MDEV-25883 Galera Cluster hangs while "DELETE FROM mysql.wsrep_cluster"

Using `innodb_thread_concurrency` will call `wsrep_thd_is_aborting` to
check WSREP thread state. This call should be protected by taking
`LOCK_thd_data` before entering function.
Applier and TOI threads should no be affected with usage of
`innodb_thread_concurrency` variable so returning before any checks.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

sql/service_wsrep.cc

@@ -269,12 +269,11 @@ extern "C" my_bool wsrep_thd_order_before(const THD *left, const THD *right)
 extern "C" my_bool wsrep_thd_is_aborting(const MYSQL_THD thd)
 {
   mysql_mutex_assert_owner(&thd->LOCK_thd_data);
-  if (thd != 0)
+
+  const wsrep::client_state& cs(thd->wsrep_cs());
+  const enum wsrep::transaction::state tx_state(cs.transaction().state());
+  switch (tx_state)
   {
-    const wsrep::client_state& cs(thd->wsrep_cs());
-    const enum wsrep::transaction::state tx_state(cs.transaction().state());
-    switch (tx_state)
-    {
     case wsrep::transaction::s_must_abort:
       return (cs.state() == wsrep::client_state::s_exec ||
               cs.state() == wsrep::client_state::s_result);
@@ -283,8 +282,8 @@ extern "C" my_bool wsrep_thd_is_aborting(const MYSQL_THD thd)
       return true;
     default:
       return false;
-    }
   }
+
   return false;
 }
 

storage/innobase/handler/ha_innodb.cc

@@ -1689,7 +1689,11 @@ static inline void innobase_srv_conc_enter_innodb(row_prebuilt_t *prebuilt)
 	trx_t* trx = prebuilt->trx;
 
 #ifdef WITH_WSREP
-	if (trx->is_wsrep() && wsrep_thd_is_BF(trx->mysql_thd, FALSE)) return;
+	if (global_system_variables.wsrep_on &&
+	    (wsrep_thd_is_applying(trx->mysql_thd)
+	     || wsrep_thd_is_toi(trx->mysql_thd))) {
+		return;
+	}
 #endif /* WITH_WSREP */
 
 	if (srv_thread_concurrency) {
@@ -1725,7 +1729,11 @@ static inline void innobase_srv_conc_exit_innodb(row_prebuilt_t *prebuilt)
 	trx_t* trx = prebuilt->trx;
 
 #ifdef WITH_WSREP
-	if (trx->is_wsrep() && wsrep_thd_is_BF(trx->mysql_thd, FALSE)) return;
+	if (global_system_variables.wsrep_on &&
+	    (wsrep_thd_is_applying(trx->mysql_thd)
+	     || wsrep_thd_is_toi(trx->mysql_thd))) {
+		return;
+	}
 #endif /* WITH_WSREP */
 
 	/* This is to avoid making an unnecessary function call. */

storage/innobase/srv/srv0conc.cc

@@ -118,7 +118,12 @@ srv_conc_enter_innodb_with_atomics(
 	for (;;) {
 		ulint	sleep_in_us;
 #ifdef WITH_WSREP
+		/* We need to take `thd->LOCK_thd_data` to check WSREP thread state */
+		if (trx->is_wsrep()) {
+			wsrep_thd_LOCK(trx->mysql_thd);
+		}
 		if (trx->is_wsrep() && wsrep_thd_is_aborting(trx->mysql_thd)) {
+			wsrep_thd_UNLOCK(trx->mysql_thd);
 			if (UNIV_UNLIKELY(wsrep_debug)) {
 				ib::info() <<
 					"srv_conc_enter due to MUST_ABORT";
@@ -126,6 +131,9 @@ srv_conc_enter_innodb_with_atomics(
 			srv_conc_force_enter_innodb(trx);
 			return;
 		}
+		if (trx->is_wsrep()) {
+			wsrep_thd_UNLOCK(trx->mysql_thd);
+		}
 #endif /* WITH_WSREP */
 
 		if (srv_thread_concurrency == 0) {