Re: [PATCH v5 6/6] signal: Don't restart fork when signals come in.

[Linus Torvalds]

On Wed, Aug 8, 2018 at 11:57 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>
> The code was being overly pesimistic.

Pessimistic.

> +       if (type > PIDTYPE_TGID) {
> +               struct multiprocess_signals *delayed;
> +               hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
> +                       sigset_t *signal = &delayed->signal;
> +                       /* Can't queue both a stop and a continue signal */
> +                       if (sig == SIGCONT) {
> +                               sigset_t flush;
> +                               siginitset(&flush, SIG_KERNEL_STOP_MASK);
> +                               sigandnsets(signal, signal, &flush);

This looks odd and unnecessary.

Why isn't this just a

        sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);

since all of the traditional stop bits should be in the low mask.

I see that we apparently have this stupid pattern elsewhere too, and
it looks like it's because we stupidly say "are the RT signals in the
non-legacy set", when that definitely cannot be the case for the (very
much legacy) tty flow control signals.

                 Linus