From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751894AbeCUNiL (ORCPT ); Wed, 21 Mar 2018 09:38:11 -0400 Received: from mga09.intel.com ([134.134.136.24]:52900 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751615AbeCUNiJ (ORCPT ); Wed, 21 Mar 2018 09:38:09 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,340,1517904000"; d="scan'208";a="213344490" Date: Wed, 21 Mar 2018 08:38:06 -0500 From: Shiraz Saleem 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" , "Latif, Faisal" , Doug Ledford , Jason Gunthorpe , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4 3/6] RDMA/i40iw: Eliminate duplicate barriers on weakly-ordered archs Message-ID: <20180321133805.GA25412@ssaleem-MOBL4.amr.corp.intel.com> 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/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 19, 2018 at 08:47:45PM -0600, 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 Acked-by: Shiraz Saleem