Merge branch 'late/dt' into next/dt2

This is support for the ARM Chromebook, originally scheduled
as a "late" pull request. Since it's already late now, we
can combine this into the existing next/dt2 branch.

* late/dt:
  ARM: exynos: dts: cros5250: add EC device
  ARM: dts: Add sbs-battery for exynos5250-snow
  ARM: dts: Add i2c-arbitrator bus for exynos5250-snow
  ARM: dts: Add chip-id controller node on Exynos4/5 SoC
  ARM: EXYNOS: Create virtual I/O mapping for Chip-ID controller using device tree

1 files changed, 14 insertions, 8 deletions

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 5a710b9c578e..87a03c746f17 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -93,14 +93,20 @@ do { \
 
 #else /* !CONFIG_PREEMPT_COUNT */
 
-#define preempt_disable()               do { } while (0)
-#define sched_preempt_enable_no_resched()       do { } while (0)
-#define preempt_enable_no_resched()     do { } while (0)
-#define preempt_enable()                do { } while (0)
-
-#define preempt_disable_notrace()               do { } while (0)
-#define preempt_enable_no_resched_notrace()     do { } while (0)
-#define preempt_enable_notrace()                do { } while (0)
+/*
+ * Even if we don't have any preemption, we need preempt disable/enable
+ * to be barriers, so that we don't have things like get_user/put_user
+ * that can cause faults and scheduling migrate into our preempt-protected
+ * region.
+ */
+#define preempt_disable()               barrier()
+#define sched_preempt_enable_no_resched()       barrier()
+#define preempt_enable_no_resched()     barrier()
+#define preempt_enable()                barrier()
+
+#define preempt_disable_notrace()               barrier()
+#define preempt_enable_no_resched_notrace()     barrier()
+#define preempt_enable_notrace()                barrier()
 
 #endif /* CONFIG_PREEMPT_COUNT */