From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753939AbbLIXDQ (ORCPT ); Wed, 9 Dec 2015 18:03:16 -0500 Received: from e37.co.us.ibm.com ([32.97.110.158]:45691 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297AbbLIXDO (ORCPT ); Wed, 9 Dec 2015 18:03:14 -0500 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH v2 tip/core/rcu 02/11] rcu: Clarify role of ->expmaskinitnext Date: Wed, 9 Dec 2015 15:02:59 -0800 Message-Id: <1449702188-493-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20151209230243.GA32518@linux.vnet.ibm.com> References: <20151209230243.GA32518@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15120923-0025-0000-0000-00001F6D7274 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Analogy with the ->qsmaskinitnext field might lead one to believe that ->expmaskinitnext tracks online CPUs. This belief is incorrect: Any CPU that has ever been online will have its bit set in the ->expmaskinitnext field. This commit therefore adds a comment to make this clear, at least to people who read comments. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index f32bebb6bc90..8151971a8978 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -178,6 +178,8 @@ struct rcu_node { /* beginning of each expedited GP. */ unsigned long expmaskinitnext; /* Online CPUs for next expedited GP. */ + /* Any CPU that has ever been online will */ + /* have its bit set. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ /* Only one bit will be set in this mask. */ int grplo; /* lowest-numbered CPU or group here. */ -- 2.5.2