sched: sched_clock() improvement: use in_nmi()
make sure we dont execute more complex sched_clock() code in NMI context.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index a0b0852..db69174 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -29,6 +29,7 @@
#include <linux/spinlock.h>
#include <linux/ktime.h>
#include <linux/module.h>
+#include <linux/hardirq.h>
/*
* Scheduler clock - returns current time in nanosec units.
@@ -151,6 +152,13 @@
struct sched_clock_data *scd = cpu_sdc(cpu);
u64 now, clock, this_clock, remote_clock;
+ /*
+ * 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;
