[PATCH 3.12 22/86] net/mlx4_en: Fix bad WQE issue

[Jiri Slaby]

From: Eugenia Emantayev <eugenia@xxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 6496bbf0ec481966ef9ffe5b6660d8d1b55c60cc upstream.

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@xxxxxxxxxxxx>
Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 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 afe2efa69c86..4267de129197 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -384,8 +384,14 @@ 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;
-- 
2.12.2