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=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 5B6C6C31E5B for ; Mon, 17 Jun 2019 21:31:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BB60204FD for ; Mon, 17 Jun 2019 21:31:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560807076; bh=eoircKri8yZq6TBBlqggoJktGga+3JD24JCOXyw7Q5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cVpBhLF2xyVECYed202CvnFj388g5wnMZLnWCtGwYjWnLGMeJjxManx7NV2/0maRt RV0VhQr4JaPNRiE5HXwmMLY7pPSsDmWXJBGCdPmustf0W93i3o3bZCcJb3cLiX43ac 6GOFflFGL6ex4Eq+ghCge6mloIJrHNOoQGkzFL5s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730192AbfFQVbO (ORCPT ); Mon, 17 Jun 2019 17:31:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:56328 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730129AbfFQV3J (ORCPT ); Mon, 17 Jun 2019 17:29:09 -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 7CA39204FD; Mon, 17 Jun 2019 21:29:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560806949; bh=eoircKri8yZq6TBBlqggoJktGga+3JD24JCOXyw7Q5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cJSYzBz+F7zIYIT6azmVS+fz2gndgzvgsPudy8yurAfg6uKo3+JR8sZK8eR4PpAqQ 4M+7XeecaowjRuAyTMBg/n7ySjkgOzfnlhePu9JWQPw18zA0uaWq9f9ptSv69FDJsG TpPA0J/ytwkCg/3kYuADWJLTWPHMnAAH2Dd/Lw4s= 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 4.14 38/53] usbnet: ipheth: fix racing condition Date: Mon, 17 Jun 2019 23:10:21 +0200 Message-Id: <20190617210751.822790637@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190617210745.104187490@linuxfoundation.org> References: <20190617210745.104187490@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 3d8a70d3ea9b..3d71f1716390 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