On Mon, Sep 09, 2002 at 10:33:17PM +0200, Ingo Molnar wrote:
>
> the attached patch fixes one bug in the way we did zap_thread() - but this
> alone does not fix the lockup.
>
> the bug was that list_for_each_safe() is not 'safe enough' - zap_thread()
> drops the tasklist lock at which point anything might happen to the child
> list.
>
> the lockup is likely in the while loop - ie. zap_thread() not actually
> reparenting a thread and thus causing an infinite loop - is that possible?
Well, it shouldn't be. forget_original_parent should update
real_parent for every child on either list, and then zap_thread unlinks
each child from the current parent and links it to the new real_parent.
A couple of printks in there should be able to work out if I'm wrong,
though...
> @@ -554,17 +553,16 @@
> do_notify_parent(current, current->exit_signal);
>
> zap_again:
> - list_for_each_safe(_p, _n, ¤t->children)
> - zap_thread(list_entry(_p,struct task_struct,sibling), current, 0);
> - list_for_each_safe(_p, _n, ¤t->ptrace_children)
> - zap_thread(list_entry(_p,struct task_struct,ptrace_list), current, 1);
> + while (!list_empty(¤t->children))
> + zap_thread(list_entry(current->children.next,struct task_struct,sibling), current, 0);
> + while (!list_empty(¤t->ptrace_children))
> + zap_thread(list_entry(current->ptrace_children.next,struct task_struct,sibling), current, 0);
As Linus points out, typo right there on the last argument.
-- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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