watchdog: Fix CPU hotplug regression

KAGA-KOKO · KAGA-KOKO · commit 8d4516904b39 · 2012-12-04T19:56:59.000+01:00
Norbert reported: "3.7-rc6 booted with nmi_watchdog=0 fails to suspend to RAM or offline CPUs. It's reproducable with a KVM guest and physical system." The reason is that commit bcd951c(watchdog: Use hotplug thread infrastructure) missed to take this into account. So the cpu offline code gets stuck in the teardown function because it accesses non initialized data structures. Add a check for watchdog_enabled into that path to cure the issue. Reported-and-tested-by: Norbert Warmuth <nwarmuth@t-online.de> Tested-by: Joseph Salisbury <joseph.salisbury@canonical.com> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1211231033230.2701@ionos Link: http://bugs.launchpad.net/bugs/1079534 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
@@ -368,6 +368,9 @@ static void watchdog_disable(unsigned int cpu)
 {
 	struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
 
+	if (!watchdog_enabled)
+		return;
+
 	watchdog_set_prio(SCHED_NORMAL, 0);
 	hrtimer_cancel(hrtimer);
 	/* disable the perf event */

Original file line number	Diff line number	Diff line change
`@@ -368,6 +368,9 @@ static void watchdog_disable(unsigned int cpu)`
`368`	`368`	`{`
`369`	`369`	`struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);`
`370`	`370`
	`371`	`+ if (!watchdog_enabled)`
	`372`	`+ return;`
	`373`	`+`
`371`	`374`	`watchdog_set_prio(SCHED_NORMAL, 0);`
`372`	`375`	`hrtimer_cancel(hrtimer);`
`373`	`376`	`/* disable the perf event */`