Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752883Ab3EHGyw (ORCPT ); Wed, 8 May 2013 02:54:52 -0400 Received: from mail-ee0-f42.google.com ([74.125.83.42]:34136 "EHLO mail-ee0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752081Ab3EHGyv (ORCPT ); Wed, 8 May 2013 02:54:51 -0400 Date: Wed, 8 May 2013 08:54:47 +0200 From: Ingo Molnar To: David Ahern Cc: Stephane Eranian , Arnaldo Carvalho de Melo , LKML , Mike Galbraith , Frederic Weisbecker , Peter Zijlstra , Jiri Olsa , Namhyung Kim Subject: Re: [PATCH] perf record: handle death by SIGTERM Message-ID: <20130508065447.GB5378@gmail.com> References: <1367864663-1309-1-git-send-email-dsahern@gmail.com> <20130507062947.GB17705@gmail.com> <51896A71.8010007@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51896A71.8010007@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1971 Lines: 61 * David Ahern wrote: > On 5/7/13 12:29 AM, Ingo Molnar wrote: > > > >* Stephane Eranian wrote: > > > >>This is a good fix. I have run into this infinite loop in perf report > >>many times. > > > >Hm, perf record should really not assume much about the perf.data and > >should avoid infinite loops ... > > > >So while making perf.data more consistent on SIGTERM is a nice fix, perf > >report should be fixed as well to detect loops and such. > > > >Thanks, > > > > Ingo > > > > This seems to do the trick: > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index 326068a..e82646f 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -2802,6 +2802,17 @@ int perf_session__read_header(struct > perf_session *session, int fd) > if (perf_file_header__read(&f_header, header, fd) < 0) > return -EINVAL; > > + /* > + * sanity check that perf.data was written cleanly: data size > + * is initialized to 0 and updated only if the on_exit function > + * is run. If data size is still 0 then the file cannot be > + * processed. > + */ > + if (f_header.data.size == 0) { > + pr_err("data size is 0. Was record properly terminated?\n"); > + return -1; > + } Hm, this detects the condition - but where does the looping come from? Can it happen with a perf.data that 'seems' clean but is corrupted (because not fully written, buggy kernel just crashed, etc.). In essence it would be _very_ nice if someone reproduced the looping and checked what to do to fix the looping itself. Or does the above data.size == 0 check fully fix the looping under every possible state of a perf.data? Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/