From: Dmitry Fleytman <dmitry@daynix.com>
Date: Tue, 13 Oct 2015 09:48:18 +0000 (+0300)
Subject: e1000e: fix division by zero on jumbo MTUs
X-Git-Tag: firefly_0821_release~176^2~4^2~31^2~177
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c6210760f2428690255e1fd91cf084b12e827a0a;p=firefly-linux-kernel-4.4.55.git

e1000e: fix division by zero on jumbo MTUs

[ 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 <dmitry@daynix.com>
Signed-off-by: Leonid Bloch <leonid@daynix.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 0a854a47d31a..80ec587d510e 100644
--- 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(int __always_unused irq, void *data)
 	 * 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;
 	}