From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit Date: Fri, 6 Feb 2015 23:14:53 -0800 Message-ID: <20150207071453.GA12268@linux.vnet.ibm.com> References: <1423167832-17609-1-git-send-email-riel@redhat.com> <1423167832-17609-2-git-send-email-riel@redhat.com> <20150206172209.GC21905@lerouge> <54D505E5.9000003@redhat.com> <20150206182258.GH21905@lerouge> <54D50D4C.8010505@redhat.com> <20150206231511.GA18934@lerouge> <54D58C3E.50804@redhat.com> <20150207063421.GY5418@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Frederic Weisbecker , kvm@vger.kernel.org, borntraeger@de.ibm.com, linux-kernel@vger.kernel.org, mtosatti@redhat.com, mingo@kernel.orgm, ak@linux.intel.com, oleg@redhat.com, masami.hiramatsu.pt@hitachi.com, lcapitulino@redhat.com, pbonzini@redhat.com To: Rik van Riel Return-path: Content-Disposition: inline In-Reply-To: <20150207063421.GY5418@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Fri, Feb 06, 2015 at 10:34:21PM -0800, Paul E. McKenney wrote: > On Fri, Feb 06, 2015 at 10:53:34PM -0500, Rik van Riel wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On 02/06/2015 06:15 PM, Frederic Weisbecker wrote: > > > > > Just a few things then: > > > > > > 1) In this case rename context_tracking_user_enter/exit() to > > > context_tracking_enter() and context_tracking_exit(), since it's > > > not anymore about user only but about any generic context. > > > > > > 2) We have the "WARN_ON_ONCE(!current->mm);" condition that is a > > > debug check specific to userspace transitions because kernel > > > threads aren't expected to resume to userspace. Can we also expect > > > that we never switch to/from guest from a kernel thread? AFAICS > > > this happens from an ioctl (thus user task) in x86 for kvm. But I > > > only know this case. > > > > > > 3) You might want to update a few comments that assume we only deal > > > with userspace transitions. > > > > > > 4) trace_user_enter/exit() should stay user-transitions specific. > > > > Paul, would you like me to send follow-up patches with the cleanups > > suggested by Frederic, or would you prefer me to send a new series > > with the cleanups integrated? > > I would prefer a new series, in order to prevent possible future > confusion. Of course, if Frederic would rather push them himself, I am fine with that. And in that case, you should ask him for his preferences, which just might differ from mine. ;-) Thanx, Paul