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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,URIBL_RED,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 6A90DC7618F for ; Mon, 15 Jul 2019 15:04:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 443942054F for ; Mon, 15 Jul 2019 15:04:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563203075; bh=y3JRFyP6Z6LQye0vFZIpV0p99KiojwddtijmBPKCz4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xznyOWcY15CWwZX4GGmOlwOm9f89zarPmEhotFXQyPNj8zu9JWMR3y7PMxetLwnUF vnikf46Ujl2JrwiPqmKlHa0kUy82i61F5Nb88llCkc1zNdxYsufHae+3zgibmXez7d 8Bj7mS0/Ez0lgoVUk8ZriWlU30sGhqXZlFPsKkUY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388405AbfGOOHt (ORCPT ); Mon, 15 Jul 2019 10:07:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:56790 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388219AbfGOOHs (ORCPT ); Mon, 15 Jul 2019 10:07:48 -0400 Received: from sasha-vm.mshome.net (unknown [73.61.17.35]) (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 2E10E206B8; Mon, 15 Jul 2019 14:07:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563199668; bh=y3JRFyP6Z6LQye0vFZIpV0p99KiojwddtijmBPKCz4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UG/80HU47v0bFBZRWPiIgeamvPFtEFEP5HEz5AQdJrJw8AXROHmUqMH3I1fyV+tkg st4yKfybRcItiMvSTdITzrjhyAH3mlyLR+g4fE5mqz+0zPh0V6zBoL9wXozuFVljh0 x0omt0y33QnAUljHgVKL6MbSxT9lIfZOfZ45FLdg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Robert Hancock , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.1 066/219] net: axienet: Fix race condition causing TX hang Date: Mon, 15 Jul 2019 10:01:07 -0400 Message-Id: <20190715140341.6443-66-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190715140341.6443-1-sashal@kernel.org> References: <20190715140341.6443-1-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: Robert Hancock [ 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 4041c75997ba..38a8ef194e05 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); } @@ -669,9 +673,19 @@ 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