[RFC v2 6/7] touch softlockup watchdog

[Glauber Costa <glommer@redhat.com>]

With a reliable steal time mechanism, we can tell if we're
out of the cpu for very long, differentiating from the case
that we simply got a real softlockup.

In the case we were out of cpu, the watchdog is fed, making
bogus softlockups disappear.

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 arch/x86/kernel/kvmclock.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index a1f4852..d217475 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -91,6 +91,7 @@ cputime_t kvm_get_steal_time(void)
 {
 	u64 delta = 0;
 	u64 *last_steal_info, this_steal_info;
+	int touch_wd;
 	struct pvclock_vcpu_time_info *src;
 
 	src = &get_cpu_var(hv_clock);
@@ -104,6 +105,10 @@ cputime_t kvm_get_steal_time(void)
 
 	delta = this_steal_info - *last_steal_info;
 
+	touch_wd = softlockup_thresh * 1000UL;
+	if ((touch_wd > 0) && (delta > touch_wd))
+		touch_softlockup_watchdog();
+
 	*last_steal_info = this_steal_info;
 	put_cpu_var(steal_info);
 
-- 
1.6.2.2