From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753449AbdDJUPg (ORCPT ); Mon, 10 Apr 2017 16:15:36 -0400 Received: from mail-pg0-f53.google.com ([74.125.83.53]:36810 "EHLO mail-pg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752351AbdDJUPJ (ORCPT ); Mon, 10 Apr 2017 16:15:09 -0400 From: David Carrillo-Cisneros To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Andi Kleen , Simon Que , Wang Nan , Jiri Olsa , He Kuang , Masami Hiramatsu , Stephane Eranian , Paul Turner , David Carrillo-Cisneros Subject: [PATCH 6/7] perf tool: protect empty evlists Date: Mon, 10 Apr 2017 13:14:31 -0700 Message-Id: <20170410201432.24807-7-davidcc@google.com> X-Mailer: git-send-email 2.12.2.715.g7642488e1d-goog In-Reply-To: <20170410201432.24807-1-davidcc@google.com> References: <20170410201432.24807-1-davidcc@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A common pattern in in pipe-mode bugs is accessing an empty evlist. Return NULL to make it easier to catch this problems. Signed-off-by: David Carrillo-Cisneros --- tools/perf/util/evlist.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 39942995f537..ba4788462325 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -257,11 +257,15 @@ void perf_evlist__splice_list_tail(struct perf_evlist *evlist, static inline struct perf_evsel *perf_evlist__first(struct perf_evlist *evlist) { + if (list_empty(&evlist->entries)) + return NULL; return list_entry(evlist->entries.next, struct perf_evsel, node); } static inline struct perf_evsel *perf_evlist__last(struct perf_evlist *evlist) { + if (list_empty(&evlist->entries)) + return NULL; return list_entry(evlist->entries.prev, struct perf_evsel, node); } -- 2.12.2.715.g7642488e1d-goog