[SRU][Yakkety][PATCH 1/4] net/mlx4_en: Fix bad WQE issue

[Joseph Salisbury]

From: Eugenia Emantayev <eugenia at mellanox.com>

BugLink: http://bugs.launchpad.net/bugs/1650058

Single send WQE in RX buffer should be stamped with software
ownership in order to prevent the flow of QP in error in FW
once UPDATE_QP is called.

Fixes: 9f519f68cfff ('mlx4_en: Not using Shared Receive Queues')
Signed-off-by: Eugenia Emantayev <eugenia at mellanox.com>
Signed-off-by: Tariq Toukan <tariqt at mellanox.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 6496bbf0ec481966ef9ffe5b6660d8d1b55c60cc)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 2040dad..dfc3cd0 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -443,8 +443,14 @@ int mlx4_en_activate_rx_rings(struct mlx4_en_priv *priv)
 		ring->cqn = priv->rx_cq[ring_ind]->mcq.cqn;
 
 		ring->stride = stride;
-		if (ring->stride <= TXBB_SIZE)
+		if (ring->stride <= TXBB_SIZE) {
+			/* Stamp first unused send wqe */
+			__be32 *ptr = (__be32 *)ring->buf;
+			__be32 stamp = cpu_to_be32(1 << STAMP_SHIFT);
+			*ptr = stamp;
+			/* Move pointer to start of rx section */
 			ring->buf += TXBB_SIZE;
+		}
 
 		ring->log_stride = ffs(ring->stride) - 1;
 		ring->buf_size = ring->size * ring->stride;
-- 
2.7.4