Re: [PATCH] signal: remove the wrong signal_pending() check in restore_user_sigmask()

[Oleg Nesterov <oleg@redhat.com>]

On 06/04, Linus Torvalds wrote:
>
> On Tue, Jun 4, 2019 at 6:41 AM Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > This is the minimal fix for stable, I'll send cleanups later.
>
> Ugh. I htink this is correct, but I wish we had a better and more
> intuitive interface.

Yes,

> In particular, since restore_user_sigmask() basically wants to check
> for "signal_pending()" anyway

No, the caller should check signal_pending() anyway and this is enough.

> > -       restore_user_sigmask(ksig.sigmask, &sigsaved);
> > -       if (signal_pending(current) && !ret)
> > +
> > +       interrupted = signal_pending(current);
> > +       restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
> > +       if (interrupted && !ret)
> >                 ret = -ERESTARTNOHAND;
>
> are wrong to begin with,

This is fs/aio.c and I have already mentioned that this code doesn't look
right anyway.

> IOW, I think the above could become
>
>         ret = restore_user_sigmask(ksig.sigmask, &sigsaved, ret, -ERESTARTHAND);
>
> instead if we just made the right interface decision.

I think this particular code should simply do

		ret = do_io_getevents(...);

		if (ret == -ERESTARTSYS)
			ret = -EINTR;

		restore_user_sigmask(ret == -EINTR);

However I agree that another helper(s) which takes/returns the error code makes
sense and I was going to do this. Lets do this step by step, I think we should
kill sigmask/sigsaved first.

Oleg.