From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761210AbYDZSyT (ORCPT ); Sat, 26 Apr 2008 14:54:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756096AbYDZSyI (ORCPT ); Sat, 26 Apr 2008 14:54:08 -0400 Received: from tomts20.bellnexxia.net ([209.226.175.74]:33862 "EHLO tomts20-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755558AbYDZSyH (ORCPT ); Sat, 26 Apr 2008 14:54:07 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhoFAOwWE0hMROPA/2dsb2JhbACBU6hj Date: Sat, 26 Apr 2008 14:54:03 -0400 From: Mathieu Desnoyers To: Greg Kroah-Hartman , Ingo Molnar Cc: linux-kernel@vger.kernel.org Subject: ftrace and debugfs weird interaction Message-ID: <20080426185403.GA22522@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 14:48:12 up 57 days, 14:59, 5 users, load average: 0.21, 0.44, 0.44 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, When trying to figure out what was going on with the sched tracer "tracing_enabled" file (sched-devel.git tree), I fell on this strange behavior : echo 1>tracing_enabled seems _not_ to send 1 to the tracing_ctrl_write callback. However, sending garbage, e.g. echo s> tracing_enabled, correctly sends the 's' character down the chain. echo 0>tracing_enabled sometimes results in the callback not even being called. The debugfs file has been created with entry = debugfs_create_file("tracing_enabled", 0644, d_tracer, &global_trace, &tracing_ctrl_fops); if (!entry) pr_warning("Could not create debugfs 'tracing_enabled' entry\n"); I wonder what kind of weird debugfs interaction we might have here ? Mathieu -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68