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-rw-r--r--kernel/sched_clock.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index 390f332..819f17a 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -25,6 +25,7 @@
* consistent between cpus (never more than 2 jiffies difference).
*/
#include <linux/spinlock.h>
+#include <linux/hardirq.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/ktime.h>
@@ -154,6 +155,17 @@ u64 sched_clock_cpu(int cpu)
return sched_clock();
scd = cpu_sdc(cpu);
+
+ /*
+ * Normally this is not called in NMI context - but if it is,
+ * trying to do any locking here is totally lethal.
+ */
+ if (unlikely(in_nmi()))
+ return scd->clock;
+
+ if (unlikely(!sched_clock_running))
+ return 0ull;
+
WARN_ON_ONCE(!irqs_disabled());
now = sched_clock();
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