linux-kernel - [PATCH v3 net-next 5/9] sunvnet: add memory barrier before check for tx enable

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Message-Id: <1486748305-240339-6-git-send-email-shannon.nelson@oracle.com>
Date:   Fri, 10 Feb 2017 09:38:21 -0800
From:   Shannon Nelson <shannon.nelson@...cle.com>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shannon Nelson <shannon.nelson@...cle.com>
Subject: [PATCH v3 net-next 5/9] 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.

Signed-off-by: Shannon Nelson <shannon.nelson@...cle.com>
---
 drivers/net/ethernet/sun/sunvnet_common.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/sun/sunvnet_common.c b/drivers/net/ethernet/sun/sunvnet_common.c
index 624ad65..05fe85f 100644
--- a/drivers/net/ethernet/sun/sunvnet_common.c
+++ b/drivers/net/ethernet/sun/sunvnet_common.c
@@ -1429,6 +1429,7 @@ int sunvnet_start_xmit_common(struct sk_buff *skb, struct net_device *dev,
 	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);
 	}
-- 
1.7.1