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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 C4BBDC2D0C2 for ; Thu, 2 Jan 2020 19:22:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B7B821D7D for ; Thu, 2 Jan 2020 19:22:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=maine.edu header.i=@maine.edu header.b="Fj90E7Xr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728280AbgABTWy (ORCPT ); Thu, 2 Jan 2020 14:22:54 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:36309 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727989AbgABTWy (ORCPT ); Thu, 2 Jan 2020 14:22:54 -0500 Received: by mail-qk1-f194.google.com with SMTP id a203so32491027qkc.3 for ; Thu, 02 Jan 2020 11:22:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=maine.edu; s=google; h=from:date:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=79zMLHtVC8xs2RALirflwpQq5tYiUVAhO2rVoiGE7aQ=; b=Fj90E7Xrg7UIIOshQt+/7b8UWs93Fl4Ty9jh3sOXmr3Njz5CMuipkdCaDqdycn4S2V grswIkrOntOtjjUwGZuOJlp2QdJyGMANs2uKmgqrfUGD8CROlm5neqQeV7USsAHio35Q zfoVVJTUX1crQojZHf/r9EyfdpHGY9WPByQ1M= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=79zMLHtVC8xs2RALirflwpQq5tYiUVAhO2rVoiGE7aQ=; b=FqTfkEAmTEHq4ZzKsMsIxn43o7ObDTmp5qurpcF1z9PRHU3GWwojKRUrsgRt3dAeyd EEgCwXjywzPHmFPaG2Kxn51aYgplfXs2xNbwm4XkDeo78Fsz+GJFf9qbVPv4wr3XXFqm FP7nqxY1iA/1itdG0FCc5o54cAdx1URve2zQ48DAR9l1TDOWv4EDRnYK7n49MTF8Uvyu 3yrnKw7X+Q1W9hpYSdzPEn1KoKzsm+CtKOP+xxagFldzTRWPLnv+L5q8Pw0KwuUlemAh Wa2jYQdTOv/Rk4oLzdjP506e7CxKYySWxEMOCVnNO2VcQ59KAb5us1b8qt2U7OW841Bo mbFg== X-Gm-Message-State: APjAAAVyF8qW2VGv3DTFVCfehSbn5cy9cSVyykpZS8hoMtFPILRjPACg 5oNPxG3ZYj6hsQn8Px/OUrJIDRS82CY= X-Google-Smtp-Source: APXvYqyN43NJDeYwEB+a6cY1qrCyvp6ADY9/wy2AlNTQvPM45PU9X08mtxGnArWV5fVF4LtNRzCFcg== X-Received: by 2002:a05:620a:166a:: with SMTP id d10mr67568449qko.37.1577992973148; Thu, 02 Jan 2020 11:22:53 -0800 (PST) Received: from macbook-air (weaver.eece.maine.edu. [130.111.218.23]) by smtp.gmail.com with ESMTPSA id r66sm15305288qkd.125.2020.01.02.11.22.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jan 2020 11:22:50 -0800 (PST) From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Thu, 2 Jan 2020 14:22:47 -0500 (EST) X-X-Sender: vince@macbook-air To: linux-kernel@vger.kernel.org cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim Subject: Re: [perf] perf_event_open() sometimes returning 0 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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) Vince