From patchwork Tue Aug 19 18:52:51 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Poirier X-Patchwork-Id: 381464 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id ED47514010C for ; Wed, 20 Aug 2014 04:53:53 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753705AbaHSSxe (ORCPT ); Tue, 19 Aug 2014 14:53:34 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:40414 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753614AbaHSSx2 (ORCPT ); Tue, 19 Aug 2014 14:53:28 -0400 Received: by mail-pa0-f50.google.com with SMTP id et14so10768299pad.9 for ; Tue, 19 Aug 2014 11:53:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=i08sLYaPjyCcEVga4Y2LR55z/zZq8XzJZFy859mXgV8=; b=WyJDTc6rdnO5IJmrnqxW2d7ac6uWjb0SW6wZpR0p+80qZxx2NAyQyKLKJ8QM9x+80N 3jcqkXMhs2zWty2un6Lim3fgAVSSaqBMUWQ9xQZF/7m0wztsEKC71KzLexb1eulSWrFE 62qd4cOoqHuRfUkaUa/NY/3xNQyuAZb1COqYZJcYt+9pg3TAOPUMGPDn4qPMhAokQkq2 T1sBTAhBm4+6xpwn4VlHOZx9KkoVHjHzotibfcQDBXAOpq8rpLW0vT2uaKvVZZJKC350 kEJAFEdIxzz7ikLD1RX3uhM3h6bejX5M0g8eecS9TOuBGXNKGjJ7nAMIZr/StMR0j3s6 SGpQ== X-Received: by 10.70.34.104 with SMTP id y8mr52012044pdi.7.1408474406614; Tue, 19 Aug 2014 11:53:26 -0700 (PDT) Received: from f1.synalogic.ca (adsl-108-203-76-248.dsl.scrm01.sbcglobal.net. [108.203.76.248]) by mx.google.com with ESMTPSA id i2sm9947133pdl.86.2014.08.19.11.53.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Aug 2014 11:53:26 -0700 (PDT) From: Benjamin Poirier To: Prashant Sreedharan , Michael Chan Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] tg3: Fix tx_pending check for MAX_SKB_FRAGS Date: Tue, 19 Aug 2014 11:52:51 -0700 Message-Id: <1408474371-19509-3-git-send-email-bpoirier@suse.de> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1408474371-19509-1-git-send-email-bpoirier@suse.de> References: <1408474371-19509-1-git-send-email-bpoirier@suse.de> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The rest of the driver assumes at least one free descriptor in the tx ring. Therefore, since an skb with max frags takes up (MAX_SKB_FRAGS + 1) descriptors, tx_pending must be > (MAX_SKB_FRAGS + 1). Signed-off-by: Benjamin Poirier --- Currently, it is possible to set tx_pending = MAX_SKB_FRAGS + 1. This leads to a netdev watchdog tx timeout. Depending on whether the previous patches in this series are applied or not, the timeout happens as soon as tx_pending is updated or after an skb with max frags is submitted for transmission. I reproduced this bug using the same approach explained in patch 1. The bug reproduces with tx_pending = 18 --- drivers/net/ethernet/broadcom/tg3.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c index 7022f6d..27e2701 100644 --- a/drivers/net/ethernet/broadcom/tg3.c +++ b/drivers/net/ethernet/broadcom/tg3.c @@ -12328,7 +12328,7 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e if ((ering->rx_pending > tp->rx_std_ring_mask) || (ering->rx_jumbo_pending > tp->rx_jmb_ring_mask) || (ering->tx_pending > TG3_TX_RING_SIZE - 1) || - (ering->tx_pending <= MAX_SKB_FRAGS)) + (ering->tx_pending <= MAX_SKB_FRAGS + 1)) return -EINVAL; if (netif_running(dev)) {