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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,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 EB9B6C28D18 for ; Tue, 4 Jun 2019 23:25:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C232C206C1 for ; Tue, 4 Jun 2019 23:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690747; bh=xHZbjZKGwvdeTJRemHBIVesdOZlSKG+NWWZhLikmVVM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2LYhg2CA9hMHnWe245Ba99SRnFN88mmicDMR9es6/on+P4IurB7/xSIDZ/ARRumzS +A2Hfm8gIrjG7fJJPMu8JviihIRHwPEn3r/OL375FMfCz6v9olv0Oy5vpe0gEVZzua w2IfiQ83L4RH8iVl0UipI4z7xMWwTWU6y6UNsvmg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728134AbfFDXZq (ORCPT ); Tue, 4 Jun 2019 19:25:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:37694 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727217AbfFDXZp (ORCPT ); Tue, 4 Jun 2019 19:25:45 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EA75F20859; Tue, 4 Jun 2019 23:25:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690744; bh=xHZbjZKGwvdeTJRemHBIVesdOZlSKG+NWWZhLikmVVM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T12f+PmGi363ry9ObmA5799tpoZGzaXaBoanM8EmUSAgqLz84rVIrY2u33R/LQWQv 4XMALCSNJwLWQGMb8qK/yweOupJ8h6EHx6VYszNq7JwjUBH07wrHRryE/BJ8PqPpFU weeYUzXeTaY/6QA6Uy6ETKUpvOJzwaN090j/QTxw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Bernd Eckstein <3erndeckstein@gmail.com>, Oliver Zweigle , Bernd Eckstein <3ernd.Eckstein@gmail.com>, "David S . Miller" , Sasha Levin , linux-usb@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 07/10] usbnet: ipheth: fix racing condition Date: Tue, 4 Jun 2019 19:25:28 -0400 Message-Id: <20190604232532.7953-7-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190604232532.7953-1-sashal@kernel.org> References: <20190604232532.7953-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Bernd Eckstein <3erndeckstein@gmail.com> [ 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