Merge 10.3 into 10.4

1 files changed, 48 insertions, 25 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index ceb8dc1ade8..9d1588a7ce1 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -1,6 +1,6 @@
 /*
    Copyright (c) 2000, 2015, Oracle and/or its affiliates.
-   Copyright (c) 2008, 2020, MariaDB Corporation.
+   Copyright (c) 2008, 2021, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1512,16 +1512,29 @@ void THD::reset_db(const LEX_CSTRING *new_db)
 
 /* Do operations that may take a long time */
 
-void THD::cleanup(void)
+void THD::cleanup(bool have_mutex)
 {
   DBUG_ENTER("THD::cleanup");
   DBUG_ASSERT(cleanup_done == 0);
 
-  set_killed(KILL_CONNECTION);
+  if (have_mutex)
+    set_killed_no_mutex(KILL_CONNECTION,0,0);
+  else
+    set_killed(KILL_CONNECTION);
 #ifdef WITH_WSREP
   if (wsrep_cs().state() != wsrep::client_state::s_none)
   {
-    wsrep_cs().cleanup();
+    if (have_mutex)
+    {
+      mysql_mutex_assert_owner(static_cast<mysql_mutex_t*>
+                               (m_wsrep_mutex.native()));
+      // Below wsrep-lib function will not acquire any mutexes
+      wsrep::unique_lock<wsrep::mutex> lock(m_wsrep_mutex, std::adopt_lock);
+      wsrep_cs().cleanup(lock);
+      lock.release();
+    }
+    else
+      wsrep_cs().cleanup();
   }
   wsrep_client_thread= false;
 #endif /* WITH_WSREP */
@@ -1598,16 +1611,38 @@ void THD::cleanup(void)
 void THD::free_connection()
 {
   DBUG_ASSERT(free_connection_done == 0);
-  my_free((char*) db.str);
+  /* Make sure threads are not available via server_threads.  */
+  assert_not_linked();
+
+  /*
+    Other threads may have a lock on THD::LOCK_thd_data or
+    THD::LOCK_thd_kill to ensure that this THD is not deleted
+    while they access it. The following mutex_lock ensures
+    that no one else is using this THD and it's now safe to
+    continue.
+
+    For example consider KILL-statement execution on
+    sql_parse.cc kill_one_thread() that will use
+    THD::LOCK_thd_data to protect victim thread during
+    THD::awake().
+  */
+  mysql_mutex_lock(&LOCK_thd_data);
+  mysql_mutex_lock(&LOCK_thd_kill);
+
+#ifdef WITH_WSREP
+  delete wsrep_rgi;
+  wsrep_rgi= nullptr;
+#endif /* WITH_WSREP */
+  my_free(const_cast<char*>(db.str));
   db= null_clex_str;
 #ifndef EMBEDDED_LIBRARY
   if (net.vio)
     vio_delete(net.vio);
-  net.vio= 0;
+  net.vio= nullptr;
   net_end(&net);
 #endif
- if (!cleanup_done)
-   cleanup();
+  if (!cleanup_done)
+    cleanup(true); // We have locked THD::LOCK_thd_kill
   ha_close_connection(this);
   plugin_thdvar_cleanup(this);
   mysql_audit_free_thd(this);
@@ -1618,6 +1653,8 @@ void THD::free_connection()
 #if defined(ENABLED_PROFILING)
   profiling.restart();                          // Reset profiling
 #endif
+  mysql_mutex_unlock(&LOCK_thd_kill);
+  mysql_mutex_unlock(&LOCK_thd_data);
 }
 
 /*
@@ -1671,24 +1708,10 @@ THD::~THD()
   if (!status_in_global)
     add_status_to_global();
 
-  /*
-    Other threads may have a lock on LOCK_thd_kill to ensure that this
-    THD is not deleted while they access it. The following mutex_lock
-    ensures that no one else is using this THD and it's now safe to delete
-  */
-  if (WSREP_NNULL(this)) mysql_mutex_lock(&LOCK_thd_data);
-  mysql_mutex_lock(&LOCK_thd_kill);
-  mysql_mutex_unlock(&LOCK_thd_kill);
-  if (WSREP_NNULL(this)) mysql_mutex_unlock(&LOCK_thd_data);
-
   if (!free_connection_done)
     free_connection();
 
 #ifdef WITH_WSREP
-  if (wsrep_rgi != NULL) {
-    delete wsrep_rgi;
-    wsrep_rgi = NULL;
-  }
   mysql_cond_destroy(&COND_wsrep_thd);
 #endif
   mdl_context.destroy();
@@ -3142,12 +3165,12 @@ static File create_file(THD *thd, char *path, sql_exchange *exchange,
   }
   /* Create the file world readable */
   if ((file= mysql_file_create(key_select_to_file,
-                               path, 0666, O_WRONLY|O_EXCL, MYF(MY_WME))) < 0)
+                               path, 0644, O_WRONLY|O_EXCL, MYF(MY_WME))) < 0)
     return file;
 #ifdef HAVE_FCHMOD
-  (void) fchmod(file, 0666);			// Because of umask()
+  (void) fchmod(file, 0644);			// Because of umask()
 #else
-  (void) chmod(path, 0666);
+  (void) chmod(path, 0644);
 #endif
   if (init_io_cache(cache, file, 0L, WRITE_CACHE, 0L, 1, MYF(MY_WME)))
   {