"Paul E. McKenney" wrote:
>
> > > + while (p->group_leader != p)
> > > + p = p->group_leader;
> >
> > No, this is definitely not right. de_thread() does not change leader->group_leader
> > when non-leader execs, so p->group_leader == p always.
>
> This was intended for the case where the group leader does pthread_exit,
> which would cause some other thread to assume group leadership. Or am
> I missing something from that code path? (Quite likely that I am...)
When group leader exits it goes into TASK_ZOMBIE state (if it is not the
only one thread in the same group). It is still the ->group_leader for all
threads including itself. Only when release_task(last_thread_in_thread_group)
happens, it will notice not yet released group_leader, and release it, see
'repeat:' patch in release_task().
The ->group_leader is changed only when non-leader thread does exec, it kills
other threads and becomes ->group_leader for itself.
So, I think send_group_sigqueue() should do:
read_lock(tasklist_lock);
if (!tsk->signal) {
// Can happen only if de_thread did release_task(tsk)
// while switching to new leader.
// We can't figure out the new leader, but it does not
// matter - we should drop the signal anyway.
unlock(tasklist);
return;
}
Oleg.
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