Received: by 10.213.65.68 with SMTP id h4csp1360476imn; Wed, 14 Mar 2018 18:51:14 -0700 (PDT) X-Google-Smtp-Source: AG47ELutkrpRiGtV4B39N1wbEvF7bB2dlCEbEQ3xs5O6Hcm1nRi3tAJ7es15kEfo7qd9pymk02So X-Received: by 10.99.97.130 with SMTP id v124mr5374679pgb.351.1521078673929; Wed, 14 Mar 2018 18:51:13 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1521078673; cv=none; d=google.com; s=arc-20160816; b=NAdsBxPektN/CmMzXVQP3BG9ladWAd4nOfdCOyfpHR8zHsaiob7n5laZGIrKWrndlB rjF/YV34T/JodOE8nj+QYiT7HX2YR13BkBatOmwP0L/QNSuTbrOGLjtyouESy1FF9HuF I2+/KVuo+is8SViHBHOa7qgMmnqSrTn3aMIG4N6XKHt6sLOEuRU/SRzmYjzaYemGVpDe 3Tkwv/IqjqGRlmo0lNrB4DbCLR8rddvo4QFenPlbWY6l225CtkhdrJn96LkLLJAQq4BN 98xzKy5URM/31WC49faljqucL0tmrSJQqwL4U+Z9vz2Z1JUtW6E+lrgZar+dTqbi3aSk dfBA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:cc:to:subject:message-id:date:from :references:in-reply-to:mime-version:dkim-signature :arc-authentication-results; bh=oNiB+jVHutez2VuK2xcIga6ti2APg1mS9cQzBeIlo3A=; b=0SLCWGB8+AyKgA6U0syCojxMz1MbURsfzhHzl7YGfZk3vL6EuWtREVrYbsciNlmI5O 9FZzxRljqX+chwvmq+gm5yM7OEcOgt2lJdOhXmZpZaQluNK3eAvCvzoDTZJeFG63phdJ Ie0tFa3oWPI+jOwcpOsNAo/gYLaihkHAlyPKCP3pG6vg9eX9SixAz7+IWg+/99+QwEPH QFBKNEs7XoO7EL99pBgrRAbYTSmIaF2ZRIi/qOSpzkx98Qo5gHZGEHZb6fG440hObDQc QB8E7CmktplImqDpvlCMoZVgz90TX4lLV8N5k8QCeHmg4T1EybYLUkmdTvooFzJWuJ2o XwqA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=YcO2+U8v; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id b12-v6si2959851plk.189.2018.03.14.18.50.59; Wed, 14 Mar 2018 18:51:13 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=YcO2+U8v; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751711AbeCOBuI (ORCPT + 99 others); Wed, 14 Mar 2018 21:50:08 -0400 Received: from mail-qk0-f194.google.com ([209.85.220.194]:39264 "EHLO mail-qk0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751408AbeCOBuG (ORCPT ); Wed, 14 Mar 2018 21:50:06 -0400 Received: by mail-qk0-f194.google.com with SMTP id z197so5714741qkb.6; Wed, 14 Mar 2018 18:50:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=oNiB+jVHutez2VuK2xcIga6ti2APg1mS9cQzBeIlo3A=; b=YcO2+U8vNMLixwoe42r4jy+rkMWq5vLzgtX7yOp3WEKA4uu+T9mLw4c1Qf4nT5b7Fw viBoWotyp7EWUCtSJl74+kzstT7qZf4pJUXtkxZMkMf4ClwXkK6v1PYwe5JPax/aaqZf EGAxnSLlv90CYA8akerTdupqnMZsxZIw8ssHz0uShJCfoV+c4zTmQJG+y4a9f9ta6bee 2AmG5CuW/oIyvSn/qYObzQjPxakztoM5WQaNKVhE/TeyQUHuUOFZeoJwEq6UusBqm9Mn XzxtSJcqOljer3PNTXbVeV9eKawgmzcm2ofUmUMGaUNpbJ5JsI4HjPjGCfL5Hr1OuRNX tyYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=oNiB+jVHutez2VuK2xcIga6ti2APg1mS9cQzBeIlo3A=; b=JhI9P34ovHel5TG4MoWqTehnGQ0NDi3w3CzZkxr0T5qD2zBD8XJRXr+//6X9gEX7FR vh7b7wZKAkPTb0Xw5n2MKIo0qFnoLmw85RF8ikuzqO4hdUXZ4yuU8ijC9yG2tpcHfJui un1GZH8WxhjX14D8HQooJMqeUHHMFbKo+fYPxrdyZFYxPlGaXt2Q1Ele9TFI3wUHw+s6 BHxOSpPi2Id9ECPZQFSWSu2ml2j31yjnb6k93ve6gmwFeor1gx8+Ixxxhh4oGiXXzUx2 ll3LeUv7fIq1ar2HdK42PzOKUJQrsg2xUupzz0TavlBUs6fjQwGS6RoThnRnGXNQYFkR iO9Q== X-Gm-Message-State: AElRT7ESkZKYFFFUP6ptfrjiF9qGA1Q1uamD+hlNJNy3Kz11yH/nyCJg FNrAmW6BbHXL72/cmsvQ7Q6fLW5Z2cUwBdtcggw= X-Received: by 10.55.18.228 with SMTP id 97mr9937945qks.93.1521078605773; Wed, 14 Mar 2018 18:50:05 -0700 (PDT) MIME-Version: 1.0 Received: by 10.140.89.138 with HTTP; Wed, 14 Mar 2018 18:50:05 -0700 (PDT) In-Reply-To: <1520997629-17361-5-git-send-email-okaya@codeaurora.org> References: <1520997629-17361-1-git-send-email-okaya@codeaurora.org> <1520997629-17361-5-git-send-email-okaya@codeaurora.org> From: Alexander Duyck Date: Wed, 14 Mar 2018 18:50:05 -0700 Message-ID: Subject: Re: [PATCH 5/7] igb: eliminate duplicate barriers on weakly-ordered archs To: Sinan Kaya Cc: Netdev , Timur Tabi , sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jeff Kirsher , intel-wired-lan , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 13, 2018 at 8:20 PM, Sinan Kaya wrote: > 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/net/ethernet/intel/igb/igb_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c > index b88fae7..ba8ccb5 100644 > --- a/drivers/net/ethernet/intel/igb/igb_main.c > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > @@ -8072,7 +8072,7 @@ void igb_alloc_rx_buffers(struct igb_ring *rx_ring, u16 cleaned_count) > * such as IA-64). > */ > wmb(); > - writel(i, rx_ring->tail); > + writel_relaxed(i, rx_ring->tail); > } > } > This one missed the writel at the end of igb_tx_map().