategoryMap::TypeCategoryMap(IFormatChangeListener *lst) } void TypeCategoryMap::Add(KeyType name, const TypeCategoryImplSP &entry) { - std::lock_guard<std::recursive_mutex> guard(m_map_mutex); - m_map[name] = entry; + { + std::lock_guard<std::recursive_mutex> guard(m_map_mutex); + m_map[name] = entry; + } + // Release the mutex to avoid a potential deadlock between + // TypeCategoryMap::m_map_mutex and + // FormatManager::m_language_categories_mutex which can be acquired in + // reverse order when calling FormatManager::Changed. if (listener) listener->Changed(); } bool TypeCategoryMap::Delete(KeyType name) { - std::lock_guard<std::recursive_mutex> guard(m_map_mutex); - MapIterator iter = m_map.find(name); - if (iter == m_map.end()) - return false; - m_map.erase(name); - Disable(name); + { + std::lock_guard<std::recursive_mutex> guard(m_map_mutex); + MapIterator iter = m_map.find(name); + if (iter == m_map.end()) + return false; + m_map.erase(name); + Disable(name); + } + // Release the mutex to avoid a potential deadlock between + // TypeCategoryMap::m_map_mutex and + // FormatManager::m_language_categories_mutex which can be acquired in + // reverse order when calling FormatManager::Changed. if (listener) listener->Changed(); return true; @@ -123,9 +135,15 @@ void TypeCategoryMap::DisableAllCategories() { } void TypeCategoryMap::Clear() { - std::lock_guard<std::recursive_mutex> guard(m_map_mutex); - m_map.clear(); - m_active_categories.clear(); + { + std::lock_guard<std::recursive_mutex> guard(m_map_mutex); + m_map.clear(); + m_active_categories.clear(); + } + // Release the mutex to avoid a potential deadlock between + // TypeCategoryMap::m_map_mutex and + // FormatManager::m_language_categories_mutex which can be acquired in + // reverse order when calling FormatManager::Changed. if (listener) listener->Changed(); } _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
