On Fri, Feb 02, 2024 at 08:05:29PM +0100, Oleg Nesterov wrote:
> On 02/02, Christian Brauner wrote:
> >
> > > I think we need a simpler patch. I was going to send it as 4/4, but I'd
> > > like to think more, _perhaps_ we can also discriminate the PIDFD_THREAD
> > > and non-PIDFD_THREAD waiters. I'll try to make the patch(es) tomorrow or
> >
> > Right, I didn't go that far.
> >
> > > at least provided more info.
> > >
> > > 3 notes for now:
> > >
> > > 1. we can't use wake_up_poll(), it passes nr_exclusive => 1
> >
> > Bah. So we need the same stuff we did for io_uring and use
> > __wake_up() directly. Or we add wake_up_all_poll() and convert the other
> > three callsites:
>
> ...
>
> > +#define wake_up_all_poll(x, m) \
> > + __wake_up(x, TASK_NORMAL, 0, poll_to_key(m))
>
> Agreed, but I think this + s/wake_up/wake_up_all_poll/ conversions
> need a separate patch.
Yeah, I know. This is just a scribbled draft.
>
>
> > -void do_notify_pidfd(struct task_struct *task)
> > +void pidfd_wake_up_poll(struct task_struct *task, bool dead)
> > {
> > - struct pid *pid;
> > -
> > WARN_ON(task->exit_state == 0);
> > - pid = task_pid(task);
> > - wake_up_all(&pid->wait_pidfd);
> > + WARN_ON(mask == 0);
> > + wake_up_all_poll(&task_pid(task)->wait_pidfd,
> > + EPOLLIN | EPOLLRDNORM | dead ? EPOLLHUP : 0);
>
> No...
>
> This is still overcomplicated and is not right.
I'm all ears.
> Christian, I'll write another email tomorrow.
Sure, there's no rush. I had not intended that this patch be used. I
have another large series I need to take care of so I can't spend a lot
of time on writing this anyway. I just hadn't used the keyed apis before
and got curious. So don't get the impression that I intend to write
this. I fully expected you to do it.
