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_RED,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 F1F85C76186 for ; Wed, 24 Jul 2019 20:03:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C60E021849 for ; Wed, 24 Jul 2019 20:03:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563998600; bh=RE4zTPUW2ZaNgOYRYaTLMudAji+H2gZtX2uIvn6tZ7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZMhhF3gNdacflRcwnwXFJZzCk1v1OpNu2Z322xGBxsnOv+ipK3qQKMQ8aEJRCS3Dx T6mF3XHtE99uawJcZNa/GPrnyxACfQvYDJrowxsLPbFHaHrz+ExgJAQiihXWsWq9o1 GhmnWb0c2rSA5ZTVxHv4sDDjGvBi9/0JZz6gt4qQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388438AbfGXUDT (ORCPT ); Wed, 24 Jul 2019 16:03:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:53600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405671AbfGXUDR (ORCPT ); Wed, 24 Jul 2019 16:03:17 -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 8FB1E214AF; Wed, 24 Jul 2019 20:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563998597; bh=RE4zTPUW2ZaNgOYRYaTLMudAji+H2gZtX2uIvn6tZ7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c4uTQzVezFYCRg86q0b99G9oHZZn6B+YmYyRUVOqjNMb3ixoFXEIA6GSUJIOEYZBC YDlXYA3FBnFZ6PRTt/lYCwH0hUJLUmUdDvtXZGrRHfzxCmRXpzIboJZImOInEghhNk W6E8hXMpfQ8QVtiFiRPCXWzupuVJ5IjpTyuYeW7g= 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 4.19 049/271] net: axienet: Fix race condition causing TX hang Date: Wed, 24 Jul 2019 21:18:38 +0200 Message-Id: <20190724191659.357714775@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190724191655.268628197@linuxfoundation.org> References: <20190724191655.268628197@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 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 7cfd7ff38e86..66b30ebd45ee 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