MDEV-16401: Apply review comments to MDEV-16005

Do not hold LOCK_thd_data during my_error or WSREP_DEBUG. Similarly,
release LOCK_thd_data before close_thread_tables() call.

sql/sql_parse.cc

@@ -1271,9 +1271,9 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     if (thd->wsrep_conflict_state == ABORTED &&
         command != COM_STMT_CLOSE && command != COM_QUIT)
     {
+      mysql_mutex_unlock(&thd->LOCK_thd_data);
       my_error(ER_LOCK_DEADLOCK, MYF(0), "wsrep aborted transaction");
       WSREP_DEBUG("Deadlock error for: %s", thd->query());
-      mysql_mutex_unlock(&thd->LOCK_thd_data);
       thd->reset_killed();
       thd->mysys_var->abort     = 0;
       thd->wsrep_conflict_state = NO_CONFLICT;
@@ -7290,6 +7290,7 @@ static void wsrep_mysql_parse(THD *thd, char *rawbuf, uint length,
             thd->lex->sql_command != SQLCOM_SELECT  &&
             (thd->wsrep_retry_counter < thd->variables.wsrep_retry_autocommit))
         {
+          mysql_mutex_unlock(&thd->LOCK_thd_data);
           WSREP_DEBUG("wsrep retrying AC query: %s",
                       (thd->query()) ? thd->query() : "void");
 
@@ -7297,27 +7298,36 @@ static void wsrep_mysql_parse(THD *thd, char *rawbuf, uint length,
 	  MYSQL_END_STATEMENT(thd->m_statement_psi, thd->get_stmt_da());
 	  thd->m_statement_psi= NULL;
           thd->m_digest= NULL;
+	  // Released thd->LOCK_thd_data above as below could end up
+	  // close_thread_tables()/close_open_tables()/close_thread_table()/mysql_mutex_lock(&thd->LOCK_thd_data)
           close_thread_tables(thd);
 
+	  mysql_mutex_lock(&thd->LOCK_thd_data);
           thd->wsrep_conflict_state= RETRY_AUTOCOMMIT;
           thd->wsrep_retry_counter++;            // grow
           wsrep_copy_query(thd);
           thd->set_time();
           parser_state->reset(rawbuf, length);
+          mysql_mutex_unlock(&thd->LOCK_thd_data);
         }
         else
         {
+          mysql_mutex_unlock(&thd->LOCK_thd_data);
+	  // This does dirty read to wsrep variables but it is only a debug code
           WSREP_DEBUG("%s, thd: %lu is_AC: %d, retry: %lu - %lu SQL: %s",
                       (thd->wsrep_conflict_state == ABORTED) ?
                       "BF Aborted" : "cert failure",
                       thd->thread_id, is_autocommit, thd->wsrep_retry_counter,
                       thd->variables.wsrep_retry_autocommit, thd->query());
           my_error(ER_LOCK_DEADLOCK, MYF(0), "wsrep aborted transaction");
+
+	  mysql_mutex_lock(&thd->LOCK_thd_data);
           thd->wsrep_conflict_state= NO_CONFLICT;
           if (thd->wsrep_conflict_state != REPLAYING)
             thd->wsrep_retry_counter= 0;             //  reset
-        }
 	  mysql_mutex_unlock(&thd->LOCK_thd_data);
+        }
+
         thd->reset_killed();
       }
       else
@@ -7353,6 +7363,7 @@ static void wsrep_mysql_parse(THD *thd, char *rawbuf, uint length,
 #endif /* WITH_WSREP */
 }
 
+
 /*
   When you modify mysql_parse(), you may need to modify
   mysql_test_parse_for_slave() in this same file.