+2012-05-23 Corinna Vinschen <corinna@vinschen.de>
+
+ * thread.cc (pthread::precreate): Make sure mutex is recursive.
+ Explain why.
+
2012-05-23 Corinna Vinschen <corinna@vinschen.de>
* thread.cc (pthread::pop_cleanup_handler): Move setting the cancelstate
magic = 0;
return;
}
- /* Change the mutex type to NORMAL to speed up mutex operations */
- mutex.set_type (PTHREAD_MUTEX_NORMAL);
+ /* This mutex MUST be recursive. Consider the following scenario:
+ - The thread installs a cleanup handler.
+ - The cleanup handler calls a function which itself installs a
+ cleanup handler.
+ - pthread_cancel is called for this thread.
+ - The thread's cleanup handler is called under mutex lock condition.
+ - The cleanup handler calls the subsequent function with cleanup handler.
+ - The function runs to completion, so it calls pthread_cleanup_pop.
+ - pthread_cleanup_pop calls pthread::pop_cleanup_handler which will again
+ try to lock the mutex.
+ - Deadlock. */
+ mutex.set_type (PTHREAD_MUTEX_RECURSIVE);
if (!create_cancel_event ())
magic = 0;
}