updating @@wsrep_cluster_address deadlocks

wsrep_cluster_address_update() causes LOCK_wsrep_slave_threads
to be locked under LOCK_wsrep_cluster_config, while normally
the order should be the opposite.

Fix: don't protect @@wsrep_cluster_address value with the
LOCK_wsrep_cluster_config, LOCK_global_system_variables is enough.

Only protect wsrep reinitialization with the LOCK_wsrep_cluster_config.
And make it use a local copy of the global @@wsrep_cluster_address.

Also, introduce a helper function that checks whether
wsrep_cluster_address is set and also asserts that it can be safely
read by the caller.

1 files changed, 4 insertions, 9 deletions

diff --git a/sql/wsrep_mysqld.cc b/sql/wsrep_mysqld.cc
index 8e68f7229eb..fc54c7f6ec4 100644
--- a/sql/wsrep_mysqld.cc
+++ b/sql/wsrep_mysqld.cc
@@ -878,13 +878,13 @@ void wsrep_init_startup (bool sst_first)
   if (!strcmp(wsrep_provider, WSREP_NONE)) return;
 
   /* Skip replication start if no cluster address */
-  if (!wsrep_cluster_address || wsrep_cluster_address[0] == 0) return;
+  if (!wsrep_cluster_address_exists()) return;
 
   /*
     Read value of wsrep_new_cluster before wsrep_start_replication(),
     the value is reset to FALSE inside wsrep_start_replication.
   */
-  if (!wsrep_start_replication()) unireg_abort(1);
+  if (!wsrep_start_replication(wsrep_cluster_address)) unireg_abort(1);
 
   wsrep_create_rollbacker();
   wsrep_create_appliers(1);
@@ -1034,7 +1034,7 @@ void wsrep_shutdown_replication()
   my_pthread_setspecific_ptr(THR_THD, NULL);
 }
 
-bool wsrep_start_replication()
+bool wsrep_start_replication(const char *wsrep_cluster_address)
 {
   int rcode;
   WSREP_DEBUG("wsrep_start_replication");
@@ -1049,12 +1049,7 @@ bool wsrep_start_replication()
     return true;
   }
 
-  if (!wsrep_cluster_address || wsrep_cluster_address[0]== 0)
-  {
-    // if provider is non-trivial, but no address is specified, wait for address
-    WSREP_DEBUG("wsrep_start_replication exit due to empty address");
-    return true;
-  }
+  DBUG_ASSERT(wsrep_cluster_address[0]);
 
   bool const bootstrap(TRUE == wsrep_new_cluster);
   wsrep_new_cluster= FALSE;