From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753853AbcHQU4S (ORCPT ); Wed, 17 Aug 2016 16:56:18 -0400 Received: from mail-pf0-f182.google.com ([209.85.192.182]:33685 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753038AbcHQUzc (ORCPT ); Wed, 17 Aug 2016 16:55:32 -0400 From: David Carrillo-Cisneros To: linux-kernel@vger.kernel.org Cc: "x86@kernel.org" , Ingo Molnar , Thomas Gleixner , Andi Kleen , Kan Liang , Peter Zijlstra , Vegard Nossum , Paul Turner , Stephane Eranian , David Carrillo-Cisneros Subject: [PATCH v3 1/4] perf/core: check return value of perf_event_read IPI Date: Wed, 17 Aug 2016 13:55:04 -0700 Message-Id: <1471467307-61171-2-git-send-email-davidcc@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 In-Reply-To: <1471467307-61171-1-git-send-email-davidcc@google.com> References: <1471467307-61171-1-git-send-email-davidcc@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- kernel/events/core.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 803481c..35afbfa 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3524,9 +3524,11 @@ 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); + /* 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; -- 2.8.0.rc3.226.g39d4020