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=-8.8 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,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 34DECC43613 for ; Thu, 20 Jun 2019 18:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12787204FD for ; Thu, 20 Jun 2019 18:07:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561054026; bh=snxNge4y/YgYh8pt7CvjFkx+Ubop37dNmgxP6d0bU7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=u2U1Ls60IoUhUM5XhW4tTVFWZG/OGnvsQWoZhy4xy0+fjTEBIolbnZ756B5LZEqY/ t7GwaFGu69cIpp4A+9zLcoY7PMkH4wmB99+PbRT1HmFFs5O9lhVHlYOTwC6vvupqxz xayMOT7i9HsW6AudWfTyMLYDQd3ycRMS+dP7NB6Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727134AbfFTSHE (ORCPT ); Thu, 20 Jun 2019 14:07:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:33286 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727787AbfFTSHC (ORCPT ); Thu, 20 Jun 2019 14:07:02 -0400 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 21AFE204FD; Thu, 20 Jun 2019 18:07:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561054021; bh=snxNge4y/YgYh8pt7CvjFkx+Ubop37dNmgxP6d0bU7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LfOBuic2MvkumLRTThD/18pE4kZsN5jnvDcUl+h/jWr2g7Kz8fhXQIyXgSi/6ZEj6 vtmqGfBcDobxp2l5xYqY0UolKlFZtIH5uAnjqZUsYtysz77Xm9nJ81ynhTcZi8qopE Yl8cbAcK+bNTNNeGoDtpk8rfDIQ6xH1h4AgV0T+o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oliver Zweigle , Bernd Eckstein <3ernd.Eckstein@gmail.com>, "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 078/117] usbnet: ipheth: fix racing condition Date: Thu, 20 Jun 2019 19:56:52 +0200 Message-Id: <20190620174357.102379071@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190620174351.964339809@linuxfoundation.org> References: <20190620174351.964339809@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 94d250fae48e6f873d8362308f5c4d02cd1b1fd2 ] Fix a racing condition in ipheth.c that can lead to slow performance. Bug: In ipheth_tx(), netif_wake_queue() may be called on the callback ipheth_sndbulk_callback(), _before_ netif_stop_queue() is called. When this happens, the queue is stopped longer than it needs to be, thus reducing network performance. Fix: Move netif_stop_queue() in front of usb_submit_urb(). Now the order is always correct. In case, usb_submit_urb() fails, the queue is woken up again as callback will not fire. Testing: This racing condition is usually not noticeable, as it has to occur very frequently to slowdown the network. The callback from the USB is usually triggered slow enough, so the situation does not appear. However, on a Ubuntu Linux on VMWare Workstation, running on Windows 10, the we loose the race quite often and the following speedup can be noticed: Without this patch: Download: 4.10 Mbit/s, Upload: 4.01 Mbit/s With this patch: Download: 36.23 Mbit/s, Upload: 17.61 Mbit/s Signed-off-by: Oliver Zweigle Signed-off-by: Bernd Eckstein <3ernd.Eckstein@gmail.com> Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/usb/ipheth.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c index 01f95d192d25..2b16a5fed9de 100644 --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -437,17 +437,18 @@ static int ipheth_tx(struct sk_buff *skb, struct net_device *net) dev); dev->tx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; + netif_stop_queue(net); retval = usb_submit_urb(dev->tx_urb, GFP_ATOMIC); if (retval) { dev_err(&dev->intf->dev, "%s: usb_submit_urb: %d\n", __func__, retval); dev->net->stats.tx_errors++; dev_kfree_skb_any(skb); + netif_wake_queue(net); } else { dev->net->stats.tx_packets++; dev->net->stats.tx_bytes += skb->len; dev_consume_skb_any(skb); - netif_stop_queue(net); } return NETDEV_TX_OK; -- 2.20.1