From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752164Ab3LBOwx (ORCPT ); Mon, 2 Dec 2013 09:52:53 -0500 Received: from mail-pd0-f182.google.com ([209.85.192.182]:56309 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691Ab3LBOwv (ORCPT ); Mon, 2 Dec 2013 09:52:51 -0500 Message-ID: <529C9EC0.70607@gmail.com> Date: Mon, 02 Dec 2013 07:52:48 -0700 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Masami Hiramatsu CC: acme@ghostprotocols.net, linux-kernel@vger.kernel.org, Srikar Dronamraju , "yrl.pp-manager.tt@hitachi.com" Subject: Re: [PATCH 1/2] perf probe: Improve error message when function not found References: <1385942827-11637-1-git-send-email-dsahern@gmail.com> <529C21C5.3030007@hitachi.com> In-Reply-To: <529C21C5.3030007@hitachi.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/1/13, 10:59 PM, Masami Hiramatsu wrote: > (2013/12/02 9:07), David Ahern wrote: >> When requesting a function from a userspace library the error message to >> the user is less than helpful. e.g., >> >> perf probe -x /lib64/libpthread-2.14.90.so -a 'lock_full=__pthread_mutex_lock_full' >> no symbols found in /lib64/libpthread-2.14.90.so, maybe install a debug package? >> Failed to load map. >> Error: Failed to add events. (-22) >> >> In this cae the symbol really does exist but is a local symbol which is >> filtered: >> >> nm /lib64/libpthread-2.14.90.so | grep __pthread_mutex_lock_full >> 0000000000005700 t __pthread_mutex_lock_full >> >> With this patch: >> perf probe -x /lib64/libpthread-2.14.90.so -a 'lock_full=__pthread_mutex_lock_full' >> >> no symbols found in /lib64/libpthread-2.14.90.so, maybe install a debug package? >> Failed to find function in /lib64/libpthread-2.14.90.so. Perhaps it is a local variable? > > Hmm, indeed current message is too less information, but your message looks > wired. I think just showing "Failed to find requested symbol in %s" is enough. :) I disagree. perf-probe filters non-global variables: if (sym->binding == STB_GLOBAL && strfilter__compare(available_func_filter, sym->name)) return 0; That needs to be explicitly stated in the error message -- only global symbols may be given. Between the 2 original error messages I wasted 2 hours strace'ing perf looking at files -- including all the debuginfo variants -- that perf opens. nm/objdump and every other tool sees the symbols yet perf throws out bizarre error messages -- "no symbols found in ..." and "Failed to load map". Let's fix those messages with something meaningful. David