rb_mutex_owned_p 1420 internal.h     VALUE rb_mutex_owned_p(VALUE self);
rb_mutex_owned_p 1077 io.c           	if (rb_mutex_owned_p(fptr->write_lock))
rb_mutex_owned_p 4101 io.c           		if (fptr->write_lock && rb_mutex_owned_p(fptr->write_lock))
rb_mutex_owned_p 1249 thread_sync.c      rb_define_method(rb_cMutex, "owned?", rb_mutex_owned_p, 0);