Ingo Molnar <[EMAIL PROTECTED]> writes: > * Eric W. Biederman <[EMAIL PROTECTED]> wrote: > >> Ingo Molnar <[EMAIL PROTECTED]> writes: >> >> > no. Two _completely separate_ lists. >> > >> > i.e. a to-be-reaped task will still be on the main list _too_. The >> > main list is for all the PID semantics rules. The reap-list is just >> > for wait4() processing. The two would be completely separate. >> >> And what pray tell except for heuristics is the list of children used >> for? > > on a second thought: the p->children list is needed for the whole > child/parent task tree, which is needed for sys_getppid().
Yes, something Oleg said made me realize that. As long as the reparent isn't to complex it isn't required that we have exactly one list . > The question > is, does anything require us to reparent to within the same thread > group? I think my head is finally on straight about this question. Currently there is the silly linux specific parent death signal (pdeath_signal). Oleg's memory was a better than mine on this score. However there is no indication that the parent death signal being sent when a thread leader dies is actually correct, or even interesting. It probably should only be sent when getppid changes. So with pdeath_signal fixed that is nothing that requires us to reparent within the same thread group. I'm trying to remember what the story is now. There is a nasty race somewhere with reparenting, a threaded parent setting SIGCHLD to SIGIGN, and non-default signals that results in an zombie that no one can wait for and reap. It requires being reparented twice to trigger. Anyway it is a real mess and if we can remove the stupid multi-headed child lists things would become much simpler and the problem could not occur. Plus the code would become much simpler... utrace appears to have removed the ptrace_children list and the special cases that entailed. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
