[tip:perf/core] perf: Allow for custom overflow handlers

[tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>]

Commit-ID:  453f19eea7dbad837425e9b07d84568d14898794
Gitweb:     http://git.kernel.org/tip/453f19eea7dbad837425e9b07d84568d14898794
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Fri, 20 Nov 2009 22:19:43 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 21 Nov 2009 14:11:35 +0100

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>
---
 include/linux/perf_event.h |    6 ++++++
 kernel/perf_event.c        |    8 +++++++-
 2 files changed, 13 insertions(+), 1 deletions(-)

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 @@ struct perf_pending_entry {
 
 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 perf_event {
 	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
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3852e26..1dfb6cc 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3710,7 +3710,11 @@ static int __perf_event_overflow(struct perf_event *event, int nmi,
 			perf_event_disable(event);
 	}
 
-	perf_event_output(event, nmi, data, regs);
+	if (event->overflow_handler)
+		event->overflow_handler(event, nmi, data, regs);
+	else
+		perf_event_output(event, nmi, data, regs);
+
 	return ret;
 }
 
@@ -4836,6 +4840,8 @@ inherit_event(struct perf_event *parent_event,
 	if (parent_event->attr.freq)
 		child_event->hw.sample_period = parent_event->hw.sample_period;
 
+	child_event->overflow_handler = parent_event->overflow_handler;
+
 	/*
 	 * Link it up in the child's context:
 	 */