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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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180316_121725_436112_D39442FD X-CRM114-Status: GOOD ( 12.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-rdma@vger.kernel.org, linux-arm-msm@vger.kernel.org, Yishai Hadas , linux-kernel@vger.kernel.org, Sinan Kaya , Jason Gunthorpe , Doug Ledford , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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