From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752544AbaBZQPp (ORCPT ); Wed, 26 Feb 2014 11:15:45 -0500 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.225]:33796 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751078AbaBZQPo (ORCPT ); Wed, 26 Feb 2014 11:15:44 -0500 Date: Wed, 26 Feb 2014 11:15:42 -0500 From: Steven Rostedt To: Mathieu Desnoyers Cc: Peter Zijlstra , LKML , Ingo Molnar , Rusty Russell , Frederic Weisbecker , Andrew Morton Subject: Re: [RFC][PATCH] tracing: Warn and notify if tracepoints are not loaded due to module taint Message-ID: <20140226111542.15657cd6@gandalf.local.home> In-Reply-To: <192956891.30659.1393418892222.JavaMail.zimbra@efficios.com> References: <20140225191505.32b56105@gandalf.local.home> <188130295.30493.1393375141631.JavaMail.zimbra@efficios.com> <20140225194926.4eac5872@gandalf.local.home> <20140226085926.GF18404@twins.programming.kicks-ass.net> <192956891.30659.1393418892222.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 26 Feb 2014 12:48:12 +0000 (UTC) Mathieu Desnoyers wrote: > > How about instead of a WARN, you use a normal KERN_ERR printk(). There's > > no point to the entire WARN state dump, that's needlessly verbose. > > > > When you have a normal error print you can have as many as are required > > and put the mod name back in. > > The good old printk KERN_ERR is a very good idea. I agree that WARN() is > too verbose for our needs here. Actually, it's not so bad for the WARN() after my last patch to only allocate (or even process tracepoints) if mod->num_tracepionts is greater than zero. I didn't realize you were wasting memory for all modules that were loaded. My fear with the KERN_ERR is that it wont be noticeable enough. Where as a stack dump is something that will catch people's attention. And as Rusty has said, if you are loading a module that is forced, or something strange, it is broken. The failure of loading the tracepoints of a module is a bug if the module happens to have tracepoints. After the MOD_SIG fix, any failure should be a big banner bug. Either they are using a forced module with tracepoints that should not be loaded. Or they have tracepoints is a non-GPL module (which is also a big no-no). -- Steve