On 03/18, Linus Torvalds wrote:
>
> On Wed, Mar 14, 2012 at 11:55 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> > +       if (clone_flags & CLONE_THREAD)
> > +               p->exit_signal = -1;
> > +       else if (clone_flags & CLONE_PARENT)
> > +               p->exit_signal = current->group_leader->exit_signal;
> > +       else
> > +               p->exit_signal = (clone_flags & CSIGNAL);
>
> So why is it "current->group_leader->exit_signal" rather than the much
> more logical (imho) and simpler "current->exit_signal"?

This would be wrong if current is not the main thread. In this
case current->exit_signal = -1. Only group_leader has the "real"
exit_signal used for notification.

Historically "exit_signal = -1" meant different things, currently
it only means "I am not the leader", see thread_group_leader().

I'll write another email tomorrow. Yes, I do remember I promised
the security fixes in this area, sorry for delay.

Oleg.

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