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Commit 0e90b49c authored by Mitch A Williams's avatar Mitch A Williams Committed by David S. Miller
Browse files

igbvf: fix divide by zero 



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 <stable@vger.kernel.org> [3.3+]
CC: David Ahern <daahern@cisco.com>
Signed-off-by: default avatarMitch Williams <mitch.a.williams@intel.com>
Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0c12d91b

drivers/net/ethernet/intel/igbvf/ethtool.c

+18 −11
Original line number Diff line number Diff line
@@ -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);