From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755233Ab2IHPZj (ORCPT ); Sat, 8 Sep 2012 11:25:39 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:33471 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754993Ab2IHPZh (ORCPT ); Sat, 8 Sep 2012 11:25:37 -0400 Date: Sat, 8 Sep 2012 08:25:33 -0700 From: gregkh To: Jianpeng Ma Cc: linux-kernel Subject: Re: About function __create_file in debugfs Message-ID: <20120908152533.GB1838@kroah.com> References: <201209081741013286843@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201209081741013286843@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 On Sat, Sep 08, 2012 at 05:41:05PM +0800, Jianpeng Ma wrote: > Hi: > At present,i used blktrace to trace block io.But i always met error, the message like: > >BLKTRACESETUP(2) /dev/sdc failed: 2/No such file or directory > >Thread 0 failed open /sys/kernel/debug/block/(null)/trace0: 2/No such file or directory > >Thread 2 failed open /sys/kernel/debug/block/(null)/trace2: 2/No such file or directory > >Thread 3 failed open /sys/kernel/debug/block/(null)/trace3: 2/No such file or directory > > >Thread 1 failed open /sys/kernel/debug/block/(null)/trace1: 2/No such file or directory > >FAILED to start thread on CPU 0: 1/Operation not permitted > >FAILED to start thread on CPU 1: 1/Operation not permitted > >FAILED to start thread on CPU 2: 1/Operation not permitted > >FAILED to start thread on CPU 3: 1/Operation not permitted > > But those isn't important. I add some message in kernel and found the reason is inode already existed. > But the function __create_file dosen't return correctly errno.So blktrace tool can't print correctly message. > I think func __create_file should return correctly message(ERR_PTR(error)) not NULL. Patches are always welcome :) greg k-h