xdp: fix leak of IDA cyclic id if rhashtable_insert_slow fails

Fix error handling case, where inserting ID with rhashtable_insert_slow
fails in xdp_rxq_info_reg_mem_model, which leads to never releasing the IDA
ID, as the lookup in xdp_rxq_info_unreg_mem_model fails and thus
ida_simple_remove() is never called.

Fix by releasing ID via ida_simple_remove(), and mark xdp_rxq->mem.id with
zero, which is already checked in xdp_rxq_info_unreg_mem_model().
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/xdp.c

@@ -301,6 +301,8 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 	/* Insert allocator into ID lookup table */
 	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
 	if (IS_ERR(ptr)) {
+		ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
+		xdp_rxq->mem.id = 0;
 		errno = PTR_ERR(ptr);
 		goto err;
 	}