IB/mlx4: Update QP state if query QP succeeds

If the QP was moved to another state (such as SQE) by the hardware,
then after this change the user won't have to set the IBV_QP_CUR_STATE
mask in order to execute modify QP in order to recover from this state.

Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 38e651a..b75efae 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -1785,7 +1785,9 @@
 	struct mlx4_ib_qp *qp = to_mqp(ibqp);
 	struct mlx4_qp_context context;
 	int mlx4_state;
-	int err;
+	int err = 0;
+
+	mutex_lock(&qp->mutex);
 
 	if (qp->state == IB_QPS_RESET) {
 		qp_attr->qp_state = IB_QPS_RESET;
@@ -1793,12 +1795,15 @@
 	}
 
 	err = mlx4_qp_query(dev->dev, &qp->mqp, &context);
-	if (err)
-		return -EINVAL;
+	if (err) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	mlx4_state = be32_to_cpu(context.flags) >> 28;
 
-	qp_attr->qp_state	     = to_ib_qp_state(mlx4_state);
+	qp->state		     = to_ib_qp_state(mlx4_state);
+	qp_attr->qp_state	     = qp->state;
 	qp_attr->path_mtu	     = context.mtu_msgmax >> 5;
 	qp_attr->path_mig_state	     =
 		to_ib_mig_state((be32_to_cpu(context.flags) >> 11) & 0x3);
@@ -1857,6 +1862,8 @@
 
 	qp_init_attr->cap	     = qp_attr->cap;
 
-	return 0;
+out:
+	mutex_unlock(&qp->mutex);
+	return err;
 }