deadlock; recursive lock

thread.c

/*  
 * call-seq: 
 *    mutex.try_lock  -> true or false
 *
 * Attempts to obtain the lock and returns immediately. Returns +true+ if the
 * lock was granted.
 */ 
VALUE 
rb_mutex_trylock(VALUE self) { 

    /*
     * line 3936
     */
    if (rb_mutex_trylock(self) == Qfalse) { 
        rb_mutex_t *mutex;
        rb_thread_t *th = GET_THREAD();
        GetMutexPtr(self, mutex);    
        if (mutex->th == GET_THREAD()) {
            rb_raise(rb_eThreadError, "deadlock; recursive locking");
    }


}