From: cheloha <cheloha@openbsd.org>
Date: Fri, 3 Mar 2023 20:16:44 +0000 (+0000)
Subject: initclocks: don't reinitialize ticks, jiffies at runtime
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=d8920042b55e882518faeefa665ee7f67ce9c555;p=openbsd

initclocks: don't reinitialize ticks, jiffies at runtime

Various drivers use ticks/jiffies before initclocks().  It isn't
generally safe to reinitialize them at runtime.  Hoist the conditional
definition of HZ from param.c into sys/kernel.h so we can see it from
kern_clock.c and statically initialize ticks/jiffies to the desired
offset.

With this change, timeouts scheduled before initclocks() do not all
fire immediately during the first softclock().

With input from kettenis@.

Link: https://marc.info/?l=openbsd-tech&m=167753870803378&w=2
---

diff --git a/sys/conf/param.c b/sys/conf/param.c
index 6a3cd398c55..42f56d1eab2 100644
--- a/sys/conf/param.c
+++ b/sys/conf/param.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.c,v 1.47 2022/04/13 10:08:10 sthen Exp $	*/
+/*	$OpenBSD: param.c,v 1.48 2023/03/03 20:16:44 cheloha Exp $	*/
 /*	$NetBSD: param.c,v 1.16 1996/03/12 03:08:40 mrg Exp $	*/
 
 /*
@@ -69,9 +69,6 @@
  * Compiled with -DHZ=xx -DMAXUSERS=xx
  */
 
-#ifndef HZ
-#define	HZ 100
-#endif
 int	hz = HZ;
 int	tick = 1000000 / HZ;
 int	tick_nsec = 1000000000 / HZ;
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
index fc6d90486c3..1265d740dea 100644
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_clock.c,v 1.106 2023/02/04 19:33:03 cheloha Exp $	*/
+/*	$OpenBSD: kern_clock.c,v 1.107 2023/03/03 20:16:44 cheloha Exp $	*/
 /*	$NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $	*/
 
 /*-
@@ -86,11 +86,11 @@ int	stathz;
 int	schedhz;
 int	profhz;
 int	profprocs;
-int	ticks;
+int	ticks = INT_MAX - (15 * 60 * HZ);
 static int psdiv, pscnt;		/* prof => stat divider */
 int	psratio;			/* ratio: prof / stat */
 
-volatile unsigned long jiffies;		/* XXX Linux API for drm(4) */
+volatile unsigned long jiffies = ULONG_MAX - (10 * 60 * HZ);
 
 /*
  * Initialize clock frequencies and start both clocks running.
@@ -98,9 +98,6 @@ volatile unsigned long jiffies;		/* XXX Linux API for drm(4) */
 void
 initclocks(void)
 {
-	ticks = INT_MAX - (15 * 60 * hz);
-	jiffies = ULONG_MAX - (10 * 60 * hz);
-
 	/*
 	 * Set divisors to 1 (normal case) and let the machine-specific
 	 * code do its bit.
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index b0a66fdd47c..0147fde22c0 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kernel.h,v 1.25 2021/01/13 16:28:50 cheloha Exp $	*/
+/*	$OpenBSD: kernel.h,v 1.26 2023/03/03 20:16:44 cheloha Exp $	*/
 /*	$NetBSD: kernel.h,v 1.11 1995/03/03 01:24:16 cgd Exp $	*/
 
 /*-
@@ -56,3 +56,7 @@ extern int hz;			/* system clock's frequency */
 extern int stathz;		/* statistics clock's frequency */
 extern int profhz;		/* profiling clock's frequency */
 extern int lbolt;		/* once a second sleep address */
+
+#ifndef HZ
+#define HZ 100
+#endif