IB/mlx4: Fix error path in create_qp_common()

    
The error handling code at err_wrid in create_qp_common() does not
handle a userspace QP attached to an SRQ correctly, since it ends up
in the else clause of the if statement.  This means it tries to
kfree() the uninitialized qp->sq.wrid and qp->rq.wrid pointers.  Fix
this so we only free the wrid arrays for kernel QPs.

Pointed out by Michael S. Tsirkin <mst@dev.mellanox.co.il>.
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/qp.c

@@ -415,9 +415,11 @@ static int create_qp_common(struct mlx4_ib_dev *dev, struct ib_pd *pd,
 	return 0;
 
 err_wrid:
-	if (pd->uobject && !init_attr->srq)
-		mlx4_ib_db_unmap_user(to_mucontext(pd->uobject->context), &qp->db);
-	else {
+	if (pd->uobject) {
+		if (!init_attr->srq)
+			mlx4_ib_db_unmap_user(to_mucontext(pd->uobject->context),
+					      &qp->db);
+	} else {
 		kfree(qp->sq.wrid);
 		kfree(qp->rq.wrid);
 	}