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: v4.1.12-105.0.20170622_2100~147
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0726f8e64e588bfac3c100a9e29427270497146e;p=users%2Fjedix%2Flinux-maple.git

e1000e: fix division by zero on jumbo MTUs

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>

Orabug: 26243014
(cherry picked from commit b77ac46bbae862dcb3f51296825c940404c69b0f)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>
---

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 3c7d06210c27b..b0a5b2eaa07a2 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;
 	}