ftrace: split out hardirq ftrace code into own header

Impact: moving of function prototypes into own header file

ftrace.h is too big of a file for hardirq.h, and some archs will fail
to build because of the include dependencies not being met.

This patch pulls out the required prototypes for hardirq.h into a smaller
and safer ftrace_irq.h file.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/ftrace.h

@@ -104,9 +104,6 @@ extern void ftrace_release(void *start, unsigned long size);
 
 extern void ftrace_disable_daemon(void);
 extern void ftrace_enable_daemon(void);
-extern void ftrace_nmi_enter(void);
-extern void ftrace_nmi_exit(void);
-
 #else
 # define skip_trace(ip)				({ 0; })
 # define ftrace_force_update()			({ 0; })
@@ -114,8 +111,6 @@ extern void ftrace_nmi_exit(void);
 # define ftrace_disable_daemon()		do { } while (0)
 # define ftrace_enable_daemon()			do { } while (0)
 static inline void ftrace_release(void *start, unsigned long size) { }
-static inline void ftrace_nmi_enter(void) { }
-static inline void ftrace_nmi_exit(void) { }
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 /* totally disable ftrace - can not re-enable after this */

include/linux/ftrace_irq.h

+#ifndef _LINUX_FTRACE_IRQ_H
+#define _LINUX_FTRACE_IRQ_H
+
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_nmi_enter(void);
+extern void ftrace_nmi_exit(void);
+#else
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
+#endif
+
+#endif /* _LINUX_FTRACE_IRQ_H */

include/linux/hardirq.h

@@ -4,7 +4,7 @@
 #include <linux/preempt.h>
 #include <linux/smp_lock.h>
 #include <linux/lockdep.h>
-#include <linux/ftrace.h>
+#include <linux/ftrace_irq.h>
 #include <asm/hardirq.h>
 #include <asm/system.h>