From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 D8900C33CB3 for ; Thu, 30 Jan 2020 18:44:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE6F52173E for ; Thu, 30 Jan 2020 18:44:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580409871; bh=m6bc5YESLPX3tHV+DdMc2TMiL3pkOqdd2l98jsO9fXw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ST7jwzHP7Zc36qAh6Tub8H7aTrNDRTYDy26WtyQCRjm4UhPdrfnrjhCDJWfzrRoLS kgBaiWn9TAC3dAAxSq6uXw+b7AcqIPH//qm/f/Yw8hFDeDjcFtHynA0kSRWyNOY0L9 LJAtMNuQXZDb9f02n16lGxo97MRs3OIUJRtveVqo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730601AbgA3Soa (ORCPT ); Thu, 30 Jan 2020 13:44:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:53656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730835AbgA3So3 (ORCPT ); Thu, 30 Jan 2020 13:44:29 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A043C2173E; Thu, 30 Jan 2020 18:44:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580409869; bh=m6bc5YESLPX3tHV+DdMc2TMiL3pkOqdd2l98jsO9fXw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JBzlMkxoxBC8pAejmHCjkHUdzR6miySMfAzyiiCO28sKTKrYP0ToxVQek63yc4/d0 TqAcO0xPtA7UBiCQNtwezVsI7bvjvAqSZg6aEY6Af4jtiaP7Skeq5hgAPF+ALwfVKL 1fDvOO75sPN/jt4eRHjbVJL3Y6zPcoxhWcdkHUw8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Si-Wei Liu , Liran Alon , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 066/110] net: Google gve: Remove dma_wmb() before ringing doorbell Date: Thu, 30 Jan 2020 19:38:42 +0100 Message-Id: <20200130183622.527019051@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200130183613.810054545@linuxfoundation.org> References: <20200130183613.810054545@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Liran Alon [ Upstream commit b54ef37b1ce892fdf6b632d566246d2f2f539910 ] Current code use dma_wmb() to ensure Rx/Tx descriptors are visible to device before writing to doorbell. However, these dma_wmb() are wrong and unnecessary. Therefore, they should be removed. iowrite32be() called from gve_rx_write_doorbell()/gve_tx_put_doorbell() should guaratee that all previous writes to WB/UC memory is visible to device before the write done by iowrite32be(). E.g. On ARM64, iowrite32be() calls __iowmb() which expands to dma_wmb() and only then calls __raw_writel(). Reviewed-by: Si-Wei Liu Signed-off-by: Liran Alon Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/ethernet/google/gve/gve_rx.c | 2 -- drivers/net/ethernet/google/gve/gve_tx.c | 6 ------ 2 files changed, 8 deletions(-) diff --git a/drivers/net/ethernet/google/gve/gve_rx.c b/drivers/net/ethernet/google/gve/gve_rx.c index edec61dfc8687..9f52e72ff641d 100644 --- a/drivers/net/ethernet/google/gve/gve_rx.c +++ b/drivers/net/ethernet/google/gve/gve_rx.c @@ -418,8 +418,6 @@ bool gve_clean_rx_done(struct gve_rx_ring *rx, int budget, rx->cnt = cnt; rx->fill_cnt += work_done; - /* restock desc ring slots */ - dma_wmb(); /* Ensure descs are visible before ringing doorbell */ gve_rx_write_doorbell(priv, rx); return gve_rx_work_pending(rx); } diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c index f4889431f9b70..d0244feb03011 100644 --- a/drivers/net/ethernet/google/gve/gve_tx.c +++ b/drivers/net/ethernet/google/gve/gve_tx.c @@ -487,10 +487,6 @@ netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev) * may have added descriptors without ringing the doorbell. */ - /* Ensure tx descs from a prior gve_tx are visible before - * ringing doorbell. - */ - dma_wmb(); gve_tx_put_doorbell(priv, tx->q_resources, tx->req); return NETDEV_TX_BUSY; } @@ -505,8 +501,6 @@ netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev) if (!netif_xmit_stopped(tx->netdev_txq) && netdev_xmit_more()) return NETDEV_TX_OK; - /* Ensure tx descs are visible before ringing doorbell */ - dma_wmb(); gve_tx_put_doorbell(priv, tx->q_resources, tx->req); return NETDEV_TX_OK; } -- 2.20.1