Re: [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask

From: Oleg Nesterov
Date: Wed Jun 12 2019 - 11:42:54 EST

On 06/12, Eric W. Biederman wrote:
> David Laight <David.Laight@xxxxxxxxxx> writes:
> > From: Oleg Nesterov
> >> Sent: 12 June 2019 14:46
> >> On 06/11, David Laight wrote:
> >> >
> >> > If I have an application that has a loop with a pselect call that
> >> > enables SIGINT (without a handler) and, for whatever reason,
> >> > one of the fd is always 'ready' then I'd expect a SIGINT
> >> > (from ^C) to terminate the program.
> I think this gets into a quality of implementation.
> I suspect that set_user_sigmask should do:
> if (signal_pending())
> return -ERESTARNOSIGHAND; /* -EINTR that restarts if nothing was pending */
> Which should be safe as nothing has blocked yet to consume any of the
> timeouts, and it should ensure that none of the routines miss a signal.

Why? I don't think this makes any sense.

Perhaps we could do this _after_ set_current_blocked() for the case when
the already pending SIGINT was unblocked but a) I am not sure this would
be really better and b) I think it is too late to change this.