Connection: Fix deadlock in debug mode (#9550)

diff --git a/src/network/connection.cpp b/src/network/connection.cpp
index a99e5b145229edb3d8aac18a18e4553edda0afc8..36124ce3c0d5c2e1adfc6b5a1711ac1010e05060 100644 (file)
--- a/src/network/connection.cpp
+++ b/src/network/connection.cpp
@@ -41,17 +41,23 @@ namespace con
 /* defines used for debugging and profiling                                   */
 /******************************************************************************/
 #ifdef NDEBUG
-#define LOG(a) a
-#define PROFILE(a)
+       #define LOG(a) a
+       #define PROFILE(a)
 #else
-/* this mutex is used to achieve log message consistency */
-std::mutex log_message_mutex;
-#define LOG(a)                                                                 \
-       {                                                                          \
-       MutexAutoLock loglock(log_message_mutex);                                 \
-       a;                                                                         \
-       }
-#define PROFILE(a) a
+       #if 0
+       /* this mutex is used to achieve log message consistency */
+       std::mutex log_message_mutex;
+       #define LOG(a)                                                                 \
+               {                                                                          \
+               MutexAutoLock loglock(log_message_mutex);                                 \
+               a;                                                                         \
+               }
+       #else
+       // Prevent deadlocks until a solution is found after 5.2.0 (TODO)
+       #define LOG(a) a
+       #endif
+
+       #define PROFILE(a) a
 #endif
 
 #define PING_TIMEOUT 5.0
@@ -1073,6 +1079,10 @@ bool UDPPeer::processReliableSendCommand(
                FATAL_ERROR_IF(!successfully_put_back_sequence_number, "error");
        }
 
+       // DO NOT REMOVE n_queued! It avoids a deadlock of async locked
+       // 'log_message_mutex' and 'm_list_mutex'.
+       u32 n_queued = channels[c.channelnum].outgoing_reliables_sent.size();
+
        LOG(dout_con<<m_connection->getDesc()
                        << " Windowsize exceeded on reliable sending "
                        << c.data.getSize() << " bytes"
@@ -1081,7 +1091,7 @@ bool UDPPeer::processReliableSendCommand(
                        << std::endl << "\t\tgot at most            : "
                        << packets_available << " packets"
                        << std::endl << "\t\tpackets queued         : "
-                       << channels[c.channelnum].outgoing_reliables_sent.size()
+                       << n_queued
                        << std::endl);
 
        return false;