From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759584AbcDEQiC (ORCPT ); Tue, 5 Apr 2016 12:38:02 -0400 Received: from smtprelay0149.hostedemail.com ([216.40.44.149]:35792 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758170AbcDEQiA (ORCPT ); Tue, 5 Apr 2016 12:38:00 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:1981:2194:2199:2393:2553:2559:2562:2693:2894:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4250:5007:6119:6261:7875:7903:10004:10400:10848:10967:11026:11232:11473:11658:11914:12296:12517:12519:12740:13069:13311:13357:13439:14096:14097:14181:14659:14721:21080:30054:30062:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: year49_2869020519a03 X-Filterd-Recvd-Size: 2442 Date: Tue, 5 Apr 2016 12:37:54 -0400 From: Steven Rostedt To: Joerg Roedel Cc: Paul Gortmaker , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH] drivers/iommu: don't select DEBUG_FS for AMD_IOMMU_STATS Message-ID: <20160405123754.30786ede@grimm.local.home> In-Reply-To: <20160405151951.GG11519@8bytes.org> References: <1459041524-30929-1-git-send-email-paul.gortmaker@windriver.com> <20160405151951.GG11519@8bytes.org> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 Apr 2016 17:19:51 +0200 Joerg Roedel wrote: > On Sat, Mar 26, 2016 at 09:18:44PM -0400, Paul Gortmaker wrote: > > We have at least one big banner telling people that they should > > not deploy production kernels with DEBUG options enabled, but > > at the same time, we make it hard for people to turn DEBUG_FS > > off when we select (vs. depend on) the CONFIG_DEBUG_FS option. > > > > Since we actively discourage people using debug-like features > > on any builds that are production oriented (see trace_printk > > banner for one example), so a generic sounding option should > > not select DEBUG_FS. > > That reasoning sounds a bit odd, as most production kernels have > DEBUG_FS enabled anyway, and I see no problem with that. > > Disabling all debug features in 'production kernels' is a bit overkill. > Only if the feature has any runtime impact (performance, memory > consumption, security, ...) it makes sense to disable it for production > kernels. > > Other features could stay enabled, and DEBUG_FS is one of them. For some > debug features we even don't offer a way to disable them, see BUG_ON, > WARN_ON and friends. > I will argue that people have asked me to move tracing out of debugfs (which is why I created tracefs) because the problem with debugfs is that it opens up a entire system that is not well scrutinized, and holds lots of possible ways to crack the kernel. Disabling debugfs does help with the "security" point you mentioned above. -- Steve