From patchwork Sun Mar 25 14:39:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10306645 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 2AA23600F6 for ; Sun, 25 Mar 2018 14:40:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 12A44281B7 for ; Sun, 25 Mar 2018 14:40:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 05D4428DC9; Sun, 25 Mar 2018 14:40:18 +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=unavailable 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 4F688281B7 for ; Sun, 25 Mar 2018 14:40:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753553AbeCYOj4 (ORCPT ); Sun, 25 Mar 2018 10:39:56 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:59770 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753401AbeCYOjv (ORCPT ); Sun, 25 Mar 2018 10:39:51 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 2229760F6E; Sun, 25 Mar 2018 14:39:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521988790; bh=8hMjSv5miS58mapSBDKZufE4YDJkH2D8RQ+VOBGww/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QEbL+a0P59sDZBQP2biYdnLHdwaHSG7O9mlsoShpEpKr9e27tFPyMH4ejbmlKDcyu gl5nzxLTLf9DursnQ64R9cdJ6y5Qwu25xEAAMXzKi5ed8NbiRd9oI6x0rF0MJo2D1u zEqiD8B0Lbq6E7gvfHQUBB6h/oCGe2NUWA/jOBV0= 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 96AAA6030F; Sun, 25 Mar 2018 14:39:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521988788; bh=8hMjSv5miS58mapSBDKZufE4YDJkH2D8RQ+VOBGww/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LZnlqHvkgHl16UN6kJJ85KXqPeNyCGVYt2/+MUO8TltTc8HlNz+OIGFYOhQx92oyB ea3YXymjEk4wVmzUy2rMdLZS6qU7iIuGH/VeHFJxTfW0oO+RMz+6oBpyYU2bXeToWS QS6A8ZPI0BmxDAmLWshxy0nDwJcTv8BMBc1i4iac= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 96AAA6030F 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 , Netanel Belgazal , Saeed Bishara , Zorik Machulsky , "David S. Miller" , Tobias Klauser , linux-kernel@vger.kernel.org Subject: [PATCH v7 7/7] net: ena: Eliminate duplicate barriers on weakly-ordered archs Date: Sun, 25 Mar 2018 10:39:21 -0400 Message-Id: <1521988761-30344-8-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521988761-30344-1-git-send-email-okaya@codeaurora.org> References: <1521988761-30344-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Code includes barrier() 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 barrier(). Since code already has an explicit barrier call, changing writel() to writel_relaxed() and adding mmiowb() for ordering protection. Signed-off-by: Sinan Kaya --- drivers/net/ethernet/amazon/ena/ena_com.c | 8 ++++++-- drivers/net/ethernet/amazon/ena/ena_eth_com.h | 8 ++++++-- drivers/net/ethernet/amazon/ena/ena_netdev.c | 5 +++-- 3 files changed, 15 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c index bf2de52..1b9d3130 100644 --- a/drivers/net/ethernet/amazon/ena/ena_com.c +++ b/drivers/net/ethernet/amazon/ena/ena_com.c @@ -631,8 +631,10 @@ static u32 ena_com_reg_bar_read32(struct ena_com_dev *ena_dev, u16 offset) */ wmb(); - writel(mmio_read_reg, ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF); + writel_relaxed(mmio_read_reg, + ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF); + mmiowb(); for (i = 0; i < timeout; i++) { if (read_resp->req_id == mmio_read->seq_num) break; @@ -1826,7 +1828,9 @@ void ena_com_aenq_intr_handler(struct ena_com_dev *dev, void *data) /* write the aenq doorbell after all AENQ descriptors were read */ mb(); - writel((u32)aenq->head, dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF); + writel_relaxed((u32)aenq->head, + dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF); + mmiowb(); } int ena_com_dev_reset(struct ena_com_dev *ena_dev, diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.h b/drivers/net/ethernet/amazon/ena/ena_eth_com.h index 2f76572..6fdc753 100644 --- a/drivers/net/ethernet/amazon/ena/ena_eth_com.h +++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.h @@ -107,7 +107,8 @@ static inline int ena_com_sq_empty_space(struct ena_com_io_sq *io_sq) return io_sq->q_depth - 1 - cnt; } -static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq) +static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq, + bool relaxed) { u16 tail; @@ -116,7 +117,10 @@ static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq) pr_debug("write submission queue doorbell for queue: %d tail: %d\n", io_sq->qid, tail); - writel(tail, io_sq->db_addr); + if (relaxed) + writel_relaxed(tail, io_sq->db_addr); + else + writel(tail, io_sq->db_addr); return 0; } diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c index 6975150..a822e70 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c @@ -556,7 +556,8 @@ static int ena_refill_rx_bufs(struct ena_ring *rx_ring, u32 num) * issue a doorbell */ wmb(); - ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq); + ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq, true); + mmiowb(); } rx_ring->next_to_use = next_to_use; @@ -2151,7 +2152,7 @@ static netdev_tx_t ena_start_xmit(struct sk_buff *skb, struct net_device *dev) if (netif_xmit_stopped(txq) || !skb->xmit_more) { /* trigger the dma engine */ - ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq); + ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq, false); u64_stats_update_begin(&tx_ring->syncp); tx_ring->tx_stats.doorbells++; u64_stats_update_end(&tx_ring->syncp);