[src/trunk]: src/sys/kern Set EV_ONESHOT to prevent rescheduling

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b3456a631c0c
branches:  trunk
changeset: 828963:b3456a631c0c
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Jan 12 17:58:51 2018 +0000

description:
Set EV_ONESHOT to prevent rescheduling
XXX: pullup-8

diffstat:

 sys/kern/kern_event.c |  10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diffs (31 lines):

diff -r 1423f19483bc -r b3456a631c0c sys/kern/kern_event.c
--- a/sys/kern/kern_event.c     Fri Jan 12 17:54:36 2018 +0000
+++ b/sys/kern/kern_event.c     Fri Jan 12 17:58:51 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_event.c,v 1.102 2018/01/09 03:31:13 christos Exp $        */
+/*     $NetBSD: kern_event.c,v 1.103 2018/01/12 17:58:51 christos Exp $        */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.102 2018/01/09 03:31:13 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.103 2018/01/12 17:58:51 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -710,6 +710,12 @@
 filt_timerdetach(struct knote *kn)
 {
        callout_t *calloutp;
+       struct kqueue *kq = kn->kn_kq;
+
+       mutex_spin_enter(&kq->kq_lock);
+       /* prevent rescheduling when we expire */
+       kn->kn_flags |= EV_ONESHOT;
+       mutex_spin_exit(&kq->kq_lock);
 
        calloutp = (callout_t *)kn->kn_hook;
        callout_halt(calloutp, NULL);