[PATCH v2 1/4] perf/core: check return value of perf_event_read IPI

[David Carrillo-Cisneros]

The call to smp_call_function_single in perf_event_read() may fail and,
when it does, its error value is the one to return.

Signed-off-by: David Carrillo-Cisneros <davi...@google.com>
Reviewed-by: Stephane Eranian <eran...@google.com>
---
 kernel/events/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9345028..96523fd 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3469,9 +3469,9 @@ static int perf_event_read(struct perf_event *event, bool 
group)
                        .group = group,
                        .ret = 0,
                };
-               smp_call_function_single(event->oncpu,
-                                        __perf_event_read, &data, 1);
-               ret = data.ret;
+               ret = smp_call_function_single(event->oncpu,
+                                              __perf_event_read, &data, 1);
+               ret = ret ? : data.ret;
        } else if (event->state == PERF_EVENT_STATE_INACTIVE) {
                struct perf_event_context *ctx = event->ctx;
                unsigned long flags;
-- 
2.8.0.rc3.226.g39d4020