From 3a22be5ae011a2484674d29bfc23eaf175685b96 Mon Sep 17 00:00:00 2001
From: visa <visa@openbsd.org>
Date: Mon, 20 Dec 2021 16:22:24 +0000
Subject: [PATCH] Let poll(2) register EVFILT_EXCEPT filter with dead vnodes

This enables the system deliver POLLHUP when pollfd.events == 0.
---
 sys/miscfs/deadfs/dead_vnops.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sys/miscfs/deadfs/dead_vnops.c b/sys/miscfs/deadfs/dead_vnops.c
index c36111f1cb2..3459569c0e6 100644
--- a/sys/miscfs/deadfs/dead_vnops.c
+++ b/sys/miscfs/deadfs/dead_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dead_vnops.c,v 1.39 2021/12/12 09:14:59 visa Exp $	*/
+/*	$OpenBSD: dead_vnops.c,v 1.40 2021/12/20 16:22:24 visa Exp $	*/
 /*	$NetBSD: dead_vnops.c,v 1.16 1996/02/13 13:12:48 mycroft Exp $	*/
 
 /*
@@ -180,6 +180,11 @@ dead_kqfilter(void *v)
 	case EVFILT_WRITE:
 		ap->a_kn->kn_fop = &dead_filtops;
 		break;
+	case EVFILT_EXCEPT:
+		if ((ap->a_kn->kn_flags & __EV_POLL) == 0)
+			return (EINVAL);
+		ap->a_kn->kn_fop = &dead_filtops;
+		break;
 	default:
 		return (EINVAL);
 	}
-- 
2.20.1