From 71e7bc2bab77e64882c031c2af943c3256c1adb0 Mon Sep 17 00:00:00 2001 From: David Carrillo-Cisneros Date: Wed, 17 Aug 2016 13:55:04 -0700 Subject: [PATCH] perf/core: Check return value of the perf_event_read() IPI The call to smp_call_function_single in perf_event_read() may fail if an invalid or not online CPU index is passed. Warn user if such bug is present and return error. Signed-off-by: David Carrillo-Cisneros Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Paul Turner Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vegard Nossum Cc: Vince Weaver Link: http://lkml.kernel.org/r/1471467307-61171-2-git-send-email-davidcc@google.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index a5fc5c8cdfb0..5650f5317e0c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3549,9 +3549,10 @@ 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); + /* The event must have been read from an online CPU: */ + WARN_ON_ONCE(ret); + ret = ret ? : data.ret; } else if (event->state == PERF_EVENT_STATE_INACTIVE) { struct perf_event_context *ctx = event->ctx; unsigned long flags; -- 2.20.1