Merge branch 'tracing/core-v2' into tracing-for-linus

[linux-2.6-omap-h63xx.git] / kernel / sched_clock.c

diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index 390f33234bd007ea41da7006f252e715b6293b43..819f17ac796efeeee1068efe3e6a27ac952d3a16 100644 (file)
--- 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();