From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755650Ab3KFUA7 (ORCPT ); Wed, 6 Nov 2013 15:00:59 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:53465 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755427Ab3KFUA5 (ORCPT ); Wed, 6 Nov 2013 15:00:57 -0500 Date: Wed, 6 Nov 2013 12:00:44 -0800 From: "Paul E. McKenney" To: Lai Jiangshan Cc: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] srcu: API for barrier after srcu read unlock Message-ID: <20131106200044.GN18245@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1383592884-2535-1-git-send-email-mst@redhat.com> <20131104205524.GY3947@linux.vnet.ibm.com> <527A5985.6050309@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <527A5985.6050309@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13110620-6688-0000-0000-0000033C7B57 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 06, 2013 at 11:00:21PM +0800, Lai Jiangshan wrote: > On 11/05/2013 04:55 AM, Paul E. McKenney wrote: > > On Mon, Nov 04, 2013 at 10:36:17PM +0200, Michael S. Tsirkin wrote: > >> srcu read lock/unlock include a full memory barrier > >> but that's an implementation detail. > >> Add an API for make memory fencing explicit for > >> users that need this barrier, to make sure we > >> can change it as needed without breaking all users. > >> > >> Acked-by: "Paul E. McKenney" > >> Signed-off-by: Michael S. Tsirkin > > > > Reviewed-by: Paul E. McKenney > > Acked-by: "Lai Jiangshan" Very good, queued for 3.14. Thanx, Paul > >> --- > >> include/linux/srcu.h | 14 ++++++++++++++ > >> 1 file changed, 14 insertions(+) > >> > >> diff --git a/include/linux/srcu.h b/include/linux/srcu.h > >> index c114614..9b058ee 100644 > >> --- a/include/linux/srcu.h > >> +++ b/include/linux/srcu.h > >> @@ -237,4 +237,18 @@ static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) > >> __srcu_read_unlock(sp, idx); > >> } > >> > >> +/** > >> + * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock > >> + * > >> + * Converts the preceding srcu_read_unlock into a two-way memory barrier. > >> + * > >> + * Call this after srcu_read_unlock, to guarantee that all memory operations > >> + * that occur after smp_mb__after_srcu_read_unlock will appear to happen after > >> + * the preceding srcu_read_unlock. > >> + */ > >> +static inline void smp_mb__after_srcu_read_unlock(void) > >> +{ > >> + /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ > >> +} > >> + > >> #endif > >> -- > >> MST > >> > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > >