Always set the timeout at least one tick in the future for EVFILT_TIMER

to avoid looping in softclock()

based on diff by sthen@
ok sthen@

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index b0f6c8e..5911147 100644 (file)
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_event.c,v 1.64 2015/10/10 16:35:08 deraadt Exp $ */
+/*     $OpenBSD: kern_event.c,v 1.65 2015/10/11 01:53:39 guenther Exp $        */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -323,22 +323,28 @@ filt_proc(struct knote *kn, long hint)
        return (kn->kn_fflags != 0);
 }
 
+static void
+filt_timer_timeout_add(struct knote *kn)
+{
+       struct timeval tv;
+       int tticks;
+
+       tv.tv_sec = kn->kn_sdata / 1000;
+       tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
+       tticks = tvtohz(&tv);
+       timeout_add(kn->kn_hook, tticks ? tticks : 1);
+}
+
 void
 filt_timerexpire(void *knx)
 {
        struct knote *kn = knx;
-       struct timeval tv;
-       int tticks;
 
        kn->kn_data++;
        KNOTE_ACTIVATE(kn);
 
-       if ((kn->kn_flags & EV_ONESHOT) == 0) {
-               tv.tv_sec = kn->kn_sdata / 1000;
-               tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
-               tticks = tvtohz(&tv);
-               timeout_add((struct timeout *)kn->kn_hook, tticks);
-       }
+       if ((kn->kn_flags & EV_ONESHOT) == 0)
+               filt_timer_timeout_add(kn);
 }
 
 
@@ -349,22 +355,16 @@ int
 filt_timerattach(struct knote *kn)
 {
        struct timeout *to;
-       struct timeval tv;
-       int tticks;
 
        if (kq_ntimeouts > kq_timeoutmax)
                return (ENOMEM);
        kq_ntimeouts++;
 
-       tv.tv_sec = kn->kn_sdata / 1000;
-       tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
-       tticks = tvtohz(&tv);
-
        kn->kn_flags |= EV_CLEAR;       /* automatically set */
        to = malloc(sizeof(*to), M_KEVENT, M_WAITOK);
        timeout_set(to, filt_timerexpire, kn);
-       timeout_add(to, tticks);
        kn->kn_hook = to;
+       filt_timer_timeout_add(kn);
 
        return (0);
 }