From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755181Ab3EHPS4 (ORCPT ); Wed, 8 May 2013 11:18:56 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:50305 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753581Ab3EHPSx (ORCPT ); Wed, 8 May 2013 11:18:53 -0400 From: David Ahern To: acme@ghostprotocols.net, linux-kernel@vger.kernel.org Cc: David Ahern , Ingo Molnar , Frederic Weisbecker , Peter Zijlstra , Jiri Olsa , Namhyung Kim , Stephane Eranian Subject: [PATCH] perf: detect loops processing events Date: Wed, 8 May 2013 09:18:47 -0600 Message-Id: <1368026327-4741-1-git-send-email-dsahern@gmail.com> X-Mailer: git-send-email 1.7.10.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recovery algorithm in __perf_session__process_events attempts to remap a perf.data file with a different file_offset and try again at a new head position. Both of these adjustment rely on page_offset. If page_offset is 0 then file_offset and head never change which means the remap attempt is the same and the fetch_mmaped_event is the same and the processing just loops forever. Detect this condition and warn the user. Signed-off-by: David Ahern Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian --- tools/perf/util/session.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index cf1fe01..1c4dc45 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1235,6 +1235,12 @@ more: } page_offset = page_size * (head / page_size); + /* catch looping where we never make forward progress. */ + if (page_offset == 0) { + pr_err("Loop detection processing events. Is file corrupted?\n"); + return -1; + } + file_offset += page_offset; head -= page_offset; goto remap; -- 1.7.10.1