From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737AbaHSSxf (ORCPT ); Tue, 19 Aug 2014 14:53:35 -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 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: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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)) { -- 1.8.4.5