On 03/14, Josh Triplett wrote: > > On Sat, Mar 14, 2015 at 11:38:29AM -0700, Thiago Macieira wrote: > > On Saturday 14 March 2015 15:32:35 Oleg Nesterov wrote: > > > It is not clear to me what do_wait() should do with ->autoreap child, even > > > ignoring ptrace. > > > > > > Just suppose that real_parent has a single "autoreap" child. Should > > > wait(NULL) hanf then? > > > > It should ignore the child that is set to autoreap. wait(NULL) should return - > > ECHILD, indicating there are no children waiting to be reaped. > > Right. And I don't think the current code does this. I think we need > to change wait_consider_task to early-return for ->autoreap just as it > does for task_state == EXIT_DEAD. No. This EXIT_DEAD is absolutely different. And this is another indication that you might use it wrongly ;) What we actually want is BUG_ON(task_state == EXIT_DEAD) here. We do not want the EXIT_DEAD tasks in ->children/ptraced lists. These EXIT_DEAD tasks complicate the exit/wait/reparent paths. However, currently this is TODO. The main problem is the locking in wait_task_zombie(), we can set EXIT_DEAD and remove the task from list under read_lock(). And please see another email from me. So far I disagree that wait(NULL) should return ECHILD unconditionally. At least unless this is discussed separately. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
