[net] igbvf: fix divide by zero
From: Jeff Kirsher <hidden>
Date: 2012-06-30 10:23:21
From: Mitch A Williams <redacted> 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 <redacted> [3.3+] CC: David Ahern <redacted> Signed-off-by: Mitch Williams <redacted> Tested-by: Aaron Brown <redacted> Signed-off-by: Jeff Kirsher <redacted> --- 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