From: Shannon Nelson <shannon.nelson@oracle.com>
Date: Mon, 13 Feb 2017 18:57:00 +0000 (-0800)
Subject: sunvnet: add memory barrier before check for tx enable
X-Git-Tag: v4.1.12-98.0.20170517_2143~37^2~10
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=39a39999d30ad7487a25c969ca23102fcc427dce;p=users%2Fjedix%2Flinux-maple.git

sunvnet: add memory barrier before check for tx enable

In order to allow the underlying LDC and outstanding memory operations
to potentially catch up with the driver's Tx requests, add a memory
barrier before checking again for available tx descriptors.

Orabug: 23293104

Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit fd263fb6e718c5bdf35cbc1de4f781c71794d2a4)
Signed-off-by: Allen Pais <allen.pais@oracle.com>
---

diff --git a/drivers/net/ethernet/sun/sunvnet_common.c b/drivers/net/ethernet/sun/sunvnet_common.c
index 170d866ea5d8c..3c70fca99ff38 100644
--- a/drivers/net/ethernet/sun/sunvnet_common.c
+++ b/drivers/net/ethernet/sun/sunvnet_common.c
@@ -1449,6 +1449,7 @@ ldc_start_done:
 	dr->prod = (dr->prod + 1) & (VNET_TX_RING_SIZE - 1);
 	if (unlikely(vnet_tx_dring_avail(dr) < 1)) {
 		netif_tx_stop_queue(txq);
+		smp_rmb();
 		if (vnet_tx_dring_avail(dr) > VNET_TX_WAKEUP_THRESH(dr))
 			netif_tx_wake_queue(txq);
 	}