[PATCH v2] net/mlx4: fix flow creation before start

The corrupted code causes segmentation fault when user creates
flow with drop action before device starting.

For example, failsafe PMD recreates all the flows before calling
dev_start in plug-in sequence and mlx4 allocated its flow drop
queue in dev_start.
Hence, when failsafe created flow with drop action after plug-in
event, mlx4 tried to dereference flow drop queue which was uninitialized.

The fix added check to the drop qp accesibale and conditioned the
ibv_create_flow calling on device starting.

Fixes: 642fe56a1ba5 ("net/mlx4: use a single drop queue for all drop flows")
Fixes: 46d5736a7049 ("net/mlx4: support basic flow items and actions")
Cc: stable@dpdk.org

Signed-off-by: Matan Azrad <redacted>
Acked-by: Adrien Mazarguil <redacted>
---
 drivers/net/mlx4/mlx4_flow.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

v2 to fix the qp accesible by other way and fix the ibv_create_flow calling
before dev_start.  

diff --git a/drivers/net/mlx4/mlx4_flow.c b/drivers/net/mlx4/mlx4_flow.c
index 8ade106..925c89c 100644
--- a/drivers/net/mlx4/mlx4_flow.c
+++ b/drivers/net/mlx4/mlx4_flow.c

@@ -977,7 +977,7 @@ struct rte_flow_drop {
 		return NULL;
 	}
 	if (action->drop) {
-		qp = priv->flow_drop_queue->qp;
+		qp = priv->flow_drop_queue ? priv->flow_drop_queue->qp : NULL;
 	} else {
 		int ret;
 		unsigned int i;

@@ -1015,6 +1015,8 @@ struct rte_flow_drop {
 		rte_flow->qp = qp;
 	}
 	rte_flow->ibv_attr = ibv_attr;
+	if (!priv->started)
+		return rte_flow;
 	rte_flow->ibv_flow = ibv_create_flow(qp, rte_flow->ibv_attr);
 	if (!rte_flow->ibv_flow) {
 		rte_flow_error_set(error, ENOMEM, RTE_FLOW_ERROR_TYPE_HANDLE,

-- 
1.8.3.1