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| author | Avi Kivity <avi@redhat.com> | 2011-11-15 14:59:07 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-11-20 10:53:48 +0200 |
| commit | 95ef1e52922cf75b1ea2eae54ef886f2cc47eecb (patch) | |
| tree | 158082c19666aa589b539f20b4cf29e99f205f4f | |
| parent | bb75c627fb0dfb8c0ab75d3033709ff928896e16 (diff) | |
| download | ocfs2-95ef1e52922cf75b1ea2eae54ef886f2cc47eecb.tar.gz | |
KVM guest: prevent tracing recursion with kvmclock
Prevent tracing of preempt_disable() in get_cpu_var() in
kvm_clock_read(). When CONFIG_DEBUG_PREEMPT is enabled,
preempt_disable/enable() are traced and this causes the function_graph
tracer to go into an infinite recursion. By open coding the
preempt_disable() around the get_cpu_var(), we can use the notrace
version which prevents preempt_disable/enable() from being traced and
prevents the recursion.
Based on a similar patch for Xen from Jeremy Fitzhardinge.
Tested-by: Gleb Natapov <gleb@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | arch/x86/kernel/kvmclock.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index c1a0188e29aef6..44842d756b29fa 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -74,9 +74,10 @@ static cycle_t kvm_clock_read(void) struct pvclock_vcpu_time_info *src; cycle_t ret; - src = &get_cpu_var(hv_clock); + preempt_disable_notrace(); + src = &__get_cpu_var(hv_clock); ret = pvclock_clocksource_read(src); - put_cpu_var(hv_clock); + preempt_enable_notrace(); return ret; } |