From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753044AbbJFU3m (ORCPT ); Tue, 6 Oct 2015 16:29:42 -0400 Received: from casper.infradead.org ([85.118.1.10]:41432 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752574AbbJFU3l (ORCPT ); Tue, 6 Oct 2015 16:29:41 -0400 Date: Tue, 6 Oct 2015 22:29:37 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to allow consolidation Message-ID: <20151006202937.GX3604@twins.programming.kicks-ass.net> References: <20151006162907.GA12020@linux.vnet.ibm.com> <1444148977-14108-1-git-send-email-paulmck@linux.vnet.ibm.com> <1444148977-14108-2-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1444148977-14108-2-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 06, 2015 at 09:29:21AM -0700, Paul E. McKenney wrote: > +static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp, > + struct rcu_node *rnp, bool wake) > +{ > + unsigned long flags; > + unsigned long mask; > + > + raw_spin_lock_irqsave(&rnp->lock, flags); Normally we require a comment with barriers, explaining the order and the pairing etc.. :-) > + smp_mb__after_unlock_lock(); > + for (;;) { > + if (!sync_rcu_preempt_exp_done(rnp)) { > + raw_spin_unlock_irqrestore(&rnp->lock, flags); > + break; > + } > + if (rnp->parent == NULL) { > + raw_spin_unlock_irqrestore(&rnp->lock, flags); > + if (wake) { > + smp_mb(); /* EGP done before wake_up(). */ > + wake_up(&rsp->expedited_wq); > + } > + break; > + } > + mask = rnp->grpmask; > + raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ > + rnp = rnp->parent; > + raw_spin_lock(&rnp->lock); /* irqs already disabled */ > + smp_mb__after_unlock_lock(); > + rnp->expmask &= ~mask; > + } > +}