1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index f83288347dda..f3cf86e1465b 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -61,6 +61,12 @@
 #error PREEMPT_ACTIVE is too low!
 #endif
 
+#define NMI_OFFSET      (PREEMPT_ACTIVE << 1)
+
+#if NMI_OFFSET >= 0x80000000
+#error PREEMPT_ACTIVE too high!
+#endif
+
 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
@@ -73,6 +79,11 @@
 #define in_softirq()            (softirq_count())
 #define in_interrupt()          (irq_count())
 
+/*
+ * Are we in NMI context?
+ */
+#define in_nmi()        (preempt_count() & NMI_OFFSET)
+
 #if defined(CONFIG_PREEMPT)
 # define PREEMPT_INATOMIC_BASE kernel_locked()
 # define PREEMPT_CHECK_OFFSET 1
@@ -167,6 +178,8 @@ extern void irq_exit(void);
 #define nmi_enter()                             \
         do {                                    \
                 ftrace_nmi_enter();             \
+                BUG_ON(in_nmi());               \
+                add_preempt_count(NMI_OFFSET);  \
                 lockdep_off();                  \
                 rcu_nmi_enter();                \
                 __irq_enter();                  \
@@ -177,6 +190,8 @@ extern void irq_exit(void);
                 __irq_exit();                   \
                 rcu_nmi_exit();                 \
                 lockdep_on();                   \
+                BUG_ON(!in_nmi());              \
+                sub_preempt_count(NMI_OFFSET);  \
                 ftrace_nmi_exit();              \
         } while (0)