IB/mlx4: Fix memory ordering of VLAN insertion control bits

We must fully update the control segment before marking it as valid,
so that hardware doesn't start executing it before we're ready.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>

[ Move VLAN control bit setting to before wmb().  - Roland ]
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/qp.c

@@ -1816,6 +1816,11 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 		ctrl->fence_size = (wr->send_flags & IB_SEND_FENCE ?
 				    MLX4_WQE_CTRL_FENCE : 0) | size;
 
+		if (be16_to_cpu(vlan) < 0x1000) {
+			ctrl->ins_vlan = 1 << 6;
+			ctrl->vlan_tag = vlan;
+		}
+
 		/*
 		 * Make sure descriptor is fully written before
 		 * setting ownership bit (because HW can start
@@ -1831,11 +1836,6 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 		ctrl->owner_opcode = mlx4_ib_opcode[wr->opcode] |
 			(ind & qp->sq.wqe_cnt ? cpu_to_be32(1 << 31) : 0) | blh;
 
-		if (be16_to_cpu(vlan) < 0x1000) {
-			ctrl->ins_vlan = 1 << 6;
-			ctrl->vlan_tag = vlan;
-		}
-
 		stamp = ind + qp->sq_spare_wqes;
 		ind += DIV_ROUND_UP(size * 16, 1U << qp->sq.wqe_shift);