// SPDX-License-Identifier: GPL-2.0
/*
 * Data gathering module for Linux-VM Monitor Stream, Stage 1.
 * Collects accumulated network statistics (Packets received/transmitted,
 * dropped, errors, ...).
 *
 * Copyright IBM Corp. 2003, 2006
 *
 * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/netdevice.h>
#include <net/net_namespace.h>

#include "appldata.h"


/*
 * Network data
 *
 * This is accessed as binary data by z/VM. If changes to it can't be avoided,
 * the structure version (product ID, see appldata_base.c) needs to be changed
 * as well and all documentation and z/VM applications using it must be updated.
 */
struct appldata_net_sum_data {
        u64 timestamp;
        u32 sync_count_1;       /* after VM collected the record data, */
        u32 sync_count_2;       /* sync_count_1 and sync_count_2 should be the
                                   same. If not, the record has been updated on
                                   the Linux side while VM was collecting the
                                   (possibly corrupt) data */

        u32 nr_interfaces;      /* nr. of network interfaces being monitored */

        u32 padding;            /* next value is 64-bit aligned, so these */
                                /* 4 byte would be padded out by compiler */

        u64 rx_packets;         /* total packets received        */
        u64 tx_packets;         /* total packets transmitted     */
        u64 rx_bytes;           /* total bytes received          */
        u64 tx_bytes;           /* total bytes transmitted       */
        u64 rx_errors;          /* bad packets received          */
        u64 tx_errors;          /* packet transmit problems      */
        u64 rx_dropped;         /* no space in linux buffers     */
        u64 tx_dropped;         /* no space available in linux   */
        u64 collisions;         /* collisions while transmitting */
} __packed;


/*
 * appldata_get_net_sum_data()
 *
 * gather accumulated network statistics
 */
static void appldata_get_net_sum_data(void *data)
{
        int i;
        struct appldata_net_sum_data *net_data;
        struct net_device *dev;
        unsigned long rx_packets, tx_packets, rx_bytes, tx_bytes, rx_errors,
                        tx_errors, rx_dropped, tx_dropped, collisions;

        net_data = data;
        net_data->sync_count_1++;

        i = 0;
        rx_packets = 0;
        tx_packets = 0;
        rx_bytes   = 0;
        tx_bytes   = 0;
        rx_errors  = 0;
        tx_errors  = 0;
        rx_dropped = 0;
        tx_dropped = 0;
        collisions = 0;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, dev) {
                const struct rtnl_link_stats64 *stats;
                struct rtnl_link_stats64 temp;

                stats = dev_get_stats(dev, &temp);
                rx_packets += stats->rx_packets;
                tx_packets += stats->tx_packets;
                rx_bytes   += stats->rx_bytes;
                tx_bytes   += stats->tx_bytes;
                rx_errors  += stats->rx_errors;
                tx_errors  += stats->tx_errors;
                rx_dropped += stats->rx_dropped;
                tx_dropped += stats->tx_dropped;
                collisions += stats->collisions;
                i++;
        }
        rcu_read_unlock();

        net_data->nr_interfaces = i;
        net_data->rx_packets = rx_packets;
        net_data->tx_packets = tx_packets;
        net_data->rx_bytes   = rx_bytes;
        net_data->tx_bytes   = tx_bytes;
        net_data->rx_errors  = rx_errors;
        net_data->tx_errors  = tx_errors;
        net_data->rx_dropped = rx_dropped;
        net_data->tx_dropped = tx_dropped;
        net_data->collisions = collisions;

        net_data->timestamp = get_tod_clock();
        net_data->sync_count_2++;
}


static struct appldata_ops ops = {
        .name      = "net_sum",
        .record_nr = APPLDATA_RECORD_NET_SUM_ID,
        .size      = sizeof(struct appldata_net_sum_data),
        .callback  = &appldata_get_net_sum_data,
        .owner     = THIS_MODULE,
        .mod_lvl   = {0xF0, 0xF0},              /* EBCDIC "00" */
};


/*
 * appldata_net_init()
 *
 * init data, register ops
 */
static int __init appldata_net_init(void)
{
        int ret;

        ops.data = kzalloc_obj(struct appldata_net_sum_data);
        if (!ops.data)
                return -ENOMEM;

        ret = appldata_register_ops(&ops);
        if (ret)
                kfree(ops.data);

        return ret;
}

/*
 * appldata_net_exit()
 *
 * unregister ops
 */
static void __exit appldata_net_exit(void)
{
        appldata_unregister_ops(&ops);
        kfree(ops.data);
}


module_init(appldata_net_init);
module_exit(appldata_net_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gerald Schaefer");
MODULE_DESCRIPTION("Linux-VM Monitor Stream, accumulated network statistics");