[Lldb-commits] [lldb] eebda15 - [lldb] Guarded GDBRemoteCommunicationServerLLGS::m_saved_registers_map (#219431)

[via lldb-commits]

Author: Raphael Isemann
Date: 2026-09-17T15:00:26+01:00
New Revision: eebda156ed5330e03c603b018cec3f20b2d9a113

URL: https://github.com/llvm/llvm-project/commit/eebda156ed5330e03c603b018cec3f20b2d9a113
DIFF: https://github.com/llvm/llvm-project/commit/eebda156ed5330e03c603b018cec3f20b2d9a113.diff

LOG: [lldb] Guarded GDBRemoteCommunicationServerLLGS::m_saved_registers_map (#219431)

m_saved_registers_map and m_next_saved_registers_id were guarded by a
dedicated std::mutex. This replaces the manual locking logic with
`Guarded`.

This also fixes the missing lock in the Handle_QSaveRegisterState
assert which was previously a race condition.

Added: 
    

Modified: 
    lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
    lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
index 38aeb1bb40903..14e2a65c63aea 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -3624,13 +3624,13 @@ GDBRemoteCommunicationServerLLGS::Handle_QSaveRegisterState(
 
   // Allocate a new save id.
   const uint32_t save_id = GetNextSavedRegistersID();
-  assert((m_saved_registers_map.find(save_id) == m_saved_registers_map.end()) &&
-         "GetNextRegisterSaveID() returned an existing register save id");
 
   // Save the register data buffer under the save id.
   {
-    std::lock_guard<std::mutex> guard(m_saved_registers_mutex);
-    m_saved_registers_map[save_id] = register_data_sp;
+    auto saved_registers = m_saved_registers.Lock();
+    assert((saved_registers->map.find(save_id) == saved_registers->map.end()) &&
+           "GetNextRegisterSaveID() returned an existing register save id");
+    saved_registers->map[save_id] = register_data_sp;
   }
 
   // Write the response.
@@ -3674,11 +3674,11 @@ GDBRemoteCommunicationServerLLGS::Handle_QRestoreRegisterState(
   // Retrieve register state buffer, then remove from the list.
   DataBufferSP register_data_sp;
   {
-    std::lock_guard<std::mutex> guard(m_saved_registers_mutex);
+    auto saved_registers = m_saved_registers.Lock();
 
     // Find the register set buffer for the given save id.
-    auto it = m_saved_registers_map.find(save_id);
-    if (it == m_saved_registers_map.end()) {
+    auto it = saved_registers->map.find(save_id);
+    if (it == saved_registers->map.end()) {
       LLDB_LOG(log,
                "pid {0} does not have a register set save buffer for id {1}",
                m_current_process->GetID(), save_id);
@@ -3687,7 +3687,7 @@ GDBRemoteCommunicationServerLLGS::Handle_QRestoreRegisterState(
     register_data_sp = it->second;
 
     // Remove it from the map.
-    m_saved_registers_map.erase(it);
+    saved_registers->map.erase(it);
   }
 
   Status error = reg_context.WriteAllRegisterValues(register_data_sp);
@@ -4476,8 +4476,7 @@ lldb::tid_t GDBRemoteCommunicationServerLLGS::GetCurrentThreadID() const {
 }
 
 uint32_t GDBRemoteCommunicationServerLLGS::GetNextSavedRegistersID() {
-  std::lock_guard<std::mutex> guard(m_saved_registers_mutex);
-  return m_next_saved_registers_id++;
+  return m_saved_registers.Lock()->next_id++;
 }
 
 void GDBRemoteCommunicationServerLLGS::ClearProcessSpecificData() {

diff  --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
index f3f1bbc557244..873f24d10a627 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
@@ -16,6 +16,7 @@
 #include "lldb/Core/Communication.h"
 #include "lldb/Host/MainLoop.h"
 #include "lldb/Host/common/NativeProcessProtocol.h"
+#include "lldb/Utility/Locked.h"
 #include "lldb/Utility/RegisterValue.h"
 #include "lldb/lldb-private-forward.h"
 
@@ -133,9 +134,13 @@ class GDBRemoteCommunicationServerLLGS
   std::mutex m_pending_output_mutex;
 
   llvm::StringMap<std::unique_ptr<llvm::MemoryBuffer>> m_xfer_buffer_map;
-  std::mutex m_saved_registers_mutex;
-  std::unordered_map<uint32_t, lldb::DataBufferSP> m_saved_registers_map;
-  uint32_t m_next_saved_registers_id = 1;
+
+  struct SavedRegisters {
+    std::unordered_map<uint32_t, lldb::DataBufferSP> map;
+    uint32_t next_id = 1;
+  };
+  Guarded<SavedRegisters, std::mutex> m_saved_registers;
+
   bool m_thread_suffix_supported = false;
   bool m_address_space_suffix_supported = false;
   bool m_list_threads_in_stop_reply = false;