From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH] drivers/iommu: don't select DEBUG_FS for AMD_IOMMU_STATS Date: Tue, 5 Apr 2016 12:37:54 -0400 Message-ID: <20160405123754.30786ede@grimm.local.home> References: <1459041524-30929-1-git-send-email-paul.gortmaker@windriver.com> <20160405151951.GG11519@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160405151951.GG11519@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org To: Joerg Roedel Cc: Paul Gortmaker , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org List-Id: iommu@lists.linux-foundation.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