static int receive_protocol()

in drbd/drbd_receiver.c [3667:3814]

• 114 lines of code
• 21 McCabe index (conditional complexity)

static int receive_protocol(struct drbd_connection *connection, struct packet_info *pi)
{
	struct p_protocol *p = pi->data;
	enum drbd_after_sb_p p_after_sb_0p, p_after_sb_1p, p_after_sb_2p;
	int p_proto, p_discard_my_data, p_two_primaries, cf;
	struct net_conf *nc, *old_net_conf, *new_net_conf = NULL;
	char integrity_alg[SHARED_SECRET_MAX] = "";
	struct crypto_shash *peer_integrity_tfm = NULL;
	void *int_dig_in = NULL, *int_dig_vv = NULL;

	p_proto		= be32_to_cpu(p->protocol);
	p_after_sb_0p	= be32_to_cpu(p->after_sb_0p);
	p_after_sb_1p	= be32_to_cpu(p->after_sb_1p);
	p_after_sb_2p	= be32_to_cpu(p->after_sb_2p);
	p_two_primaries = be32_to_cpu(p->two_primaries);
	cf		= be32_to_cpu(p->conn_flags);
	p_discard_my_data = cf & CF_DISCARD_MY_DATA;

	if (connection->agreed_pro_version >= 87) {
		int err;

		if (pi->size > sizeof(integrity_alg))
			return -EIO;
		err = drbd_recv_all(connection, integrity_alg, pi->size);
		if (err)
			return err;
		integrity_alg[SHARED_SECRET_MAX - 1] = 0;
	}

	if (pi->cmd != P_PROTOCOL_UPDATE) {
		clear_bit(CONN_DRY_RUN, &connection->flags);

		if (cf & CF_DRY_RUN)
			set_bit(CONN_DRY_RUN, &connection->flags);

		rcu_read_lock();
		nc = rcu_dereference(connection->net_conf);

		if (p_proto != nc->wire_protocol) {
			drbd_err(connection, "incompatible %s settings\n", "protocol");
			goto disconnect_rcu_unlock;
		}

		if (convert_after_sb(p_after_sb_0p) != nc->after_sb_0p) {
			drbd_err(connection, "incompatible %s settings\n", "after-sb-0pri");
			goto disconnect_rcu_unlock;
		}

		if (convert_after_sb(p_after_sb_1p) != nc->after_sb_1p) {
			drbd_err(connection, "incompatible %s settings\n", "after-sb-1pri");
			goto disconnect_rcu_unlock;
		}

		if (convert_after_sb(p_after_sb_2p) != nc->after_sb_2p) {
			drbd_err(connection, "incompatible %s settings\n", "after-sb-2pri");
			goto disconnect_rcu_unlock;
		}

		if (p_discard_my_data && nc->discard_my_data) {
			drbd_err(connection, "incompatible %s settings\n", "discard-my-data");
			goto disconnect_rcu_unlock;
		}

		if (p_two_primaries != nc->two_primaries) {
			drbd_err(connection, "incompatible %s settings\n", "allow-two-primaries");
			goto disconnect_rcu_unlock;
		}

		if (strcmp(integrity_alg, nc->integrity_alg)) {
			drbd_err(connection, "incompatible %s settings\n", "data-integrity-alg");
			goto disconnect_rcu_unlock;
		}

		rcu_read_unlock();
	}

	if (integrity_alg[0]) {
		int hash_size;

		/*
		 * We can only change the peer data integrity algorithm
		 * here.  Changing our own data integrity algorithm
		 * requires that we send a P_PROTOCOL_UPDATE packet at
		 * the same time; otherwise, the peer has no way to
		 * tell between which packets the algorithm should
		 * change.
		 */

		peer_integrity_tfm = crypto_alloc_shash(integrity_alg, 0, 0);
		if (IS_ERR(peer_integrity_tfm)) {
			peer_integrity_tfm = NULL;
			drbd_err(connection, "peer data-integrity-alg %s not supported\n",
				 integrity_alg);
			goto disconnect;
		}

		hash_size = crypto_shash_digestsize(peer_integrity_tfm);
		int_dig_in = kmalloc(hash_size, GFP_KERNEL);
		int_dig_vv = kmalloc(hash_size, GFP_KERNEL);
		if (!(int_dig_in && int_dig_vv)) {
			drbd_err(connection, "Allocation of buffers for data integrity checking failed\n");
			goto disconnect;
		}
	}

	new_net_conf = kmalloc(sizeof(struct net_conf), GFP_KERNEL);
	if (!new_net_conf)
		goto disconnect;

	mutex_lock(&connection->data.mutex);
	mutex_lock(&connection->resource->conf_update);
	old_net_conf = connection->net_conf;
	*new_net_conf = *old_net_conf;

	new_net_conf->wire_protocol = p_proto;
	new_net_conf->after_sb_0p = convert_after_sb(p_after_sb_0p);
	new_net_conf->after_sb_1p = convert_after_sb(p_after_sb_1p);
	new_net_conf->after_sb_2p = convert_after_sb(p_after_sb_2p);
	new_net_conf->two_primaries = p_two_primaries;

	rcu_assign_pointer(connection->net_conf, new_net_conf);
	mutex_unlock(&connection->resource->conf_update);
	mutex_unlock(&connection->data.mutex);

	crypto_free_shash(connection->peer_integrity_tfm);
	kfree(connection->int_dig_in);
	kfree(connection->int_dig_vv);
	connection->peer_integrity_tfm = peer_integrity_tfm;
	connection->int_dig_in = int_dig_in;
	connection->int_dig_vv = int_dig_vv;

	if (strcmp(old_net_conf->integrity_alg, integrity_alg))
		drbd_info(connection, "peer data-integrity-alg: %s\n",
			  integrity_alg[0] ? integrity_alg : "(none)");

	synchronize_rcu();
	kfree(old_net_conf);
	return 0;

disconnect_rcu_unlock:
	rcu_read_unlock();
disconnect:
	crypto_free_shash(peer_integrity_tfm);
	kfree(int_dig_in);
	kfree(int_dig_vv);
	conn_request_state(connection, NS(conn, C_DISCONNECTING), CS_HARD);
	return -EIO;
}