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 0026FC76191 for ; Mon, 15 Jul 2019 14:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD93D205ED for ; Mon, 15 Jul 2019 14:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563202648; bh=KDIPda6ETVhl73GW+MNwgRR0QeCIRzIkTai8t5mEsR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NIlsLyZiUYhGNk6RWKzRc28212PwsGXuk2tMcWr9kJA6S8skYpKPbRbgPolq7pIg4 PjAYNO+r10ZuBy+OaButwLaN/DjmL7g/QSfw36HcnO+jctBGBtlbxvvgPXswrzg08m KZIatpcZwVEGemjommlvIrqK1RDezbSacHlBp4fs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389915AbfGOOUf (ORCPT ); Mon, 15 Jul 2019 10:20:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:44784 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390240AbfGOOUc (ORCPT ); Mon, 15 Jul 2019 10:20:32 -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 8049721530; Mon, 15 Jul 2019 14:20:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563200431; bh=KDIPda6ETVhl73GW+MNwgRR0QeCIRzIkTai8t5mEsR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F6O37oBZais3Y8WNq+PlERUZHnJ7enCKHESrCFCVZXWKQ69ff0DkeAVnY6nmykKyv NjOUeSscOw/P6Uis0G98cWU6E+vjIAGKd6/858ub4qFSWsiSjhytHWPqxDrSftJfyu FV+1pIPxDJQ9N2wgmgliai+8KIG6H7bcSXPL+LTA= 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 4.19 047/158] net: axienet: Fix race condition causing TX hang Date: Mon, 15 Jul 2019 10:16:18 -0400 Message-Id: <20190715141809.8445-47-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190715141809.8445-1-sashal@kernel.org> References: <20190715141809.8445-1-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 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