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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 CB649C34047 for ; Wed, 19 Feb 2020 10:53:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3F322464E for ; Wed, 19 Feb 2020 10:53:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b="QDWUVQDT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727021AbgBSKxv (ORCPT ); Wed, 19 Feb 2020 05:53:51 -0500 Received: from first.geanix.com ([116.203.34.67]:57102 "EHLO first.geanix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726469AbgBSKxv (ORCPT ); Wed, 19 Feb 2020 05:53:51 -0500 Received: from localhost (_gateway [172.20.0.1]) by first.geanix.com (Postfix) with ESMTPSA id 1C78BC002E; Wed, 19 Feb 2020 10:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=geanix.com; s=first; t=1582109629; bh=KvmUZ7RpfqddUx8uLthfjCMTy9g+ZYpZDHIMYzR1KoQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QDWUVQDTAquUov6+PXtSzsOfsH4R3+bYJ3ZFFOC28FYbLNwgyFlsz7nSieXIiZObI 6RS5Cq28tPzIwWfbHZgOkd/XyTSlCRafR7TkPqfGeqwDLdmzmY3nyS3CqkX3Q9PJhU 41iR4DuU8ZKbDxt5N1tCKXPCncY6kOy4RZGxwdCWezT2xTMbB9JFcf58WjgZZVSiu0 PhJW2zacPec6lzoZSjXu+5GzHFR4kDgIjvxC8bUA1n3K5gZSROG0Ay/8sJ1WvKJn2u kFX78mjFRB31JsHAvVbmiSBDVwE5dJFSitJCWTyiKjyr3uggxs94cQnuO3kc8Bb+E4 oHuj6tj7RiLWw== From: Esben Haabendal To: netdev@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Lunn , "David S . Miller" , Michal Simek , =?UTF-8?q?Petr=20=C5=A0tetiar?= Subject: [PATCH net 1/4] net: ll_temac: Fix race condition causing TX hang Date: Wed, 19 Feb 2020 11:53:48 +0100 Message-Id: X-Mailer: git-send-email 2.25.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 temac_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. This is a port of the similar fix in axienet driver, commit 7de44285c1f6 ("net: axienet: Fix race condition causing TX hang"). Fixes: 23ecc4bde21f ("net: ll_temac: fix checksum offload logic") Signed-off-by: Esben Haabendal --- drivers/net/ethernet/xilinx/ll_temac_main.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index 6f11f52c9a9e..996004ef8bd4 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -788,6 +788,9 @@ static void temac_start_xmit_done(struct net_device *ndev) stat = be32_to_cpu(cur_p->app0); } + /* Matches barrier in temac_start_xmit */ + smp_mb(); + netif_wake_queue(ndev); } @@ -830,9 +833,19 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) cur_p = &lp->tx_bd_v[lp->tx_bd_tail]; if (temac_check_tx_bd_space(lp, num_frag + 1)) { - 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 temac_start_xmit_done */ + smp_mb(); + + /* Space might have just been freed - check again */ + if (temac_check_tx_bd_space(lp, num_frag)) + return NETDEV_TX_BUSY; + + netif_wake_queue(ndev); } cur_p->app0 = 0; -- 2.25.0