x86/nmi: Push duration printk() to irq context

Calling printk() from NMI context is bad (TM), so move it to IRQ
context.

In doing so we slightly change (probably wreck) the debugfs
nmi_longest_ns thingy, in that it doesn't update to reflect the
longest, nor does writing to it reset the count.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-rdw0au56a5ymis1u8p48c12d@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 86f9301..5f2fc44 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -1,6 +1,7 @@
 #ifndef _ASM_X86_NMI_H
 #define _ASM_X86_NMI_H
 
+#include <linux/irq_work.h>
 #include <linux/pm.h>
 #include <asm/irq.h>
 #include <asm/io.h>
@@ -38,6 +39,8 @@
 struct nmiaction {
 	struct list_head	list;
 	nmi_handler_t		handler;
+	u64			max_duration;
+	struct irq_work		irq_work;
 	unsigned long		flags;
 	const char		*name;
 };