From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH v3 tip/core/rcu 0/14] Sparse-related updates for 3.13 Date: Sun, 13 Oct 2013 04:17:16 -0700 Message-ID: <20131013111716.GG5790@linux.vnet.ibm.com> References: <20131011231659.GA28062@linux.vnet.ibm.com> <20131012065326.GG15339@leaf> <20131012171345.GB5790@linux.vnet.ibm.com> <20131012173930.GD20321@order.stressinduktion.org> <20131012174354.GE20321@order.stressinduktion.org> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Josh Triplett , peterz@infradead.org, fweisbec@gmail.com, dhowells@redhat.com, edumazet@google.com, gaofeng@cn.fujitsu.com, mingo@kernel.org, bridge@lists.linux-foundation.org, jmorris@namei.org, dipankar@in.ibm.com, darren@dvhart.com, rostedt@goodmis.org, niv@us.ibm.com, mathieu.desnoyers@efficios.com, kuznet@ms2.inr.ac.ru, tglx@linutronix.de, johannes@sipsolutions.net, laijs@cn.fujitsu.com, yoshfuji@linux-ipv6.org, netdev@vger.kernel.org, linux-decnet-user@lists.sourceforge.net, linux-kernel@vger.kernel.org, kaber@trash.net, stephen@networkplumber.org, sbw@mit.edu, tgraf@suug.ch, akpm@linux-foundation.org, fengguang.wu@intel.com, davem@davemloft.net Return-path: Content-Disposition: inline In-Reply-To: <20131012174354.GE20321@order.stressinduktion.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: bridge-bounces@lists.linux-foundation.org Errors-To: bridge-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Sat, Oct 12, 2013 at 07:43:54PM +0200, Hannes Frederic Sowa wrote: > On Sat, Oct 12, 2013 at 07:39:30PM +0200, Hannes Frederic Sowa wrote: > > On Sat, Oct 12, 2013 at 10:13:45AM -0700, Paul E. McKenney wrote: > > > On Fri, Oct 11, 2013 at 11:53:27PM -0700, Josh Triplett wrote: > > > > On Fri, Oct 11, 2013 at 04:16:59PM -0700, Paul E. McKenney wrote: > > > > > Changes from v2: > > > > > > > > > > o Switch from rcu_assign_pointer() to ACCESS_ONCE() given that > > > > > the pointers are all --rcu and already visible to readers, > > > > > as suggested by Eric Dumazet and Josh Triplett. > > > > > > > > Hang on a moment. Do *none* of these cases need write memory barriers? > > > > > > Sigh. Some afternoons it doesn't pay to touch the keyboard. > > > > > > Thank you for catching this. I will fix, but at this point, I am thinking > > > in terms of 3.14 rather than 3.13 for this series. > > > > Some of them looked safe. You could also replace --rcu with __rcu in the > > comments while at it. > > Most of them deal with management, maybe a rtnl_assign_pointer with lockdep > check for rtnl lock could help to not clean up the wrong bits. > > I don't know if rtnl_assign_pointer is that a could name as it does not really > explain why the barrier is not needed there. :/ Beyond a certain point, I need to let people who know more about Linux's networking implementation handle this sort of thing. Thanx, Paul