Test case and a different fix for MySQL bug#14485479

mysql-test/suite/plugins/r/audit_null_debug.result

+call mtr.add_suppression("mysql/plugin.MYI");
+SET debug_dbug='+d,myisam_pretend_crashed_table_on_usage';
+install plugin audit_null soname 'adt_null';
+ERROR HY000: Incorrect key file for table './mysql/plugin.MYI'; try to repair it
+SET debug_dbug='-d,myisam_pretend_crashed_table_on_usage';
+install plugin audit_null soname 'adt_null';
+SET debug_dbug='+d,myisam_pretend_crashed_table_on_usage';
+uninstall plugin audit_null;
+ERROR HY000: Incorrect key file for table './mysql/plugin.MYI'; try to repair it
+SET debug_dbug='-d,myisam_pretend_crashed_table_on_usage';
+uninstall plugin audit_null;
+ERROR 42000: PLUGIN audit_null does not exist

mysql-test/suite/plugins/t/audit_null_debug.test

+--source include/have_debug.inc
+--source include/not_embedded.inc
+
+if (!$ADT_NULL_SO) {
+  skip No NULL_AUDIT plugin;
+}
+
+call mtr.add_suppression("mysql/plugin.MYI");
+
+#
+# MySQL BUG#14485479 - INSTALL AUDIT PLUGIN HANGS IF WE TRY TO DISABLE AND ENABLED DURING DDL OPERATION
+# (a.k.a. audit event caused by the table access during audit plugin initialization)
+#
+SET debug_dbug='+d,myisam_pretend_crashed_table_on_usage';
+--error 126
+install plugin audit_null soname 'adt_null';
+SET debug_dbug='-d,myisam_pretend_crashed_table_on_usage';
+
+install plugin audit_null soname 'adt_null';
+SET debug_dbug='+d,myisam_pretend_crashed_table_on_usage';
+--error 126
+uninstall plugin audit_null;
+SET debug_dbug='-d,myisam_pretend_crashed_table_on_usage';
+
+--error 1305
+uninstall plugin audit_null;
+

sql/sql_audit.cc

@@ -132,12 +132,9 @@ static const uint audit_handlers_count=
 
 static my_bool acquire_plugins(THD *thd, plugin_ref plugin, void *arg)
 {
-  uint event_class= *(uint*) arg;
-  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
+  ulong *event_class_mask= (ulong*) arg;
   st_mysql_audit *data= plugin_data(plugin, struct st_mysql_audit *);
 
-  set_audit_mask(event_class_mask, event_class);
-
   /* Check if this plugin is interested in the event */
   if (check_audit_mask(data->class_mask, event_class_mask))
     return 0;
@@ -176,15 +173,13 @@ static my_bool acquire_plugins(THD *thd, plugin_ref plugin, void *arg)
   @details Ensure that audit plugins interested in given event
   class are locked by current thread.
 */
-void mysql_audit_acquire_plugins(THD *thd, uint event_class)
+void mysql_audit_acquire_plugins(THD *thd, ulong *event_class_mask)
 {
-  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
   DBUG_ENTER("mysql_audit_acquire_plugins");
-  set_audit_mask(event_class_mask, event_class);
   if (thd && !check_audit_mask(mysql_global_audit_mask, event_class_mask) &&
       check_audit_mask(thd->audit_class_mask, event_class_mask))
   {
-    plugin_foreach(thd, acquire_plugins, MYSQL_AUDIT_PLUGIN, &event_class);
+    plugin_foreach(thd, acquire_plugins, MYSQL_AUDIT_PLUGIN, event_class_mask);
     add_audit_mask(thd->audit_class_mask, event_class_mask);
   }
   DBUG_VOID_RETURN;
@@ -206,7 +201,9 @@ void mysql_audit_notify(THD *thd, uint event_class, uint event_subtype, ...)
   va_list ap;
   audit_handler_t *handlers= audit_handlers + event_class;
   DBUG_ASSERT(event_class < audit_handlers_count);
-  mysql_audit_acquire_plugins(thd, event_class);
+  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
+  set_audit_mask(event_class_mask, event_class);
+  mysql_audit_acquire_plugins(thd, event_class_mask);
   va_start(ap, event_subtype);  
   (*handlers)(thd, event_subtype, ap);
   va_end(ap);
@@ -364,6 +361,34 @@ int initialize_audit_plugin(st_plugin_int *plugin)
   add_audit_mask(mysql_global_audit_mask, data->class_mask);
   mysql_mutex_unlock(&LOCK_audit_mask);
 
+  /*
+    Pre-acquire the newly inslalled audit plugin for events that
+    may potentially occur further during INSTALL PLUGIN.
+
+    When audit event is triggered, audit subsystem acquires interested
+    plugins by walking through plugin list. Evidently plugin list
+    iterator protects plugin list by acquiring LOCK_plugin, see
+    plugin_foreach_with_mask().
+
+    On the other hand [UN]INSTALL PLUGIN is acquiring LOCK_plugin
+    rather for a long time.
+
+    When audit event is triggered during [UN]INSTALL PLUGIN, plugin
+    list iterator acquires the same lock (within the same thread)
+    second time.
+
+    This hack should be removed when LOCK_plugin is fixed so it
+    protects only what it supposed to protect.
+
+    See also mysql_install_plugin() and mysql_uninstall_plugin()
+  */
+  THD *thd= current_thd;
+  if (thd)
+  {
+    acquire_plugins(thd, plugin_int_to_ref(plugin), data->class_mask);
+    add_audit_mask(thd->audit_class_mask, data->class_mask);
+  }
+
   return 0;
 }
 
@@ -494,7 +519,7 @@ static void event_class_dispatch(THD *thd, unsigned int event_class,
 #else /* EMBEDDED_LIBRARY */
 
 
-void mysql_audit_acquire_plugins(THD *thd, uint event_class)
+void mysql_audit_acquire_plugins(THD *thd, ulong *event_class_mask)
 {
 }
 

sql/sql_audit.h

@@ -31,7 +31,7 @@ extern void mysql_audit_finalize();
 
 extern void mysql_audit_init_thd(THD *thd);
 extern void mysql_audit_free_thd(THD *thd);
-extern void mysql_audit_acquire_plugins(THD *thd, uint event_class);
+extern void mysql_audit_acquire_plugins(THD *thd, ulong *event_class_mask);
 
 
 #ifndef EMBEDDED_LIBRARY

sql/sql_plugin.cc

@@ -2018,7 +2018,7 @@ static bool finalize_install(THD *thd, TABLE *table, const LEX_STRING *name)
   struct st_plugin_int *tmp= plugin_find_internal(name, MYSQL_ANY_PLUGIN);
   int error;
   DBUG_ASSERT(tmp);
-  mysql_mutex_assert_owner(&LOCK_plugin);
+  mysql_mutex_assert_owner(&LOCK_plugin); // because of tmp->state
 
   if (tmp->state == PLUGIN_IS_DISABLED)
   {
@@ -2105,8 +2105,12 @@ bool mysql_install_plugin(THD *thd, const LEX_STRING *name,
 
     This hack should be removed when LOCK_plugin is fixed so it
     protects only what it supposed to protect.
+
+    See also mysql_uninstall_plugin() and initialize_audit_plugin()
   */
-  mysql_audit_acquire_plugins(thd, MYSQL_AUDIT_GENERAL_CLASS);
+  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE] =
+  { MYSQL_AUDIT_GENERAL_CLASSMASK };
+  mysql_audit_acquire_plugins(thd, event_class_mask);
 
   mysql_mutex_lock(&LOCK_plugin);
   mysql_rwlock_wrlock(&LOCK_system_variables_hash);
@@ -2249,8 +2253,15 @@ bool mysql_uninstall_plugin(THD *thd, const LEX_STRING *name,
     When audit event is triggered during [UN]INSTALL PLUGIN, plugin
     list iterator acquires the same lock (within the same thread)
     second time.
+
+    This hack should be removed when LOCK_plugin is fixed so it
+    protects only what it supposed to protect.
+
+    See also mysql_install_plugin() and initialize_audit_plugin()
   */
-  mysql_audit_acquire_plugins(thd, MYSQL_AUDIT_GENERAL_CLASS);
+  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE] =
+  { MYSQL_AUDIT_GENERAL_CLASSMASK };
+  mysql_audit_acquire_plugins(thd, event_class_mask);
 
   mysql_mutex_lock(&LOCK_plugin);