From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751594AbeCTO4e (ORCPT ); Tue, 20 Mar 2018 10:56:34 -0400 Received: from mail-wr0-f195.google.com ([209.85.128.195]:33930 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751269AbeCTO4c (ORCPT ); Tue, 20 Mar 2018 10:56:32 -0400 X-Google-Smtp-Source: AG47ELsTS2GOOmnie80H7CRja+ArE+TW4GWbBE9ic98x0Ae5IEUo6cbnNKLDL2U04+nRjLvPbKp/YA== Date: Tue, 20 Mar 2018 08:56:26 -0600 From: Jason Gunthorpe To: Sinan Kaya Cc: linux-rdma@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Faisal Latif , Shiraz Saleem , Doug Ledford , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 3/6] RDMA/i40iw: Eliminate duplicate barriers on weakly-ordered archs Message-ID: <20180320145626.GJ19744@ziepe.ca> References: <1521514068-8856-1-git-send-email-okaya@codeaurora.org> <1521514068-8856-4-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1521514068-8856-4-git-send-email-okaya@codeaurora.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 19, 2018 at 10:47:45PM -0400, Sinan Kaya wrote: > Code includes wmb() followed by writel(). writel() already has a barrier on > some architectures like arm64. > > This ends up CPU observing two barriers back to back before executing the > register write. > > Create a new wrapper function with relaxed write operator. Use the new > wrapper when a write is following a wmb(). > > Since code already has an explicit barrier call, changing writel() to > writel_relaxed(). > > Signed-off-by: Sinan Kaya > drivers/infiniband/hw/i40iw/i40iw_ctrl.c | 6 ++++-- > drivers/infiniband/hw/i40iw/i40iw_osdep.h | 1 + > drivers/infiniband/hw/i40iw/i40iw_uk.c | 2 +- > drivers/infiniband/hw/i40iw/i40iw_utils.c | 11 +++++++++++ > 4 files changed, 17 insertions(+), 3 deletions(-) The one looks fine Reviewed-by: Jason Gunthorpe Jason