I still think that the changelog and the comment look a bit confusing... it could simply say that exit_notify() can see these STORE's out of order. And we can set ->notify_count after ->exit_state check, but again this is cosmetic, I won't insist. The main problem with this patch is that it was ignored ;)
Kirill, could you resend? Feel free to add my ack. On 02/05, Kirill Tkhai wrote: > > The write operation may be reordered with the setting of group_exit_task. > If so, this fires in exit_notify(). > > Looks like, it's not good to add smp barriers for this case, especially > in exit_notify(), so let's put the notify_count write under write lock. > > Signed-off-by: Kirill Tkhai <[email protected]> > --- > fs/exec.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/exec.c b/fs/exec.c > index ad8798e..42782d5 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -920,10 +920,16 @@ static int de_thread(struct task_struct *tsk) > if (!thread_group_leader(tsk)) { > struct task_struct *leader = tsk->group_leader; > > - sig->notify_count = -1; /* for exit_notify() */ > for (;;) { > threadgroup_change_begin(tsk); > write_lock_irq(&tasklist_lock); > + /* > + * We could set it once outside the for() cycle, but > + * this requires to use SMP barriers there and in > + * exit_notify(), because the write operation may > + * be reordered with the setting of group_exit_task. > + */ > + sig->notify_count = -1; /* for exit_notify() */ > if (likely(leader->exit_state)) > break; > __set_current_state(TASK_KILLABLE); > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
