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=-9.8 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 30983C433FF for ; Mon, 29 Jul 2019 19:25:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0663E2186A for ; Mon, 29 Jul 2019 19:25:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564428317; bh=8Ie5Xw53bMiiM6/Q6Ge+iLo/VCKw3UW9XdVJk2rAF60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=AOtJe1P3d8CD05s8SLkanuUz4HkIvFYCtLEbJRifwBvE65xiEY3u/uM1Z1BcCUt9s UykQfMAaqD9crGnaNQ2r2wMI9cAyV8lR+8E63myiculxW4jtg4tPbq2bv3sYtBIfb6 vUtH8DO+RpNBAsYYIk3TGcuaY+Lspdqv9I1TcS5M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388157AbfG2TZP (ORCPT ); Mon, 29 Jul 2019 15:25:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:37546 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388138AbfG2TZP (ORCPT ); Mon, 29 Jul 2019 15:25:15 -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 B3FCD20C01; Mon, 29 Jul 2019 19:25:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564428314; bh=8Ie5Xw53bMiiM6/Q6Ge+iLo/VCKw3UW9XdVJk2rAF60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zb6+FJ3AufPB2gzzmK7i2MGbTI4b2vggwQCM6mkybgOrLrtGzTKFBzcnmntlwWpnF vREsxhbgAotfDxQj+OnIGKRLxHh1NPj7RkCmSPfbFOrHQZKirs2OeLcuKPdstlPLEh k+zhKUq1Yl6cXaxmtA7V7zJTSIjvWwW1SiYwhDXA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Robert Hancock , "David S. Miller" , Sasha Levin Subject: [PATCH 4.14 036/293] net: axienet: Fix race condition causing TX hang Date: Mon, 29 Jul 2019 21:18:47 +0200 Message-Id: <20190729190825.012472396@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190820.321094988@linuxfoundation.org> References: <20190729190820.321094988@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 7de44285c1f69ccfbe8be1d6a16fcd956681fee6 ] It is possible that the interrupt handler fires and frees up space in the TX ring in between checking for sufficient TX ring space and stopping the TX queue in axienet_start_xmit. If this happens, the queue wake from the interrupt handler will occur before the queue is stopped, causing a lost wakeup and the adapter's transmit hanging. To avoid this, after stopping the queue, check again whether there is sufficient space in the TX ring. If so, wake up the queue again. Signed-off-by: Robert Hancock Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- .../net/ethernet/xilinx/xilinx_axienet_main.c | 20 ++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c index d46dc8cd1670..b481cb174b23 100644 --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c @@ -614,6 +614,10 @@ static void axienet_start_xmit_done(struct net_device *ndev) ndev->stats.tx_packets += packets; ndev->stats.tx_bytes += size; + + /* Matches barrier in axienet_start_xmit */ + smp_mb(); + netif_wake_queue(ndev); } @@ -668,9 +672,19 @@ static int axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev) cur_p = &lp->tx_bd_v[lp->tx_bd_tail]; if (axienet_check_tx_bd_space(lp, num_frag)) { - if (!netif_queue_stopped(ndev)) - netif_stop_queue(ndev); - return NETDEV_TX_BUSY; + if (netif_queue_stopped(ndev)) + return NETDEV_TX_BUSY; + + netif_stop_queue(ndev); + + /* Matches barrier in axienet_start_xmit_done */ + smp_mb(); + + /* Space might have just been freed - check again */ + if (axienet_check_tx_bd_space(lp, num_frag)) + return NETDEV_TX_BUSY; + + netif_wake_queue(ndev); } if (skb->ip_summed == CHECKSUM_PARTIAL) { -- 2.20.1