From: Masami Hiramatsu (Google) <[email protected]>

Instead of checking whether event->overflow_handler everytime in
is_default_overflow_handler(), just use a flag to check it once when
registering the handler.

Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
---
 include/linux/perf_event.h |    9 ++-------
 kernel/events/core.c       |    2 ++
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fd1d91017b99..40dd897e26b0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -902,6 +902,7 @@ struct perf_event {
        u64                             (*clock)(void);
        perf_overflow_handler_t         overflow_handler;
        void                            *overflow_handler_context;
+       bool                            default_overflow_compatible;
        struct bpf_prog                 *prog;
        u64                             bpf_cookie;
 
@@ -1505,13 +1506,7 @@ extern int perf_event_output(struct perf_event *event,
 static inline bool
 is_default_overflow_handler(struct perf_event *event)
 {
-       perf_overflow_handler_t overflow_handler = event->overflow_handler;
-
-       if (likely(overflow_handler == perf_event_output_forward))
-               return true;
-       if (unlikely(overflow_handler == perf_event_output_backward))
-               return true;
-       return false;
+       return event->default_overflow_compatible;
 }
 
 extern void
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 177e57c1a362..6bbbde82cb21 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12946,9 +12946,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
        } else if (is_write_backward(event)){
                event->overflow_handler = perf_event_output_backward;
                event->overflow_handler_context = NULL;
+               event->default_overflow_compatible = true;
        } else {
                event->overflow_handler = perf_event_output_forward;
                event->overflow_handler_context = NULL;
+               event->default_overflow_compatible = true;
        }
 
        perf_event__state_init(event);


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