From patchwork Fri Jun 18 10:52:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Esben Haabendal X-Patchwork-Id: 12331035 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B9C7C48BDF for ; Fri, 18 Jun 2021 10:53:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6BBD26128C for ; Fri, 18 Jun 2021 10:53:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233847AbhFRKzO (ORCPT ); Fri, 18 Jun 2021 06:55:14 -0400 Received: from first.geanix.com ([116.203.34.67]:53890 "EHLO first.geanix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230437AbhFRKym (ORCPT ); Fri, 18 Jun 2021 06:54:42 -0400 Received: from localhost (80-62-117-165-mobile.dk.customer.tdc.net [80.62.117.165]) by first.geanix.com (Postfix) with ESMTPSA id E13034C3657; Fri, 18 Jun 2021 10:52:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=geanix.com; s=first; t=1624013551; bh=AhyE6isg6VavideXUV32Ga9HpCHHdtL8iBqEJ8xAQ6Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IBx7ezM/tE3xoRjX27fCXGRC6JiArooX8DWHvrAmbc5gsTw9UGnifXZ/PUnf17VS8 LL45QuuEQM7jgugfFVuGNSrYphhFALh2z5m+CUNW9dS7fFFxiMADwNq7cjdBwtYOcO vA3b7VqQ9snsOZ3nqWo9OlpWBB1lGf5E4AELnxbM/BCbXNADpTv+Hh/fFF9BK86O1K a8Nkr4kN6tRAVoQtpRFsP+16OnqOn4rui7XFCfn7EQ0D66cDSGvaEeqJEeB0O2x/LV pFOl/ajZfNBseSyssqyr0/XyzyYTD4MEQpRz09wOximhLXBRZMsEID4e9ZYxOyqdA6 wzhGIdKwl7ANg== From: Esben Haabendal To: netdev@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , Michal Simek , Michael Walle , Jesse Brandeburg , Andrew Lunn , Wang Hai , Zhang Changzhong , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] net: ll_temac: Add memory-barriers for TX BD access Date: Fri, 18 Jun 2021 12:52:28 +0200 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Add a couple of memory-barriers to ensure correct ordering of read/write access to TX BDs. In xmit_done, we should ensure that reading the additional BD fields are only done after STS_CTRL_APP0_CMPLT bit is set. When xmit_done marks the BD as free by setting APP0=0, we need to ensure that the other BD fields are reset first, so we avoid racing with the xmit path, which writes to the same fields. Finally, making sure to read APP0 of next BD after the current BD, ensures that we see all available buffers. Signed-off-by: Esben Haabendal --- drivers/net/ethernet/xilinx/ll_temac_main.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index e82f162cd80c..9797aa3221d1 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -774,12 +774,15 @@ static void temac_start_xmit_done(struct net_device *ndev) stat = be32_to_cpu(cur_p->app0); while (stat & STS_CTRL_APP0_CMPLT) { + /* Make sure that the other fields are read after bd is + * released by dma + */ + rmb(); dma_unmap_single(ndev->dev.parent, be32_to_cpu(cur_p->phys), be32_to_cpu(cur_p->len), DMA_TO_DEVICE); skb = (struct sk_buff *)ptr_from_txbd(cur_p); if (skb) dev_consume_skb_irq(skb); - cur_p->app0 = 0; cur_p->app1 = 0; cur_p->app2 = 0; cur_p->app3 = 0; @@ -788,6 +791,12 @@ static void temac_start_xmit_done(struct net_device *ndev) ndev->stats.tx_packets++; ndev->stats.tx_bytes += be32_to_cpu(cur_p->len); + /* app0 must be visible last, as it is used to flag + * availability of the bd + */ + smp_mb(); + cur_p->app0 = 0; + lp->tx_bd_ci++; if (lp->tx_bd_ci >= lp->tx_bd_num) lp->tx_bd_ci = 0; @@ -814,6 +823,9 @@ static inline int temac_check_tx_bd_space(struct temac_local *lp, int num_frag) if (cur_p->app0) return NETDEV_TX_BUSY; + /* Make sure to read next bd app0 after this one */ + rmb(); + tail++; if (tail >= lp->tx_bd_num) tail = 0;