void hv_fcopy_onchannelcallback()

in hv_fcopy.c [226:307]
61 lines of code
10 McCabe index (conditional complexity)

void hv_fcopy_onchannelcallback(void *context)
{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct hv_fcopy_hdr *fcopy_msg;
	struct icmsg_hdr *icmsghdr;
	int fcopy_srv_version;

	if (fcopy_transaction.state > HVUTIL_READY)
		return;

	if (vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 2, &recvlen, &requestid)) {
		pr_err_ratelimited("Fcopy request received. Could not read into recv buf\n");
		return;
	}

	if (!recvlen)
		return;

	/* Ensure recvlen is big enough to read header data */
	if (recvlen < ICMSG_HDR) {
		pr_err_ratelimited("Fcopy request received. Packet length too small: %d\n",
				   recvlen);
		return;
	}

	icmsghdr = (struct icmsg_hdr *)&recv_buffer[
			sizeof(struct vmbuspipe_hdr)];

	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
		if (vmbus_prep_negotiate_resp(icmsghdr,
				recv_buffer, recvlen,
				fw_versions, FW_VER_COUNT,
				fcopy_versions, FCOPY_VER_COUNT,
				NULL, &fcopy_srv_version)) {

			pr_info("FCopy IC version %d.%d\n",
				fcopy_srv_version >> 16,
				fcopy_srv_version & 0xFFFF);
		}
	} else if (icmsghdr->icmsgtype == ICMSGTYPE_FCOPY) {
		/* Ensure recvlen is big enough to contain hv_fcopy_hdr */
		if (recvlen < ICMSG_HDR + sizeof(struct hv_fcopy_hdr)) {
			pr_err_ratelimited("Invalid Fcopy hdr. Packet length too small: %u\n",
					   recvlen);
			return;
		}
		fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[ICMSG_HDR];

		/*
		 * Stash away this global state for completing the
		 * transaction; note transactions are serialized.
		 */

		fcopy_transaction.recv_len = recvlen;
		fcopy_transaction.recv_req_id = requestid;
		fcopy_transaction.fcopy_msg = fcopy_msg;

		if (fcopy_transaction.state < HVUTIL_READY) {
			/* Userspace is not registered yet */
			fcopy_respond_to_host(HV_E_FAIL);
			return;
		}
		fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;

		/*
		 * Send the information to the user-level daemon.
		 */
		schedule_work(&fcopy_send_work);
		schedule_delayed_work(&fcopy_timeout_work,
				      HV_UTIL_TIMEOUT * HZ);
		return;
	} else {
		pr_err_ratelimited("Fcopy request received. Invalid msg type: %d\n",
				   icmsghdr->icmsgtype);
		return;
	}
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
			VM_PKT_DATA_INBAND, 0);
}