Messages in this thread |  | | Date | Mon, 9 Sep 2002 16:40:26 -0400 | From | Daniel Jacobowitz <> | Subject | Re: do_syslog/__down_trylock lockup in current BK |
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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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