MDEV-22458: Server with WSREP hangs after INSERT, wrong usage of mutex 'LOCK_thd_data' and 'share->intern_lock' / 'lock->mutex'

Add `find_thread_by_id_with_thd_data_lock` which will be used only when killing thread.
This version needs to take `thd->LOCK_thd_data` lock.

3 files changed, 57 insertions, 2 deletions

diff --git a/mysql-test/suite/galera/r/MDEV-22458.result b/mysql-test/suite/galera/r/MDEV-22458.result
new file mode 100644
index 00000000000..d1f9d94bd1c
--- /dev/null
+++ b/mysql-test/suite/galera/r/MDEV-22458.result
@@ -0,0 +1,10 @@
+connection node_2;
+connection node_1;
+CREATE TABLE t1 (a INT);
+connect  con1,localhost,root,,test;
+INSERT INTO t1 VALUES (1),(2),(3),(4);
+SHOW EXPLAIN FOR $con1;
+ERROR HY000: Target is not running an EXPLAINable command
+connection con1;
+INSERT INTO t1 VALUES (5),(6),(7),(8);
+DROP TABLE t1;
diff --git a/mysql-test/suite/galera/t/MDEV-22458.test b/mysql-test/suite/galera/t/MDEV-22458.test
new file mode 100644
index 00000000000..8f9ba1bb107
--- /dev/null
+++ b/mysql-test/suite/galera/t/MDEV-22458.test
@@ -0,0 +1,21 @@
+# MDEV-22458
+# 
+# When running SHOW command, thread lock `LOCK_thd_data` should not be taken.
+# Lock will be taken only when we are killing thread
+#
+
+--source include/galera_cluster.inc
+CREATE TABLE t1 (a INT);
+
+--connect (con1,localhost,root,,test)
+--let $con1 = `SELECT CONNECTION_ID()`
+
+INSERT INTO t1 VALUES (1),(2),(3),(4);
+
+--error ER_TARGET_NOT_EXPLAINABLE
+EVALP SHOW EXPLAIN FOR $con1;
+
+--connection con1
+INSERT INTO t1 VALUES (5),(6),(7),(8);
+
+DROP TABLE t1;
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 3c5c52e2aa1..4596915b096 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -9019,7 +9019,6 @@ my_bool find_thread_callback(THD *thd, find_thread_callback_arg *arg)
   if (thd->get_command() != COM_DAEMON &&
       arg->id == (arg->query_id ? thd->query_id : (longlong) thd->thread_id))
   {
-    if (WSREP(thd)) mysql_mutex_lock(&thd->LOCK_thd_data);
     mysql_mutex_lock(&thd->LOCK_thd_kill);    // Lock from delete
     arg->thd= thd;
     return 1;
@@ -9035,6 +9034,26 @@ THD *find_thread_by_id(longlong id, bool query_id)
   return arg.thd;
 }
 
+#ifdef WITH_WSREP
+my_bool find_thread_with_thd_data_lock_callback(THD *thd, find_thread_callback_arg *arg)
+{
+  if (thd->get_command() != COM_DAEMON &&
+      arg->id == (arg->query_id ? thd->query_id : (longlong) thd->thread_id))
+  {
+    if (WSREP(thd)) mysql_mutex_lock(&thd->LOCK_thd_data);
+    mysql_mutex_lock(&thd->LOCK_thd_kill);    // Lock from delete
+    arg->thd= thd;
+    return 1;
+  }
+  return 0;
+}
+THD *find_thread_by_id_with_thd_data_lock(longlong id, bool query_id)
+{
+  find_thread_callback_arg arg(id, query_id);
+  server_threads.iterate(find_thread_with_thd_data_lock_callback, &arg);
+  return arg.thd;
+}
+#endif
 
 /**
   kill one thread.
@@ -9052,7 +9071,11 @@ kill_one_thread(THD *thd, longlong id, killed_state kill_signal, killed_type typ
   uint error= (type == KILL_TYPE_QUERY ? ER_NO_SUCH_QUERY : ER_NO_SUCH_THREAD);
   DBUG_ENTER("kill_one_thread");
   DBUG_PRINT("enter", ("id: %lld  signal: %u", id, (uint) kill_signal));
+#ifdef WITH_WSREP
+  if (id && (tmp= find_thread_by_id_with_thd_data_lock(id, type == KILL_TYPE_QUERY)))
+#else
   if (id && (tmp= find_thread_by_id(id, type == KILL_TYPE_QUERY)))
+#endif
   {
     /*
       If we're SUPER, we can KILL anything, including system-threads.
@@ -9106,8 +9129,9 @@ kill_one_thread(THD *thd, longlong id, killed_state kill_signal, killed_type typ
     else
       error= (type == KILL_TYPE_QUERY ? ER_KILL_QUERY_DENIED_ERROR :
                                         ER_KILL_DENIED_ERROR);
-
+#ifdef WITH_WSREP
     if (WSREP(tmp)) mysql_mutex_unlock(&tmp->LOCK_thd_data);
+#endif
     mysql_mutex_unlock(&tmp->LOCK_thd_kill);
   }
   DBUG_PRINT("exit", ("%d", error));