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>

2 files changed, 13 insertions, 1 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b5cdac0de370..a430ac3074af 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 3852e2656bb0..1dfb6cc4fdea 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:
          */