IB/mlx4: Fix memory leak if QP creation failed

BugLink: http://bugs.launchpad.net/bugs/1615620

commit 5b420d9c upstream.

When RC, UC, or RAW QPs are created, a qp object is allocated (kzalloc).
If at a later point (in procedure create_qp_common) the qp creation fails,
this qp object must be freed.

Fixes: 1ffeb2eb ("IB/mlx4: SR-IOV IB context objects and proxy/tunnel SQP support")
Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/infiniband/hw/mlx4/qp.c

@@ -1162,8 +1162,10 @@ struct ib_qp *mlx4_ib_create_qp(struct ib_pd *pd,
 	{
 		err = create_qp_common(to_mdev(pd->device), pd, init_attr,
 				       udata, 0, &qp, gfp);
-		if (err)
+		if (err) {
+			kfree(qp);
 			return ERR_PTR(err);
+		}
 
 		qp->ibqp.qp_num = qp->mqp.qpn;
 		qp->xrcdn = xrcdn;