MDEV-17801: Galera test failure on galera_var_reject_queries

Problem was that controlling connection i.e. connection that
executed the query SET GLOBAL wsrep_reject_queries = ALL_KILL;
was also killed but server would try to send result from that
query to controlling connection resulting a assertion
mysqld: /home/jan/mysql/10.2-sst/include/mysql/psi/mysql_socket.h:738: inline_mysql_socket_send: Assertion `mysql_socket.fd != -1' failed.
as socket was closed when controlling connection was closed.

wsrep_close_client_connections()
	Do not close controlling connection and instead of
	wsrep_close_thread() we do now soft kill by THD::awake

wsrep_reject_queries_update()
	Call wsrep_close_client_connections using current thd.

1 files changed, 19 insertions, 3 deletions

diff --git a/sql/wsrep_mysqld.cc b/sql/wsrep_mysqld.cc
index c3f5dd1ce97..47aea6d3824 100644
--- a/sql/wsrep_mysqld.cc
+++ b/sql/wsrep_mysqld.cc
@@ -2229,7 +2229,7 @@ int wsrep_wait_committing_connections_close(int wait_time)
 }
 
 
-void wsrep_close_client_connections(my_bool wait_to_end)
+void wsrep_close_client_connections(my_bool wait_to_end, THD *except_caller_thd)
 {
   /*
     First signal all threads that it's time to die
@@ -2251,6 +2251,12 @@ void wsrep_close_client_connections(my_bool wait_to_end)
     if (!is_client_connection(tmp))
       continue;
 
+    if (tmp == except_caller_thd)
+    {
+      DBUG_ASSERT(is_client_connection(tmp));
+      continue;
+    }
+
     if (is_replaying_connection(tmp))
     {
       tmp->set_killed(KILL_CONNECTION);
@@ -2262,7 +2268,16 @@ void wsrep_close_client_connections(my_bool wait_to_end)
       continue;
 
     WSREP_DEBUG("closing connection %ld", tmp->thread_id);
-    wsrep_close_thread(tmp);
+
+    /*
+      instead of wsrep_close_thread() we do now  soft kill by THD::awake
+     */
+    mysql_mutex_lock(&tmp->LOCK_thd_data);
+
+    tmp->awake(KILL_CONNECTION);
+
+    mysql_mutex_unlock(&tmp->LOCK_thd_data);
+
   }
   mysql_mutex_unlock(&LOCK_thread_count);
 
@@ -2280,7 +2295,8 @@ void wsrep_close_client_connections(my_bool wait_to_end)
 #ifndef __bsdi__				// Bug in BSDI kernel
     if (is_client_connection(tmp) &&
         !abort_replicated(tmp)    &&
-	!is_replaying_connection(tmp))
+        !is_replaying_connection(tmp) &&
+        tmp != except_caller_thd)
     {
       WSREP_INFO("killing local connection: %ld",tmp->thread_id);
       close_connection(tmp,0);