perf: Allow for custom overflow handlers

in-kernel perf users might wish to have custom actions on the
sample interrupt.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091120212508.222339539@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b5cdac0..a430ac3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -567,6 +567,8 @@
 
 typedef void (*perf_callback_t)(struct perf_event *, void *);
 
+struct perf_sample_data;
+
 /**
  * struct perf_event - performance event kernel representation:
  */
@@ -658,6 +660,10 @@
 	struct pid_namespace		*ns;
 	u64				id;
 
+	void (*overflow_handler)(struct perf_event *event,
+			int nmi, struct perf_sample_data *data,
+			struct pt_regs *regs);
+
 #ifdef CONFIG_EVENT_PROFILE
 	struct event_filter		*filter;
 #endif