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[209.132.180.67]) by mx.google.com with ESMTP id p69si3048946pfl.309.2018.03.14.18.49.46; Wed, 14 Mar 2018 18:50:00 -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=HrJaIBf6; 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 S1752025AbeCOBsp (ORCPT + 99 others); Wed, 14 Mar 2018 21:48:45 -0400 Received: from mail-qk0-f194.google.com ([209.85.220.194]:39142 "EHLO mail-qk0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751711AbeCOBsm (ORCPT ); Wed, 14 Mar 2018 21:48:42 -0400 Received: by mail-qk0-f194.google.com with SMTP id z197so5711928qkb.6; Wed, 14 Mar 2018 18:48:41 -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=0iGeT7iE9cextZ4bUIvhP08fPPuH4lbTaObO5kp4Uws=; b=HrJaIBf6+hPwpAsj9y31YmPG2p/AAdS7aMH6ue44yX/Gfn4/uPnCYHZGjfgbNxdebS TKMM03tU58cC8sLLvpbZrnUJaMfrfOneKRX0JuCXGqjEGFRlJYbX2Tc2sFs46UpT3sdD 1SC96XAtwIBxZigkPqG68MW92baYHKJF/NDf1Ro/4Iynq0JZu3sWu9znacwmcd8Fhlb5 v6pBmce93JxUqFj9RCFcYTCC0EPpXeGKTPa8/rUBYrwJ8wF+q7idt+/5hoTyL0SfiCEl eu+X5mT2iT2KIUYL/xpwOORyGn2bGuJOhYSMwjEarzCiPJpl54mcgMxK2xx3M6Jua5xS h6TA== 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=0iGeT7iE9cextZ4bUIvhP08fPPuH4lbTaObO5kp4Uws=; b=ZW1VIivY9HBVEmDxe/yFYAyNjUDiO8aL0FqyE1Bp2VVUBFLn69ZSe6hC2MkLJIVWXU 6bL0DENG8g60630GqdvlF1QBcgp1w7kIG46T65pl3af7JhhwS7bIbMcyiKMW/AI2FJOy YXScy2BW7DQ9++BCN4z3HVpVkyV2bDcaFqoZ8O2BpYge2zMPAxxPiCN8t61r9xGoUIc+ gnKMumkNryXHGt868VSEs5CUGI4hcCtpRTy+rp3mOjueAck9tYK5LzWAFHTpEvIT8L4R wXYcYCJPpI6VsTHDVYCCmqPVtZGLDZ9JFd8t1GpbzQFfM9FYDs1Pc0bZFx7//+cdjBFS 9pXg== X-Gm-Message-State: AElRT7H6fUISCp5g6ejuiq4KlPFvuwSFFn+SCqBjyuvSNn3XKbhSZVcf BhpQhiVlPMxRHzjBSdTUekf+qC9fjVlYZY8Sh1E= X-Received: by 10.55.0.203 with SMTP id t72mr10403746qkg.110.1521078521336; Wed, 14 Mar 2018 18:48:41 -0700 (PDT) MIME-Version: 1.0 Received: by 10.140.89.138 with HTTP; Wed, 14 Mar 2018 18:48:40 -0700 (PDT) In-Reply-To: <1520997629-17361-4-git-send-email-okaya@codeaurora.org> References: <1520997629-17361-1-git-send-email-okaya@codeaurora.org> <1520997629-17361-4-git-send-email-okaya@codeaurora.org> From: Alexander Duyck Date: Wed, 14 Mar 2018 18:48:40 -0700 Message-ID: Subject: Re: [PATCH 4/7] igbvf: 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/igbvf/netdev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c > index 4214c15..fe3441b 100644 > --- a/drivers/net/ethernet/intel/igbvf/netdev.c > +++ b/drivers/net/ethernet/intel/igbvf/netdev.c > @@ -251,7 +251,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, > * such as IA-64). > */ > wmb(); > - writel(i, adapter->hw.hw_addr + rx_ring->tail); > + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail); > } > } > This one missed the writel at the end of igbvf_tx_queue_adv().