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=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 9E199C433FF for ; Fri, 2 Aug 2019 10:04:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 753662067D for ; Fri, 2 Aug 2019 10:04:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564740260; bh=i/RkCux2/qSe+RvX0SoGsoZJJS7duwt+AOFDJsmwiyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i1M9pdAnAx0e/NTs1JFMxL8G3uWNpAZ1syn+D7SLzb1yHQme95nf34y8sdGT2f7xk Zzvv1vliA2/N2YKkzeWZwHJ+GzqKtNnxSl1Vt9ofnQ8fCISQ1dWaY5N8IWb4jmA0mK n9lDKFIbxurm6DvfDYYQMEWGRjqoEpY0NhnxyLgU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407192AbfHBKDV (ORCPT ); Fri, 2 Aug 2019 06:03:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:43396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404657AbfHBJli (ORCPT ); Fri, 2 Aug 2019 05:41:38 -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 01F642171F; Fri, 2 Aug 2019 09:41:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738897; bh=i/RkCux2/qSe+RvX0SoGsoZJJS7duwt+AOFDJsmwiyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nOebadgWoeXcPIwKPpYN2cCghnIc849L88mivf40130b3g6EJ2pLkHpxkFRM1TSqM VZqMa80RAJT3MDh48mjevHnMMgtW6A1t3b1AZ5eVJETASjmhxk5mfFDO4+2rTo33Xl 9JmVMaPla1AmAm7sO11WrKmFkskJf0EPAKWXzPl4= 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 4.9 030/223] net: axienet: Fix race condition causing TX hang Date: Fri, 2 Aug 2019 11:34:15 +0200 Message-Id: <20190802092240.953467634@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@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 a8afc92cbfca..5f21ddff9e0f 100644 --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c @@ -612,6 +612,10 @@ 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); } @@ -666,9 +670,19 @@ 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