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authorSteven Rostedt <srostedt@redhat.com>2009-02-06 00:51:37 -0500
committerSteven Rostedt <srostedt@redhat.com>2009-02-07 20:01:23 -0500
commit375b38b4214f29109a393ab762d468054bf52354 (patch)
treed57e22648d1e07659db308abdcb8d5b23d63891f
parent4e6ea1440c67de32d7c89aacf233472dfc3bce82 (diff)
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nmi: add generic nmi tracking state
This code adds an in_nmi() macro that uses the current tasks preempt count to track when it is in NMI context. Other parts of the kernel can use this to determine if the context is in NMI context or not. This code was inspired by the -rt patch in_nmi version that was written by Peter Zijlstra, who borrowed that code from Mathieu Desnoyers. Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
-rw-r--r--include/linux/hardirq.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index f83288347dd..f3cf86e1465 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)