Module Name: src
Committed By: riastradh
Date: Sat Sep 2 17:44:23 UTC 2023
Modified Files:
src/sys/kern: kern_heartbeat.c
Log Message:
heartbeat(9): Ignore stale tc if primary CPU heartbeat is suspended.
The timecounter ticks only on the primary CPU, so of course it will
go stale if it's suspended.
(It is, perhaps, a mistake that it only ticks on the primary CPU,
even if the primary CPU is offlined or in a polled-input console
loop, but that's a separate issue.)
To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/sys/kern/kern_heartbeat.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_heartbeat.c
diff -u src/sys/kern/kern_heartbeat.c:1.6 src/sys/kern/kern_heartbeat.c:1.7
--- src/sys/kern/kern_heartbeat.c:1.6 Sat Sep 2 17:43:37 2023
+++ src/sys/kern/kern_heartbeat.c Sat Sep 2 17:44:23 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_heartbeat.c,v 1.6 2023/09/02 17:43:37 riastradh Exp $ */
+/* $NetBSD: kern_heartbeat.c,v 1.7 2023/09/02 17:44:23 riastradh Exp $ */
/*-
* Copyright (c) 2023 The NetBSD Foundation, Inc.
@@ -78,7 +78,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_heartbeat.c,v 1.6 2023/09/02 17:43:37 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_heartbeat.c,v 1.7 2023/09/02 17:44:23 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -199,6 +199,41 @@ heartbeat_resume(void)
}
/*
+ * heartbeat_timecounter_suspended()
+ *
+ * True if timecounter heartbeat checks are suspended because the
+ * timecounter may not be advancing, false if heartbeat checks
+ * should check for timecounter progress.
+ */
+static bool
+heartbeat_timecounter_suspended(void)
+{
+ CPU_INFO_ITERATOR cii;
+ struct cpu_info *ci;
+
+ /*
+ * The timecounter ticks only on the primary CPU. Check
+ * whether it's suspended.
+ *
+ * XXX Would be nice if we could find the primary CPU without
+ * iterating over all CPUs.
+ */
+ for (CPU_INFO_FOREACH(cii, ci)) {
+ if (CPU_IS_PRIMARY(ci)) {
+ return ci->ci_schedstate.spc_flags &
+ SPCF_HEARTBEATSUSPENDED;
+ }
+ }
+
+ /*
+ * This should be unreachable -- there had better be a primary
+ * CPU in the system! If not, the timecounter will be busted
+ * anyway.
+ */
+ panic("no primary CPU");
+}
+
+/*
* heartbeat_reset_xc(a, b)
*
* Cross-call handler to reset heartbeat state just prior to
@@ -598,7 +633,8 @@ heartbeat(void)
/*
* Timecounter hasn't advanced by more than a second.
* Make sure the timecounter isn't stuck according to
- * our heartbeats.
+ * our heartbeats -- unless timecounter heartbeats are
+ * suspended too.
*
* Our own heartbeat count can't roll back, and
* time_uptime should be updated before it wraps
@@ -608,7 +644,8 @@ heartbeat(void)
stamp =
atomic_load_relaxed(&curcpu()->ci_heartbeat_uptime_stamp);
d = count - stamp;
- if (__predict_false(d > period_ticks)) {
+ if (__predict_false(d > period_ticks) &&
+ !heartbeat_timecounter_suspended()) {
panic("%s: time has not advanced in %u heartbeats",
cpu_name(curcpu()), d);
}
