From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 208FDC33C99 for ; Tue, 7 Jan 2020 07:39:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5F13206DB for ; Tue, 7 Jan 2020 07:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727328AbgAGHjz (ORCPT ); Tue, 7 Jan 2020 02:39:55 -0500 Received: from mga07.intel.com ([134.134.136.100]:33726 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725781AbgAGHjy (ORCPT ); Tue, 7 Jan 2020 02:39:54 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Jan 2020 23:39:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,404,1571727600"; d="scan'208";a="223097653" Received: from um.fi.intel.com (HELO um) ([10.237.72.57]) by orsmga003.jf.intel.com with ESMTP; 06 Jan 2020 23:39:51 -0800 From: Alexander Shishkin To: Mark Rutland , Vince Weaver , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , alexander.shishkin@linux.intel.com Subject: Re: [PATCH] perf: correctly handle failed perf_get_aux_event() (was: Re: [perf] perf_event_open() sometimes returning 0) In-Reply-To: <20200106120338.GC9630@lakrids.cambridge.arm.com> References: <20200106120338.GC9630@lakrids.cambridge.arm.com> Date: Tue, 07 Jan 2020 09:39:51 +0200 Message-ID: <87o8vfbtq0.fsf@ashishki-desk.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mark Rutland writes: > On Thu, Jan 02, 2020 at 02:22:47PM -0500, Vince Weaver wrote: >> On Thu, 2 Jan 2020, Vince Weaver wrote: >> >> > so I was tracking down some odd behavior in the perf_fuzzer which turns >> > out to be because perf_even_open() sometimes returns 0 (indicating a file >> > descriptor of 0) even though as far as I can tell stdin is still open. > > Yikes. > >> error is triggered if aux_sample_size has non-zero value. >> >> seems to be this line in kernel/events/core.c: >> >> >> if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) >> goto err_locked; >> >> >> (note, err is never set) > > Looks like that was introduced in commit: > > ab43762ef010967e ("perf: Allow normal events to output AUX data") > > I guess we should return -EINVAL in this case. That's right. Thanks for looking into this! > diff --git a/kernel/events/core.c b/kernel/events/core.c > index a1f8bde19b56..2173c23c25b4 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -11465,8 +11465,10 @@ SYSCALL_DEFINE5(perf_event_open, > } > } > > - if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) > + if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) { > + err = -EINVAL; > goto err_locked; > + } > FWIW, Acked-by: Alexander Shishkin Thanks, -- Alex