[PATCH 4.4 016/192] [PATCH 016/135] e1000e: fix division by zero on jumbo MTUs

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit b77ac46bbae862dcb3f51296825c940404c69b0f ]

This patch fixes possible division by zero in receive
interrupt handler when working without adaptive interrupt
moderation.

The adaptive interrupt moderation mechanism is typically
disabled on jumbo MTUs.

Signed-off-by: Dmitry Fleytman <dmi...@daynix.com>
Signed-off-by: Leonid Bloch <leo...@daynix.com>
Tested-by: Aaron Brown <aaron.f.br...@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/ethernet/intel/e1000e/netdev.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -1959,8 +1959,10 @@ static irqreturn_t e1000_intr_msix_rx(in
         * previous interrupt.
         */
        if (rx_ring->set_itr) {
-               writel(1000000000 / (rx_ring->itr_val * 256),
-                      rx_ring->itr_register);
+               u32 itr = rx_ring->itr_val ?
+                         1000000000 / (rx_ring->itr_val * 256) : 0;
+
+               writel(itr, rx_ring->itr_register);
                rx_ring->set_itr = 0;
        }