From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next 11/13] fm10k: avoid divide by zero in rare cases when device is resetting Date: Mon, 2 Oct 2017 08:42:34 -0700 Message-ID: <20171002154236.84043-12-jeffrey.t.kirsher@intel.com> References: <20171002154236.84043-1-jeffrey.t.kirsher@intel.com> Cc: Jacob Keller , netdev@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, jogreene@redhat.com, Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga09.intel.com ([134.134.136.24]:24370 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751797AbdJBPnA (ORCPT ); Mon, 2 Oct 2017 11:43:00 -0400 In-Reply-To: <20171002154236.84043-1-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Jacob Keller It is possible that under rare circumstances the device is undergoing a reset, such as when a PFLR occurs, and the device may be transmitting simultaneously. In this case, we might attempt to divide by zero when finding the proper r_idx. Instead, lets read the num_tx_queues once, and make sure it's non-zero. Signed-off-by: Jacob Keller Tested-by: Krishneil Singh Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/fm10k/fm10k_netdev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c index e69d49d91d67..77d495fedced 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c @@ -643,9 +643,13 @@ int fm10k_close(struct net_device *netdev) static netdev_tx_t fm10k_xmit_frame(struct sk_buff *skb, struct net_device *dev) { struct fm10k_intfc *interface = netdev_priv(dev); + int num_tx_queues = READ_ONCE(interface->num_tx_queues); unsigned int r_idx = skb->queue_mapping; int err; + if (!num_tx_queues) + return NETDEV_TX_BUSY; + if ((skb->protocol == htons(ETH_P_8021Q)) && !skb_vlan_tag_present(skb)) { /* FM10K only supports hardware tagging, any tags in frame @@ -698,8 +702,8 @@ static netdev_tx_t fm10k_xmit_frame(struct sk_buff *skb, struct net_device *dev) __skb_put(skb, pad_len); } - if (r_idx >= interface->num_tx_queues) - r_idx %= interface->num_tx_queues; + if (r_idx >= num_tx_queues) + r_idx %= num_tx_queues; err = fm10k_xmit_frame_ring(skb, interface->tx_ring[r_idx]); -- 2.14.2