net-sysfs.c

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/*
 * net-sysfs.c - network device class and attributes
 *
 * Copyright (c) 2003 Stephen Hemminger <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#include <net/net_namespace.h>
#include <linux/rtnetlink.h>
#include <linux/wireless.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <net/wext.h>

#include "net-sysfs.h"

#ifdef CONFIG_SYSFS
static const char fmt_hex[] = "%#x\n";
static const char fmt_long_hex[] = "%#lx\n";
static const char fmt_dec[] = "%d\n";
static const char fmt_udec[] = "%u\n";
static const char fmt_ulong[] = "%lu\n";
static const char fmt_u64[] = "%llu\n";

static inline int dev_isalive(const struct net_device *dev)
{
    return dev->reg_state <= NETREG_REGISTERED;
}

/* use same locking rules as GIF* ioctl's */
static ssize_t netdev_show(const struct device *dev,
               struct device_attribute *attr, char *buf,
               ssize_t (*format)(const struct net_device *, char *))
{
    struct net_device *net = to_net_dev(dev);
    ssize_t ret = -EINVAL;

    read_lock(&dev_base_lock);
    if (dev_isalive(net))
        ret = (*format)(net, buf);
    read_unlock(&dev_base_lock);

    return ret;
}

/* generate a show function for simple field */
#define NETDEVICE_SHOW(field, format_string)                \
static ssize_t format_##field(const struct net_device *net, char *buf)  \
{                                   \
    return sprintf(buf, format_string, net->field);         \
}                                   \
static ssize_t show_##field(struct device *dev,             \
                struct device_attribute *attr, char *buf)   \
{                                   \
    return netdev_show(dev, attr, buf, format_##field);     \
}


/* use same locking and permission rules as SIF* ioctl's */
static ssize_t netdev_store(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t len,
                int (*set)(struct net_device *, unsigned long))
{
    struct net_device *net = to_net_dev(dev);
    unsigned long new;
    int ret = -EINVAL;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    ret = kstrtoul(buf, 0, &new);
    if (ret)
        goto err;

    if (!rtnl_trylock())
        return restart_syscall();

    if (dev_isalive(net)) {
        if ((ret = (*set)(net, new)) == 0)
            ret = len;
    }
    rtnl_unlock();
 err:
    return ret;
}

NETDEVICE_SHOW(dev_id, fmt_hex);
NETDEVICE_SHOW(addr_assign_type, fmt_dec);
NETDEVICE_SHOW(addr_len, fmt_dec);
NETDEVICE_SHOW(iflink, fmt_dec);
NETDEVICE_SHOW(ifindex, fmt_dec);
NETDEVICE_SHOW(type, fmt_dec);
NETDEVICE_SHOW(link_mode, fmt_dec);

/* use same locking rules as GIFHWADDR ioctl's */
static ssize_t show_address(struct device *dev, struct device_attribute *attr,
                char *buf)
{
    struct net_device *net = to_net_dev(dev);
    ssize_t ret = -EINVAL;

    read_lock(&dev_base_lock);
    if (dev_isalive(net))
        ret = sysfs_format_mac(buf, net->dev_addr, net->addr_len);
    read_unlock(&dev_base_lock);
    return ret;
}

static ssize_t show_broadcast(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct net_device *net = to_net_dev(dev);
    if (dev_isalive(net))
        return sysfs_format_mac(buf, net->broadcast, net->addr_len);
    return -EINVAL;
}

static ssize_t show_carrier(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct net_device *netdev = to_net_dev(dev);
    if (netif_running(netdev)) {
        return sprintf(buf, fmt_dec, !!netif_carrier_ok(netdev));
    }
    return -EINVAL;
}

static ssize_t show_speed(struct device *dev,
              struct device_attribute *attr, char *buf)
{
    struct net_device *netdev = to_net_dev(dev);
    int ret = -EINVAL;

    if (!rtnl_trylock())
        return restart_syscall();

    if (netif_running(netdev)) {
        struct ethtool_cmd cmd;
        if (!__ethtool_get_settings(netdev, &cmd))
            ret = sprintf(buf, fmt_udec, ethtool_cmd_speed(&cmd));
    }
    rtnl_unlock();
    return ret;
}

static ssize_t show_duplex(struct device *dev,
               struct device_attribute *attr, char *buf)
{
    struct net_device *netdev = to_net_dev(dev);
    int ret = -EINVAL;

    if (!rtnl_trylock())
        return restart_syscall();

    if (netif_running(netdev)) {
        struct ethtool_cmd cmd;
        if (!__ethtool_get_settings(netdev, &cmd)) {
            const char *duplex;
            switch (cmd.duplex) {
            case DUPLEX_HALF:
                duplex = "half";
                break;
            case DUPLEX_FULL:
                duplex = "full";
                break;
            default:
                duplex = "unknown";
                break;
            }
            ret = sprintf(buf, "%s\n", duplex);
        }
    }
    rtnl_unlock();
    return ret;
}

static ssize_t show_dormant(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct net_device *netdev = to_net_dev(dev);

    if (netif_running(netdev))
        return sprintf(buf, fmt_dec, !!netif_dormant(netdev));

    return -EINVAL;
}

static const char *const operstates[] = {
    "unknown",
    "notpresent", /* currently unused */
    "down",
    "lowerlayerdown",
    "testing", /* currently unused */
    "dormant",
    "up"
};

static ssize_t show_operstate(struct device *dev,
                  struct device_attribute *attr, char *buf)
{
    const struct net_device *netdev = to_net_dev(dev);
    unsigned char operstate;

    read_lock(&dev_base_lock);
    operstate = netdev->operstate;
    if (!netif_running(netdev))
        operstate = IF_OPER_DOWN;
    read_unlock(&dev_base_lock);

    if (operstate >= ARRAY_SIZE(operstates))
        return -EINVAL; /* should not happen */

    return sprintf(buf, "%s\n", operstates[operstate]);
}

/* read-write attributes */
NETDEVICE_SHOW(mtu, fmt_dec);

static int change_mtu(struct net_device *net, unsigned long new_mtu)
{
    return dev_set_mtu(net, (int) new_mtu);
}

static ssize_t store_mtu(struct device *dev, struct device_attribute *attr,
             const char *buf, size_t len)
{
    return netdev_store(dev, attr, buf, len, change_mtu);
}

NETDEVICE_SHOW(flags, fmt_hex);

static int change_flags(struct net_device *net, unsigned long new_flags)
{
    return dev_change_flags(net, (unsigned int) new_flags);
}

static ssize_t store_flags(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t len)
{
    return netdev_store(dev, attr, buf, len, change_flags);
}

NETDEVICE_SHOW(tx_queue_len, fmt_ulong);

static int change_tx_queue_len(struct net_device *net, unsigned long new_len)
{
    net->tx_queue_len = new_len;
    return 0;
}

static ssize_t store_tx_queue_len(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t len)
{
    return netdev_store(dev, attr, buf, len, change_tx_queue_len);
}

static ssize_t store_ifalias(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t len)
{
    struct net_device *netdev = to_net_dev(dev);
    size_t count = len;
    ssize_t ret;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    /* ignore trailing newline */
    if (len >  0 && buf[len - 1] == '\n')
        --count;

    if (!rtnl_trylock())
        return restart_syscall();
    ret = dev_set_alias(netdev, buf, count);
    rtnl_unlock();

    return ret < 0 ? ret : len;
}

static ssize_t show_ifalias(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    const struct net_device *netdev = to_net_dev(dev);
    ssize_t ret = 0;

    if (!rtnl_trylock())
        return restart_syscall();
    if (netdev->ifalias)
        ret = sprintf(buf, "%s\n", netdev->ifalias);
    rtnl_unlock();
    return ret;
}

NETDEVICE_SHOW(group, fmt_dec);

static int change_group(struct net_device *net, unsigned long new_group)
{
    dev_set_group(net, (int) new_group);
    return 0;
}

static ssize_t store_group(struct device *dev, struct device_attribute *attr,
             const char *buf, size_t len)
{
    return netdev_store(dev, attr, buf, len, change_group);
}

static struct device_attribute net_class_attributes[] = {
    __ATTR(addr_assign_type, S_IRUGO, show_addr_assign_type, NULL),
    __ATTR(addr_len, S_IRUGO, show_addr_len, NULL),
    __ATTR(dev_id, S_IRUGO, show_dev_id, NULL),
    __ATTR(ifalias, S_IRUGO | S_IWUSR, show_ifalias, store_ifalias),
    __ATTR(iflink, S_IRUGO, show_iflink, NULL),
    __ATTR(ifindex, S_IRUGO, show_ifindex, NULL),
    __ATTR(type, S_IRUGO, show_type, NULL),
    __ATTR(link_mode, S_IRUGO, show_link_mode, NULL),
    __ATTR(address, S_IRUGO, show_address, NULL),
    __ATTR(broadcast, S_IRUGO, show_broadcast, NULL),
    __ATTR(carrier, S_IRUGO, show_carrier, NULL),
    __ATTR(speed, S_IRUGO, show_speed, NULL),
    __ATTR(duplex, S_IRUGO, show_duplex, NULL),
    __ATTR(dormant, S_IRUGO, show_dormant, NULL),
    __ATTR(operstate, S_IRUGO, show_operstate, NULL),
    __ATTR(mtu, S_IRUGO | S_IWUSR, show_mtu, store_mtu),
    __ATTR(flags, S_IRUGO | S_IWUSR, show_flags, store_flags),
    __ATTR(tx_queue_len, S_IRUGO | S_IWUSR, show_tx_queue_len,
           store_tx_queue_len),
    __ATTR(netdev_group, S_IRUGO | S_IWUSR, show_group, store_group),
    {}
};

/* Show a given an attribute in the statistics group */
static ssize_t netstat_show(const struct device *d,
                struct device_attribute *attr, char *buf,
                unsigned long offset)
{
    struct net_device *dev = to_net_dev(d);
    ssize_t ret = -EINVAL;

    WARN_ON(offset > sizeof(struct rtnl_link_stats64) ||
            offset % sizeof(u64) != 0);

    read_lock(&dev_base_lock);
    if (dev_isalive(dev)) {
        struct rtnl_link_stats64 temp;
        const struct rtnl_link_stats64 *stats = dev_get_stats(dev, &temp);

        ret = sprintf(buf, fmt_u64, *(u64 *)(((u8 *) stats) + offset));
    }
    read_unlock(&dev_base_lock);
    return ret;
}

/* generate a read-only statistics attribute */
#define NETSTAT_ENTRY(name)                     \
static ssize_t show_##name(struct device *d,                \
               struct device_attribute *attr, char *buf)    \
{                                   \
    return netstat_show(d, attr, buf,               \
                offsetof(struct rtnl_link_stats64, name));  \
}                                   \
static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)

NETSTAT_ENTRY(rx_packets);
NETSTAT_ENTRY(tx_packets);
NETSTAT_ENTRY(rx_bytes);
NETSTAT_ENTRY(tx_bytes);
NETSTAT_ENTRY(rx_errors);
NETSTAT_ENTRY(tx_errors);
NETSTAT_ENTRY(rx_dropped);
NETSTAT_ENTRY(tx_dropped);
NETSTAT_ENTRY(multicast);
NETSTAT_ENTRY(collisions);
NETSTAT_ENTRY(rx_length_errors);
NETSTAT_ENTRY(rx_over_errors);
NETSTAT_ENTRY(rx_crc_errors);
NETSTAT_ENTRY(rx_frame_errors);
NETSTAT_ENTRY(rx_fifo_errors);
NETSTAT_ENTRY(rx_missed_errors);
NETSTAT_ENTRY(tx_aborted_errors);
NETSTAT_ENTRY(tx_carrier_errors);
NETSTAT_ENTRY(tx_fifo_errors);
NETSTAT_ENTRY(tx_heartbeat_errors);
NETSTAT_ENTRY(tx_window_errors);
NETSTAT_ENTRY(rx_compressed);
NETSTAT_ENTRY(tx_compressed);

static struct attribute *netstat_attrs[] = {
    &dev_attr_rx_packets.attr,
    &dev_attr_tx_packets.attr,
    &dev_attr_rx_bytes.attr,
    &dev_attr_tx_bytes.attr,
    &dev_attr_rx_errors.attr,
    &dev_attr_tx_errors.attr,
    &dev_attr_rx_dropped.attr,
    &dev_attr_tx_dropped.attr,
    &dev_attr_multicast.attr,
    &dev_attr_collisions.attr,
    &dev_attr_rx_length_errors.attr,
    &dev_attr_rx_over_errors.attr,
    &dev_attr_rx_crc_errors.attr,
    &dev_attr_rx_frame_errors.attr,
    &dev_attr_rx_fifo_errors.attr,
    &dev_attr_rx_missed_errors.attr,
    &dev_attr_tx_aborted_errors.attr,
    &dev_attr_tx_carrier_errors.attr,
    &dev_attr_tx_fifo_errors.attr,
    &dev_attr_tx_heartbeat_errors.attr,
    &dev_attr_tx_window_errors.attr,
    &dev_attr_rx_compressed.attr,
    &dev_attr_tx_compressed.attr,
    NULL
};


static struct attribute_group netstat_group = {
    .name  = "statistics",
    .attrs  = netstat_attrs,
};

#if IS_ENABLED(CONFIG_WIRELESS_EXT) || IS_ENABLED(CONFIG_CFG80211)
static struct attribute *wireless_attrs[] = {
    NULL
};

static struct attribute_group wireless_group = {
    .name = "wireless",
    .attrs = wireless_attrs,
};
#endif
#endif /* CONFIG_SYSFS */

#ifdef CONFIG_RPS
/*
 * RX queue sysfs structures and functions.
 */
struct rx_queue_attribute {
    struct attribute attr;
    ssize_t (*show)(struct netdev_rx_queue *queue,
        struct rx_queue_attribute *attr, char *buf);
    ssize_t (*store)(struct netdev_rx_queue *queue,
        struct rx_queue_attribute *attr, const char *buf, size_t len);
};
#define to_rx_queue_attr(_attr) container_of(_attr,     \
    struct rx_queue_attribute, attr)

#define to_rx_queue(obj) container_of(obj, struct netdev_rx_queue, kobj)

static ssize_t rx_queue_attr_show(struct kobject *kobj, struct attribute *attr,
                  char *buf)
{
    struct rx_queue_attribute *attribute = to_rx_queue_attr(attr);
    struct netdev_rx_queue *queue = to_rx_queue(kobj);

    if (!attribute->show)
        return -EIO;

    return attribute->show(queue, attribute, buf);
}

static ssize_t rx_queue_attr_store(struct kobject *kobj, struct attribute *attr,
                   const char *buf, size_t count)
{
    struct rx_queue_attribute *attribute = to_rx_queue_attr(attr);
    struct netdev_rx_queue *queue = to_rx_queue(kobj);

    if (!attribute->store)
        return -EIO;

    return attribute->store(queue, attribute, buf, count);
}

static const struct sysfs_ops rx_queue_sysfs_ops = {
    .show = rx_queue_attr_show,
    .store = rx_queue_attr_store,
};

static ssize_t show_rps_map(struct netdev_rx_queue *queue,
                struct rx_queue_attribute *attribute, char *buf)
{
    struct rps_map *map;
    cpumask_var_t mask;
    size_t len = 0;
    int i;

    if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
        return -ENOMEM;

    rcu_read_lock();
    map = rcu_dereference(queue->rps_map);
    if (map)
        for (i = 0; i < map->len; i++)
            cpumask_set_cpu(map->cpus[i], mask);

    len += cpumask_scnprintf(buf + len, PAGE_SIZE, mask);
    if (PAGE_SIZE - len < 3) {
        rcu_read_unlock();
        free_cpumask_var(mask);
        return -EINVAL;
    }
    rcu_read_unlock();

    free_cpumask_var(mask);
    len += sprintf(buf + len, "\n");
    return len;
}

static ssize_t store_rps_map(struct netdev_rx_queue *queue,
              struct rx_queue_attribute *attribute,
              const char *buf, size_t len)
{
    struct rps_map *old_map, *map;
    cpumask_var_t mask;
    int err, cpu, i;
    static DEFINE_SPINLOCK(rps_map_lock);

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
        return -ENOMEM;

    err = bitmap_parse(buf, len, cpumask_bits(mask), nr_cpumask_bits);
    if (err) {
        free_cpumask_var(mask);
        return err;
    }

    map = kzalloc(max_t(unsigned int,
        RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
        GFP_KERNEL);
    if (!map) {
        free_cpumask_var(mask);
        return -ENOMEM;
    }

    i = 0;
    for_each_cpu_and(cpu, mask, cpu_online_mask)
        map->cpus[i++] = cpu;

    if (i)
        map->len = i;
    else {
        kfree(map);
        map = NULL;
    }

    spin_lock(&rps_map_lock);
    old_map = rcu_dereference_protected(queue->rps_map,
                        lockdep_is_held(&rps_map_lock));
    rcu_assign_pointer(queue->rps_map, map);
    spin_unlock(&rps_map_lock);

    if (map)
        static_key_slow_inc(&rps_needed);
    if (old_map) {
        kfree_rcu(old_map, rcu);
        static_key_slow_dec(&rps_needed);
    }
    free_cpumask_var(mask);
    return len;
}

static ssize_t show_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
                       struct rx_queue_attribute *attr,
                       char *buf)
{
    struct rps_dev_flow_table *flow_table;
    unsigned long val = 0;

    rcu_read_lock();
    flow_table = rcu_dereference(queue->rps_flow_table);
    if (flow_table)
        val = (unsigned long)flow_table->mask + 1;
    rcu_read_unlock();

    return sprintf(buf, "%lu\n", val);
}

static void rps_dev_flow_table_release_work(struct work_struct *work)
{
    struct rps_dev_flow_table *table = container_of(work,
        struct rps_dev_flow_table, free_work);

    vfree(table);
}

static void rps_dev_flow_table_release(struct rcu_head *rcu)
{
    struct rps_dev_flow_table *table = container_of(rcu,
        struct rps_dev_flow_table, rcu);

    INIT_WORK(&table->free_work, rps_dev_flow_table_release_work);
    schedule_work(&table->free_work);
}

static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
                     struct rx_queue_attribute *attr,
                     const char *buf, size_t len)
{
    unsigned long mask, count;
    struct rps_dev_flow_table *table, *old_table;
    static DEFINE_SPINLOCK(rps_dev_flow_lock);
    int rc;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    rc = kstrtoul(buf, 0, &count);
    if (rc < 0)
        return rc;

    if (count) {
        mask = count - 1;
        /* mask = roundup_pow_of_two(count) - 1;
         * without overflows...
         */
        while ((mask | (mask >> 1)) != mask)
            mask |= (mask >> 1);
        /* On 64 bit arches, must check mask fits in table->mask (u32),
         * and on 32bit arches, must check RPS_DEV_FLOW_TABLE_SIZE(mask + 1)
         * doesnt overflow.
         */
#if BITS_PER_LONG > 32
        if (mask > (unsigned long)(u32)mask)
            return -EINVAL;
#else
        if (mask > (ULONG_MAX - RPS_DEV_FLOW_TABLE_SIZE(1))
                / sizeof(struct rps_dev_flow)) {
            /* Enforce a limit to prevent overflow */
            return -EINVAL;
        }
#endif
        table = vmalloc(RPS_DEV_FLOW_TABLE_SIZE(mask + 1));
        if (!table)
            return -ENOMEM;

        table->mask = mask;
        for (count = 0; count <= mask; count++)
            table->flows[count].cpu = RPS_NO_CPU;
    } else
        table = NULL;

    spin_lock(&rps_dev_flow_lock);
    old_table = rcu_dereference_protected(queue->rps_flow_table,
                          lockdep_is_held(&rps_dev_flow_lock));
    rcu_assign_pointer(queue->rps_flow_table, table);
    spin_unlock(&rps_dev_flow_lock);

    if (old_table)
        call_rcu(&old_table->rcu, rps_dev_flow_table_release);

    return len;
}

static struct rx_queue_attribute rps_cpus_attribute =
    __ATTR(rps_cpus, S_IRUGO | S_IWUSR, show_rps_map, store_rps_map);


static struct rx_queue_attribute rps_dev_flow_table_cnt_attribute =
    __ATTR(rps_flow_cnt, S_IRUGO | S_IWUSR,
        show_rps_dev_flow_table_cnt, store_rps_dev_flow_table_cnt);

static struct attribute *rx_queue_default_attrs[] = {
    &rps_cpus_attribute.attr,
    &rps_dev_flow_table_cnt_attribute.attr,
    NULL
};

static void rx_queue_release(struct kobject *kobj)
{
    struct netdev_rx_queue *queue = to_rx_queue(kobj);
    struct rps_map *map;
    struct rps_dev_flow_table *flow_table;


    map = rcu_dereference_protected(queue->rps_map, 1);
    if (map) {
        RCU_INIT_POINTER(queue->rps_map, NULL);
        kfree_rcu(map, rcu);
    }

    flow_table = rcu_dereference_protected(queue->rps_flow_table, 1);
    if (flow_table) {
        RCU_INIT_POINTER(queue->rps_flow_table, NULL);
        call_rcu(&flow_table->rcu, rps_dev_flow_table_release);
    }

    memset(kobj, 0, sizeof(*kobj));
    dev_put(queue->dev);
}

static struct kobj_type rx_queue_ktype = {
    .sysfs_ops = &rx_queue_sysfs_ops,
    .release = rx_queue_release,
    .default_attrs = rx_queue_default_attrs,
};

static int rx_queue_add_kobject(struct net_device *net, int index)
{
    struct netdev_rx_queue *queue = net->_rx + index;
    struct kobject *kobj = &queue->kobj;
    int error = 0;

    kobj->kset = net->queues_kset;
    error = kobject_init_and_add(kobj, &rx_queue_ktype, NULL,
        "rx-%u", index);
    if (error) {
        kobject_put(kobj);
        return error;
    }

    kobject_uevent(kobj, KOBJ_ADD);
    dev_hold(queue->dev);

    return error;
}
#endif /* CONFIG_RPS */

int
net_rx_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
{
#ifdef CONFIG_RPS
    int i;
    int error = 0;

    for (i = old_num; i < new_num; i++) {
        error = rx_queue_add_kobject(net, i);
        if (error) {
            new_num = old_num;
            break;
        }
    }

    while (--i >= new_num)
        kobject_put(&net->_rx[i].kobj);

    return error;
#else
    return 0;
#endif
}

#ifdef CONFIG_SYSFS
/*
 * netdev_queue sysfs structures and functions.
 */
struct netdev_queue_attribute {
    struct attribute attr;
    ssize_t (*show)(struct netdev_queue *queue,
        struct netdev_queue_attribute *attr, char *buf);
    ssize_t (*store)(struct netdev_queue *queue,
        struct netdev_queue_attribute *attr, const char *buf, size_t len);
};
#define to_netdev_queue_attr(_attr) container_of(_attr,     \
    struct netdev_queue_attribute, attr)

#define to_netdev_queue(obj) container_of(obj, struct netdev_queue, kobj)

static ssize_t netdev_queue_attr_show(struct kobject *kobj,
                      struct attribute *attr, char *buf)
{
    struct netdev_queue_attribute *attribute = to_netdev_queue_attr(attr);
    struct netdev_queue *queue = to_netdev_queue(kobj);

    if (!attribute->show)
        return -EIO;

    return attribute->show(queue, attribute, buf);
}

static ssize_t netdev_queue_attr_store(struct kobject *kobj,
                       struct attribute *attr,
                       const char *buf, size_t count)
{
    struct netdev_queue_attribute *attribute = to_netdev_queue_attr(attr);
    struct netdev_queue *queue = to_netdev_queue(kobj);

    if (!attribute->store)
        return -EIO;

    return attribute->store(queue, attribute, buf, count);
}

static const struct sysfs_ops netdev_queue_sysfs_ops = {
    .show = netdev_queue_attr_show,
    .store = netdev_queue_attr_store,
};

static ssize_t show_trans_timeout(struct netdev_queue *queue,
                  struct netdev_queue_attribute *attribute,
                  char *buf)
{
    unsigned long trans_timeout;

    spin_lock_irq(&queue->_xmit_lock);
    trans_timeout = queue->trans_timeout;
    spin_unlock_irq(&queue->_xmit_lock);

    return sprintf(buf, "%lu", trans_timeout);
}

static struct netdev_queue_attribute queue_trans_timeout =
    __ATTR(tx_timeout, S_IRUGO, show_trans_timeout, NULL);

#ifdef CONFIG_BQL
/*
 * Byte queue limits sysfs structures and functions.
 */
static ssize_t bql_show(char *buf, unsigned int value)
{
    return sprintf(buf, "%u\n", value);
}

static ssize_t bql_set(const char *buf, const size_t count,
               unsigned int *pvalue)
{
    unsigned int value;
    int err;

    if (!strcmp(buf, "max") || !strcmp(buf, "max\n"))
        value = DQL_MAX_LIMIT;
    else {
        err = kstrtouint(buf, 10, &value);
        if (err < 0)
            return err;
        if (value > DQL_MAX_LIMIT)
            return -EINVAL;
    }

    *pvalue = value;

    return count;
}

static ssize_t bql_show_hold_time(struct netdev_queue *queue,
                  struct netdev_queue_attribute *attr,
                  char *buf)
{
    struct dql *dql = &queue->dql;

    return sprintf(buf, "%u\n", jiffies_to_msecs(dql->slack_hold_time));
}

static ssize_t bql_set_hold_time(struct netdev_queue *queue,
                 struct netdev_queue_attribute *attribute,
                 const char *buf, size_t len)
{
    struct dql *dql = &queue->dql;
    unsigned int value;
    int err;

    err = kstrtouint(buf, 10, &value);
    if (err < 0)
        return err;

    dql->slack_hold_time = msecs_to_jiffies(value);

    return len;
}

static struct netdev_queue_attribute bql_hold_time_attribute =
    __ATTR(hold_time, S_IRUGO | S_IWUSR, bql_show_hold_time,
        bql_set_hold_time);

static ssize_t bql_show_inflight(struct netdev_queue *queue,
                 struct netdev_queue_attribute *attr,
                 char *buf)
{
    struct dql *dql = &queue->dql;

    return sprintf(buf, "%u\n", dql->num_queued - dql->num_completed);
}

static struct netdev_queue_attribute bql_inflight_attribute =
    __ATTR(inflight, S_IRUGO, bql_show_inflight, NULL);

#define BQL_ATTR(NAME, FIELD)                       \
static ssize_t bql_show_ ## NAME(struct netdev_queue *queue,        \
                 struct netdev_queue_attribute *attr,   \
                 char *buf)             \
{                                   \
    return bql_show(buf, queue->dql.FIELD);             \
}                                   \
                                    \
static ssize_t bql_set_ ## NAME(struct netdev_queue *queue,     \
                struct netdev_queue_attribute *attr,    \
                const char *buf, size_t len)        \
{                                   \
    return bql_set(buf, len, &queue->dql.FIELD);            \
}                                   \
                                    \
static struct netdev_queue_attribute bql_ ## NAME ## _attribute =   \
    __ATTR(NAME, S_IRUGO | S_IWUSR, bql_show_ ## NAME,      \
        bql_set_ ## NAME);

BQL_ATTR(limit, limit)
BQL_ATTR(limit_max, max_limit)
BQL_ATTR(limit_min, min_limit)

static struct attribute *dql_attrs[] = {
    &bql_limit_attribute.attr,
    &bql_limit_max_attribute.attr,
    &bql_limit_min_attribute.attr,
    &bql_hold_time_attribute.attr,
    &bql_inflight_attribute.attr,
    NULL
};

static struct attribute_group dql_group = {
    .name  = "byte_queue_limits",
    .attrs  = dql_attrs,
};
#endif /* CONFIG_BQL */

#ifdef CONFIG_XPS
static inline unsigned int get_netdev_queue_index(struct netdev_queue *queue)
{
    struct net_device *dev = queue->dev;
    int i;

    for (i = 0; i < dev->num_tx_queues; i++)
        if (queue == &dev->_tx[i])
            break;

    BUG_ON(i >= dev->num_tx_queues);

    return i;
}


static ssize_t show_xps_map(struct netdev_queue *queue,
                struct netdev_queue_attribute *attribute, char *buf)
{
    struct net_device *dev = queue->dev;
    struct xps_dev_maps *dev_maps;
    cpumask_var_t mask;
    unsigned long index;
    size_t len = 0;
    int i;

    if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
        return -ENOMEM;

    index = get_netdev_queue_index(queue);

    rcu_read_lock();
    dev_maps = rcu_dereference(dev->xps_maps);
    if (dev_maps) {
        for_each_possible_cpu(i) {
            struct xps_map *map =
                rcu_dereference(dev_maps->cpu_map[i]);
            if (map) {
                int j;
                for (j = 0; j < map->len; j++) {
                    if (map->queues[j] == index) {
                        cpumask_set_cpu(i, mask);
                        break;
                    }
                }
            }
        }
    }
    rcu_read_unlock();

    len += cpumask_scnprintf(buf + len, PAGE_SIZE, mask);
    if (PAGE_SIZE - len < 3) {
        free_cpumask_var(mask);
        return -EINVAL;
    }

    free_cpumask_var(mask);
    len += sprintf(buf + len, "\n");
    return len;
}

static DEFINE_MUTEX(xps_map_mutex);
#define xmap_dereference(P)     \
    rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))

static void xps_queue_release(struct netdev_queue *queue)
{
    struct net_device *dev = queue->dev;
    struct xps_dev_maps *dev_maps;
    struct xps_map *map;
    unsigned long index;
    int i, pos, nonempty = 0;

    index = get_netdev_queue_index(queue);

    mutex_lock(&xps_map_mutex);
    dev_maps = xmap_dereference(dev->xps_maps);

    if (dev_maps) {
        for_each_possible_cpu(i) {
            map = xmap_dereference(dev_maps->cpu_map[i]);
            if (!map)
                continue;

            for (pos = 0; pos < map->len; pos++)
                if (map->queues[pos] == index)
                    break;

            if (pos < map->len) {
                if (map->len > 1)
                    map->queues[pos] =
                        map->queues[--map->len];
                else {
                    RCU_INIT_POINTER(dev_maps->cpu_map[i],
                        NULL);
                    kfree_rcu(map, rcu);
                    map = NULL;
                }
            }
            if (map)
                nonempty = 1;
        }

        if (!nonempty) {
            RCU_INIT_POINTER(dev->xps_maps, NULL);
            kfree_rcu(dev_maps, rcu);
        }
    }
    mutex_unlock(&xps_map_mutex);
}

static ssize_t store_xps_map(struct netdev_queue *queue,
              struct netdev_queue_attribute *attribute,
              const char *buf, size_t len)
{
    struct net_device *dev = queue->dev;
    cpumask_var_t mask;
    int err, i, cpu, pos, map_len, alloc_len, need_set;
    unsigned long index;
    struct xps_map *map, *new_map;
    struct xps_dev_maps *dev_maps, *new_dev_maps;
    int nonempty = 0;
    int numa_node_id = -2;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
        return -ENOMEM;

    index = get_netdev_queue_index(queue);

    err = bitmap_parse(buf, len, cpumask_bits(mask), nr_cpumask_bits);
    if (err) {
        free_cpumask_var(mask);
        return err;
    }

    new_dev_maps = kzalloc(max_t(unsigned int,
        XPS_DEV_MAPS_SIZE, L1_CACHE_BYTES), GFP_KERNEL);
    if (!new_dev_maps) {
        free_cpumask_var(mask);
        return -ENOMEM;
    }

    mutex_lock(&xps_map_mutex);

    dev_maps = xmap_dereference(dev->xps_maps);

    for_each_possible_cpu(cpu) {
        map = dev_maps ?
            xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
        new_map = map;
        if (map) {
            for (pos = 0; pos < map->len; pos++)
                if (map->queues[pos] == index)
                    break;
            map_len = map->len;
            alloc_len = map->alloc_len;
        } else
            pos = map_len = alloc_len = 0;

        need_set = cpumask_test_cpu(cpu, mask) && cpu_online(cpu);
#ifdef CONFIG_NUMA
        if (need_set) {
            if (numa_node_id == -2)
                numa_node_id = cpu_to_node(cpu);
            else if (numa_node_id != cpu_to_node(cpu))
                numa_node_id = -1;
        }
#endif
        if (need_set && pos >= map_len) {
            /* Need to add queue to this CPU's map */
            if (map_len >= alloc_len) {
                alloc_len = alloc_len ?
                    2 * alloc_len : XPS_MIN_MAP_ALLOC;
                new_map = kzalloc_node(XPS_MAP_SIZE(alloc_len),
                               GFP_KERNEL,
                               cpu_to_node(cpu));
                if (!new_map)
                    goto error;
                new_map->alloc_len = alloc_len;
                for (i = 0; i < map_len; i++)
                    new_map->queues[i] = map->queues[i];
                new_map->len = map_len;
            }
            new_map->queues[new_map->len++] = index;
        } else if (!need_set && pos < map_len) {
            /* Need to remove queue from this CPU's map */
            if (map_len > 1)
                new_map->queues[pos] =
                    new_map->queues[--new_map->len];
            else
                new_map = NULL;
        }
        RCU_INIT_POINTER(new_dev_maps->cpu_map[cpu], new_map);
    }

    /* Cleanup old maps */
    for_each_possible_cpu(cpu) {
        map = dev_maps ?
            xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
        if (map && xmap_dereference(new_dev_maps->cpu_map[cpu]) != map)
            kfree_rcu(map, rcu);
        if (new_dev_maps->cpu_map[cpu])
            nonempty = 1;
    }

    if (nonempty) {
        rcu_assign_pointer(dev->xps_maps, new_dev_maps);
    } else {
        kfree(new_dev_maps);
        RCU_INIT_POINTER(dev->xps_maps, NULL);
    }

    if (dev_maps)
        kfree_rcu(dev_maps, rcu);

    netdev_queue_numa_node_write(queue, (numa_node_id >= 0) ? numa_node_id :
                        NUMA_NO_NODE);

    mutex_unlock(&xps_map_mutex);

    free_cpumask_var(mask);
    return len;

error:
    mutex_unlock(&xps_map_mutex);

    if (new_dev_maps)
        for_each_possible_cpu(i)
            kfree(rcu_dereference_protected(
                new_dev_maps->cpu_map[i],
                1));
    kfree(new_dev_maps);
    free_cpumask_var(mask);
    return -ENOMEM;
}

static struct netdev_queue_attribute xps_cpus_attribute =
    __ATTR(xps_cpus, S_IRUGO | S_IWUSR, show_xps_map, store_xps_map);
#endif /* CONFIG_XPS */

static struct attribute *netdev_queue_default_attrs[] = {
    &queue_trans_timeout.attr,
#ifdef CONFIG_XPS
    &xps_cpus_attribute.attr,
#endif
    NULL
};

static void netdev_queue_release(struct kobject *kobj)
{
    struct netdev_queue *queue = to_netdev_queue(kobj);

#ifdef CONFIG_XPS
    xps_queue_release(queue);
#endif

    memset(kobj, 0, sizeof(*kobj));
    dev_put(queue->dev);
}

static struct kobj_type netdev_queue_ktype = {
    .sysfs_ops = &netdev_queue_sysfs_ops,
    .release = netdev_queue_release,
    .default_attrs = netdev_queue_default_attrs,
};

static int netdev_queue_add_kobject(struct net_device *net, int index)
{
    struct netdev_queue *queue = net->_tx + index;
    struct kobject *kobj = &queue->kobj;
    int error = 0;

    kobj->kset = net->queues_kset;
    error = kobject_init_and_add(kobj, &netdev_queue_ktype, NULL,
        "tx-%u", index);
    if (error)
        goto exit;

#ifdef CONFIG_BQL
    error = sysfs_create_group(kobj, &dql_group);
    if (error)
        goto exit;
#endif

    kobject_uevent(kobj, KOBJ_ADD);
    dev_hold(queue->dev);

    return 0;
exit:
    kobject_put(kobj);
    return error;
}
#endif /* CONFIG_SYSFS */

int
netdev_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
{
#ifdef CONFIG_SYSFS
    int i;
    int error = 0;

    for (i = old_num; i < new_num; i++) {
        error = netdev_queue_add_kobject(net, i);
        if (error) {
            new_num = old_num;
            break;
        }
    }

    while (--i >= new_num) {
        struct netdev_queue *queue = net->_tx + i;

#ifdef CONFIG_BQL
        sysfs_remove_group(&queue->kobj, &dql_group);
#endif
        kobject_put(&queue->kobj);
    }

    return error;
#else
    return 0;
#endif /* CONFIG_SYSFS */
}

static int register_queue_kobjects(struct net_device *net)
{
    int error = 0, txq = 0, rxq = 0, real_rx = 0, real_tx = 0;

#ifdef CONFIG_SYSFS
    net->queues_kset = kset_create_and_add("queues",
        NULL, &net->dev.kobj);
    if (!net->queues_kset)
        return -ENOMEM;
#endif

#ifdef CONFIG_RPS
    real_rx = net->real_num_rx_queues;
#endif
    real_tx = net->real_num_tx_queues;

    error = net_rx_queue_update_kobjects(net, 0, real_rx);
    if (error)
        goto error;
    rxq = real_rx;

    error = netdev_queue_update_kobjects(net, 0, real_tx);
    if (error)
        goto error;
    txq = real_tx;

    return 0;

error:
    netdev_queue_update_kobjects(net, txq, 0);
    net_rx_queue_update_kobjects(net, rxq, 0);
    return error;
}

static void remove_queue_kobjects(struct net_device *net)
{
    int real_rx = 0, real_tx = 0;

#ifdef CONFIG_RPS
    real_rx = net->real_num_rx_queues;
#endif
    real_tx = net->real_num_tx_queues;

    net_rx_queue_update_kobjects(net, real_rx, 0);
    netdev_queue_update_kobjects(net, real_tx, 0);
#ifdef CONFIG_SYSFS
    kset_unregister(net->queues_kset);
#endif
}

static void *net_grab_current_ns(void)
{
    struct net *ns = current->nsproxy->net_ns;
#ifdef CONFIG_NET_NS
    if (ns)
        atomic_inc(&ns->passive);
#endif
    return ns;
}

static const void *net_initial_ns(void)
{
    return &init_net;
}

static const void *net_netlink_ns(struct sock *sk)
{
    return sock_net(sk);
}

struct kobj_ns_type_operations net_ns_type_operations = {
    .type = KOBJ_NS_TYPE_NET,
    .grab_current_ns = net_grab_current_ns,
    .netlink_ns = net_netlink_ns,
    .initial_ns = net_initial_ns,
    .drop_ns = net_drop_ns,
};
EXPORT_SYMBOL_GPL(net_ns_type_operations);

#ifdef CONFIG_HOTPLUG
static int netdev_uevent(struct device *d, struct kobj_uevent_env *env)
{
    struct net_device *dev = to_net_dev(d);
    int retval;

    /* pass interface to uevent. */
    retval = add_uevent_var(env, "INTERFACE=%s", dev->name);
    if (retval)
        goto exit;

    /* pass ifindex to uevent.
     * ifindex is useful as it won't change (interface name may change)
     * and is what RtNetlink uses natively. */
    retval = add_uevent_var(env, "IFINDEX=%d", dev->ifindex);

exit:
    return retval;
}
#endif

/*
 *  netdev_release -- destroy and free a dead device.
 *  Called when last reference to device kobject is gone.
 */
static void netdev_release(struct device *d)
{
    struct net_device *dev = to_net_dev(d);

    BUG_ON(dev->reg_state != NETREG_RELEASED);

    kfree(dev->ifalias);
    kfree((char *)dev - dev->padded);
}

static const void *net_namespace(struct device *d)
{
    struct net_device *dev;
    dev = container_of(d, struct net_device, dev);
    return dev_net(dev);
}

static struct class net_class = {
    .name = "net",
    .dev_release = netdev_release,
#ifdef CONFIG_SYSFS
    .dev_attrs = net_class_attributes,
#endif /* CONFIG_SYSFS */
#ifdef CONFIG_HOTPLUG
    .dev_uevent = netdev_uevent,
#endif
    .ns_type = &net_ns_type_operations,
    .namespace = net_namespace,
};

/* Delete sysfs entries but hold kobject reference until after all
 * netdev references are gone.
 */
void netdev_unregister_kobject(struct net_device * net)
{
    struct device *dev = &(net->dev);

    kobject_get(&dev->kobj);

    remove_queue_kobjects(net);

    device_del(dev);
}

/* Create sysfs entries for network device. */
int netdev_register_kobject(struct net_device *net)
{
    struct device *dev = &(net->dev);
    const struct attribute_group **groups = net->sysfs_groups;
    int error = 0;

    device_initialize(dev);
    dev->class = &net_class;
    dev->platform_data = net;
    dev->groups = groups;

    dev_set_name(dev, "%s", net->name);

#ifdef CONFIG_SYSFS
    /* Allow for a device specific group */
    if (*groups)
        groups++;

    *groups++ = &netstat_group;

#if IS_ENABLED(CONFIG_WIRELESS_EXT) || IS_ENABLED(CONFIG_CFG80211)
    if (net->ieee80211_ptr)
        *groups++ = &wireless_group;
#if IS_ENABLED(CONFIG_WIRELESS_EXT)
    else if (net->wireless_handlers)
        *groups++ = &wireless_group;
#endif
#endif
#endif /* CONFIG_SYSFS */

    error = device_add(dev);
    if (error)
        return error;

    error = register_queue_kobjects(net);
    if (error) {
        device_del(dev);
        return error;
    }

    return error;
}

int netdev_class_create_file(struct class_attribute *class_attr)
{
    return class_create_file(&net_class, class_attr);
}
EXPORT_SYMBOL(netdev_class_create_file);

void netdev_class_remove_file(struct class_attribute *class_attr)
{
    class_remove_file(&net_class, class_attr);
}
EXPORT_SYMBOL(netdev_class_remove_file);

int netdev_kobject_init(void)
{
    kobj_ns_type_register(&net_ns_type_operations);
    return class_register(&net_class);
}