From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net] igbvf: fix divide by zero Date: Sat, 30 Jun 2012 03:23:19 -0700 Message-ID: <1341051799-8824-1-git-send-email-jeffrey.t.kirsher@intel.com> Cc: Mitch A Williams , netdev@vger.kernel.org, gospo@redhat.com, sassmann@redhat.com, stable@vger.kernel.org, daahern@cisco.com, Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga02.intel.com ([134.134.136.20]:7259 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752847Ab2F3KXV (ORCPT ); Sat, 30 Jun 2012 06:23:21 -0400 Sender: netdev-owner@vger.kernel.org List-ID: From: Mitch A Williams Using ethtool -C ethX rx-usecs 0 crashes with a divide by zero. Refactor this function to fix this issue and make it more clear what the intent of each conditional is. Add comment regarding using a setting of zero. CC: stable [3.3+] CC: David Ahern Signed-off-by: Mitch Williams Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/igbvf/ethtool.c | 29 +++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/ethtool.c b/drivers/net/ethernet/intel/igbvf/ethtool.c index 8ce6706..90eef07 100644 --- a/drivers/net/ethernet/intel/igbvf/ethtool.c +++ b/drivers/net/ethernet/intel/igbvf/ethtool.c @@ -357,21 +357,28 @@ static int igbvf_set_coalesce(struct net_device *netdev, struct igbvf_adapter *adapter = netdev_priv(netdev); struct e1000_hw *hw = &adapter->hw; - if ((ec->rx_coalesce_usecs > IGBVF_MAX_ITR_USECS) || - ((ec->rx_coalesce_usecs > 3) && - (ec->rx_coalesce_usecs < IGBVF_MIN_ITR_USECS)) || - (ec->rx_coalesce_usecs == 2)) - return -EINVAL; - - /* convert to rate of irq's per second */ - if (ec->rx_coalesce_usecs && ec->rx_coalesce_usecs <= 3) { + if ((ec->rx_coalesce_usecs >= IGBVF_MIN_ITR_USECS) && + (ec->rx_coalesce_usecs <= IGBVF_MAX_ITR_USECS)) { + adapter->current_itr = ec->rx_coalesce_usecs << 2; + adapter->requested_itr = 1000000000 / + (adapter->current_itr * 256); + } else if ((ec->rx_coalesce_usecs == 3) || + (ec->rx_coalesce_usecs == 2)) { adapter->current_itr = IGBVF_START_ITR; adapter->requested_itr = ec->rx_coalesce_usecs; - } else { - adapter->current_itr = ec->rx_coalesce_usecs << 2; + } else if (ec->rx_coalesce_usecs == 0) { + /* + * The user's desire is to turn off interrupt throttling + * altogether, but due to HW limitations, we can't do that. + * Instead we set a very small value in EITR, which would + * allow ~967k interrupts per second, but allow the adapter's + * internal clocking to still function properly. + */ + adapter->current_itr = 4; adapter->requested_itr = 1000000000 / (adapter->current_itr * 256); - } + } else + return -EINVAL; writel(adapter->current_itr, hw->hw_addr + adapter->rx_ring->itr_register); -- 1.7.10.4