There are several places where multiple threads are accessing the same
variables simultaneously without any kind of protection. I propose using
std::atomic<> to make it safer. I did a special build of lldb, using the
google tool 'thread sanitizer' which identified many cases of multiple threads
accessing the same memory. std::atomic is low overhead and does not use any
locks for simple types such as int/bool.
http://reviews.llvm.org/D5302
Files:
include/lldb/Core/Communication.h
include/lldb/Core/ConnectionFileDescriptor.h
include/lldb/Target/Process.h
source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
source/lldb-log.cpp
Index: include/lldb/Core/Communication.h
===================================================================
--- include/lldb/Core/Communication.h
+++ include/lldb/Core/Communication.h
@@ -352,7 +352,7 @@
protected:
lldb::ConnectionSP m_connection_sp; ///< The connection that is current in use by this communications class.
HostThread m_read_thread; ///< The read thread handle in case we need to cancel the thread.
- bool m_read_thread_enabled;
+ std::atomic<bool> m_read_thread_enabled;
std::string m_bytes; ///< A buffer to cache bytes read in the ReadThread function.
Mutex m_bytes_mutex; ///< A mutex to protect multi-threaded access to the cached bytes.
Mutex m_write_mutex; ///< Don't let multiple threads write at the same time...
Index: include/lldb/Core/ConnectionFileDescriptor.h
===================================================================
--- include/lldb/Core/ConnectionFileDescriptor.h
+++ include/lldb/Core/ConnectionFileDescriptor.h
@@ -106,8 +106,8 @@
Pipe m_pipe;
Mutex m_mutex;
- bool m_shutting_down; // This marks that we are shutting down so if we get woken up from
- // BytesAvailable to disconnect, we won't try to read again.
+ std::atomic<bool> m_shutting_down; // This marks that we are shutting down so if we get woken up from
+ // BytesAvailable to disconnect, we won't try to read again.
bool m_waiting_for_accept;
private:
DISALLOW_COPY_AND_ASSIGN (ConnectionFileDescriptor);
Index: include/lldb/Target/Process.h
===================================================================
--- include/lldb/Target/Process.h
+++ include/lldb/Target/Process.h
@@ -3048,7 +3048,7 @@
uint32_t m_process_unique_id; ///< Each lldb_private::Process class that is created gets a unique integer ID that increments with each new instance
uint32_t m_thread_index_id; ///< Each thread is created with a 1 based index that won't get re-used.
std::map<uint64_t, uint32_t> m_thread_id_to_index_id_map;
- int m_exit_status; ///< The exit status of the process, or -1 if not set.
+ std::atomic<int> m_exit_status; ///< The exit status of the process, or -1 if not set.
std::string m_exit_string; ///< A textual description of why a process exited.
Mutex m_thread_mutex;
ThreadList m_thread_list_real; ///< The threads for this process as are known to the protocol we are debugging with
Index: source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
===================================================================
--- source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
+++ source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
@@ -328,7 +328,7 @@
lldb_private::Flags m_flags; // Process specific flags (see eFlags enums)
GDBRemoteCommunicationClient m_gdb_comm;
- lldb::pid_t m_debugserver_pid;
+ std::atomic<lldb::pid_t> m_debugserver_pid;
StringExtractorGDBRemote m_last_stop_packet;
lldb_private::Mutex m_last_stop_packet_mutex;
GDBRemoteDynamicRegisterInfo m_register_info;
Index: source/lldb-log.cpp
===================================================================
--- source/lldb-log.cpp
+++ source/lldb-log.cpp
@@ -27,7 +27,7 @@
// that will construct the static g_lob_sp the first time this function is
// called.
-static bool g_log_enabled = false;
+static std::atomic<bool> g_log_enabled {false};
static Log * g_log = NULL;
static Log *
GetLog ()
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