Race condition between XA COMMIT/ROLLBACK and disconnect

--source include/have_debug_sync.inc

# Note that this test is meaningful only with valgrind.

let $op= XA COMMIT 'xatest';

let $i= 2;

while ($i)

{

  connect con1, localhost, root;

  connect con2, localhost, root;

  connection con1;

  XA START 'xatest';

  XA END 'xatest';

  XA PREPARE 'xatest';

  connection con2;

  SET debug_sync='xa_after_search SIGNAL parked WAIT_FOR go';

  send_eval $op;

  connection default;

  SET debug_sync='now WAIT_FOR parked';

  disconnect con1;

  disable_query_log;

  echo # Waiting for thread to get deleted;

  while (`SELECT VARIABLE_VALUE!=2 FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME='max_used_connections'`)

  {

    real_sleep 0.1;

    FLUSH STATUS;

  }

  enable_query_log;

  SET debug_sync='now SIGNAL go';

  connection con2;

  --error ER_XAER_NOTA

  reap;

  disconnect con2;

  connection default;

  SET debug_sync='RESET';

  let $op= XA ROLLBACK 'xatest';

  dec $i;

}

diff --git a/sql/sql_class.cc b/sql/sql_class.cc

index 3071ba6..5f744d5 100644

--- a/sql/sql_class.cc

+++ b/sql/sql_class.cc

@@ -5312,6 +5312,7 @@ XID_STATE *xid_cache_search(THD *thd, XID *xid)

   if (element)

   {

     lf_hash_search_unpin(thd->xid_hash_pins);

+    DEBUG_SYNC(current_thd, "xa_after_search");

     return element->m_xid_state;

   }

   return 0;