From patchwork Fri Mar 16 16:16:29 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10289007 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 645066061F for ; Fri, 16 Mar 2018 16:18:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5553528FB6 for ; Fri, 16 Mar 2018 16:18:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 49CD328FB8; Fri, 16 Mar 2018 16:18:50 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BDE9C28FB6 for ; Fri, 16 Mar 2018 16:18:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754635AbeCPQSV (ORCPT ); Fri, 16 Mar 2018 12:18:21 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:40058 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754758AbeCPQRP (ORCPT ); Fri, 16 Mar 2018 12:17:15 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 63AF460F6B; Fri, 16 Mar 2018 16:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521217034; bh=C7ppIVAn7oBg48ynG45Ehi411LvHhXrVvznztRVFPXE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VWbYjBL8K/+T9SBCzdUtQo/eDGEvDztBl2Di1LdD5Y35yHsrSMib1w2FZWUxQlQRZ d25v7gxIQkGcwkSARcfahvs6yrmNuUTdbV7Oec+OmzhA/MJCxjV77RgIroYfPXSqpU El8yv/VHpgvyf3E9GaqYrPEd+VR6OUY7PTVeDsVI= Received: from drakthul.qualcomm.com (global_nat1_iad_fw.qualcomm.com [129.46.232.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: okaya@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 8A19060F78; Fri, 16 Mar 2018 16:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521217033; bh=C7ppIVAn7oBg48ynG45Ehi411LvHhXrVvznztRVFPXE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CRVzgWwPLMypyYZXU7pf8+UTaXcEvTw0aOrzYf3Q12UqgOXBgiPDCLkDNKtVjSVrz ij1Xa8QiMWqhy/w91eFtFzjd6Q+A7llQ5yB5N542226QSiky5+3hGuJeIcVr9UA3Yx LTwK6++ZKHpzpQ+sGVdZbXpHmjaGT+kbDWFtZA1Y= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8A19060F78 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya To: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , Yishai Hadas , Doug Ledford , Jason Gunthorpe , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 16/18] IB/mlx4: Eliminate duplicate barriers on weakly-ordered archs Date: Fri, 16 Mar 2018 12:16:29 -0400 Message-Id: <1521216991-28706-17-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521216991-28706-1-git-send-email-okaya@codeaurora.org> References: <1521216991-28706-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/infiniband/hw/mlx4/qp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c index f045491..74b27b0 100644 --- a/drivers/infiniband/hw/mlx4/qp.c +++ b/drivers/infiniband/hw/mlx4/qp.c @@ -3880,8 +3880,8 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, */ wmb(); - writel(qp->doorbell_qpn, - to_mdev(ibqp->device)->uar_map + MLX4_SEND_DOORBELL); + writel_relaxed(qp->doorbell_qpn, + to_mdev(ibqp->device)->uar_map + MLX4_SEND_DOORBELL); /* * Make sure doorbells don't leak out of SQ spinlock