// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net-sysfs.c - network device class and attributes
 *
 * Copyright (c) 2003 Stephen Hemminger <shemminger@osdl.org>
 */

#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/sched/isolation.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#include <net/net_namespace.h>
#include <linux/rtnetlink.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_net.h>
#include <linux/cpu.h>
#include <net/netdev_lock.h>
#include <net/netdev_rx_queue.h>
#include <net/rps.h>

#include "dev.h"
#include "net-sysfs.h"

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

/* Caller holds RTNL, netdev->lock or RCU */
static inline int dev_isalive(const struct net_device *dev)
{
        return READ_ONCE(dev->reg_state) <= NETREG_REGISTERED;
}

/* There is a possible ABBA deadlock between rtnl_lock and kernfs_node->active,
 * when unregistering a net device and accessing associated sysfs files. The
 * potential deadlock is as follow:
 *
 *         CPU 0                                         CPU 1
 *
 *    rtnl_lock                                   vfs_read
 *    unregister_netdevice_many                   kernfs_seq_start
 *    device_del / kobject_put                      kernfs_get_active (kn->active++)
 *    kernfs_drain                                sysfs_kf_seq_show
 *    wait_event(                                 rtnl_lock
 *       kn->active == KN_DEACTIVATED_BIAS)       -> waits on CPU 0 to release
 *    -> waits on CPU 1 to decrease kn->active       the rtnl lock.
 *
 * The historical fix was to use rtnl_trylock with restart_syscall to bail out
 * of sysfs operations when the lock couldn't be taken. This fixed the above
 * issue as it allowed CPU 1 to bail out of the ABBA situation.
 *
 * But it came with performances issues, as syscalls are being restarted in
 * loops when there was contention on the rtnl lock, with huge slow downs in
 * specific scenarios (e.g. lots of virtual interfaces created and userspace
 * daemons querying their attributes).
 *
 * The idea below is to bail out of the active kernfs_node protection
 * (kn->active) while trying to take the rtnl lock.
 *
 * This replaces rtnl_lock() and still has to be used with rtnl_unlock(). The
 * net device is guaranteed to be alive if this returns successfully.
 */
static int sysfs_rtnl_lock(struct kobject *kobj, struct attribute *attr,
                           struct net_device *ndev)
{
        struct kernfs_node *kn;
        int ret = 0;

        /* First, we hold a reference to the net device as the unregistration
         * path might run in parallel. This will ensure the net device and the
         * associated sysfs objects won't be freed while we try to take the rtnl
         * lock.
         */
        dev_hold(ndev);
        /* sysfs_break_active_protection was introduced to allow self-removal of
         * devices and their associated sysfs files by bailing out of the
         * sysfs/kernfs protection. We do this here to allow the unregistration
         * path to complete in parallel. The following takes a reference on the
         * kobject and the kernfs_node being accessed.
         *
         * This works because we hold a reference onto the net device and the
         * unregistration path will wait for us eventually in netdev_run_todo
         * (outside an rtnl lock section).
         */
        kn = sysfs_break_active_protection(kobj, attr);
        /* We can now try to take the rtnl lock. This can't deadlock us as the
         * unregistration path is able to drain sysfs files (kernfs_node) thanks
         * to the above dance.
         */
        if (rtnl_lock_interruptible()) {
                ret = -ERESTARTSYS;
                goto unbreak;
        }
        /* Check dismantle on the device hasn't started, otherwise deny the
         * operation.
         */
        if (!dev_isalive(ndev)) {
                rtnl_unlock();
                ret = -ENODEV;
                goto unbreak;
        }
        /* We are now sure the device dismantle hasn't started nor that it can
         * start before we exit the locking section as we hold the rtnl lock.
         * There's no need to keep unbreaking the sysfs protection nor to hold
         * a net device reference from that point; that was only needed to take
         * the rtnl lock.
         */
unbreak:
        sysfs_unbreak_active_protection(kn);
        dev_put(ndev);

        return ret;
}

/* 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 *ndev = to_net_dev(dev);
        ssize_t ret = -EINVAL;

        rcu_read_lock();
        if (dev_isalive(ndev))
                ret = (*format)(ndev, buf);
        rcu_read_unlock();

        return ret;
}

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

#define NETDEVICE_SHOW_RO(field, format_string)                         \
NETDEVICE_SHOW(field, format_string);                                   \
static DEVICE_ATTR_RO(field)

#define NETDEVICE_SHOW_RW(field, format_string)                         \
NETDEVICE_SHOW(field, format_string);                                   \
static DEVICE_ATTR_RW(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 *netdev = to_net_dev(dev);
        struct net *net = dev_net(netdev);
        unsigned long new;
        int ret;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

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

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                goto err;

        ret = (*set)(netdev, new);
        if (ret == 0)
                ret = len;

        rtnl_unlock();
 err:
        return ret;
}

/* Same as netdev_store() but takes netdev_lock() instead of rtnl_lock() */
static ssize_t
netdev_lock_store(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t len,
                  int (*set)(struct net_device *, unsigned long))
{
        struct net_device *netdev = to_net_dev(dev);
        struct net *net = dev_net(netdev);
        unsigned long new;
        int ret;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

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

        netdev_lock(netdev);

        if (dev_isalive(netdev)) {
                ret = (*set)(netdev, new);
                if (ret == 0)
                        ret = len;
        }
        netdev_unlock(netdev);

        return ret;
}

NETDEVICE_SHOW_RO(dev_id, fmt_hex);
NETDEVICE_SHOW_RO(dev_port, fmt_dec);
NETDEVICE_SHOW_RO(addr_assign_type, fmt_dec);
NETDEVICE_SHOW_RO(addr_len, fmt_dec);
NETDEVICE_SHOW_RO(ifindex, fmt_dec);
NETDEVICE_SHOW_RO(type, fmt_dec);
NETDEVICE_SHOW_RO(link_mode, fmt_dec);

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

        return sysfs_emit(buf, fmt_dec, dev_get_iflink(ndev));
}
static DEVICE_ATTR_RO(iflink);

static ssize_t format_name_assign_type(const struct net_device *dev, char *buf)
{
        return sysfs_emit(buf, fmt_dec, READ_ONCE(dev->name_assign_type));
}

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

        if (READ_ONCE(ndev->name_assign_type) != NET_NAME_UNKNOWN)
                ret = netdev_show(dev, attr, buf, format_name_assign_type);

        return ret;
}
static DEVICE_ATTR_RO(name_assign_type);

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

        down_read(&dev_addr_sem);

        rcu_read_lock();
        if (dev_isalive(ndev))
                ret = sysfs_format_mac(buf, ndev->dev_addr, ndev->addr_len);
        rcu_read_unlock();

        up_read(&dev_addr_sem);
        return ret;
}
static DEVICE_ATTR_RO(address);

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

        rcu_read_lock();
        if (dev_isalive(ndev))
                ret = sysfs_format_mac(buf, ndev->broadcast, ndev->addr_len);
        rcu_read_unlock();
        return ret;
}
static DEVICE_ATTR_RO(broadcast);

static int change_carrier(struct net_device *dev, unsigned long new_carrier)
{
        if (!netif_running(dev))
                return -EINVAL;
        return dev_change_carrier(dev, (bool)new_carrier);
}

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

        /* The check is also done in change_carrier; this helps returning early
         * without hitting the locking section in netdev_store.
         */
        if (!netdev->netdev_ops->ndo_change_carrier)
                return -EOPNOTSUPP;

        return netdev_store(dev, attr, buf, len, change_carrier);
}

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

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = -EINVAL;
        if (netif_running(netdev)) {
                /* Synchronize carrier state with link watch,
                 * see also rtnl_getlink().
                 */
                linkwatch_sync_dev(netdev);

                ret = sysfs_emit(buf, fmt_dec, !!netif_carrier_ok(netdev));
        }

        rtnl_unlock();
        return ret;
}
static DEVICE_ATTR_RW(carrier);

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

        /* The check is also done in __ethtool_get_link_ksettings; this helps
         * returning early without hitting the locking section below.
         */
        if (!netdev->ethtool_ops->get_link_ksettings)
                return ret;

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = -EINVAL;
        if (netif_running(netdev)) {
                struct ethtool_link_ksettings cmd;

                if (!__ethtool_get_link_ksettings(netdev, &cmd))
                        ret = sysfs_emit(buf, fmt_dec, cmd.base.speed);
        }
        rtnl_unlock();
        return ret;
}
static DEVICE_ATTR_RO(speed);

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

        /* The check is also done in __ethtool_get_link_ksettings; this helps
         * returning early without hitting the locking section below.
         */
        if (!netdev->ethtool_ops->get_link_ksettings)
                return ret;

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = -EINVAL;
        if (netif_running(netdev)) {
                struct ethtool_link_ksettings cmd;

                if (!__ethtool_get_link_ksettings(netdev, &cmd)) {
                        const char *duplex;

                        switch (cmd.base.duplex) {
                        case DUPLEX_HALF:
                                duplex = "half";
                                break;
                        case DUPLEX_FULL:
                                duplex = "full";
                                break;
                        default:
                                duplex = "unknown";
                                break;
                        }
                        ret = sysfs_emit(buf, "%s\n", duplex);
                }
        }
        rtnl_unlock();
        return ret;
}
static DEVICE_ATTR_RO(duplex);

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

        if (netif_running(netdev))
                return sysfs_emit(buf, fmt_dec, !!netif_testing(netdev));

        return -EINVAL;
}
static DEVICE_ATTR_RO(testing);

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

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

        return -EINVAL;
}
static DEVICE_ATTR_RO(dormant);

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

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

        operstate = READ_ONCE(netdev->operstate);
        if (!netif_running(netdev))
                operstate = IF_OPER_DOWN;

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

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

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

        return sysfs_emit(buf, fmt_dec,
                          atomic_read(&netdev->carrier_up_count) +
                          atomic_read(&netdev->carrier_down_count));
}
static DEVICE_ATTR_RO(carrier_changes);

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

        return sysfs_emit(buf, fmt_dec, atomic_read(&netdev->carrier_up_count));
}
static DEVICE_ATTR_RO(carrier_up_count);

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

        return sysfs_emit(buf, fmt_dec, atomic_read(&netdev->carrier_down_count));
}
static DEVICE_ATTR_RO(carrier_down_count);

/* read-write attributes */

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

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

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

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

static ssize_t tx_queue_len_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t len)
{
        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        return netdev_store(dev, attr, buf, len, dev_change_tx_queue_len);
}
NETDEVICE_SHOW_RW(tx_queue_len, fmt_dec);

static int change_gro_flush_timeout(struct net_device *dev, unsigned long val)
{
        netdev_set_gro_flush_timeout(dev, val);
        return 0;
}

static ssize_t gro_flush_timeout_store(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf, size_t len)
{
        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        return netdev_lock_store(dev, attr, buf, len, change_gro_flush_timeout);
}
NETDEVICE_SHOW_RW(gro_flush_timeout, fmt_ulong);

static int change_napi_defer_hard_irqs(struct net_device *dev, unsigned long val)
{
        if (val > S32_MAX)
                return -ERANGE;

        netdev_set_defer_hard_irqs(dev, (u32)val);
        return 0;
}

static ssize_t napi_defer_hard_irqs_store(struct device *dev,
                                          struct device_attribute *attr,
                                          const char *buf, size_t len)
{
        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        return netdev_lock_store(dev, attr, buf, len,
                                 change_napi_defer_hard_irqs);
}
NETDEVICE_SHOW_RW(napi_defer_hard_irqs, fmt_uint);

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

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

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

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = dev_set_alias(netdev, buf, count);
        if (ret < 0)
                goto err;
        ret = len;
        netdev_state_change(netdev);
err:
        rtnl_unlock();

        return ret;
}

static ssize_t ifalias_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        const struct net_device *netdev = to_net_dev(dev);
        char tmp[IFALIASZ];
        ssize_t ret;

        ret = dev_get_alias(netdev, tmp, sizeof(tmp));
        if (ret > 0)
                ret = sysfs_emit(buf, "%s\n", tmp);
        return ret;
}
static DEVICE_ATTR_RW(ifalias);

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

static ssize_t group_store(struct device *dev, struct device_attribute *attr,
                           const char *buf, size_t len)
{
        return netdev_store(dev, attr, buf, len, change_group);
}
NETDEVICE_SHOW(group, fmt_dec);
static DEVICE_ATTR(netdev_group, 0644, group_show, group_store);

static int change_proto_down(struct net_device *dev, unsigned long proto_down)
{
        return dev_change_proto_down(dev, (bool)proto_down);
}

static ssize_t proto_down_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t len)
{
        return netdev_store(dev, attr, buf, len, change_proto_down);
}
NETDEVICE_SHOW_RW(proto_down, fmt_dec);

static ssize_t phys_port_id_show(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct net_device *netdev = to_net_dev(dev);
        struct netdev_phys_item_id ppid;
        ssize_t ret;

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = dev_get_phys_port_id(netdev, &ppid);
        if (!ret)
                ret = sysfs_emit(buf, "%*phN\n", ppid.id_len, ppid.id);

        rtnl_unlock();

        return ret;
}
static DEVICE_ATTR_RO(phys_port_id);

static ssize_t phys_port_name_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct net_device *netdev = to_net_dev(dev);
        char name[IFNAMSIZ];
        ssize_t ret;

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = dev_get_phys_port_name(netdev, name, sizeof(name));
        if (!ret)
                ret = sysfs_emit(buf, "%s\n", name);

        rtnl_unlock();

        return ret;
}
static DEVICE_ATTR_RO(phys_port_name);

static ssize_t phys_switch_id_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct net_device *netdev = to_net_dev(dev);
        struct netdev_phys_item_id ppid = { };
        ssize_t ret;

        ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
        if (ret)
                return ret;

        ret = netif_get_port_parent_id(netdev, &ppid, false);
        if (!ret)
                ret = sysfs_emit(buf, "%*phN\n", ppid.id_len, ppid.id);

        rtnl_unlock();

        return ret;
}
static DEVICE_ATTR_RO(phys_switch_id);

static struct attribute *netdev_phys_attrs[] __ro_after_init = {
        &dev_attr_phys_port_id.attr,
        &dev_attr_phys_port_name.attr,
        &dev_attr_phys_switch_id.attr,
        NULL,
};

static umode_t netdev_phys_is_visible(struct kobject *kobj,
                                      struct attribute *attr, int index)
{
        struct device *dev = kobj_to_dev(kobj);
        struct net_device *netdev = to_net_dev(dev);

        if (attr == &dev_attr_phys_port_id.attr) {
                if (!netdev->netdev_ops->ndo_get_phys_port_id)
                        return 0;
        } else if (attr == &dev_attr_phys_port_name.attr) {
                if (!netdev->netdev_ops->ndo_get_phys_port_name &&
                    !netdev->devlink_port)
                        return 0;
        } else if (attr == &dev_attr_phys_switch_id.attr) {
                if (!netdev->netdev_ops->ndo_get_port_parent_id &&
                    !netdev->devlink_port)
                        return 0;
        }

        return attr->mode;
}

static const struct attribute_group netdev_phys_group = {
        .attrs = netdev_phys_attrs,
        .is_visible = netdev_phys_is_visible,
};

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

        rcu_read_lock();

        if (dev_isalive(netdev))
                ret = sysfs_emit(buf, fmt_dec, READ_ONCE(netdev->threaded));

        rcu_read_unlock();

        return ret;
}

static int modify_napi_threaded(struct net_device *dev, unsigned long val)
{
        int ret;

        if (list_empty(&dev->napi_list))
                return -EOPNOTSUPP;

        if (val != 0 && val != 1)
                return -EOPNOTSUPP;

        ret = netif_set_threaded(dev, val);

        return ret;
}

static ssize_t threaded_store(struct device *dev,
                              struct device_attribute *attr,
                              const char *buf, size_t len)
{
        return netdev_lock_store(dev, attr, buf, len, modify_napi_threaded);
}
static DEVICE_ATTR_RW(threaded);

static struct attribute *net_class_attrs[] __ro_after_init = {
        &dev_attr_netdev_group.attr,
        &dev_attr_type.attr,
        &dev_attr_dev_id.attr,
        &dev_attr_dev_port.attr,
        &dev_attr_iflink.attr,
        &dev_attr_ifindex.attr,
        &dev_attr_name_assign_type.attr,
        &dev_attr_addr_assign_type.attr,
        &dev_attr_addr_len.attr,
        &dev_attr_link_mode.attr,
        &dev_attr_address.attr,
        &dev_attr_broadcast.attr,
        &dev_attr_speed.attr,
        &dev_attr_duplex.attr,
        &dev_attr_dormant.attr,
        &dev_attr_testing.attr,
        &dev_attr_operstate.attr,
        &dev_attr_carrier_changes.attr,
        &dev_attr_ifalias.attr,
        &dev_attr_carrier.attr,
        &dev_attr_mtu.attr,
        &dev_attr_flags.attr,
        &dev_attr_tx_queue_len.attr,
        &dev_attr_gro_flush_timeout.attr,
        &dev_attr_napi_defer_hard_irqs.attr,
        &dev_attr_proto_down.attr,
        &dev_attr_carrier_up_count.attr,
        &dev_attr_carrier_down_count.attr,
        &dev_attr_threaded.attr,
        NULL,
};
ATTRIBUTE_GROUPS(net_class);

/* 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);

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

                ret = sysfs_emit(buf, fmt_u64, *(u64 *)(((u8 *)stats) + offset));
        }
        rcu_read_unlock();
        return ret;
}

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

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);
NETSTAT_ENTRY(rx_nohandler);

static struct attribute *netstat_attrs[] __ro_after_init = {
        &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,
        &dev_attr_rx_nohandler.attr,
        NULL
};

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

static struct attribute *wireless_attrs[] = {
        NULL
};

static const struct attribute_group wireless_group = {
        .name = "wireless",
        .attrs = wireless_attrs,
};

static bool wireless_group_needed(struct net_device *ndev)
{
#if IS_ENABLED(CONFIG_CFG80211)
        if (ndev->ieee80211_ptr)
                return true;
#endif
#if IS_ENABLED(CONFIG_WIRELESS_EXT)
        if (ndev->wireless_handlers)
                return true;
#endif
        return false;
}

#else /* CONFIG_SYSFS */
#define net_class_groups        NULL
#endif /* CONFIG_SYSFS */

#ifdef CONFIG_SYSFS
#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)
{
        const 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, buf);
}

static ssize_t rx_queue_attr_store(struct kobject *kobj, struct attribute *attr,
                                   const char *buf, size_t count)
{
        const 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, buf, count);
}

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

#ifdef CONFIG_RPS
static ssize_t show_rps_map(struct netdev_rx_queue *queue, char *buf)
{
        struct rps_map *map;
        cpumask_var_t mask;
        int i, len;

        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 = sysfs_emit(buf, "%*pb\n", cpumask_pr_args(mask));
        rcu_read_unlock();
        free_cpumask_var(mask);

        return len < PAGE_SIZE ? len : -EINVAL;
}

static int netdev_rx_queue_set_rps_mask(struct netdev_rx_queue *queue,
                                        cpumask_var_t mask)
{
        static DEFINE_MUTEX(rps_map_mutex);
        struct rps_map *old_map, *map;
        int cpu, i;

        map = kzalloc(max_t(unsigned int,
                            RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
                      GFP_KERNEL);
        if (!map)
                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;
        }

        mutex_lock(&rps_map_mutex);
        old_map = rcu_dereference_protected(queue->rps_map,
                                            mutex_is_locked(&rps_map_mutex));
        rcu_assign_pointer(queue->rps_map, map);

        if (map)
                static_branch_inc(&rps_needed);
        if (old_map)
                static_branch_dec(&rps_needed);

        mutex_unlock(&rps_map_mutex);

        if (old_map)
                kfree_rcu(old_map, rcu);
        return 0;
}

int rps_cpumask_housekeeping(struct cpumask *mask)
{
        if (!cpumask_empty(mask)) {
                cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT));
                cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_WQ));
                if (cpumask_empty(mask))
                        return -EINVAL;
        }
        return 0;
}

static ssize_t store_rps_map(struct netdev_rx_queue *queue,
                             const char *buf, size_t len)
{
        cpumask_var_t mask;
        int err;

        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)
                goto out;

        err = rps_cpumask_housekeeping(mask);
        if (err)
                goto out;

        err = netdev_rx_queue_set_rps_mask(queue, mask);

out:
        free_cpumask_var(mask);
        return err ? : len;
}

static ssize_t show_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
                                           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 = 1UL << flow_table->log;
        rcu_read_unlock();

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

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);
        vfree(table);
}

static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
                                            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) doesn't 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->log = ilog2(mask) + 1;
                for (count = 0; count <= mask; count++) {
                        table->flows[count].cpu = RPS_NO_CPU;
                        table->flows[count].filter = RPS_NO_FILTER;
                }
        } 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 __ro_after_init
        = __ATTR(rps_cpus, 0644, show_rps_map, store_rps_map);

static struct rx_queue_attribute rps_dev_flow_table_cnt_attribute __ro_after_init
        = __ATTR(rps_flow_cnt, 0644,
                 show_rps_dev_flow_table_cnt, store_rps_dev_flow_table_cnt);
#endif /* CONFIG_RPS */

static struct attribute *rx_queue_default_attrs[] __ro_after_init = {
#ifdef CONFIG_RPS
        &rps_cpus_attribute.attr,
        &rps_dev_flow_table_cnt_attribute.attr,
#endif
        NULL
};
ATTRIBUTE_GROUPS(rx_queue_default);

static void rx_queue_release(struct kobject *kobj)
{
        struct netdev_rx_queue *queue = to_rx_queue(kobj);
#ifdef CONFIG_RPS
        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);
        }
#endif

        memset(kobj, 0, sizeof(*kobj));
        netdev_put(queue->dev, &queue->dev_tracker);
}

static const void *rx_queue_namespace(const struct kobject *kobj)
{
        struct netdev_rx_queue *queue = to_rx_queue(kobj);
        struct device *dev = &queue->dev->dev;
        const void *ns = NULL;

        if (dev->class && dev->class->namespace)
                ns = dev->class->namespace(dev);

        return ns;
}

static void rx_queue_get_ownership(const struct kobject *kobj,
                                   kuid_t *uid, kgid_t *gid)
{
        const struct net *net = rx_queue_namespace(kobj);

        net_ns_get_ownership(net, uid, gid);
}

static const struct kobj_type rx_queue_ktype = {
        .sysfs_ops = &rx_queue_sysfs_ops,
        .release = rx_queue_release,
        .namespace = rx_queue_namespace,
        .get_ownership = rx_queue_get_ownership,
};

static int rx_queue_default_mask(struct net_device *dev,
                                 struct netdev_rx_queue *queue)
{
#if IS_ENABLED(CONFIG_RPS) && IS_ENABLED(CONFIG_SYSCTL)
        struct cpumask *rps_default_mask;
        int res = 0;

        mutex_lock(&rps_default_mask_mutex);

        rps_default_mask = dev_net(dev)->core.rps_default_mask;
        if (rps_default_mask && !cpumask_empty(rps_default_mask))
                res = netdev_rx_queue_set_rps_mask(queue, rps_default_mask);

        mutex_unlock(&rps_default_mask_mutex);

        return res;
#else
        return 0;
#endif
}

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

        /* Rx queues are cleared in rx_queue_release to allow later
         * re-registration. This is triggered when their kobj refcount is
         * dropped.
         *
         * If a queue is removed while both a read (or write) operation and a
         * the re-addition of the same queue are pending (waiting on rntl_lock)
         * it might happen that the re-addition will execute before the read,
         * making the initial removal to never happen (queue's kobj refcount
         * won't drop enough because of the pending read). In such rare case,
         * return to allow the removal operation to complete.
         */
        if (unlikely(kobj->state_initialized)) {
                netdev_warn_once(dev, "Cannot re-add rx queues before their removal completed");
                return -EAGAIN;
        }

        /* Kobject_put later will trigger rx_queue_release call which
         * decreases dev refcount: Take that reference here
         */
        netdev_hold(queue->dev, &queue->dev_tracker, GFP_KERNEL);

        kobj->kset = dev->queues_kset;
        error = kobject_init_and_add(kobj, &rx_queue_ktype, NULL,
                                     "rx-%u", index);
        if (error)
                goto err;

        queue->groups = rx_queue_default_groups;
        error = sysfs_create_groups(kobj, queue->groups);
        if (error)
                goto err;

        if (dev->sysfs_rx_queue_group) {
                error = sysfs_create_group(kobj, dev->sysfs_rx_queue_group);
                if (error)
                        goto err_default_groups;
        }

        error = rx_queue_default_mask(dev, queue);
        if (error)
                goto err_default_groups;

        kobject_uevent(kobj, KOBJ_ADD);

        return error;

err_default_groups:
        sysfs_remove_groups(kobj, queue->groups);
err:
        kobject_put(kobj);
        return error;
}

static int rx_queue_change_owner(struct net_device *dev, int index, kuid_t kuid,
                                 kgid_t kgid)
{
        struct netdev_rx_queue *queue = dev->_rx + index;
        struct kobject *kobj = &queue->kobj;
        int error;

        error = sysfs_change_owner(kobj, kuid, kgid);
        if (error)
                return error;

        if (dev->sysfs_rx_queue_group)
                error = sysfs_group_change_owner(
                        kobj, dev->sysfs_rx_queue_group, kuid, kgid);

        return error;
}
#endif /* CONFIG_SYSFS */

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

#ifndef CONFIG_RPS
        if (!dev->sysfs_rx_queue_group)
                return 0;
#endif
        for (i = old_num; i < new_num; i++) {
                error = rx_queue_add_kobject(dev, i);
                if (error) {
                        new_num = old_num;
                        break;
                }
        }

        while (--i >= new_num) {
                struct netdev_rx_queue *queue = &dev->_rx[i];
                struct kobject *kobj = &queue->kobj;

                if (!check_net(dev_net(dev)))
                        kobj->uevent_suppress = 1;
                if (dev->sysfs_rx_queue_group)
                        sysfs_remove_group(kobj, dev->sysfs_rx_queue_group);
                sysfs_remove_groups(kobj, queue->groups);
                kobject_put(kobj);
        }

        return error;
#else
        return 0;
#endif
}

static int net_rx_queue_change_owner(struct net_device *dev, int num,
                                     kuid_t kuid, kgid_t kgid)
{
#ifdef CONFIG_SYSFS
        int error = 0;
        int i;

#ifndef CONFIG_RPS
        if (!dev->sysfs_rx_queue_group)
                return 0;
#endif
        for (i = 0; i < num; i++) {
                error = rx_queue_change_owner(dev, i, kuid, kgid);
                if (error)
                        break;
        }

        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 kobject *kobj, struct attribute *attr,
                        struct netdev_queue *queue, char *buf);
        ssize_t (*store)(struct kobject *kobj, struct attribute *attr,
                         struct netdev_queue *queue, 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)
{
        const 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(kobj, attr, queue, buf);
}

static ssize_t netdev_queue_attr_store(struct kobject *kobj,
                                       struct attribute *attr,
                                       const char *buf, size_t count)
{
        const 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(kobj, attr, queue, buf, count);
}

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

static ssize_t tx_timeout_show(struct kobject *kobj, struct attribute *attr,
                               struct netdev_queue *queue, char *buf)
{
        unsigned long trans_timeout = atomic_long_read(&queue->trans_timeout);

        return sysfs_emit(buf, fmt_ulong, trans_timeout);
}

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

        i = queue - dev->_tx;
        BUG_ON(i >= dev->num_tx_queues);

        return i;
}

static ssize_t traffic_class_show(struct kobject *kobj, struct attribute *attr,
                                  struct netdev_queue *queue, char *buf)
{
        struct net_device *dev = queue->dev;
        int num_tc, tc, index, ret;

        if (!netif_is_multiqueue(dev))
                return -ENOENT;

        ret = sysfs_rtnl_lock(kobj, attr, queue->dev);
        if (ret)
                return ret;

        index = get_netdev_queue_index(queue);

        /* If queue belongs to subordinate dev use its TC mapping */
        dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;

        num_tc = dev->num_tc;
        tc = netdev_txq_to_tc(dev, index);

        rtnl_unlock();

        if (tc < 0)
                return -EINVAL;

        /* We can report the traffic class one of two ways:
         * Subordinate device traffic classes are reported with the traffic
         * class first, and then the subordinate class so for example TC0 on
         * subordinate device 2 will be reported as "0-2". If the queue
         * belongs to the root device it will be reported with just the
         * traffic class, so just "0" for TC 0 for example.
         */
        return num_tc < 0 ? sysfs_emit(buf, "%d%d\n", tc, num_tc) :
                            sysfs_emit(buf, "%d\n", tc);
}

#ifdef CONFIG_XPS
static ssize_t tx_maxrate_show(struct kobject *kobj, struct attribute *attr,
                               struct netdev_queue *queue, char *buf)
{
        return sysfs_emit(buf, "%lu\n", queue->tx_maxrate);
}

static ssize_t tx_maxrate_store(struct kobject *kobj, struct attribute *attr,
                                struct netdev_queue *queue, const char *buf,
                                size_t len)
{
        int err, index = get_netdev_queue_index(queue);
        struct net_device *dev = queue->dev;
        u32 rate = 0;

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

        /* The check is also done later; this helps returning early without
         * hitting the locking section below.
         */
        if (!dev->netdev_ops->ndo_set_tx_maxrate)
                return -EOPNOTSUPP;

        err = kstrtou32(buf, 10, &rate);
        if (err < 0)
                return err;

        err = sysfs_rtnl_lock(kobj, attr, dev);
        if (err)
                return err;

        err = -EOPNOTSUPP;
        netdev_lock_ops(dev);
        if (dev->netdev_ops->ndo_set_tx_maxrate)
                err = dev->netdev_ops->ndo_set_tx_maxrate(dev, index, rate);
        netdev_unlock_ops(dev);

        if (!err) {
                queue->tx_maxrate = rate;
                rtnl_unlock();
                return len;
        }

        rtnl_unlock();
        return err;
}

static struct netdev_queue_attribute queue_tx_maxrate __ro_after_init
        = __ATTR_RW(tx_maxrate);
#endif

static struct netdev_queue_attribute queue_trans_timeout __ro_after_init
        = __ATTR_RO(tx_timeout);

static struct netdev_queue_attribute queue_traffic_class __ro_after_init
        = __ATTR_RO(traffic_class);

#ifdef CONFIG_BQL
/*
 * Byte queue limits sysfs structures and functions.
 */
static ssize_t bql_show(char *buf, unsigned int value)
{
        return sysfs_emit(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 kobject *kobj, struct attribute *attr,
                                  struct netdev_queue *queue, char *buf)
{
        struct dql *dql = &queue->dql;

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

static ssize_t bql_set_hold_time(struct kobject *kobj, struct attribute *attr,
                                 struct netdev_queue *queue, 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 __ro_after_init
        = __ATTR(hold_time, 0644,
                 bql_show_hold_time, bql_set_hold_time);

static ssize_t bql_show_stall_thrs(struct kobject *kobj, struct attribute *attr,
                                   struct netdev_queue *queue, char *buf)
{
        struct dql *dql = &queue->dql;

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

static ssize_t bql_set_stall_thrs(struct kobject *kobj, struct attribute *attr,
                                  struct netdev_queue *queue, 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;

        value = msecs_to_jiffies(value);
        if (value && (value < 4 || value > 4 / 2 * BITS_PER_LONG))
                return -ERANGE;

        if (!dql->stall_thrs && value)
                dql->last_reap = jiffies;
        /* Force last_reap to be live */
        smp_wmb();
        dql->stall_thrs = value;

        return len;
}

static struct netdev_queue_attribute bql_stall_thrs_attribute __ro_after_init =
        __ATTR(stall_thrs, 0644, bql_show_stall_thrs, bql_set_stall_thrs);

static ssize_t bql_show_stall_max(struct kobject *kobj, struct attribute *attr,
                                  struct netdev_queue *queue, char *buf)
{
        return sysfs_emit(buf, "%u\n", READ_ONCE(queue->dql.stall_max));
}

static ssize_t bql_set_stall_max(struct kobject *kobj, struct attribute *attr,
                                 struct netdev_queue *queue, const char *buf,
                                 size_t len)
{
        WRITE_ONCE(queue->dql.stall_max, 0);
        return len;
}

static struct netdev_queue_attribute bql_stall_max_attribute __ro_after_init =
        __ATTR(stall_max, 0644, bql_show_stall_max, bql_set_stall_max);

static ssize_t bql_show_stall_cnt(struct kobject *kobj, struct attribute *attr,
                                  struct netdev_queue *queue, char *buf)
{
        struct dql *dql = &queue->dql;

        return sysfs_emit(buf, "%lu\n", dql->stall_cnt);
}

static struct netdev_queue_attribute bql_stall_cnt_attribute __ro_after_init =
        __ATTR(stall_cnt, 0444, bql_show_stall_cnt, NULL);

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

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

static struct netdev_queue_attribute bql_inflight_attribute __ro_after_init =
        __ATTR(inflight, 0444, bql_show_inflight, NULL);

#define BQL_ATTR(NAME, FIELD)                                           \
static ssize_t bql_show_ ## NAME(struct kobject *kobj,                  \
                                 struct attribute *attr,                \
                                 struct netdev_queue *queue, char *buf) \
{                                                                       \
        return bql_show(buf, queue->dql.FIELD);                         \
}                                                                       \
                                                                        \
static ssize_t bql_set_ ## NAME(struct kobject *kobj,                   \
                                struct attribute *attr,                 \
                                struct netdev_queue *queue,             \
                                const char *buf, size_t len)            \
{                                                                       \
        return bql_set(buf, len, &queue->dql.FIELD);                    \
}                                                                       \
                                                                        \
static struct netdev_queue_attribute bql_ ## NAME ## _attribute __ro_after_init \
        = __ATTR(NAME, 0644,                            \
                 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[] __ro_after_init = {
        &bql_limit_attribute.attr,
        &bql_limit_max_attribute.attr,
        &bql_limit_min_attribute.attr,
        &bql_hold_time_attribute.attr,
        &bql_inflight_attribute.attr,
        &bql_stall_thrs_attribute.attr,
        &bql_stall_cnt_attribute.attr,
        &bql_stall_max_attribute.attr,
        NULL
};

static const struct attribute_group dql_group = {
        .name  = "byte_queue_limits",
        .attrs  = dql_attrs,
};
#else
/* Fake declaration, all the code using it should be dead */
static const struct attribute_group dql_group = {};
#endif /* CONFIG_BQL */

#ifdef CONFIG_XPS
static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
                              int tc, char *buf, enum xps_map_type type)
{
        struct xps_dev_maps *dev_maps;
        unsigned long *mask;
        unsigned int nr_ids;
        int j, len;

        rcu_read_lock();
        dev_maps = rcu_dereference(dev->xps_maps[type]);

        /* Default to nr_cpu_ids/dev->num_rx_queues and do not just return 0
         * when dev_maps hasn't been allocated yet, to be backward compatible.
         */
        nr_ids = dev_maps ? dev_maps->nr_ids :
                 (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);

        mask = bitmap_zalloc(nr_ids, GFP_NOWAIT);
        if (!mask) {
                rcu_read_unlock();
                return -ENOMEM;
        }

        if (!dev_maps || tc >= dev_maps->num_tc)
                goto out_no_maps;

        for (j = 0; j < nr_ids; j++) {
                int i, tci = j * dev_maps->num_tc + tc;
                struct xps_map *map;

                map = rcu_dereference(dev_maps->attr_map[tci]);
                if (!map)
                        continue;

                for (i = map->len; i--;) {
                        if (map->queues[i] == index) {
                                __set_bit(j, mask);
                                break;
                        }
                }
        }
out_no_maps:
        rcu_read_unlock();

        len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
        bitmap_free(mask);

        return len < PAGE_SIZE ? len : -EINVAL;
}

static ssize_t xps_cpus_show(struct kobject *kobj, struct attribute *attr,
                             struct netdev_queue *queue, char *buf)
{
        struct net_device *dev = queue->dev;
        unsigned int index;
        int len, tc, ret;

        if (!netif_is_multiqueue(dev))
                return -ENOENT;

        index = get_netdev_queue_index(queue);

        ret = sysfs_rtnl_lock(kobj, attr, queue->dev);
        if (ret)
                return ret;

        /* If queue belongs to subordinate dev use its map */
        dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;

        tc = netdev_txq_to_tc(dev, index);
        if (tc < 0) {
                rtnl_unlock();
                return -EINVAL;
        }

        /* Increase the net device refcnt to make sure it won't be freed while
         * xps_queue_show is running.
         */
        dev_hold(dev);
        rtnl_unlock();

        len = xps_queue_show(dev, index, tc, buf, XPS_CPUS);

        dev_put(dev);
        return len;
}

static ssize_t xps_cpus_store(struct kobject *kobj, struct attribute *attr,
                              struct netdev_queue *queue, const char *buf,
                              size_t len)
{
        struct net_device *dev = queue->dev;
        unsigned int index;
        cpumask_var_t mask;
        int err;

        if (!netif_is_multiqueue(dev))
                return -ENOENT;

        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;
        }

        err = sysfs_rtnl_lock(kobj, attr, dev);
        if (err) {
                free_cpumask_var(mask);
                return err;
        }

        err = netif_set_xps_queue(dev, mask, index);
        rtnl_unlock();

        free_cpumask_var(mask);

        return err ? : len;
}

static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
        = __ATTR_RW(xps_cpus);

static ssize_t xps_rxqs_show(struct kobject *kobj, struct attribute *attr,
                             struct netdev_queue *queue, char *buf)
{
        struct net_device *dev = queue->dev;
        unsigned int index;
        int tc, ret;

        index = get_netdev_queue_index(queue);

        ret = sysfs_rtnl_lock(kobj, attr, dev);
        if (ret)
                return ret;

        tc = netdev_txq_to_tc(dev, index);

        /* Increase the net device refcnt to make sure it won't be freed while
         * xps_queue_show is running.
         */
        dev_hold(dev);
        rtnl_unlock();

        ret = tc >= 0 ? xps_queue_show(dev, index, tc, buf, XPS_RXQS) : -EINVAL;
        dev_put(dev);
        return ret;
}

static ssize_t xps_rxqs_store(struct kobject *kobj, struct attribute *attr,
                              struct netdev_queue *queue, const char *buf,
                              size_t len)
{
        struct net_device *dev = queue->dev;
        struct net *net = dev_net(dev);
        unsigned long *mask;
        unsigned int index;
        int err;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL);
        if (!mask)
                return -ENOMEM;

        index = get_netdev_queue_index(queue);

        err = bitmap_parse(buf, len, mask, dev->num_rx_queues);
        if (err) {
                bitmap_free(mask);
                return err;
        }

        err = sysfs_rtnl_lock(kobj, attr, dev);
        if (err) {
                bitmap_free(mask);
                return err;
        }

        cpus_read_lock();
        err = __netif_set_xps_queue(dev, mask, index, XPS_RXQS);
        cpus_read_unlock();

        rtnl_unlock();

        bitmap_free(mask);
        return err ? : len;
}

static struct netdev_queue_attribute xps_rxqs_attribute __ro_after_init
        = __ATTR_RW(xps_rxqs);
#endif /* CONFIG_XPS */

static struct attribute *netdev_queue_default_attrs[] __ro_after_init = {
        &queue_trans_timeout.attr,
        &queue_traffic_class.attr,
#ifdef CONFIG_XPS
        &xps_cpus_attribute.attr,
        &xps_rxqs_attribute.attr,
        &queue_tx_maxrate.attr,
#endif
        NULL
};
ATTRIBUTE_GROUPS(netdev_queue_default);

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

        memset(kobj, 0, sizeof(*kobj));
        netdev_put(queue->dev, &queue->dev_tracker);
}

static const void *netdev_queue_namespace(const struct kobject *kobj)
{
        struct netdev_queue *queue = to_netdev_queue(kobj);
        struct device *dev = &queue->dev->dev;
        const void *ns = NULL;

        if (dev->class && dev->class->namespace)
                ns = dev->class->namespace(dev);

        return ns;
}

static void netdev_queue_get_ownership(const struct kobject *kobj,
                                       kuid_t *uid, kgid_t *gid)
{
        const struct net *net = netdev_queue_namespace(kobj);

        net_ns_get_ownership(net, uid, gid);
}

static const struct kobj_type netdev_queue_ktype = {
        .sysfs_ops = &netdev_queue_sysfs_ops,
        .release = netdev_queue_release,
        .namespace = netdev_queue_namespace,
        .get_ownership = netdev_queue_get_ownership,
};

static bool netdev_uses_bql(const struct net_device *dev)
{
        if (dev->lltx || (dev->priv_flags & IFF_NO_QUEUE))
                return false;

        return IS_ENABLED(CONFIG_BQL);
}

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

        /* Tx queues are cleared in netdev_queue_release to allow later
         * re-registration. This is triggered when their kobj refcount is
         * dropped.
         *
         * If a queue is removed while both a read (or write) operation and a
         * the re-addition of the same queue are pending (waiting on rntl_lock)
         * it might happen that the re-addition will execute before the read,
         * making the initial removal to never happen (queue's kobj refcount
         * won't drop enough because of the pending read). In such rare case,
         * return to allow the removal operation to complete.
         */
        if (unlikely(kobj->state_initialized)) {
                netdev_warn_once(dev, "Cannot re-add tx queues before their removal completed");
                return -EAGAIN;
        }

        /* Kobject_put later will trigger netdev_queue_release call
         * which decreases dev refcount: Take that reference here
         */
        netdev_hold(queue->dev, &queue->dev_tracker, GFP_KERNEL);

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

        queue->groups = netdev_queue_default_groups;
        error = sysfs_create_groups(kobj, queue->groups);
        if (error)
                goto err;

        if (netdev_uses_bql(dev)) {
                error = sysfs_create_group(kobj, &dql_group);
                if (error)
                        goto err_default_groups;
        }

        kobject_uevent(kobj, KOBJ_ADD);
        return 0;

err_default_groups:
        sysfs_remove_groups(kobj, queue->groups);
err:
        kobject_put(kobj);
        return error;
}

static int tx_queue_change_owner(struct net_device *ndev, int index,
                                 kuid_t kuid, kgid_t kgid)
{
        struct netdev_queue *queue = ndev->_tx + index;
        struct kobject *kobj = &queue->kobj;
        int error;

        error = sysfs_change_owner(kobj, kuid, kgid);
        if (error)
                return error;

        if (netdev_uses_bql(ndev))
                error = sysfs_group_change_owner(kobj, &dql_group, kuid, kgid);

        return error;
}
#endif /* CONFIG_SYSFS */

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

        /* Tx queue kobjects are allowed to be updated when a device is being
         * unregistered, but solely to remove queues from qdiscs. Any path
         * adding queues should be fixed.
         */
        WARN(dev->reg_state == NETREG_UNREGISTERING && new_num > old_num,
             "New queues can't be registered after device unregistration.");

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

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

                if (!check_net(dev_net(dev)))
                        queue->kobj.uevent_suppress = 1;

                if (netdev_uses_bql(dev))
                        sysfs_remove_group(&queue->kobj, &dql_group);

                sysfs_remove_groups(&queue->kobj, queue->groups);
                kobject_put(&queue->kobj);
        }

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

static int net_tx_queue_change_owner(struct net_device *dev, int num,
                                     kuid_t kuid, kgid_t kgid)
{
#ifdef CONFIG_SYSFS
        int error = 0;
        int i;

        for (i = 0; i < num; i++) {
                error = tx_queue_change_owner(dev, i, kuid, kgid);
                if (error)
                        break;
        }

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

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

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

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

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

        return 0;

error:
        netdev_queue_update_kobjects(dev, txq, 0);
        net_rx_queue_update_kobjects(dev, rxq, 0);
#ifdef CONFIG_SYSFS
        kset_unregister(dev->queues_kset);
#endif
        return error;
}

static int queue_change_owner(struct net_device *ndev, kuid_t kuid, kgid_t kgid)
{
        int error = 0, real_rx = 0, real_tx = 0;

#ifdef CONFIG_SYSFS
        if (ndev->queues_kset) {
                error = sysfs_change_owner(&ndev->queues_kset->kobj, kuid, kgid);
                if (error)
                        return error;
        }
        real_rx = ndev->real_num_rx_queues;
#endif
        real_tx = ndev->real_num_tx_queues;

        error = net_rx_queue_change_owner(ndev, real_rx, kuid, kgid);
        if (error)
                return error;

        error = net_tx_queue_change_owner(ndev, real_tx, kuid, kgid);
        if (error)
                return error;

        return 0;
}

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

#ifdef CONFIG_SYSFS
        real_rx = dev->real_num_rx_queues;
#endif
        real_tx = dev->real_num_tx_queues;

        net_rx_queue_update_kobjects(dev, real_rx, 0);
        netdev_queue_update_kobjects(dev, real_tx, 0);

        netdev_lock_ops(dev);
        dev->real_num_rx_queues = 0;
        dev->real_num_tx_queues = 0;
        netdev_unlock_ops(dev);
#ifdef CONFIG_SYSFS
        kset_unregister(dev->queues_kset);
#endif
}

static bool net_current_may_mount(void)
{
        struct net *net = current->nsproxy->net_ns;

        return ns_capable(net->user_ns, CAP_SYS_ADMIN);
}

static void *net_grab_current_ns(void)
{
        struct net *ns = current->nsproxy->net_ns;
#ifdef CONFIG_NET_NS
        if (ns)
                refcount_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);
}

const struct kobj_ns_type_operations net_ns_type_operations = {
        .type = KOBJ_NS_TYPE_NET,
        .current_may_mount = net_current_may_mount,
        .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);

static int netdev_uevent(const struct device *d, struct kobj_uevent_env *env)
{
        const 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;
}

/*
 *      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);

        /* no need to wait for rcu grace period:
         * device is dead and about to be freed.
         */
        kfree(rcu_access_pointer(dev->ifalias));
        kvfree(dev);
}

static const void *net_namespace(const struct device *d)
{
        const struct net_device *dev = to_net_dev(d);

        return dev_net(dev);
}

static void net_get_ownership(const struct device *d, kuid_t *uid, kgid_t *gid)
{
        const struct net_device *dev = to_net_dev(d);
        const struct net *net = dev_net(dev);

        net_ns_get_ownership(net, uid, gid);
}

static const struct class net_class = {
        .name = "net",
        .dev_release = netdev_release,
        .dev_groups = net_class_groups,
        .dev_uevent = netdev_uevent,
        .ns_type = &net_ns_type_operations,
        .namespace = net_namespace,
        .get_ownership = net_get_ownership,
};

#ifdef CONFIG_OF
static int of_dev_node_match(struct device *dev, const void *data)
{
        for (; dev; dev = dev->parent) {
                if (dev->of_node == data)
                        return 1;
        }

        return 0;
}

/*
 * of_find_net_device_by_node - lookup the net device for the device node
 * @np: OF device node
 *
 * Looks up the net_device structure corresponding with the device node.
 * If successful, returns a pointer to the net_device with the embedded
 * struct device refcount incremented by one, or NULL on failure. The
 * refcount must be dropped when done with the net_device.
 */
struct net_device *of_find_net_device_by_node(struct device_node *np)
{
        struct device *dev;

        dev = class_find_device(&net_class, NULL, np, of_dev_node_match);
        if (!dev)
                return NULL;

        return to_net_dev(dev);
}
EXPORT_SYMBOL(of_find_net_device_by_node);
#endif

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

        if (!check_net(dev_net(ndev)))
                dev_set_uevent_suppress(dev, 1);

        kobject_get(&dev->kobj);

        remove_queue_kobjects(ndev);

        pm_runtime_set_memalloc_noio(dev, false);

        device_del(dev);
}

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

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

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

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

        *groups++ = &netstat_group;
        *groups++ = &netdev_phys_group;

        if (wireless_group_needed(ndev))
                *groups++ = &wireless_group;
#endif /* CONFIG_SYSFS */

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

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

        pm_runtime_set_memalloc_noio(dev, true);

        return error;
}

/* Change owner for sysfs entries when moving network devices across network
 * namespaces owned by different user namespaces.
 */
int netdev_change_owner(struct net_device *ndev, const struct net *net_old,
                        const struct net *net_new)
{
        kuid_t old_uid = GLOBAL_ROOT_UID, new_uid = GLOBAL_ROOT_UID;
        kgid_t old_gid = GLOBAL_ROOT_GID, new_gid = GLOBAL_ROOT_GID;
        struct device *dev = &ndev->dev;
        int error;

        net_ns_get_ownership(net_old, &old_uid, &old_gid);
        net_ns_get_ownership(net_new, &new_uid, &new_gid);

        /* The network namespace was changed but the owning user namespace is
         * identical so there's no need to change the owner of sysfs entries.
         */
        if (uid_eq(old_uid, new_uid) && gid_eq(old_gid, new_gid))
                return 0;

        error = device_change_owner(dev, new_uid, new_gid);
        if (error)
                return error;

        error = queue_change_owner(ndev, new_uid, new_gid);
        if (error)
                return error;

        return 0;
}

int netdev_class_create_file_ns(const struct class_attribute *class_attr,
                                const void *ns)
{
        return class_create_file_ns(&net_class, class_attr, ns);
}
EXPORT_SYMBOL(netdev_class_create_file_ns);

void netdev_class_remove_file_ns(const struct class_attribute *class_attr,
                                 const void *ns)
{
        class_remove_file_ns(&net_class, class_attr, ns);
}
EXPORT_SYMBOL(netdev_class_remove_file_ns);

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