static void tcf_chain_tp_delete_empty(struct tcf_chain *chain,
				      struct tcf_proto *tp, bool rtnl_held,
				      struct netlink_ext_ack *extack)
{
	struct tcf_chain_info chain_info;
	struct tcf_proto *tp_iter;
	struct tcf_proto **pprev;
	struct tcf_proto *next;

	mutex_lock(&chain->filter_chain_lock);

	/* Atomically find and remove tp from chain. */
	for (pprev = &chain->filter_chain;
	     (tp_iter = tcf_chain_dereference(*pprev, chain));
	     pprev = &tp_iter->next) {
		if (tp_iter == tp) {
			chain_info.pprev = pprev;
			chain_info.next = tp_iter->next;
			WARN_ON(tp_iter->deleting);
			break;
		}
	}
	/* Verify that tp still exists and no new filters were inserted
	 * concurrently.
	 * Mark tp for deletion if it is empty.
	 */
	if (!tp_iter || !tcf_proto_check_delete(tp)) {
		mutex_unlock(&chain->filter_chain_lock);
		return;
	}

	tcf_proto_signal_destroying(chain, tp);
	next = tcf_chain_dereference(chain_info.next, chain);
	if (tp == chain->filter_chain)
		tcf_chain0_head_change(chain, next);
	RCU_INIT_POINTER(*chain_info.pprev, next);
	mutex_unlock(&chain->filter_chain_lock);

	tcf_proto_put(tp, rtnl_held, extack);
}
static void tcf_chain_tp_delete_empty(struct tcf_chain *chain,
				      struct tcf_proto *tp, bool rtnl_held,
				      struct netlink_ext_ack *extack)
{
	struct tcf_chain_info chain_info;
	struct tcf_proto *tp_iter;
	struct tcf_proto **pprev;
	struct tcf_proto *next;

	mutex_lock(&chain->filter_chain_lock);

	 
	for (pprev = &chain->filter_chain;
	     (tp_iter = tcf_chain_dereference(*pprev, chain));
	     pprev = &tp_iter->next) {
		if (tp_iter == tp) {
			chain_info.pprev = pprev;
			chain_info.next = tp_iter->next;
			WARN_ON(tp_iter->deleting);
			break;
		}
	}
	 
	if (!tp_iter || !tcf_proto_check_delete(tp)) {
		mutex_unlock(&chain->filter_chain_lock);
		return;
	}

	tcf_proto_signal_destroying(chain, tp);
	next = tcf_chain_dereference(chain_info.next, chain);
	if (tp == chain->filter_chain)
		tcf_chain0_head_change(chain, next);
	RCU_INIT_POINTER(*chain_info.pprev, next);
	mutex_unlock(&chain->filter_chain_lock);

	tcf_proto_put(tp, rtnl_held, extack);
}