From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935157AbcLOCnw (ORCPT ); Wed, 14 Dec 2016 21:43:52 -0500 Received: from mail-pg0-f66.google.com ([74.125.83.66]:34424 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754005AbcLOCnZ (ORCPT ); Wed, 14 Dec 2016 21:43:25 -0500 From: Boqun Feng To: linux-kernel@vger.kernel.org Cc: "Paul E . McKenney " , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Colin King , Mark Rutland , Boqun Feng Subject: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Date: Thu, 15 Dec 2016 10:42:03 +0800 Message-Id: <20161215024204.28620-5-boqun.feng@gmail.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161215024204.28620-1-boqun.feng@gmail.com> References: <20161215024204.28620-1-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ->qsmask of an RCU leaf node is usually more sparse than the corresponding cpu_possible_mask. So replace the for_each_leaf_node_possible_cpu() in force_qs_rnp() with for_each_leaf_node_cpu() to save several checks. [Note we need to use "1UL << bit" instead of "1 << bit" to generate the corresponding mask for a bit because @mask is unsigned long, this was spotted by Colin Ian King and CoverityScan in a previous version of this patch.] Signed-off-by: Boqun Feng --- kernel/rcu/tree.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 4e5b81c843de..1ef13e63bc95 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3046,13 +3046,11 @@ static void force_qs_rnp(struct rcu_state *rsp, continue; } } - for_each_leaf_node_possible_cpu(rnp, cpu) { - unsigned long bit = leaf_node_cpu_bit(rnp, cpu); - if ((rnp->qsmask & bit) != 0) { - if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) - mask |= bit; - } - } + + for_each_leaf_node_cpu(rnp, rnp->qsmask, cpu) + if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) + mask |= leaf_node_cpu_bit(rnp, cpu); + if (mask != 0) { /* Idle/offline CPUs, report (releases rnp->lock. */ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags); -- 2.10.2