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Wed, 14 Mar 2018 03:20:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1520997638; bh=26oYoO1jY7KROiUtX931ZvHDy54r40T7a7fQCzm8cLw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M3pkfwFBFZe3cIfpFlmk8JHfCUuc2NgRpkgqBXWZEDhHhNGkK+57gdQEYm++mALOg acprLBz3PtBLTmPxsCF5yatNX/fMjO63RyGnYO3dz65hTsAm9US4dGWNblpa9yHKid m2ZqtpunmEl6O+U72UgzDoGmPhx8tXh5eLChp6Mo= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 89BC66081A 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 3/7] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs Date: Tue, 13 Mar 2018 23:20:24 -0400 Message-Id: <1520997629-17361-3-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1520997629-17361-1-git-send-email-okaya@codeaurora.org> References: <1520997629-17361-1-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-20180313_202049_242181_98080D1E X-CRM114-Status: GOOD ( 11.76 ) 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, Doug Ledford , Michal Kalderon , linux-kernel@vger.kernel.org, Sinan Kaya , Jason Gunthorpe , Ariel Elior , 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() in multiple places. 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 Acked-by: Jason Gunthorpe --- drivers/infiniband/hw/qedr/verbs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c index 53f00db..ccd55f4 100644 --- a/drivers/infiniband/hw/qedr/verbs.c +++ b/drivers/infiniband/hw/qedr/verbs.c @@ -1870,7 +1870,7 @@ static int qedr_update_qp_state(struct qedr_dev *dev, if (rdma_protocol_roce(&dev->ibdev, 1)) { wmb(); - writel(qp->rq.db_data.raw, qp->rq.db); + writel_relaxed(qp->rq.db_data.raw, qp->rq.db); /* Make sure write takes effect */ mmiowb(); } @@ -3247,7 +3247,7 @@ int qedr_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, * redundant doorbell. */ wmb(); - writel(qp->sq.db_data.raw, qp->sq.db); + writel_relaxed(qp->sq.db_data.raw, qp->sq.db); /* Make sure write sticks */ mmiowb();