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 accessible and conditioned the
ibv_create_flow calling on device starting.
Fixes: 642fe56a1b ("net/mlx4: use a single drop queue for all drop flows")
Fixes: 46d5736a70 ("net/mlx4: support basic flow items and actions")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>