Messages in this thread | | | Date | Tue, 31 Jan 2006 13:07:43 +0300 | From | Oleg Nesterov <> | Subject | Re: [PATCH] exec: Cleanup exec from a non thread group leader. |
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"Eric W. Biederman" wrote: > > Oleg Nesterov <oleg@tv-sign.ru> writes: > > > Oleg Nesterov wrote: > >> > >> Eric W. Biederman wrote: > >> > > >> > - list_add_tail(&thread->tasks, &init_task.tasks); > >> > >> The last deletion is wrong, I beleive. > > > > Just to clarify, it looks like we can kill this line because > > de_thread() also does list_add_tail(current, &init_task.tasks). > > > > But please note that it (and probably __ptrace_link() above) > > does list_del(current->task) first, and current->task may have > > very stale values after old leader called dup_task_struct(). > > SET_LINKS() in copy_process() does nothing with ->tasks in a > > CLONE_THREAD case. > > Good point in that instance we need to remove the list_del > as well.
We can't just remove this list_del, note __ptrace_link() above. So if we remove list_add from switch_exec_pids() (like you did in your patch) we should also place list_add before ptrace_link() in de_thread(), otherwise I beleive it is a bug.
I agree, we should cleanup this. I just noticed that I forgot to add you on CC: list while sending this patch:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113862839924746
Btw, I don't understand why __ptrace_link() use REMOVE_LINKS/SET_LINKS instead of remove_parent/add_parent.
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