From owner-freebsd-net  Tue Dec 18  9:15:50 2001
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Date: Tue, 18 Dec 2001 11:15:31 -0600
From: Alfred Perlstein <alfred@FreeBSD.org>
To: Bruce Evans <bde@zeta.org.au>
Cc: wollman@FreeBSD.org, net@FreeBSD.org, cvs-committers@FreeBSD.org,
	cvs-all@FreeBSD.org
Subject: Re: fifo fix (Re: cvs commit: src/sys/fs/fifofs fifo_vnops.c)
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References: <20011215151025.A82439@elvis.mu.org> <20011217230720.N13599-100000@gamplex.bde.org> <20011217122953.G82439@elvis.mu.org>
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* Alfred Perlstein <alfred@FreeBSD.org> [011217 12:47] wrote:
> * Bruce Evans <bde@zeta.org.au> [011217 07:10] wrote:
> 
> > > +
> > >  		filetmp.f_data = (caddr_t)ap->a_vp->v_fifoinfo->fi_readsock;
> > > +		so = (struct socket *)filetmp.f_data;
> > > +		s = splnet();
> > > +		oflg = so->so_state & SS_CANTRCVMORE;
> > > +		if (ap->a_vp->v_fifoinfo->fi_writers == 0)
> > > +			so->so_state &= ~SS_CANTRCVMORE;
> > >  		if (filetmp.f_data)
> > >  			revents |= soo_poll(&filetmp, ap->a_events, ap->a_cred,
> > >  			    ap->a_td);
> > > +		so->so_state |= oflg;
> > > +		splx(s);
> > 
> > I'm not happy with frobbing the socket state.  I suggest frobbing the
> > events mask instead.  Either use a flag to tell sopoll() to ignore
> > SS_CANTRCVMORE, or use new events POLLIN_IGNORE_EOF and
> > POLLRDNORM_IGNORE_EOF (convert the userland POLLIN/POLLRDNORM to these
> > and change sopoll() to support them).

Wait, please clarify, are you suggesting that POLLIN_IGNORE_EOF
and POLLRDNORM_IGNORE_EOF must be used by userland applications?
Or would it be an internal flag for the kernel so that here you'd
see something like:

filetmp.f_data = (caddr_t)ap->a_vp->v_fifoinfo->fi_readsock;
if (filetmp.f_data) {
	if (ap->a_events & ~POLLIN)
		ap->a_events |= POLLIN_IGNORE_EOF;
	/* same for POLLRDNORM */
	revents |= soo_poll(&filetmp, ap->a_events, ap->a_cred,
			ap->a_td);
}

Or that the userland will just OR in POLLIN_IGNORE_EOF before calling
poll(2).

I'm not sure if I like the latter way of fixing things.

thanks,
-Alfred

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