dev.c

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/*
 *  NET3    Protocol independent device support routines.
 *
 *      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.
 *
 *  Derived from the non IP parts of dev.c 1.0.19
 *      Authors:    Ross Biro
 *              Fred N. van Kempen, <[email protected]>
 *              Mark Evans, <[email protected]>
 *
 *  Additional Authors:
 *      Florian la Roche <[email protected]>
 *      Alan Cox <[email protected]>
 *      David Hinds <[email protected]>
 *      Alexey Kuznetsov <[email protected]>
 *      Adam Sulmicki <[email protected]>
 *              Pekka Riikonen <[email protected]>
 *
 *  Changes:
 *              D.J. Barrow     :       Fixed bug where dev->refcnt gets set
 *                          to 2 if register_netdev gets called
 *                          before net_dev_init & also removed a
 *                          few lines of code in the process.
 *      Alan Cox    :   device private ioctl copies fields back.
 *      Alan Cox    :   Transmit queue code does relevant
 *                  stunts to keep the queue safe.
 *      Alan Cox    :   Fixed double lock.
 *      Alan Cox    :   Fixed promisc NULL pointer trap
 *      ????????    :   Support the full private ioctl range
 *      Alan Cox    :   Moved ioctl permission check into
 *                  drivers
 *      Tim Kordas  :   SIOCADDMULTI/SIOCDELMULTI
 *      Alan Cox    :   100 backlog just doesn't cut it when
 *                  you start doing multicast video 8)
 *      Alan Cox    :   Rewrote net_bh and list manager.
 *      Alan Cox    :   Fix ETH_P_ALL echoback lengths.
 *      Alan Cox    :   Took out transmit every packet pass
 *                  Saved a few bytes in the ioctl handler
 *      Alan Cox    :   Network driver sets packet type before
 *                  calling netif_rx. Saves a function
 *                  call a packet.
 *      Alan Cox    :   Hashed net_bh()
 *      Richard Kooijman:   Timestamp fixes.
 *      Alan Cox    :   Wrong field in SIOCGIFDSTADDR
 *      Alan Cox    :   Device lock protection.
 *      Alan Cox    :   Fixed nasty side effect of device close
 *                  changes.
 *      Rudi Cilibrasi  :   Pass the right thing to
 *                  set_mac_address()
 *      Dave Miller :   32bit quantity for the device lock to
 *                  make it work out on a Sparc.
 *      Bjorn Ekwall    :   Added KERNELD hack.
 *      Alan Cox    :   Cleaned up the backlog initialise.
 *      Craig Metz  :   SIOCGIFCONF fix if space for under
 *                  1 device.
 *      Thomas Bogendoerfer :   Return ENODEV for dev_open, if there
 *                  is no device open function.
 *      Andi Kleen  :   Fix error reporting for SIOCGIFCONF
 *      Michael Chastain    :   Fix signed/unsigned for SIOCGIFCONF
 *      Cyrus Durgin    :   Cleaned for KMOD
 *      Adam Sulmicki   :   Bug Fix : Network Device Unload
 *                  A network device unload needs to purge
 *                  the backlog queue.
 *  Paul Rusty Russell  :   SIOCSIFNAME
 *              Pekka Riikonen  :   Netdev boot-time settings code
 *              Andrew Morton   :       Make unregister_netdevice wait
 *                          indefinitely on dev->refcnt
 *      J Hadi Salim    :   - Backlog queue sampling
 *                      - netif_rx() feedback
 */

#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/notifier.h>
#include <linux/skbuff.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <linux/rtnetlink.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <net/dst.h>
#include <net/pkt_sched.h>
#include <net/checksum.h>
#include <net/xfrm.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/netpoll.h>
#include <linux/rcupdate.h>
#include <linux/delay.h>
#include <net/wext.h>
#include <net/iw_handler.h>
#include <asm/current.h>
#include <linux/audit.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <trace/events/napi.h>
#include <trace/events/net.h>
#include <trace/events/skb.h>
#include <linux/pci.h>
#include <linux/inetdevice.h>
#include <linux/cpu_rmap.h>
#include <linux/net_tstamp.h>
#include <linux/static_key.h>
#include <net/flow_keys.h>

#include "net-sysfs.h"

/* Instead of increasing this, you should create a hash table. */
#define MAX_GRO_SKBS 8

/* This should be increased if a protocol with a bigger head is added. */
#define GRO_MAX_HEAD (MAX_HEADER + 128)

/*
 *  The list of packet types we will receive (as opposed to discard)
 *  and the routines to invoke.
 *
 *  Why 16. Because with 16 the only overlap we get on a hash of the
 *  low nibble of the protocol value is RARP/SNAP/X.25.
 *
 *      NOTE:  That is no longer true with the addition of VLAN tags.  Not
 *             sure which should go first, but I bet it won't make much
 *             difference if we are running VLANs.  The good news is that
 *             this protocol won't be in the list unless compiled in, so
 *             the average user (w/out VLANs) will not be adversely affected.
 *             --BLG
 *
 *      0800    IP
 *      8100    802.1Q VLAN
 *      0001    802.3
 *      0002    AX.25
 *      0004    802.2
 *      8035    RARP
 *      0005    SNAP
 *      0805    X.25
 *      0806    ARP
 *      8137    IPX
 *      0009    Localtalk
 *      86DD    IPv6
 */

#define PTYPE_HASH_SIZE (16)
#define PTYPE_HASH_MASK (PTYPE_HASH_SIZE - 1)

static DEFINE_SPINLOCK(ptype_lock);
static struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
static struct list_head ptype_all __read_mostly;    /* Taps */

/*
 * The @dev_base_head list is protected by @dev_base_lock and the rtnl
 * semaphore.
 *
 * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
 *
 * Writers must hold the rtnl semaphore while they loop through the
 * dev_base_head list, and hold dev_base_lock for writing when they do the
 * actual updates.  This allows pure readers to access the list even
 * while a writer is preparing to update it.
 *
 * To put it another way, dev_base_lock is held for writing only to
 * protect against pure readers; the rtnl semaphore provides the
 * protection against other writers.
 *
 * See, for example usages, register_netdevice() and
 * unregister_netdevice(), which must be called with the rtnl
 * semaphore held.
 */
DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock);

static inline void dev_base_seq_inc(struct net *net)
{
    while (++net->dev_base_seq == 0);
}

static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
{
    unsigned int hash = full_name_hash(name, strnlen(name, IFNAMSIZ));

    return &net->dev_name_head[hash_32(hash, NETDEV_HASHBITS)];
}

static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
{
    return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
}

static inline void rps_lock(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
    spin_lock(&sd->input_pkt_queue.lock);
#endif
}

static inline void rps_unlock(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
    spin_unlock(&sd->input_pkt_queue.lock);
#endif
}

/* Device list insertion */
static int list_netdevice(struct net_device *dev)
{
    struct net *net = dev_net(dev);

    ASSERT_RTNL();

    write_lock_bh(&dev_base_lock);
    list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
    hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name));
    hlist_add_head_rcu(&dev->index_hlist,
               dev_index_hash(net, dev->ifindex));
    write_unlock_bh(&dev_base_lock);

    dev_base_seq_inc(net);

    return 0;
}

/* Device list removal
 * caller must respect a RCU grace period before freeing/reusing dev
 */
static void unlist_netdevice(struct net_device *dev)
{
    ASSERT_RTNL();

    /* Unlink dev from the device chain */
    write_lock_bh(&dev_base_lock);
    list_del_rcu(&dev->dev_list);
    hlist_del_rcu(&dev->name_hlist);
    hlist_del_rcu(&dev->index_hlist);
    write_unlock_bh(&dev_base_lock);

    dev_base_seq_inc(dev_net(dev));
}

/*
 *  Our notifier list
 */

static RAW_NOTIFIER_HEAD(netdev_chain);

/*
 *  Device drivers call our routines to queue packets here. We empty the
 *  queue in the local softnet handler.
 */

DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
EXPORT_PER_CPU_SYMBOL(softnet_data);

#ifdef CONFIG_LOCKDEP
/*
 * register_netdevice() inits txq->_xmit_lock and sets lockdep class
 * according to dev->type
 */
static const unsigned short netdev_lock_type[] =
    {ARPHRD_NETROM, ARPHRD_ETHER, ARPHRD_EETHER, ARPHRD_AX25,
     ARPHRD_PRONET, ARPHRD_CHAOS, ARPHRD_IEEE802, ARPHRD_ARCNET,
     ARPHRD_APPLETLK, ARPHRD_DLCI, ARPHRD_ATM, ARPHRD_METRICOM,
     ARPHRD_IEEE1394, ARPHRD_EUI64, ARPHRD_INFINIBAND, ARPHRD_SLIP,
     ARPHRD_CSLIP, ARPHRD_SLIP6, ARPHRD_CSLIP6, ARPHRD_RSRVD,
     ARPHRD_ADAPT, ARPHRD_ROSE, ARPHRD_X25, ARPHRD_HWX25,
     ARPHRD_PPP, ARPHRD_CISCO, ARPHRD_LAPB, ARPHRD_DDCMP,
     ARPHRD_RAWHDLC, ARPHRD_TUNNEL, ARPHRD_TUNNEL6, ARPHRD_FRAD,
     ARPHRD_SKIP, ARPHRD_LOOPBACK, ARPHRD_LOCALTLK, ARPHRD_FDDI,
     ARPHRD_BIF, ARPHRD_SIT, ARPHRD_IPDDP, ARPHRD_IPGRE,
     ARPHRD_PIMREG, ARPHRD_HIPPI, ARPHRD_ASH, ARPHRD_ECONET,
     ARPHRD_IRDA, ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL,
     ARPHRD_FCFABRIC, ARPHRD_IEEE80211, ARPHRD_IEEE80211_PRISM,
     ARPHRD_IEEE80211_RADIOTAP, ARPHRD_PHONET, ARPHRD_PHONET_PIPE,
     ARPHRD_IEEE802154, ARPHRD_VOID, ARPHRD_NONE};

static const char *const netdev_lock_name[] =
    {"_xmit_NETROM", "_xmit_ETHER", "_xmit_EETHER", "_xmit_AX25",
     "_xmit_PRONET", "_xmit_CHAOS", "_xmit_IEEE802", "_xmit_ARCNET",
     "_xmit_APPLETLK", "_xmit_DLCI", "_xmit_ATM", "_xmit_METRICOM",
     "_xmit_IEEE1394", "_xmit_EUI64", "_xmit_INFINIBAND", "_xmit_SLIP",
     "_xmit_CSLIP", "_xmit_SLIP6", "_xmit_CSLIP6", "_xmit_RSRVD",
     "_xmit_ADAPT", "_xmit_ROSE", "_xmit_X25", "_xmit_HWX25",
     "_xmit_PPP", "_xmit_CISCO", "_xmit_LAPB", "_xmit_DDCMP",
     "_xmit_RAWHDLC", "_xmit_TUNNEL", "_xmit_TUNNEL6", "_xmit_FRAD",
     "_xmit_SKIP", "_xmit_LOOPBACK", "_xmit_LOCALTLK", "_xmit_FDDI",
     "_xmit_BIF", "_xmit_SIT", "_xmit_IPDDP", "_xmit_IPGRE",
     "_xmit_PIMREG", "_xmit_HIPPI", "_xmit_ASH", "_xmit_ECONET",
     "_xmit_IRDA", "_xmit_FCPP", "_xmit_FCAL", "_xmit_FCPL",
     "_xmit_FCFABRIC", "_xmit_IEEE80211", "_xmit_IEEE80211_PRISM",
     "_xmit_IEEE80211_RADIOTAP", "_xmit_PHONET", "_xmit_PHONET_PIPE",
     "_xmit_IEEE802154", "_xmit_VOID", "_xmit_NONE"};

static struct lock_class_key netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)];
static struct lock_class_key netdev_addr_lock_key[ARRAY_SIZE(netdev_lock_type)];

static inline unsigned short netdev_lock_pos(unsigned short dev_type)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(netdev_lock_type); i++)
        if (netdev_lock_type[i] == dev_type)
            return i;
    /* the last key is used by default */
    return ARRAY_SIZE(netdev_lock_type) - 1;
}

static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                         unsigned short dev_type)
{
    int i;

    i = netdev_lock_pos(dev_type);
    lockdep_set_class_and_name(lock, &netdev_xmit_lock_key[i],
                   netdev_lock_name[i]);
}

static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
{
    int i;

    i = netdev_lock_pos(dev->type);
    lockdep_set_class_and_name(&dev->addr_list_lock,
                   &netdev_addr_lock_key[i],
                   netdev_lock_name[i]);
}
#else
static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                         unsigned short dev_type)
{
}
static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
{
}
#endif

/*******************************************************************************

        Protocol management and registration routines

*******************************************************************************/

/*
 *  Add a protocol ID to the list. Now that the input handler is
 *  smarter we can dispense with all the messy stuff that used to be
 *  here.
 *
 *  BEWARE!!! Protocol handlers, mangling input packets,
 *  MUST BE last in hash buckets and checking protocol handlers
 *  MUST start from promiscuous ptype_all chain in net_bh.
 *  It is true now, do not change it.
 *  Explanation follows: if protocol handler, mangling packet, will
 *  be the first on list, it is not able to sense, that packet
 *  is cloned and should be copied-on-write, so that it will
 *  change it and subsequent readers will get broken packet.
 *                          --ANK (980803)
 */

static inline struct list_head *ptype_head(const struct packet_type *pt)
{
    if (pt->type == htons(ETH_P_ALL))
        return &ptype_all;
    else
        return &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK];
}

void dev_add_pack(struct packet_type *pt)
{
    struct list_head *head = ptype_head(pt);

    spin_lock(&ptype_lock);
    list_add_rcu(&pt->list, head);
    spin_unlock(&ptype_lock);
}
EXPORT_SYMBOL(dev_add_pack);

void __dev_remove_pack(struct packet_type *pt)
{
    struct list_head *head = ptype_head(pt);
    struct packet_type *pt1;

    spin_lock(&ptype_lock);

    list_for_each_entry(pt1, head, list) {
        if (pt == pt1) {
            list_del_rcu(&pt->list);
            goto out;
        }
    }

    pr_warn("dev_remove_pack: %p not found\n", pt);
out:
    spin_unlock(&ptype_lock);
}
EXPORT_SYMBOL(__dev_remove_pack);

void dev_remove_pack(struct packet_type *pt)
{
    __dev_remove_pack(pt);

    synchronize_net();
}
EXPORT_SYMBOL(dev_remove_pack);

/******************************************************************************

              Device Boot-time Settings Routines

*******************************************************************************/

/* Boot time configuration table */
static struct netdev_boot_setup dev_boot_setup[NETDEV_BOOT_SETUP_MAX];

static int netdev_boot_setup_add(char *name, struct ifmap *map)
{
    struct netdev_boot_setup *s;
    int i;

    s = dev_boot_setup;
    for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++) {
        if (s[i].name[0] == '\0' || s[i].name[0] == ' ') {
            memset(s[i].name, 0, sizeof(s[i].name));
            strlcpy(s[i].name, name, IFNAMSIZ);
            memcpy(&s[i].map, map, sizeof(s[i].map));
            break;
        }
    }

    return i >= NETDEV_BOOT_SETUP_MAX ? 0 : 1;
}

int netdev_boot_setup_check(struct net_device *dev)
{
    struct netdev_boot_setup *s = dev_boot_setup;
    int i;

    for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++) {
        if (s[i].name[0] != '\0' && s[i].name[0] != ' ' &&
            !strcmp(dev->name, s[i].name)) {
            dev->irq    = s[i].map.irq;
            dev->base_addr  = s[i].map.base_addr;
            dev->mem_start  = s[i].map.mem_start;
            dev->mem_end    = s[i].map.mem_end;
            return 1;
        }
    }
    return 0;
}
EXPORT_SYMBOL(netdev_boot_setup_check);


unsigned long netdev_boot_base(const char *prefix, int unit)
{
    const struct netdev_boot_setup *s = dev_boot_setup;
    char name[IFNAMSIZ];
    int i;

    sprintf(name, "%s%d", prefix, unit);

    /*
     * If device already registered then return base of 1
     * to indicate not to probe for this interface
     */
    if (__dev_get_by_name(&init_net, name))
        return 1;

    for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++)
        if (!strcmp(name, s[i].name))
            return s[i].map.base_addr;
    return 0;
}

/*
 * Saves at boot time configured settings for any netdevice.
 */
int __init netdev_boot_setup(char *str)
{
    int ints[5];
    struct ifmap map;

    str = get_options(str, ARRAY_SIZE(ints), ints);
    if (!str || !*str)
        return 0;

    /* Save settings */
    memset(&map, 0, sizeof(map));
    if (ints[0] > 0)
        map.irq = ints[1];
    if (ints[0] > 1)
        map.base_addr = ints[2];
    if (ints[0] > 2)
        map.mem_start = ints[3];
    if (ints[0] > 3)
        map.mem_end = ints[4];

    /* Add new entry to the list */
    return netdev_boot_setup_add(str, &map);
}

__setup("netdev=", netdev_boot_setup);

/*******************************************************************************

                Device Interface Subroutines

*******************************************************************************/

struct net_device *__dev_get_by_name(struct net *net, const char *name)
{
    struct hlist_node *p;
    struct net_device *dev;
    struct hlist_head *head = dev_name_hash(net, name);

    hlist_for_each_entry(dev, p, head, name_hlist)
        if (!strncmp(dev->name, name, IFNAMSIZ))
            return dev;

    return NULL;
}
EXPORT_SYMBOL(__dev_get_by_name);

struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
{
    struct hlist_node *p;
    struct net_device *dev;
    struct hlist_head *head = dev_name_hash(net, name);

    hlist_for_each_entry_rcu(dev, p, head, name_hlist)
        if (!strncmp(dev->name, name, IFNAMSIZ))
            return dev;

    return NULL;
}
EXPORT_SYMBOL(dev_get_by_name_rcu);

struct net_device *dev_get_by_name(struct net *net, const char *name)
{
    struct net_device *dev;

    rcu_read_lock();
    dev = dev_get_by_name_rcu(net, name);
    if (dev)
        dev_hold(dev);
    rcu_read_unlock();
    return dev;
}
EXPORT_SYMBOL(dev_get_by_name);

struct net_device *__dev_get_by_index(struct net *net, int ifindex)
{
    struct hlist_node *p;
    struct net_device *dev;
    struct hlist_head *head = dev_index_hash(net, ifindex);

    hlist_for_each_entry(dev, p, head, index_hlist)
        if (dev->ifindex == ifindex)
            return dev;

    return NULL;
}
EXPORT_SYMBOL(__dev_get_by_index);

struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex)
{
    struct hlist_node *p;
    struct net_device *dev;
    struct hlist_head *head = dev_index_hash(net, ifindex);

    hlist_for_each_entry_rcu(dev, p, head, index_hlist)
        if (dev->ifindex == ifindex)
            return dev;

    return NULL;
}
EXPORT_SYMBOL(dev_get_by_index_rcu);


struct net_device *dev_get_by_index(struct net *net, int ifindex)
{
    struct net_device *dev;

    rcu_read_lock();
    dev = dev_get_by_index_rcu(net, ifindex);
    if (dev)
        dev_hold(dev);
    rcu_read_unlock();
    return dev;
}
EXPORT_SYMBOL(dev_get_by_index);

struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
                       const char *ha)
{
    struct net_device *dev;

    for_each_netdev_rcu(net, dev)
        if (dev->type == type &&
            !memcmp(dev->dev_addr, ha, dev->addr_len))
            return dev;

    return NULL;
}
EXPORT_SYMBOL(dev_getbyhwaddr_rcu);

struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type)
{
    struct net_device *dev;

    ASSERT_RTNL();
    for_each_netdev(net, dev)
        if (dev->type == type)
            return dev;

    return NULL;
}
EXPORT_SYMBOL(__dev_getfirstbyhwtype);

struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
{
    struct net_device *dev, *ret = NULL;

    rcu_read_lock();
    for_each_netdev_rcu(net, dev)
        if (dev->type == type) {
            dev_hold(dev);
            ret = dev;
            break;
        }
    rcu_read_unlock();
    return ret;
}
EXPORT_SYMBOL(dev_getfirstbyhwtype);

struct net_device *dev_get_by_flags_rcu(struct net *net, unsigned short if_flags,
                    unsigned short mask)
{
    struct net_device *dev, *ret;

    ret = NULL;
    for_each_netdev_rcu(net, dev) {
        if (((dev->flags ^ if_flags) & mask) == 0) {
            ret = dev;
            break;
        }
    }
    return ret;
}
EXPORT_SYMBOL(dev_get_by_flags_rcu);

bool dev_valid_name(const char *name)
{
    if (*name == '\0')
        return false;
    if (strlen(name) >= IFNAMSIZ)
        return false;
    if (!strcmp(name, ".") || !strcmp(name, ".."))
        return false;

    while (*name) {
        if (*name == '/' || isspace(*name))
            return false;
        name++;
    }
    return true;
}
EXPORT_SYMBOL(dev_valid_name);

static int __dev_alloc_name(struct net *net, const char *name, char *buf)
{
    int i = 0;
    const char *p;
    const int max_netdevices = 8*PAGE_SIZE;
    unsigned long *inuse;
    struct net_device *d;

    p = strnchr(name, IFNAMSIZ-1, '%');
    if (p) {
        /*
         * Verify the string as this thing may have come from
         * the user.  There must be either one "%d" and no other "%"
         * characters.
         */
        if (p[1] != 'd' || strchr(p + 2, '%'))
            return -EINVAL;

        /* Use one page as a bit array of possible slots */
        inuse = (unsigned long *) get_zeroed_page(GFP_ATOMIC);
        if (!inuse)
            return -ENOMEM;

        for_each_netdev(net, d) {
            if (!sscanf(d->name, name, &i))
                continue;
            if (i < 0 || i >= max_netdevices)
                continue;

            /*  avoid cases where sscanf is not exact inverse of printf */
            snprintf(buf, IFNAMSIZ, name, i);
            if (!strncmp(buf, d->name, IFNAMSIZ))
                set_bit(i, inuse);
        }

        i = find_first_zero_bit(inuse, max_netdevices);
        free_page((unsigned long) inuse);
    }

    if (buf != name)
        snprintf(buf, IFNAMSIZ, name, i);
    if (!__dev_get_by_name(net, buf))
        return i;

    /* It is possible to run out of possible slots
     * when the name is long and there isn't enough space left
     * for the digits, or if all bits are used.
     */
    return -ENFILE;
}

int dev_alloc_name(struct net_device *dev, const char *name)
{
    char buf[IFNAMSIZ];
    struct net *net;
    int ret;

    BUG_ON(!dev_net(dev));
    net = dev_net(dev);
    ret = __dev_alloc_name(net, name, buf);
    if (ret >= 0)
        strlcpy(dev->name, buf, IFNAMSIZ);
    return ret;
}
EXPORT_SYMBOL(dev_alloc_name);

static int dev_alloc_name_ns(struct net *net,
                 struct net_device *dev,
                 const char *name)
{
    char buf[IFNAMSIZ];
    int ret;

    ret = __dev_alloc_name(net, name, buf);
    if (ret >= 0)
        strlcpy(dev->name, buf, IFNAMSIZ);
    return ret;
}

static int dev_get_valid_name(struct net *net,
                  struct net_device *dev,
                  const char *name)
{
    BUG_ON(!net);

    if (!dev_valid_name(name))
        return -EINVAL;

    if (strchr(name, '%'))
        return dev_alloc_name_ns(net, dev, name);
    else if (__dev_get_by_name(net, name))
        return -EEXIST;
    else if (dev->name != name)
        strlcpy(dev->name, name, IFNAMSIZ);

    return 0;
}

int dev_change_name(struct net_device *dev, const char *newname)
{
    char oldname[IFNAMSIZ];
    int err = 0;
    int ret;
    struct net *net;

    ASSERT_RTNL();
    BUG_ON(!dev_net(dev));

    net = dev_net(dev);
    if (dev->flags & IFF_UP)
        return -EBUSY;

    if (strncmp(newname, dev->name, IFNAMSIZ) == 0)
        return 0;

    memcpy(oldname, dev->name, IFNAMSIZ);

    err = dev_get_valid_name(net, dev, newname);
    if (err < 0)
        return err;

rollback:
    ret = device_rename(&dev->dev, dev->name);
    if (ret) {
        memcpy(dev->name, oldname, IFNAMSIZ);
        return ret;
    }

    write_lock_bh(&dev_base_lock);
    hlist_del_rcu(&dev->name_hlist);
    write_unlock_bh(&dev_base_lock);

    synchronize_rcu();

    write_lock_bh(&dev_base_lock);
    hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name));
    write_unlock_bh(&dev_base_lock);

    ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
    ret = notifier_to_errno(ret);

    if (ret) {
        /* err >= 0 after dev_alloc_name() or stores the first errno */
        if (err >= 0) {
            err = ret;
            memcpy(dev->name, oldname, IFNAMSIZ);
            goto rollback;
        } else {
            pr_err("%s: name change rollback failed: %d\n",
                   dev->name, ret);
        }
    }

    return err;
}

int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
{
    char *new_ifalias;

    ASSERT_RTNL();

    if (len >= IFALIASZ)
        return -EINVAL;

    if (!len) {
        if (dev->ifalias) {
            kfree(dev->ifalias);
            dev->ifalias = NULL;
        }
        return 0;
    }

    new_ifalias = krealloc(dev->ifalias, len + 1, GFP_KERNEL);
    if (!new_ifalias)
        return -ENOMEM;
    dev->ifalias = new_ifalias;

    strlcpy(dev->ifalias, alias, len+1);
    return len;
}


void netdev_features_change(struct net_device *dev)
{
    call_netdevice_notifiers(NETDEV_FEAT_CHANGE, dev);
}
EXPORT_SYMBOL(netdev_features_change);

void netdev_state_change(struct net_device *dev)
{
    if (dev->flags & IFF_UP) {
        call_netdevice_notifiers(NETDEV_CHANGE, dev);
        rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
    }
}
EXPORT_SYMBOL(netdev_state_change);

void netdev_notify_peers(struct net_device *dev)
{
    rtnl_lock();
    call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
    rtnl_unlock();
}
EXPORT_SYMBOL(netdev_notify_peers);

void dev_load(struct net *net, const char *name)
{
    struct net_device *dev;
    int no_module;

    rcu_read_lock();
    dev = dev_get_by_name_rcu(net, name);
    rcu_read_unlock();

    no_module = !dev;
    if (no_module && capable(CAP_NET_ADMIN))
        no_module = request_module("netdev-%s", name);
    if (no_module && capable(CAP_SYS_MODULE)) {
        if (!request_module("%s", name))
            pr_warn("Loading kernel module for a network device with CAP_SYS_MODULE (deprecated).  Use CAP_NET_ADMIN and alias netdev-%s instead.\n",
                name);
    }
}
EXPORT_SYMBOL(dev_load);

static int __dev_open(struct net_device *dev)
{
    const struct net_device_ops *ops = dev->netdev_ops;
    int ret;

    ASSERT_RTNL();

    if (!netif_device_present(dev))
        return -ENODEV;

    ret = call_netdevice_notifiers(NETDEV_PRE_UP, dev);
    ret = notifier_to_errno(ret);
    if (ret)
        return ret;

    set_bit(__LINK_STATE_START, &dev->state);

    if (ops->ndo_validate_addr)
        ret = ops->ndo_validate_addr(dev);

    if (!ret && ops->ndo_open)
        ret = ops->ndo_open(dev);

    if (ret)
        clear_bit(__LINK_STATE_START, &dev->state);
    else {
        dev->flags |= IFF_UP;
        net_dmaengine_get();
        dev_set_rx_mode(dev);
        dev_activate(dev);
        add_device_randomness(dev->dev_addr, dev->addr_len);
    }

    return ret;
}

int dev_open(struct net_device *dev)
{
    int ret;

    if (dev->flags & IFF_UP)
        return 0;

    ret = __dev_open(dev);
    if (ret < 0)
        return ret;

    rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
    call_netdevice_notifiers(NETDEV_UP, dev);

    return ret;
}
EXPORT_SYMBOL(dev_open);

static int __dev_close_many(struct list_head *head)
{
    struct net_device *dev;

    ASSERT_RTNL();
    might_sleep();

    list_for_each_entry(dev, head, unreg_list) {
        call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);

        clear_bit(__LINK_STATE_START, &dev->state);

        /* Synchronize to scheduled poll. We cannot touch poll list, it
         * can be even on different cpu. So just clear netif_running().
         *
         * dev->stop() will invoke napi_disable() on all of it's
         * napi_struct instances on this device.
         */
        smp_mb__after_clear_bit(); /* Commit netif_running(). */
    }

    dev_deactivate_many(head);

    list_for_each_entry(dev, head, unreg_list) {
        const struct net_device_ops *ops = dev->netdev_ops;

        /*
         *  Call the device specific close. This cannot fail.
         *  Only if device is UP
         *
         *  We allow it to be called even after a DETACH hot-plug
         *  event.
         */
        if (ops->ndo_stop)
            ops->ndo_stop(dev);

        dev->flags &= ~IFF_UP;
        net_dmaengine_put();
    }

    return 0;
}

static int __dev_close(struct net_device *dev)
{
    int retval;
    LIST_HEAD(single);

    list_add(&dev->unreg_list, &single);
    retval = __dev_close_many(&single);
    list_del(&single);
    return retval;
}

static int dev_close_many(struct list_head *head)
{
    struct net_device *dev, *tmp;
    LIST_HEAD(tmp_list);

    list_for_each_entry_safe(dev, tmp, head, unreg_list)
        if (!(dev->flags & IFF_UP))
            list_move(&dev->unreg_list, &tmp_list);

    __dev_close_many(head);

    list_for_each_entry(dev, head, unreg_list) {
        rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
        call_netdevice_notifiers(NETDEV_DOWN, dev);
    }

    /* rollback_registered_many needs the complete original list */
    list_splice(&tmp_list, head);
    return 0;
}

int dev_close(struct net_device *dev)
{
    if (dev->flags & IFF_UP) {
        LIST_HEAD(single);

        list_add(&dev->unreg_list, &single);
        dev_close_many(&single);
        list_del(&single);
    }
    return 0;
}
EXPORT_SYMBOL(dev_close);


void dev_disable_lro(struct net_device *dev)
{
    /*
     * If we're trying to disable lro on a vlan device
     * use the underlying physical device instead
     */
    if (is_vlan_dev(dev))
        dev = vlan_dev_real_dev(dev);

    dev->wanted_features &= ~NETIF_F_LRO;
    netdev_update_features(dev);

    if (unlikely(dev->features & NETIF_F_LRO))
        netdev_WARN(dev, "failed to disable LRO!\n");
}
EXPORT_SYMBOL(dev_disable_lro);


static int dev_boot_phase = 1;

int register_netdevice_notifier(struct notifier_block *nb)
{
    struct net_device *dev;
    struct net_device *last;
    struct net *net;
    int err;

    rtnl_lock();
    err = raw_notifier_chain_register(&netdev_chain, nb);
    if (err)
        goto unlock;
    if (dev_boot_phase)
        goto unlock;
    for_each_net(net) {
        for_each_netdev(net, dev) {
            err = nb->notifier_call(nb, NETDEV_REGISTER, dev);
            err = notifier_to_errno(err);
            if (err)
                goto rollback;

            if (!(dev->flags & IFF_UP))
                continue;

            nb->notifier_call(nb, NETDEV_UP, dev);
        }
    }

unlock:
    rtnl_unlock();
    return err;

rollback:
    last = dev;
    for_each_net(net) {
        for_each_netdev(net, dev) {
            if (dev == last)
                goto outroll;

            if (dev->flags & IFF_UP) {
                nb->notifier_call(nb, NETDEV_GOING_DOWN, dev);
                nb->notifier_call(nb, NETDEV_DOWN, dev);
            }
            nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
        }
    }

outroll:
    raw_notifier_chain_unregister(&netdev_chain, nb);
    goto unlock;
}
EXPORT_SYMBOL(register_netdevice_notifier);

int unregister_netdevice_notifier(struct notifier_block *nb)
{
    struct net_device *dev;
    struct net *net;
    int err;

    rtnl_lock();
    err = raw_notifier_chain_unregister(&netdev_chain, nb);
    if (err)
        goto unlock;

    for_each_net(net) {
        for_each_netdev(net, dev) {
            if (dev->flags & IFF_UP) {
                nb->notifier_call(nb, NETDEV_GOING_DOWN, dev);
                nb->notifier_call(nb, NETDEV_DOWN, dev);
            }
            nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
        }
    }
unlock:
    rtnl_unlock();
    return err;
}
EXPORT_SYMBOL(unregister_netdevice_notifier);

int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
{
    ASSERT_RTNL();
    return raw_notifier_call_chain(&netdev_chain, val, dev);
}
EXPORT_SYMBOL(call_netdevice_notifiers);

static struct static_key netstamp_needed __read_mostly;
#ifdef HAVE_JUMP_LABEL
/* We are not allowed to call static_key_slow_dec() from irq context
 * If net_disable_timestamp() is called from irq context, defer the
 * static_key_slow_dec() calls.
 */
static atomic_t netstamp_needed_deferred;
#endif

void net_enable_timestamp(void)
{
#ifdef HAVE_JUMP_LABEL
    int deferred = atomic_xchg(&netstamp_needed_deferred, 0);

    if (deferred) {
        while (--deferred)
            static_key_slow_dec(&netstamp_needed);
        return;
    }
#endif
    WARN_ON(in_interrupt());
    static_key_slow_inc(&netstamp_needed);
}
EXPORT_SYMBOL(net_enable_timestamp);

void net_disable_timestamp(void)
{
#ifdef HAVE_JUMP_LABEL
    if (in_interrupt()) {
        atomic_inc(&netstamp_needed_deferred);
        return;
    }
#endif
    static_key_slow_dec(&netstamp_needed);
}
EXPORT_SYMBOL(net_disable_timestamp);

static inline void net_timestamp_set(struct sk_buff *skb)
{
    skb->tstamp.tv64 = 0;
    if (static_key_false(&netstamp_needed))
        __net_timestamp(skb);
}

#define net_timestamp_check(COND, SKB)          \
    if (static_key_false(&netstamp_needed)) {       \
        if ((COND) && !(SKB)->tstamp.tv64)  \
            __net_timestamp(SKB);       \
    }                       \

static int net_hwtstamp_validate(struct ifreq *ifr)
{
    struct hwtstamp_config cfg;
    enum hwtstamp_tx_types tx_type;
    enum hwtstamp_rx_filters rx_filter;
    int tx_type_valid = 0;
    int rx_filter_valid = 0;

    if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
        return -EFAULT;

    if (cfg.flags) /* reserved for future extensions */
        return -EINVAL;

    tx_type = cfg.tx_type;
    rx_filter = cfg.rx_filter;

    switch (tx_type) {
    case HWTSTAMP_TX_OFF:
    case HWTSTAMP_TX_ON:
    case HWTSTAMP_TX_ONESTEP_SYNC:
        tx_type_valid = 1;
        break;
    }

    switch (rx_filter) {
    case HWTSTAMP_FILTER_NONE:
    case HWTSTAMP_FILTER_ALL:
    case HWTSTAMP_FILTER_SOME:
    case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
    case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
    case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
    case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
    case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
    case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ:
    case HWTSTAMP_FILTER_PTP_V2_L2_EVENT:
    case HWTSTAMP_FILTER_PTP_V2_L2_SYNC:
    case HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ:
    case HWTSTAMP_FILTER_PTP_V2_EVENT:
    case HWTSTAMP_FILTER_PTP_V2_SYNC:
    case HWTSTAMP_FILTER_PTP_V2_DELAY_REQ:
        rx_filter_valid = 1;
        break;
    }

    if (!tx_type_valid || !rx_filter_valid)
        return -ERANGE;

    return 0;
}

static inline bool is_skb_forwardable(struct net_device *dev,
                      struct sk_buff *skb)
{
    unsigned int len;

    if (!(dev->flags & IFF_UP))
        return false;

    len = dev->mtu + dev->hard_header_len + VLAN_HLEN;
    if (skb->len <= len)
        return true;

    /* if TSO is enabled, we don't care about the length as the packet
     * could be forwarded without being segmented before
     */
    if (skb_is_gso(skb))
        return true;

    return false;
}

int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
{
    if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
        if (skb_copy_ubufs(skb, GFP_ATOMIC)) {
            atomic_long_inc(&dev->rx_dropped);
            kfree_skb(skb);
            return NET_RX_DROP;
        }
    }

    skb_orphan(skb);
    nf_reset(skb);

    if (unlikely(!is_skb_forwardable(dev, skb))) {
        atomic_long_inc(&dev->rx_dropped);
        kfree_skb(skb);
        return NET_RX_DROP;
    }
    skb->skb_iif = 0;
    skb->dev = dev;
    skb_dst_drop(skb);
    skb->tstamp.tv64 = 0;
    skb->pkt_type = PACKET_HOST;
    skb->protocol = eth_type_trans(skb, dev);
    skb->mark = 0;
    secpath_reset(skb);
    nf_reset(skb);
    return netif_rx(skb);
}
EXPORT_SYMBOL_GPL(dev_forward_skb);

static inline int deliver_skb(struct sk_buff *skb,
                  struct packet_type *pt_prev,
                  struct net_device *orig_dev)
{
    if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
        return -ENOMEM;
    atomic_inc(&skb->users);
    return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
}

static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
{
    if (!ptype->af_packet_priv || !skb->sk)
        return false;

    if (ptype->id_match)
        return ptype->id_match(ptype, skb->sk);
    else if ((struct sock *)ptype->af_packet_priv == skb->sk)
        return true;

    return false;
}

/*
 *  Support routine. Sends outgoing frames to any network
 *  taps currently in use.
 */

static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
{
    struct packet_type *ptype;
    struct sk_buff *skb2 = NULL;
    struct packet_type *pt_prev = NULL;

    rcu_read_lock();
    list_for_each_entry_rcu(ptype, &ptype_all, list) {
        /* Never send packets back to the socket
         * they originated from - MvS ([email protected])
         */
        if ((ptype->dev == dev || !ptype->dev) &&
            (!skb_loop_sk(ptype, skb))) {
            if (pt_prev) {
                deliver_skb(skb2, pt_prev, skb->dev);
                pt_prev = ptype;
                continue;
            }

            skb2 = skb_clone(skb, GFP_ATOMIC);
            if (!skb2)
                break;

            net_timestamp_set(skb2);

            /* skb->nh should be correctly
               set by sender, so that the second statement is
               just protection against buggy protocols.
             */
            skb_reset_mac_header(skb2);

            if (skb_network_header(skb2) < skb2->data ||
                skb2->network_header > skb2->tail) {
                net_crit_ratelimited("protocol %04x is buggy, dev %s\n",
                             ntohs(skb2->protocol),
                             dev->name);
                skb_reset_network_header(skb2);
            }

            skb2->transport_header = skb2->network_header;
            skb2->pkt_type = PACKET_OUTGOING;
            pt_prev = ptype;
        }
    }
    if (pt_prev)
        pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
    rcu_read_unlock();
}

static void netif_setup_tc(struct net_device *dev, unsigned int txq)
{
    int i;
    struct netdev_tc_txq *tc = &dev->tc_to_txq[0];

    /* If TC0 is invalidated disable TC mapping */
    if (tc->offset + tc->count > txq) {
        pr_warn("Number of in use tx queues changed invalidating tc mappings. Priority traffic classification disabled!\n");
        dev->num_tc = 0;
        return;
    }

    /* Invalidated prio to tc mappings set to TC0 */
    for (i = 1; i < TC_BITMASK + 1; i++) {
        int q = netdev_get_prio_tc_map(dev, i);

        tc = &dev->tc_to_txq[q];
        if (tc->offset + tc->count > txq) {
            pr_warn("Number of in use tx queues changed. Priority %i to tc mapping %i is no longer valid. Setting map to 0\n",
                i, q);
            netdev_set_prio_tc_map(dev, i, 0);
        }
    }
}

/*
 * Routine to help set real_num_tx_queues. To avoid skbs mapped to queues
 * greater then real_num_tx_queues stale skbs on the qdisc must be flushed.
 */
int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
{
    int rc;

    if (txq < 1 || txq > dev->num_tx_queues)
        return -EINVAL;

    if (dev->reg_state == NETREG_REGISTERED ||
        dev->reg_state == NETREG_UNREGISTERING) {
        ASSERT_RTNL();

        rc = netdev_queue_update_kobjects(dev, dev->real_num_tx_queues,
                          txq);
        if (rc)
            return rc;

        if (dev->num_tc)
            netif_setup_tc(dev, txq);

        if (txq < dev->real_num_tx_queues)
            qdisc_reset_all_tx_gt(dev, txq);
    }

    dev->real_num_tx_queues = txq;
    return 0;
}
EXPORT_SYMBOL(netif_set_real_num_tx_queues);

#ifdef CONFIG_RPS

int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq)
{
    int rc;

    if (rxq < 1 || rxq > dev->num_rx_queues)
        return -EINVAL;

    if (dev->reg_state == NETREG_REGISTERED) {
        ASSERT_RTNL();

        rc = net_rx_queue_update_kobjects(dev, dev->real_num_rx_queues,
                          rxq);
        if (rc)
            return rc;
    }

    dev->real_num_rx_queues = rxq;
    return 0;
}
EXPORT_SYMBOL(netif_set_real_num_rx_queues);
#endif

int netif_get_num_default_rss_queues(void)
{
    return min_t(int, DEFAULT_MAX_NUM_RSS_QUEUES, num_online_cpus());
}
EXPORT_SYMBOL(netif_get_num_default_rss_queues);

static inline void __netif_reschedule(struct Qdisc *q)
{
    struct softnet_data *sd;
    unsigned long flags;

    local_irq_save(flags);
    sd = &__get_cpu_var(softnet_data);
    q->next_sched = NULL;
    *sd->output_queue_tailp = q;
    sd->output_queue_tailp = &q->next_sched;
    raise_softirq_irqoff(NET_TX_SOFTIRQ);
    local_irq_restore(flags);
}

void __netif_schedule(struct Qdisc *q)
{
    if (!test_and_set_bit(__QDISC_STATE_SCHED, &q->state))
        __netif_reschedule(q);
}
EXPORT_SYMBOL(__netif_schedule);

void dev_kfree_skb_irq(struct sk_buff *skb)
{
    if (atomic_dec_and_test(&skb->users)) {
        struct softnet_data *sd;
        unsigned long flags;

        local_irq_save(flags);
        sd = &__get_cpu_var(softnet_data);
        skb->next = sd->completion_queue;
        sd->completion_queue = skb;
        raise_softirq_irqoff(NET_TX_SOFTIRQ);
        local_irq_restore(flags);
    }
}
EXPORT_SYMBOL(dev_kfree_skb_irq);

void dev_kfree_skb_any(struct sk_buff *skb)
{
    if (in_irq() || irqs_disabled())
        dev_kfree_skb_irq(skb);
    else
        dev_kfree_skb(skb);
}
EXPORT_SYMBOL(dev_kfree_skb_any);


void netif_device_detach(struct net_device *dev)
{
    if (test_and_clear_bit(__LINK_STATE_PRESENT, &dev->state) &&
        netif_running(dev)) {
        netif_tx_stop_all_queues(dev);
    }
}
EXPORT_SYMBOL(netif_device_detach);

void netif_device_attach(struct net_device *dev)
{
    if (!test_and_set_bit(__LINK_STATE_PRESENT, &dev->state) &&
        netif_running(dev)) {
        netif_tx_wake_all_queues(dev);
        __netdev_watchdog_up(dev);
    }
}
EXPORT_SYMBOL(netif_device_attach);

static void skb_warn_bad_offload(const struct sk_buff *skb)
{
    static const netdev_features_t null_features = 0;
    struct net_device *dev = skb->dev;
    const char *driver = "";

    if (dev && dev->dev.parent)
        driver = dev_driver_string(dev->dev.parent);

    WARN(1, "%s: caps=(%pNF, %pNF) len=%d data_len=%d gso_size=%d "
         "gso_type=%d ip_summed=%d\n",
         driver, dev ? &dev->features : &null_features,
         skb->sk ? &skb->sk->sk_route_caps : &null_features,
         skb->len, skb->data_len, skb_shinfo(skb)->gso_size,
         skb_shinfo(skb)->gso_type, skb->ip_summed);
}

/*
 * Invalidate hardware checksum when packet is to be mangled, and
 * complete checksum manually on outgoing path.
 */
int skb_checksum_help(struct sk_buff *skb)
{
    __wsum csum;
    int ret = 0, offset;

    if (skb->ip_summed == CHECKSUM_COMPLETE)
        goto out_set_summed;

    if (unlikely(skb_shinfo(skb)->gso_size)) {
        skb_warn_bad_offload(skb);
        return -EINVAL;
    }

    offset = skb_checksum_start_offset(skb);
    BUG_ON(offset >= skb_headlen(skb));
    csum = skb_checksum(skb, offset, skb->len - offset, 0);

    offset += skb->csum_offset;
    BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));

    if (skb_cloned(skb) &&
        !skb_clone_writable(skb, offset + sizeof(__sum16))) {
        ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
        if (ret)
            goto out;
    }

    *(__sum16 *)(skb->data + offset) = csum_fold(csum);
out_set_summed:
    skb->ip_summed = CHECKSUM_NONE;
out:
    return ret;
}
EXPORT_SYMBOL(skb_checksum_help);

struct sk_buff *skb_gso_segment(struct sk_buff *skb,
    netdev_features_t features)
{
    struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
    struct packet_type *ptype;
    __be16 type = skb->protocol;
    int vlan_depth = ETH_HLEN;
    int err;

    while (type == htons(ETH_P_8021Q)) {
        struct vlan_hdr *vh;

        if (unlikely(!pskb_may_pull(skb, vlan_depth + VLAN_HLEN)))
            return ERR_PTR(-EINVAL);

        vh = (struct vlan_hdr *)(skb->data + vlan_depth);
        type = vh->h_vlan_encapsulated_proto;
        vlan_depth += VLAN_HLEN;
    }

    skb_reset_mac_header(skb);
    skb->mac_len = skb->network_header - skb->mac_header;
    __skb_pull(skb, skb->mac_len);

    if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
        skb_warn_bad_offload(skb);

        if (skb_header_cloned(skb) &&
            (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
            return ERR_PTR(err);
    }

    rcu_read_lock();
    list_for_each_entry_rcu(ptype,
            &ptype_base[ntohs(type) & PTYPE_HASH_MASK], list) {
        if (ptype->type == type && !ptype->dev && ptype->gso_segment) {
            if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
                err = ptype->gso_send_check(skb);
                segs = ERR_PTR(err);
                if (err || skb_gso_ok(skb, features))
                    break;
                __skb_push(skb, (skb->data -
                         skb_network_header(skb)));
            }
            segs = ptype->gso_segment(skb, features);
            break;
        }
    }
    rcu_read_unlock();

    __skb_push(skb, skb->data - skb_mac_header(skb));

    return segs;
}
EXPORT_SYMBOL(skb_gso_segment);

/* Take action when hardware reception checksum errors are detected. */
#ifdef CONFIG_BUG
void netdev_rx_csum_fault(struct net_device *dev)
{
    if (net_ratelimit()) {
        pr_err("%s: hw csum failure\n", dev ? dev->name : "<unknown>");
        dump_stack();
    }
}
EXPORT_SYMBOL(netdev_rx_csum_fault);
#endif

/* Actually, we should eliminate this check as soon as we know, that:
 * 1. IOMMU is present and allows to map all the memory.
 * 2. No high memory really exists on this machine.
 */

static int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
{
#ifdef CONFIG_HIGHMEM
    int i;
    if (!(dev->features & NETIF_F_HIGHDMA)) {
        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
            skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
            if (PageHighMem(skb_frag_page(frag)))
                return 1;
        }
    }

    if (PCI_DMA_BUS_IS_PHYS) {
        struct device *pdev = dev->dev.parent;

        if (!pdev)
            return 0;
        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
            skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
            dma_addr_t addr = page_to_phys(skb_frag_page(frag));
            if (!pdev->dma_mask || addr + PAGE_SIZE - 1 > *pdev->dma_mask)
                return 1;
        }
    }
#endif
    return 0;
}

struct dev_gso_cb {
    void (*destructor)(struct sk_buff *skb);
};

#define DEV_GSO_CB(skb) ((struct dev_gso_cb *)(skb)->cb)

static void dev_gso_skb_destructor(struct sk_buff *skb)
{
    struct dev_gso_cb *cb;

    do {
        struct sk_buff *nskb = skb->next;

        skb->next = nskb->next;
        nskb->next = NULL;
        kfree_skb(nskb);
    } while (skb->next);

    cb = DEV_GSO_CB(skb);
    if (cb->destructor)
        cb->destructor(skb);
}

static int dev_gso_segment(struct sk_buff *skb, netdev_features_t features)
{
    struct sk_buff *segs;

    segs = skb_gso_segment(skb, features);

    /* Verifying header integrity only. */
    if (!segs)
        return 0;

    if (IS_ERR(segs))
        return PTR_ERR(segs);

    skb->next = segs;
    DEV_GSO_CB(skb)->destructor = skb->destructor;
    skb->destructor = dev_gso_skb_destructor;

    return 0;
}

static bool can_checksum_protocol(netdev_features_t features, __be16 protocol)
{
    return ((features & NETIF_F_GEN_CSUM) ||
        ((features & NETIF_F_V4_CSUM) &&
         protocol == htons(ETH_P_IP)) ||
        ((features & NETIF_F_V6_CSUM) &&
         protocol == htons(ETH_P_IPV6)) ||
        ((features & NETIF_F_FCOE_CRC) &&
         protocol == htons(ETH_P_FCOE)));
}

static netdev_features_t harmonize_features(struct sk_buff *skb,
    __be16 protocol, netdev_features_t features)
{
    if (skb->ip_summed != CHECKSUM_NONE &&
        !can_checksum_protocol(features, protocol)) {
        features &= ~NETIF_F_ALL_CSUM;
        features &= ~NETIF_F_SG;
    } else if (illegal_highdma(skb->dev, skb)) {
        features &= ~NETIF_F_SG;
    }

    return features;
}

netdev_features_t netif_skb_features(struct sk_buff *skb)
{
    __be16 protocol = skb->protocol;
    netdev_features_t features = skb->dev->features;

    if (skb_shinfo(skb)->gso_segs > skb->dev->gso_max_segs)
        features &= ~NETIF_F_GSO_MASK;

    if (protocol == htons(ETH_P_8021Q)) {
        struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
        protocol = veh->h_vlan_encapsulated_proto;
    } else if (!vlan_tx_tag_present(skb)) {
        return harmonize_features(skb, protocol, features);
    }

    features &= (skb->dev->vlan_features | NETIF_F_HW_VLAN_TX);

    if (protocol != htons(ETH_P_8021Q)) {
        return harmonize_features(skb, protocol, features);
    } else {
        features &= NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST |
                NETIF_F_GEN_CSUM | NETIF_F_HW_VLAN_TX;
        return harmonize_features(skb, protocol, features);
    }
}
EXPORT_SYMBOL(netif_skb_features);

/*
 * Returns true if either:
 *  1. skb has frag_list and the device doesn't support FRAGLIST, or
 *  2. skb is fragmented and the device does not support SG.
 */
static inline int skb_needs_linearize(struct sk_buff *skb,
                      int features)
{
    return skb_is_nonlinear(skb) &&
            ((skb_has_frag_list(skb) &&
                !(features & NETIF_F_FRAGLIST)) ||
            (skb_shinfo(skb)->nr_frags &&
                !(features & NETIF_F_SG)));
}

int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
            struct netdev_queue *txq)
{
    const struct net_device_ops *ops = dev->netdev_ops;
    int rc = NETDEV_TX_OK;
    unsigned int skb_len;

    if (likely(!skb->next)) {
        netdev_features_t features;

        /*
         * If device doesn't need skb->dst, release it right now while
         * its hot in this cpu cache
         */
        if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
            skb_dst_drop(skb);

        features = netif_skb_features(skb);

        if (vlan_tx_tag_present(skb) &&
            !(features & NETIF_F_HW_VLAN_TX)) {
            skb = __vlan_put_tag(skb, vlan_tx_tag_get(skb));
            if (unlikely(!skb))
                goto out;

            skb->vlan_tci = 0;
        }

        if (netif_needs_gso(skb, features)) {
            if (unlikely(dev_gso_segment(skb, features)))
                goto out_kfree_skb;
            if (skb->next)
                goto gso;
        } else {
            if (skb_needs_linearize(skb, features) &&
                __skb_linearize(skb))
                goto out_kfree_skb;

            /* If packet is not checksummed and device does not
             * support checksumming for this protocol, complete
             * checksumming here.
             */
            if (skb->ip_summed == CHECKSUM_PARTIAL) {
                skb_set_transport_header(skb,
                    skb_checksum_start_offset(skb));
                if (!(features & NETIF_F_ALL_CSUM) &&
                     skb_checksum_help(skb))
                    goto out_kfree_skb;
            }
        }

        if (!list_empty(&ptype_all))
            dev_queue_xmit_nit(skb, dev);

        skb_len = skb->len;
        rc = ops->ndo_start_xmit(skb, dev);
        trace_net_dev_xmit(skb, rc, dev, skb_len);
        if (rc == NETDEV_TX_OK)
            txq_trans_update(txq);
        return rc;
    }

gso:
    do {
        struct sk_buff *nskb = skb->next;

        skb->next = nskb->next;
        nskb->next = NULL;

        /*
         * If device doesn't need nskb->dst, release it right now while
         * its hot in this cpu cache
         */
        if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
            skb_dst_drop(nskb);

        if (!list_empty(&ptype_all))
            dev_queue_xmit_nit(nskb, dev);

        skb_len = nskb->len;
        rc = ops->ndo_start_xmit(nskb, dev);
        trace_net_dev_xmit(nskb, rc, dev, skb_len);
        if (unlikely(rc != NETDEV_TX_OK)) {
            if (rc & ~NETDEV_TX_MASK)
                goto out_kfree_gso_skb;
            nskb->next = skb->next;
            skb->next = nskb;
            return rc;
        }
        txq_trans_update(txq);
        if (unlikely(netif_xmit_stopped(txq) && skb->next))
            return NETDEV_TX_BUSY;
    } while (skb->next);

out_kfree_gso_skb:
    if (likely(skb->next == NULL))
        skb->destructor = DEV_GSO_CB(skb)->destructor;
out_kfree_skb:
    kfree_skb(skb);
out:
    return rc;
}

static u32 hashrnd __read_mostly;

/*
 * Returns a Tx hash based on the given packet descriptor a Tx queues' number
 * to be used as a distribution range.
 */
u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
          unsigned int num_tx_queues)
{
    u32 hash;
    u16 qoffset = 0;
    u16 qcount = num_tx_queues;

    if (skb_rx_queue_recorded(skb)) {
        hash = skb_get_rx_queue(skb);
        while (unlikely(hash >= num_tx_queues))
            hash -= num_tx_queues;
        return hash;
    }

    if (dev->num_tc) {
        u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
        qoffset = dev->tc_to_txq[tc].offset;
        qcount = dev->tc_to_txq[tc].count;
    }

    if (skb->sk && skb->sk->sk_hash)
        hash = skb->sk->sk_hash;
    else
        hash = (__force u16) skb->protocol;
    hash = jhash_1word(hash, hashrnd);

    return (u16) (((u64) hash * qcount) >> 32) + qoffset;
}
EXPORT_SYMBOL(__skb_tx_hash);

static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
{
    if (unlikely(queue_index >= dev->real_num_tx_queues)) {
        net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
                     dev->name, queue_index,
                     dev->real_num_tx_queues);
        return 0;
    }
    return queue_index;
}

static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
{
#ifdef CONFIG_XPS
    struct xps_dev_maps *dev_maps;
    struct xps_map *map;
    int queue_index = -1;

    rcu_read_lock();
    dev_maps = rcu_dereference(dev->xps_maps);
    if (dev_maps) {
        map = rcu_dereference(
            dev_maps->cpu_map[raw_smp_processor_id()]);
        if (map) {
            if (map->len == 1)
                queue_index = map->queues[0];
            else {
                u32 hash;
                if (skb->sk && skb->sk->sk_hash)
                    hash = skb->sk->sk_hash;
                else
                    hash = (__force u16) skb->protocol ^
                        skb->rxhash;
                hash = jhash_1word(hash, hashrnd);
                queue_index = map->queues[
                    ((u64)hash * map->len) >> 32];
            }
            if (unlikely(queue_index >= dev->real_num_tx_queues))
                queue_index = -1;
        }
    }
    rcu_read_unlock();

    return queue_index;
#else
    return -1;
#endif
}

struct netdev_queue *netdev_pick_tx(struct net_device *dev,
                    struct sk_buff *skb)
{
    int queue_index;
    const struct net_device_ops *ops = dev->netdev_ops;

    if (dev->real_num_tx_queues == 1)
        queue_index = 0;
    else if (ops->ndo_select_queue) {
        queue_index = ops->ndo_select_queue(dev, skb);
        queue_index = dev_cap_txqueue(dev, queue_index);
    } else {
        struct sock *sk = skb->sk;
        queue_index = sk_tx_queue_get(sk);

        if (queue_index < 0 || skb->ooo_okay ||
            queue_index >= dev->real_num_tx_queues) {
            int old_index = queue_index;

            queue_index = get_xps_queue(dev, skb);
            if (queue_index < 0)
                queue_index = skb_tx_hash(dev, skb);

            if (queue_index != old_index && sk) {
                struct dst_entry *dst =
                    rcu_dereference_check(sk->sk_dst_cache, 1);

                if (dst && skb_dst(skb) == dst)
                    sk_tx_queue_set(sk, queue_index);
            }
        }
    }

    skb_set_queue_mapping(skb, queue_index);
    return netdev_get_tx_queue(dev, queue_index);
}

static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
                 struct net_device *dev,
                 struct netdev_queue *txq)
{
    spinlock_t *root_lock = qdisc_lock(q);
    bool contended;
    int rc;

    qdisc_skb_cb(skb)->pkt_len = skb->len;
    qdisc_calculate_pkt_len(skb, q);
    /*
     * Heuristic to force contended enqueues to serialize on a
     * separate lock before trying to get qdisc main lock.
     * This permits __QDISC_STATE_RUNNING owner to get the lock more often
     * and dequeue packets faster.
     */
    contended = qdisc_is_running(q);
    if (unlikely(contended))
        spin_lock(&q->busylock);

    spin_lock(root_lock);
    if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
        kfree_skb(skb);
        rc = NET_XMIT_DROP;
    } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
           qdisc_run_begin(q)) {
        /*
         * This is a work-conserving queue; there are no old skbs
         * waiting to be sent out; and the qdisc is not running -
         * xmit the skb directly.
         */
        if (!(dev->priv_flags & IFF_XMIT_DST_RELEASE))
            skb_dst_force(skb);

        qdisc_bstats_update(q, skb);

        if (sch_direct_xmit(skb, q, dev, txq, root_lock)) {
            if (unlikely(contended)) {
                spin_unlock(&q->busylock);
                contended = false;
            }
            __qdisc_run(q);
        } else
            qdisc_run_end(q);

        rc = NET_XMIT_SUCCESS;
    } else {
        skb_dst_force(skb);
        rc = q->enqueue(skb, q) & NET_XMIT_MASK;
        if (qdisc_run_begin(q)) {
            if (unlikely(contended)) {
                spin_unlock(&q->busylock);
                contended = false;
            }
            __qdisc_run(q);
        }
    }
    spin_unlock(root_lock);
    if (unlikely(contended))
        spin_unlock(&q->busylock);
    return rc;
}

#if IS_ENABLED(CONFIG_NETPRIO_CGROUP)
static void skb_update_prio(struct sk_buff *skb)
{
    struct netprio_map *map = rcu_dereference_bh(skb->dev->priomap);

    if (!skb->priority && skb->sk && map) {
        unsigned int prioidx = skb->sk->sk_cgrp_prioidx;

        if (prioidx < map->priomap_len)
            skb->priority = map->priomap[prioidx];
    }
}
#else
#define skb_update_prio(skb)
#endif

static DEFINE_PER_CPU(int, xmit_recursion);
#define RECURSION_LIMIT 10

int dev_loopback_xmit(struct sk_buff *skb)
{
    skb_reset_mac_header(skb);
    __skb_pull(skb, skb_network_offset(skb));
    skb->pkt_type = PACKET_LOOPBACK;
    skb->ip_summed = CHECKSUM_UNNECESSARY;
    WARN_ON(!skb_dst(skb));
    skb_dst_force(skb);
    netif_rx_ni(skb);
    return 0;
}
EXPORT_SYMBOL(dev_loopback_xmit);

int dev_queue_xmit(struct sk_buff *skb)
{
    struct net_device *dev = skb->dev;
    struct netdev_queue *txq;
    struct Qdisc *q;
    int rc = -ENOMEM;

    /* Disable soft irqs for various locks below. Also
     * stops preemption for RCU.
     */
    rcu_read_lock_bh();

    skb_update_prio(skb);

    txq = netdev_pick_tx(dev, skb);
    q = rcu_dereference_bh(txq->qdisc);

#ifdef CONFIG_NET_CLS_ACT
    skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_EGRESS);
#endif
    trace_net_dev_queue(skb);
    if (q->enqueue) {
        rc = __dev_xmit_skb(skb, q, dev, txq);
        goto out;
    }

    /* The device has no queue. Common case for software devices:
       loopback, all the sorts of tunnels...

       Really, it is unlikely that netif_tx_lock protection is necessary
       here.  (f.e. loopback and IP tunnels are clean ignoring statistics
       counters.)
       However, it is possible, that they rely on protection
       made by us here.

       Check this and shot the lock. It is not prone from deadlocks.
       Either shot noqueue qdisc, it is even simpler 8)
     */
    if (dev->flags & IFF_UP) {
        int cpu = smp_processor_id(); /* ok because BHs are off */

        if (txq->xmit_lock_owner != cpu) {

            if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
                goto recursion_alert;

            HARD_TX_LOCK(dev, txq, cpu);

            if (!netif_xmit_stopped(txq)) {
                __this_cpu_inc(xmit_recursion);
                rc = dev_hard_start_xmit(skb, dev, txq);
                __this_cpu_dec(xmit_recursion);
                if (dev_xmit_complete(rc)) {
                    HARD_TX_UNLOCK(dev, txq);
                    goto out;
                }
            }
            HARD_TX_UNLOCK(dev, txq);
            net_crit_ratelimited("Virtual device %s asks to queue packet!\n",
                         dev->name);
        } else {
            /* Recursion is detected! It is possible,
             * unfortunately
             */
recursion_alert:
            net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
                         dev->name);
        }
    }

    rc = -ENETDOWN;
    rcu_read_unlock_bh();

    kfree_skb(skb);
    return rc;
out:
    rcu_read_unlock_bh();
    return rc;
}
EXPORT_SYMBOL(dev_queue_xmit);


/*=======================================================================
            Receiver routines
  =======================================================================*/

int netdev_max_backlog __read_mostly = 1000;
EXPORT_SYMBOL(netdev_max_backlog);

int netdev_tstamp_prequeue __read_mostly = 1;
int netdev_budget __read_mostly = 300;
int weight_p __read_mostly = 64;            /* old backlog weight */

/* Called with irq disabled */
static inline void ____napi_schedule(struct softnet_data *sd,
                     struct napi_struct *napi)
{
    list_add_tail(&napi->poll_list, &sd->poll_list);
    __raise_softirq_irqoff(NET_RX_SOFTIRQ);
}

/*
 * __skb_get_rxhash: calculate a flow hash based on src/dst addresses
 * and src/dst port numbers.  Sets rxhash in skb to non-zero hash value
 * on success, zero indicates no valid hash.  Also, sets l4_rxhash in skb
 * if hash is a canonical 4-tuple hash over transport ports.
 */
void __skb_get_rxhash(struct sk_buff *skb)
{
    struct flow_keys keys;
    u32 hash;

    if (!skb_flow_dissect(skb, &keys))
        return;

    if (keys.ports)
        skb->l4_rxhash = 1;

    /* get a consistent hash (same value on both flow directions) */
    if (((__force u32)keys.dst < (__force u32)keys.src) ||
        (((__force u32)keys.dst == (__force u32)keys.src) &&
         ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {
        swap(keys.dst, keys.src);
        swap(keys.port16[0], keys.port16[1]);
    }

    hash = jhash_3words((__force u32)keys.dst,
                (__force u32)keys.src,
                (__force u32)keys.ports, hashrnd);
    if (!hash)
        hash = 1;

    skb->rxhash = hash;
}
EXPORT_SYMBOL(__skb_get_rxhash);

#ifdef CONFIG_RPS

/* One global table that all flow-based protocols share. */
struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly;
EXPORT_SYMBOL(rps_sock_flow_table);

struct static_key rps_needed __read_mostly;

static struct rps_dev_flow *
set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
        struct rps_dev_flow *rflow, u16 next_cpu)
{
    if (next_cpu != RPS_NO_CPU) {
#ifdef CONFIG_RFS_ACCEL
        struct netdev_rx_queue *rxqueue;
        struct rps_dev_flow_table *flow_table;
        struct rps_dev_flow *old_rflow;
        u32 flow_id;
        u16 rxq_index;
        int rc;

        /* Should we steer this flow to a different hardware queue? */
        if (!skb_rx_queue_recorded(skb) || !dev->rx_cpu_rmap ||
            !(dev->features & NETIF_F_NTUPLE))
            goto out;
        rxq_index = cpu_rmap_lookup_index(dev->rx_cpu_rmap, next_cpu);
        if (rxq_index == skb_get_rx_queue(skb))
            goto out;

        rxqueue = dev->_rx + rxq_index;
        flow_table = rcu_dereference(rxqueue->rps_flow_table);
        if (!flow_table)
            goto out;
        flow_id = skb->rxhash & flow_table->mask;
        rc = dev->netdev_ops->ndo_rx_flow_steer(dev, skb,
                            rxq_index, flow_id);
        if (rc < 0)
            goto out;
        old_rflow = rflow;
        rflow = &flow_table->flows[flow_id];
        rflow->filter = rc;
        if (old_rflow->filter == rflow->filter)
            old_rflow->filter = RPS_NO_FILTER;
    out:
#endif
        rflow->last_qtail =
            per_cpu(softnet_data, next_cpu).input_queue_head;
    }

    rflow->cpu = next_cpu;
    return rflow;
}

/*
 * get_rps_cpu is called from netif_receive_skb and returns the target
 * CPU from the RPS map of the receiving queue for a given skb.
 * rcu_read_lock must be held on entry.
 */
static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
               struct rps_dev_flow **rflowp)
{
    struct netdev_rx_queue *rxqueue;
    struct rps_map *map;
    struct rps_dev_flow_table *flow_table;
    struct rps_sock_flow_table *sock_flow_table;
    int cpu = -1;
    u16 tcpu;

    if (skb_rx_queue_recorded(skb)) {
        u16 index = skb_get_rx_queue(skb);
        if (unlikely(index >= dev->real_num_rx_queues)) {
            WARN_ONCE(dev->real_num_rx_queues > 1,
                  "%s received packet on queue %u, but number "
                  "of RX queues is %u\n",
                  dev->name, index, dev->real_num_rx_queues);
            goto done;
        }
        rxqueue = dev->_rx + index;
    } else
        rxqueue = dev->_rx;

    map = rcu_dereference(rxqueue->rps_map);
    if (map) {
        if (map->len == 1 &&
            !rcu_access_pointer(rxqueue->rps_flow_table)) {
            tcpu = map->cpus[0];
            if (cpu_online(tcpu))
                cpu = tcpu;
            goto done;
        }
    } else if (!rcu_access_pointer(rxqueue->rps_flow_table)) {
        goto done;
    }

    skb_reset_network_header(skb);
    if (!skb_get_rxhash(skb))
        goto done;

    flow_table = rcu_dereference(rxqueue->rps_flow_table);
    sock_flow_table = rcu_dereference(rps_sock_flow_table);
    if (flow_table && sock_flow_table) {
        u16 next_cpu;
        struct rps_dev_flow *rflow;

        rflow = &flow_table->flows[skb->rxhash & flow_table->mask];
        tcpu = rflow->cpu;

        next_cpu = sock_flow_table->ents[skb->rxhash &
            sock_flow_table->mask];

        /*
         * If the desired CPU (where last recvmsg was done) is
         * different from current CPU (one in the rx-queue flow
         * table entry), switch if one of the following holds:
         *   - Current CPU is unset (equal to RPS_NO_CPU).
         *   - Current CPU is offline.
         *   - The current CPU's queue tail has advanced beyond the
         *     last packet that was enqueued using this table entry.
         *     This guarantees that all previous packets for the flow
         *     have been dequeued, thus preserving in order delivery.
         */
        if (unlikely(tcpu != next_cpu) &&
            (tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
             ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
              rflow->last_qtail)) >= 0)) {
            tcpu = next_cpu;
            rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
        }

        if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
            *rflowp = rflow;
            cpu = tcpu;
            goto done;
        }
    }

    if (map) {
        tcpu = map->cpus[((u64) skb->rxhash * map->len) >> 32];

        if (cpu_online(tcpu)) {
            cpu = tcpu;
            goto done;
        }
    }

done:
    return cpu;
}

#ifdef CONFIG_RFS_ACCEL

bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
             u32 flow_id, u16 filter_id)
{
    struct netdev_rx_queue *rxqueue = dev->_rx + rxq_index;
    struct rps_dev_flow_table *flow_table;
    struct rps_dev_flow *rflow;
    bool expire = true;
    int cpu;

    rcu_read_lock();
    flow_table = rcu_dereference(rxqueue->rps_flow_table);
    if (flow_table && flow_id <= flow_table->mask) {
        rflow = &flow_table->flows[flow_id];
        cpu = ACCESS_ONCE(rflow->cpu);
        if (rflow->filter == filter_id && cpu != RPS_NO_CPU &&
            ((int)(per_cpu(softnet_data, cpu).input_queue_head -
               rflow->last_qtail) <
             (int)(10 * flow_table->mask)))
            expire = false;
    }
    rcu_read_unlock();
    return expire;
}
EXPORT_SYMBOL(rps_may_expire_flow);

#endif /* CONFIG_RFS_ACCEL */

/* Called from hardirq (IPI) context */
static void rps_trigger_softirq(void *data)
{
    struct softnet_data *sd = data;

    ____napi_schedule(sd, &sd->backlog);
    sd->received_rps++;
}

#endif /* CONFIG_RPS */

/*
 * Check if this softnet_data structure is another cpu one
 * If yes, queue it to our IPI list and return 1
 * If no, return 0
 */
static int rps_ipi_queued(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
    struct softnet_data *mysd = &__get_cpu_var(softnet_data);

    if (sd != mysd) {
        sd->rps_ipi_next = mysd->rps_ipi_list;
        mysd->rps_ipi_list = sd;

        __raise_softirq_irqoff(NET_RX_SOFTIRQ);
        return 1;
    }
#endif /* CONFIG_RPS */
    return 0;
}

/*
 * enqueue_to_backlog is called to queue an skb to a per CPU backlog
 * queue (may be a remote CPU queue).
 */
static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
                  unsigned int *qtail)
{
    struct softnet_data *sd;
    unsigned long flags;

    sd = &per_cpu(softnet_data, cpu);

    local_irq_save(flags);

    rps_lock(sd);
    if (skb_queue_len(&sd->input_pkt_queue) <= netdev_max_backlog) {
        if (skb_queue_len(&sd->input_pkt_queue)) {
enqueue:
            __skb_queue_tail(&sd->input_pkt_queue, skb);
            input_queue_tail_incr_save(sd, qtail);
            rps_unlock(sd);
            local_irq_restore(flags);
            return NET_RX_SUCCESS;
        }

        /* Schedule NAPI for backlog device
         * We can use non atomic operation since we own the queue lock
         */
        if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) {
            if (!rps_ipi_queued(sd))
                ____napi_schedule(sd, &sd->backlog);
        }
        goto enqueue;
    }

    sd->dropped++;
    rps_unlock(sd);

    local_irq_restore(flags);

    atomic_long_inc(&skb->dev->rx_dropped);
    kfree_skb(skb);
    return NET_RX_DROP;
}

int netif_rx(struct sk_buff *skb)
{
    int ret;

    /* if netpoll wants it, pretend we never saw it */
    if (netpoll_rx(skb))
        return NET_RX_DROP;

    net_timestamp_check(netdev_tstamp_prequeue, skb);

    trace_netif_rx(skb);
#ifdef CONFIG_RPS
    if (static_key_false(&rps_needed)) {
        struct rps_dev_flow voidflow, *rflow = &voidflow;
        int cpu;

        preempt_disable();
        rcu_read_lock();

        cpu = get_rps_cpu(skb->dev, skb, &rflow);
        if (cpu < 0)
            cpu = smp_processor_id();

        ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);

        rcu_read_unlock();
        preempt_enable();
    } else
#endif
    {
        unsigned int qtail;
        ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
        put_cpu();
    }
    return ret;
}
EXPORT_SYMBOL(netif_rx);

int netif_rx_ni(struct sk_buff *skb)
{
    int err;

    preempt_disable();
    err = netif_rx(skb);
    if (local_softirq_pending())
        do_softirq();
    preempt_enable();

    return err;
}
EXPORT_SYMBOL(netif_rx_ni);

static void net_tx_action(struct softirq_action *h)
{
    struct softnet_data *sd = &__get_cpu_var(softnet_data);

    if (sd->completion_queue) {
        struct sk_buff *clist;

        local_irq_disable();
        clist = sd->completion_queue;
        sd->completion_queue = NULL;
        local_irq_enable();

        while (clist) {
            struct sk_buff *skb = clist;
            clist = clist->next;

            WARN_ON(atomic_read(&skb->users));
            trace_kfree_skb(skb, net_tx_action);
            __kfree_skb(skb);
        }
    }

    if (sd->output_queue) {
        struct Qdisc *head;

        local_irq_disable();
        head = sd->output_queue;
        sd->output_queue = NULL;
        sd->output_queue_tailp = &sd->output_queue;
        local_irq_enable();

        while (head) {
            struct Qdisc *q = head;
            spinlock_t *root_lock;

            head = head->next_sched;

            root_lock = qdisc_lock(q);
            if (spin_trylock(root_lock)) {
                smp_mb__before_clear_bit();
                clear_bit(__QDISC_STATE_SCHED,
                      &q->state);
                qdisc_run(q);
                spin_unlock(root_lock);
            } else {
                if (!test_bit(__QDISC_STATE_DEACTIVATED,
                          &q->state)) {
                    __netif_reschedule(q);
                } else {
                    smp_mb__before_clear_bit();
                    clear_bit(__QDISC_STATE_SCHED,
                          &q->state);
                }
            }
        }
    }
}

#if (defined(CONFIG_BRIDGE) || defined(CONFIG_BRIDGE_MODULE)) && \
    (defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE))
/* This hook is defined here for ATM LANE */
int (*br_fdb_test_addr_hook)(struct net_device *dev,
                 unsigned char *addr) __read_mostly;
EXPORT_SYMBOL_GPL(br_fdb_test_addr_hook);
#endif

#ifdef CONFIG_NET_CLS_ACT
/* TODO: Maybe we should just force sch_ingress to be compiled in
 * when CONFIG_NET_CLS_ACT is? otherwise some useless instructions
 * a compare and 2 stores extra right now if we dont have it on
 * but have CONFIG_NET_CLS_ACT
 * NOTE: This doesn't stop any functionality; if you dont have
 * the ingress scheduler, you just can't add policies on ingress.
 *
 */
static int ing_filter(struct sk_buff *skb, struct netdev_queue *rxq)
{
    struct net_device *dev = skb->dev;
    u32 ttl = G_TC_RTTL(skb->tc_verd);
    int result = TC_ACT_OK;
    struct Qdisc *q;

    if (unlikely(MAX_RED_LOOP < ttl++)) {
        net_warn_ratelimited("Redir loop detected Dropping packet (%d->%d)\n",
                     skb->skb_iif, dev->ifindex);
        return TC_ACT_SHOT;
    }

    skb->tc_verd = SET_TC_RTTL(skb->tc_verd, ttl);
    skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_INGRESS);

    q = rxq->qdisc;
    if (q != &noop_qdisc) {
        spin_lock(qdisc_lock(q));
        if (likely(!test_bit(__QDISC_STATE_DEACTIVATED, &q->state)))
            result = qdisc_enqueue_root(skb, q);
        spin_unlock(qdisc_lock(q));
    }

    return result;
}

static inline struct sk_buff *handle_ing(struct sk_buff *skb,
                     struct packet_type **pt_prev,
                     int *ret, struct net_device *orig_dev)
{
    struct netdev_queue *rxq = rcu_dereference(skb->dev->ingress_queue);

    if (!rxq || rxq->qdisc == &noop_qdisc)
        goto out;

    if (*pt_prev) {
        *ret = deliver_skb(skb, *pt_prev, orig_dev);
        *pt_prev = NULL;
    }

    switch (ing_filter(skb, rxq)) {
    case TC_ACT_SHOT:
    case TC_ACT_STOLEN:
        kfree_skb(skb);
        return NULL;
    }

out:
    skb->tc_verd = 0;
    return skb;
}
#endif

int netdev_rx_handler_register(struct net_device *dev,
                   rx_handler_func_t *rx_handler,
                   void *rx_handler_data)
{
    ASSERT_RTNL();

    if (dev->rx_handler)
        return -EBUSY;

    rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
    rcu_assign_pointer(dev->rx_handler, rx_handler);

    return 0;
}
EXPORT_SYMBOL_GPL(netdev_rx_handler_register);

void netdev_rx_handler_unregister(struct net_device *dev)
{

    ASSERT_RTNL();
    RCU_INIT_POINTER(dev->rx_handler, NULL);
    RCU_INIT_POINTER(dev->rx_handler_data, NULL);
}
EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);

/*
 * Limit the use of PFMEMALLOC reserves to those protocols that implement
 * the special handling of PFMEMALLOC skbs.
 */
static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
{
    switch (skb->protocol) {
    case __constant_htons(ETH_P_ARP):
    case __constant_htons(ETH_P_IP):
    case __constant_htons(ETH_P_IPV6):
    case __constant_htons(ETH_P_8021Q):
        return true;
    default:
        return false;
    }
}

static int __netif_receive_skb(struct sk_buff *skb)
{
    struct packet_type *ptype, *pt_prev;
    rx_handler_func_t *rx_handler;
    struct net_device *orig_dev;
    struct net_device *null_or_dev;
    bool deliver_exact = false;
    int ret = NET_RX_DROP;
    __be16 type;
    unsigned long pflags = current->flags;

    net_timestamp_check(!netdev_tstamp_prequeue, skb);

    trace_netif_receive_skb(skb);

    /*
     * PFMEMALLOC skbs are special, they should
     * - be delivered to SOCK_MEMALLOC sockets only
     * - stay away from userspace
     * - have bounded memory usage
     *
     * Use PF_MEMALLOC as this saves us from propagating the allocation
     * context down to all allocation sites.
     */
    if (sk_memalloc_socks() && skb_pfmemalloc(skb))
        current->flags |= PF_MEMALLOC;

    /* if we've gotten here through NAPI, check netpoll */
    if (netpoll_receive_skb(skb))
        goto out;

    orig_dev = skb->dev;

    skb_reset_network_header(skb);
    skb_reset_transport_header(skb);
    skb_reset_mac_len(skb);

    pt_prev = NULL;

    rcu_read_lock();

another_round:
    skb->skb_iif = skb->dev->ifindex;

    __this_cpu_inc(softnet_data.processed);

    if (skb->protocol == cpu_to_be16(ETH_P_8021Q)) {
        skb = vlan_untag(skb);
        if (unlikely(!skb))
            goto unlock;
    }

#ifdef CONFIG_NET_CLS_ACT
    if (skb->tc_verd & TC_NCLS) {
        skb->tc_verd = CLR_TC_NCLS(skb->tc_verd);
        goto ncls;
    }
#endif

    if (sk_memalloc_socks() && skb_pfmemalloc(skb))
        goto skip_taps;

    list_for_each_entry_rcu(ptype, &ptype_all, list) {
        if (!ptype->dev || ptype->dev == skb->dev) {
            if (pt_prev)
                ret = deliver_skb(skb, pt_prev, orig_dev);
            pt_prev = ptype;
        }
    }

skip_taps:
#ifdef CONFIG_NET_CLS_ACT
    skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
    if (!skb)
        goto unlock;
ncls:
#endif

    if (sk_memalloc_socks() && skb_pfmemalloc(skb)
                && !skb_pfmemalloc_protocol(skb))
        goto drop;

    if (vlan_tx_tag_present(skb)) {
        if (pt_prev) {
            ret = deliver_skb(skb, pt_prev, orig_dev);
            pt_prev = NULL;
        }
        if (vlan_do_receive(&skb))
            goto another_round;
        else if (unlikely(!skb))
            goto unlock;
    }

    rx_handler = rcu_dereference(skb->dev->rx_handler);
    if (rx_handler) {
        if (pt_prev) {
            ret = deliver_skb(skb, pt_prev, orig_dev);
            pt_prev = NULL;
        }
        switch (rx_handler(&skb)) {
        case RX_HANDLER_CONSUMED:
            goto unlock;
        case RX_HANDLER_ANOTHER:
            goto another_round;
        case RX_HANDLER_EXACT:
            deliver_exact = true;
        case RX_HANDLER_PASS:
            break;
        default:
            BUG();
        }
    }

    if (vlan_tx_nonzero_tag_present(skb))
        skb->pkt_type = PACKET_OTHERHOST;

    /* deliver only exact match when indicated */
    null_or_dev = deliver_exact ? skb->dev : NULL;

    type = skb->protocol;
    list_for_each_entry_rcu(ptype,
            &ptype_base[ntohs(type) & PTYPE_HASH_MASK], list) {
        if (ptype->type == type &&
            (ptype->dev == null_or_dev || ptype->dev == skb->dev ||
             ptype->dev == orig_dev)) {
            if (pt_prev)
                ret = deliver_skb(skb, pt_prev, orig_dev);
            pt_prev = ptype;
        }
    }

    if (pt_prev) {
        if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
            goto drop;
        else
            ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
    } else {
drop:
        atomic_long_inc(&skb->dev->rx_dropped);
        kfree_skb(skb);
        /* Jamal, now you will not able to escape explaining
         * me how you were going to use this. :-)
         */
        ret = NET_RX_DROP;
    }

unlock:
    rcu_read_unlock();
out:
    tsk_restore_flags(current, pflags, PF_MEMALLOC);
    return ret;
}

int netif_receive_skb(struct sk_buff *skb)
{
    net_timestamp_check(netdev_tstamp_prequeue, skb);

    if (skb_defer_rx_timestamp(skb))
        return NET_RX_SUCCESS;

#ifdef CONFIG_RPS
    if (static_key_false(&rps_needed)) {
        struct rps_dev_flow voidflow, *rflow = &voidflow;
        int cpu, ret;

        rcu_read_lock();

        cpu = get_rps_cpu(skb->dev, skb, &rflow);

        if (cpu >= 0) {
            ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
            rcu_read_unlock();
            return ret;
        }
        rcu_read_unlock();
    }
#endif
    return __netif_receive_skb(skb);
}
EXPORT_SYMBOL(netif_receive_skb);

/* Network device is going away, flush any packets still pending
 * Called with irqs disabled.
 */
static void flush_backlog(void *arg)
{
    struct net_device *dev = arg;
    struct softnet_data *sd = &__get_cpu_var(softnet_data);
    struct sk_buff *skb, *tmp;

    rps_lock(sd);
    skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
        if (skb->dev == dev) {
            __skb_unlink(skb, &sd->input_pkt_queue);
            kfree_skb(skb);
            input_queue_head_incr(sd);
        }
    }
    rps_unlock(sd);

    skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
        if (skb->dev == dev) {
            __skb_unlink(skb, &sd->process_queue);
            kfree_skb(skb);
            input_queue_head_incr(sd);
        }
    }
}

static int napi_gro_complete(struct sk_buff *skb)
{
    struct packet_type *ptype;
    __be16 type = skb->protocol;
    struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];
    int err = -ENOENT;

    BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));

    if (NAPI_GRO_CB(skb)->count == 1) {
        skb_shinfo(skb)->gso_size = 0;
        goto out;
    }

    rcu_read_lock();
    list_for_each_entry_rcu(ptype, head, list) {
        if (ptype->type != type || ptype->dev || !ptype->gro_complete)
            continue;

        err = ptype->gro_complete(skb);
        break;
    }
    rcu_read_unlock();

    if (err) {
        WARN_ON(&ptype->list == head);
        kfree_skb(skb);
        return NET_RX_SUCCESS;
    }

out:
    return netif_receive_skb(skb);
}

/* napi->gro_list contains packets ordered by age.
 * youngest packets at the head of it.
 * Complete skbs in reverse order to reduce latencies.
 */
void napi_gro_flush(struct napi_struct *napi, bool flush_old)
{
    struct sk_buff *skb, *prev = NULL;

    /* scan list and build reverse chain */
    for (skb = napi->gro_list; skb != NULL; skb = skb->next) {
        skb->prev = prev;
        prev = skb;
    }

    for (skb = prev; skb; skb = prev) {
        skb->next = NULL;

        if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
            return;

        prev = skb->prev;
        napi_gro_complete(skb);
        napi->gro_count--;
    }

    napi->gro_list = NULL;
}
EXPORT_SYMBOL(napi_gro_flush);

enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
    struct sk_buff **pp = NULL;
    struct packet_type *ptype;
    __be16 type = skb->protocol;
    struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];
    int same_flow;
    int mac_len;
    enum gro_result ret;

    if (!(skb->dev->features & NETIF_F_GRO) || netpoll_rx_on(skb))
        goto normal;

    if (skb_is_gso(skb) || skb_has_frag_list(skb))
        goto normal;

    rcu_read_lock();
    list_for_each_entry_rcu(ptype, head, list) {
        if (ptype->type != type || ptype->dev || !ptype->gro_receive)
            continue;

        skb_set_network_header(skb, skb_gro_offset(skb));
        mac_len = skb->network_header - skb->mac_header;
        skb->mac_len = mac_len;
        NAPI_GRO_CB(skb)->same_flow = 0;
        NAPI_GRO_CB(skb)->flush = 0;
        NAPI_GRO_CB(skb)->free = 0;

        pp = ptype->gro_receive(&napi->gro_list, skb);
        break;
    }
    rcu_read_unlock();

    if (&ptype->list == head)
        goto normal;

    same_flow = NAPI_GRO_CB(skb)->same_flow;
    ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;

    if (pp) {
        struct sk_buff *nskb = *pp;

        *pp = nskb->next;
        nskb->next = NULL;
        napi_gro_complete(nskb);
        napi->gro_count--;
    }

    if (same_flow)
        goto ok;

    if (NAPI_GRO_CB(skb)->flush || napi->gro_count >= MAX_GRO_SKBS)
        goto normal;

    napi->gro_count++;
    NAPI_GRO_CB(skb)->count = 1;
    NAPI_GRO_CB(skb)->age = jiffies;
    skb_shinfo(skb)->gso_size = skb_gro_len(skb);
    skb->next = napi->gro_list;
    napi->gro_list = skb;
    ret = GRO_HELD;

pull:
    if (skb_headlen(skb) < skb_gro_offset(skb)) {
        int grow = skb_gro_offset(skb) - skb_headlen(skb);

        BUG_ON(skb->end - skb->tail < grow);

        memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);

        skb->tail += grow;
        skb->data_len -= grow;

        skb_shinfo(skb)->frags[0].page_offset += grow;
        skb_frag_size_sub(&skb_shinfo(skb)->frags[0], grow);

        if (unlikely(!skb_frag_size(&skb_shinfo(skb)->frags[0]))) {
            skb_frag_unref(skb, 0);
            memmove(skb_shinfo(skb)->frags,
                skb_shinfo(skb)->frags + 1,
                --skb_shinfo(skb)->nr_frags * sizeof(skb_frag_t));
        }
    }

ok:
    return ret;

normal:
    ret = GRO_NORMAL;
    goto pull;
}
EXPORT_SYMBOL(dev_gro_receive);

static inline gro_result_t
__napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
    struct sk_buff *p;
    unsigned int maclen = skb->dev->hard_header_len;

    for (p = napi->gro_list; p; p = p->next) {
        unsigned long diffs;

        diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
        diffs |= p->vlan_tci ^ skb->vlan_tci;
        if (maclen == ETH_HLEN)
            diffs |= compare_ether_header(skb_mac_header(p),
                              skb_gro_mac_header(skb));
        else if (!diffs)
            diffs = memcmp(skb_mac_header(p),
                       skb_gro_mac_header(skb),
                       maclen);
        NAPI_GRO_CB(p)->same_flow = !diffs;
        NAPI_GRO_CB(p)->flush = 0;
    }

    return dev_gro_receive(napi, skb);
}

gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
{
    switch (ret) {
    case GRO_NORMAL:
        if (netif_receive_skb(skb))
            ret = GRO_DROP;
        break;

    case GRO_DROP:
        kfree_skb(skb);
        break;

    case GRO_MERGED_FREE:
        if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
            kmem_cache_free(skbuff_head_cache, skb);
        else
            __kfree_skb(skb);
        break;

    case GRO_HELD:
    case GRO_MERGED:
        break;
    }

    return ret;
}
EXPORT_SYMBOL(napi_skb_finish);

static void skb_gro_reset_offset(struct sk_buff *skb)
{
    const struct skb_shared_info *pinfo = skb_shinfo(skb);
    const skb_frag_t *frag0 = &pinfo->frags[0];

    NAPI_GRO_CB(skb)->data_offset = 0;
    NAPI_GRO_CB(skb)->frag0 = NULL;
    NAPI_GRO_CB(skb)->frag0_len = 0;

    if (skb->mac_header == skb->tail &&
        pinfo->nr_frags &&
        !PageHighMem(skb_frag_page(frag0))) {
        NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
        NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(frag0);
    }
}

gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
    skb_gro_reset_offset(skb);

    return napi_skb_finish(__napi_gro_receive(napi, skb), skb);
}
EXPORT_SYMBOL(napi_gro_receive);

static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
{
    __skb_pull(skb, skb_headlen(skb));
    /* restore the reserve we had after netdev_alloc_skb_ip_align() */
    skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
    skb->vlan_tci = 0;
    skb->dev = napi->dev;
    skb->skb_iif = 0;

    napi->skb = skb;
}

struct sk_buff *napi_get_frags(struct napi_struct *napi)
{
    struct sk_buff *skb = napi->skb;

    if (!skb) {
        skb = netdev_alloc_skb_ip_align(napi->dev, GRO_MAX_HEAD);
        if (skb)
            napi->skb = skb;
    }
    return skb;
}
EXPORT_SYMBOL(napi_get_frags);

gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *skb,
                   gro_result_t ret)
{
    switch (ret) {
    case GRO_NORMAL:
    case GRO_HELD:
        skb->protocol = eth_type_trans(skb, skb->dev);

        if (ret == GRO_HELD)
            skb_gro_pull(skb, -ETH_HLEN);
        else if (netif_receive_skb(skb))
            ret = GRO_DROP;
        break;

    case GRO_DROP:
    case GRO_MERGED_FREE:
        napi_reuse_skb(napi, skb);
        break;

    case GRO_MERGED:
        break;
    }

    return ret;
}
EXPORT_SYMBOL(napi_frags_finish);

static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
{
    struct sk_buff *skb = napi->skb;
    struct ethhdr *eth;
    unsigned int hlen;
    unsigned int off;

    napi->skb = NULL;

    skb_reset_mac_header(skb);
    skb_gro_reset_offset(skb);

    off = skb_gro_offset(skb);
    hlen = off + sizeof(*eth);
    eth = skb_gro_header_fast(skb, off);
    if (skb_gro_header_hard(skb, hlen)) {
        eth = skb_gro_header_slow(skb, hlen, off);
        if (unlikely(!eth)) {
            napi_reuse_skb(napi, skb);
            skb = NULL;
            goto out;
        }
    }

    skb_gro_pull(skb, sizeof(*eth));

    /*
     * This works because the only protocols we care about don't require
     * special handling.  We'll fix it up properly at the end.
     */
    skb->protocol = eth->h_proto;

out:
    return skb;
}

gro_result_t napi_gro_frags(struct napi_struct *napi)
{
    struct sk_buff *skb = napi_frags_skb(napi);

    if (!skb)
        return GRO_DROP;

    return napi_frags_finish(napi, skb, __napi_gro_receive(napi, skb));
}
EXPORT_SYMBOL(napi_gro_frags);

/*
 * net_rps_action sends any pending IPI's for rps.
 * Note: called with local irq disabled, but exits with local irq enabled.
 */
static void net_rps_action_and_irq_enable(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
    struct softnet_data *remsd = sd->rps_ipi_list;

    if (remsd) {
        sd->rps_ipi_list = NULL;

        local_irq_enable();

        /* Send pending IPI's to kick RPS processing on remote cpus. */
        while (remsd) {
            struct softnet_data *next = remsd->rps_ipi_next;

            if (cpu_online(remsd->cpu))
                __smp_call_function_single(remsd->cpu,
                               &remsd->csd, 0);
            remsd = next;
        }
    } else
#endif
        local_irq_enable();
}

static int process_backlog(struct napi_struct *napi, int quota)
{
    int work = 0;
    struct softnet_data *sd = container_of(napi, struct softnet_data, backlog);

#ifdef CONFIG_RPS
    /* Check if we have pending ipi, its better to send them now,
     * not waiting net_rx_action() end.
     */
    if (sd->rps_ipi_list) {
        local_irq_disable();
        net_rps_action_and_irq_enable(sd);
    }
#endif
    napi->weight = weight_p;
    local_irq_disable();
    while (work < quota) {
        struct sk_buff *skb;
        unsigned int qlen;

        while ((skb = __skb_dequeue(&sd->process_queue))) {
            local_irq_enable();
            __netif_receive_skb(skb);
            local_irq_disable();
            input_queue_head_incr(sd);
            if (++work >= quota) {
                local_irq_enable();
                return work;
            }
        }

        rps_lock(sd);
        qlen = skb_queue_len(&sd->input_pkt_queue);
        if (qlen)
            skb_queue_splice_tail_init(&sd->input_pkt_queue,
                           &sd->process_queue);

        if (qlen < quota - work) {
            /*
             * Inline a custom version of __napi_complete().
             * only current cpu owns and manipulates this napi,
             * and NAPI_STATE_SCHED is the only possible flag set on backlog.
             * we can use a plain write instead of clear_bit(),
             * and we dont need an smp_mb() memory barrier.
             */
            list_del(&napi->poll_list);
            napi->state = 0;

            quota = work + qlen;
        }
        rps_unlock(sd);
    }
    local_irq_enable();

    return work;
}

void __napi_schedule(struct napi_struct *n)
{
    unsigned long flags;

    local_irq_save(flags);
    ____napi_schedule(&__get_cpu_var(softnet_data), n);
    local_irq_restore(flags);
}
EXPORT_SYMBOL(__napi_schedule);

void __napi_complete(struct napi_struct *n)
{
    BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
    BUG_ON(n->gro_list);

    list_del(&n->poll_list);
    smp_mb__before_clear_bit();
    clear_bit(NAPI_STATE_SCHED, &n->state);
}
EXPORT_SYMBOL(__napi_complete);

void napi_complete(struct napi_struct *n)
{
    unsigned long flags;

    /*
     * don't let napi dequeue from the cpu poll list
     * just in case its running on a different cpu
     */
    if (unlikely(test_bit(NAPI_STATE_NPSVC, &n->state)))
        return;

    napi_gro_flush(n, false);
    local_irq_save(flags);
    __napi_complete(n);
    local_irq_restore(flags);
}
EXPORT_SYMBOL(napi_complete);

void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
            int (*poll)(struct napi_struct *, int), int weight)
{
    INIT_LIST_HEAD(&napi->poll_list);
    napi->gro_count = 0;
    napi->gro_list = NULL;
    napi->skb = NULL;
    napi->poll = poll;
    napi->weight = weight;
    list_add(&napi->dev_list, &dev->napi_list);
    napi->dev = dev;
#ifdef CONFIG_NETPOLL
    spin_lock_init(&napi->poll_lock);
    napi->poll_owner = -1;
#endif
    set_bit(NAPI_STATE_SCHED, &napi->state);
}
EXPORT_SYMBOL(netif_napi_add);

void netif_napi_del(struct napi_struct *napi)
{
    struct sk_buff *skb, *next;

    list_del_init(&napi->dev_list);
    napi_free_frags(napi);

    for (skb = napi->gro_list; skb; skb = next) {
        next = skb->next;
        skb->next = NULL;
        kfree_skb(skb);
    }

    napi->gro_list = NULL;
    napi->gro_count = 0;
}
EXPORT_SYMBOL(netif_napi_del);

static void net_rx_action(struct softirq_action *h)
{
    struct softnet_data *sd = &__get_cpu_var(softnet_data);
    unsigned long time_limit = jiffies + 2;
    int budget = netdev_budget;
    void *have;

    local_irq_disable();

    while (!list_empty(&sd->poll_list)) {
        struct napi_struct *n;
        int work, weight;

        /* If softirq window is exhuasted then punt.
         * Allow this to run for 2 jiffies since which will allow
         * an average latency of 1.5/HZ.
         */
        if (unlikely(budget <= 0 || time_after(jiffies, time_limit)))
            goto softnet_break;

        local_irq_enable();

        /* Even though interrupts have been re-enabled, this
         * access is safe because interrupts can only add new
         * entries to the tail of this list, and only ->poll()
         * calls can remove this head entry from the list.
         */
        n = list_first_entry(&sd->poll_list, struct napi_struct, poll_list);

        have = netpoll_poll_lock(n);

        weight = n->weight;

        /* This NAPI_STATE_SCHED test is for avoiding a race
         * with netpoll's poll_napi().  Only the entity which
         * obtains the lock and sees NAPI_STATE_SCHED set will
         * actually make the ->poll() call.  Therefore we avoid
         * accidentally calling ->poll() when NAPI is not scheduled.
         */
        work = 0;
        if (test_bit(NAPI_STATE_SCHED, &n->state)) {
            work = n->poll(n, weight);
            trace_napi_poll(n);
        }

        WARN_ON_ONCE(work > weight);

        budget -= work;

        local_irq_disable();

        /* Drivers must not modify the NAPI state if they
         * consume the entire weight.  In such cases this code
         * still "owns" the NAPI instance and therefore can
         * move the instance around on the list at-will.
         */
        if (unlikely(work == weight)) {
            if (unlikely(napi_disable_pending(n))) {
                local_irq_enable();
                napi_complete(n);
                local_irq_disable();
            } else {
                if (n->gro_list) {
                    /* flush too old packets
                     * If HZ < 1000, flush all packets.
                     */
                    local_irq_enable();
                    napi_gro_flush(n, HZ >= 1000);
                    local_irq_disable();
                }
                list_move_tail(&n->poll_list, &sd->poll_list);
            }
        }

        netpoll_poll_unlock(have);
    }
out:
    net_rps_action_and_irq_enable(sd);

#ifdef CONFIG_NET_DMA
    /*
     * There may not be any more sk_buffs coming right now, so push
     * any pending DMA copies to hardware
     */
    dma_issue_pending_all();
#endif

    return;

softnet_break:
    sd->time_squeeze++;
    __raise_softirq_irqoff(NET_RX_SOFTIRQ);
    goto out;
}

static gifconf_func_t *gifconf_list[NPROTO];

int register_gifconf(unsigned int family, gifconf_func_t *gifconf)
{
    if (family >= NPROTO)
        return -EINVAL;
    gifconf_list[family] = gifconf;
    return 0;
}
EXPORT_SYMBOL(register_gifconf);


/*
 *  Map an interface index to its name (SIOCGIFNAME)
 */

/*
 *  We need this ioctl for efficient implementation of the
 *  if_indextoname() function required by the IPv6 API.  Without
 *  it, we would have to search all the interfaces to find a
 *  match.  --pb
 */

static int dev_ifname(struct net *net, struct ifreq __user *arg)
{
    struct net_device *dev;
    struct ifreq ifr;

    /*
     *  Fetch the caller's info block.
     */

    if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
        return -EFAULT;

    rcu_read_lock();
    dev = dev_get_by_index_rcu(net, ifr.ifr_ifindex);
    if (!dev) {
        rcu_read_unlock();
        return -ENODEV;
    }

    strcpy(ifr.ifr_name, dev->name);
    rcu_read_unlock();

    if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
        return -EFAULT;
    return 0;
}

/*
 *  Perform a SIOCGIFCONF call. This structure will change
 *  size eventually, and there is nothing I can do about it.
 *  Thus we will need a 'compatibility mode'.
 */

static int dev_ifconf(struct net *net, char __user *arg)
{
    struct ifconf ifc;
    struct net_device *dev;
    char __user *pos;
    int len;
    int total;
    int i;

    /*
     *  Fetch the caller's info block.
     */

    if (copy_from_user(&ifc, arg, sizeof(struct ifconf)))
        return -EFAULT;

    pos = ifc.ifc_buf;
    len = ifc.ifc_len;

    /*
     *  Loop over the interfaces, and write an info block for each.
     */

    total = 0;
    for_each_netdev(net, dev) {
        for (i = 0; i < NPROTO; i++) {
            if (gifconf_list[i]) {
                int done;
                if (!pos)
                    done = gifconf_list[i](dev, NULL, 0);
                else
                    done = gifconf_list[i](dev, pos + total,
                                   len - total);
                if (done < 0)
                    return -EFAULT;
                total += done;
            }
        }
    }

    /*
     *  All done.  Write the updated control block back to the caller.
     */
    ifc.ifc_len = total;

    /*
     *  Both BSD and Solaris return 0 here, so we do too.
     */
    return copy_to_user(arg, &ifc, sizeof(struct ifconf)) ? -EFAULT : 0;
}

#ifdef CONFIG_PROC_FS

#define BUCKET_SPACE (32 - NETDEV_HASHBITS - 1)

#define get_bucket(x) ((x) >> BUCKET_SPACE)
#define get_offset(x) ((x) & ((1 << BUCKET_SPACE) - 1))
#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))

static inline struct net_device *dev_from_same_bucket(struct seq_file *seq, loff_t *pos)
{
    struct net *net = seq_file_net(seq);
    struct net_device *dev;
    struct hlist_node *p;
    struct hlist_head *h;
    unsigned int count = 0, offset = get_offset(*pos);

    h = &net->dev_name_head[get_bucket(*pos)];
    hlist_for_each_entry_rcu(dev, p, h, name_hlist) {
        if (++count == offset)
            return dev;
    }

    return NULL;
}

static inline struct net_device *dev_from_bucket(struct seq_file *seq, loff_t *pos)
{
    struct net_device *dev;
    unsigned int bucket;

    do {
        dev = dev_from_same_bucket(seq, pos);
        if (dev)
            return dev;

        bucket = get_bucket(*pos) + 1;
        *pos = set_bucket_offset(bucket, 1);
    } while (bucket < NETDEV_HASHENTRIES);

    return NULL;
}

/*
 *  This is invoked by the /proc filesystem handler to display a device
 *  in detail.
 */
void *dev_seq_start(struct seq_file *seq, loff_t *pos)
    __acquires(RCU)
{
    rcu_read_lock();
    if (!*pos)
        return SEQ_START_TOKEN;

    if (get_bucket(*pos) >= NETDEV_HASHENTRIES)
        return NULL;

    return dev_from_bucket(seq, pos);
}

void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    ++*pos;
    return dev_from_bucket(seq, pos);
}

void dev_seq_stop(struct seq_file *seq, void *v)
    __releases(RCU)
{
    rcu_read_unlock();
}

static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
{
    struct rtnl_link_stats64 temp;
    const struct rtnl_link_stats64 *stats = dev_get_stats(dev, &temp);

    seq_printf(seq, "%6s: %7llu %7llu %4llu %4llu %4llu %5llu %10llu %9llu "
           "%8llu %7llu %4llu %4llu %4llu %5llu %7llu %10llu\n",
           dev->name, stats->rx_bytes, stats->rx_packets,
           stats->rx_errors,
           stats->rx_dropped + stats->rx_missed_errors,
           stats->rx_fifo_errors,
           stats->rx_length_errors + stats->rx_over_errors +
            stats->rx_crc_errors + stats->rx_frame_errors,
           stats->rx_compressed, stats->multicast,
           stats->tx_bytes, stats->tx_packets,
           stats->tx_errors, stats->tx_dropped,
           stats->tx_fifo_errors, stats->collisions,
           stats->tx_carrier_errors +
            stats->tx_aborted_errors +
            stats->tx_window_errors +
            stats->tx_heartbeat_errors,
           stats->tx_compressed);
}

/*
 *  Called from the PROCfs module. This now uses the new arbitrary sized
 *  /proc/net interface to create /proc/net/dev
 */
static int dev_seq_show(struct seq_file *seq, void *v)
{
    if (v == SEQ_START_TOKEN)
        seq_puts(seq, "Inter-|   Receive                            "
                  "                    |  Transmit\n"
                  " face |bytes    packets errs drop fifo frame "
                  "compressed multicast|bytes    packets errs "
                  "drop fifo colls carrier compressed\n");
    else
        dev_seq_printf_stats(seq, v);
    return 0;
}

static struct softnet_data *softnet_get_online(loff_t *pos)
{
    struct softnet_data *sd = NULL;

    while (*pos < nr_cpu_ids)
        if (cpu_online(*pos)) {
            sd = &per_cpu(softnet_data, *pos);
            break;
        } else
            ++*pos;
    return sd;
}

static void *softnet_seq_start(struct seq_file *seq, loff_t *pos)
{
    return softnet_get_online(pos);
}

static void *softnet_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    ++*pos;
    return softnet_get_online(pos);
}

static void softnet_seq_stop(struct seq_file *seq, void *v)
{
}

static int softnet_seq_show(struct seq_file *seq, void *v)
{
    struct softnet_data *sd = v;

    seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
           sd->processed, sd->dropped, sd->time_squeeze, 0,
           0, 0, 0, 0, /* was fastroute */
           sd->cpu_collision, sd->received_rps);
    return 0;
}

static const struct seq_operations dev_seq_ops = {
    .start = dev_seq_start,
    .next  = dev_seq_next,
    .stop  = dev_seq_stop,
    .show  = dev_seq_show,
};

static int dev_seq_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &dev_seq_ops,
                sizeof(struct seq_net_private));
}

static const struct file_operations dev_seq_fops = {
    .owner   = THIS_MODULE,
    .open    = dev_seq_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};

static const struct seq_operations softnet_seq_ops = {
    .start = softnet_seq_start,
    .next  = softnet_seq_next,
    .stop  = softnet_seq_stop,
    .show  = softnet_seq_show,
};

static int softnet_seq_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &softnet_seq_ops);
}

static const struct file_operations softnet_seq_fops = {
    .owner   = THIS_MODULE,
    .open    = softnet_seq_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release,
};

static void *ptype_get_idx(loff_t pos)
{
    struct packet_type *pt = NULL;
    loff_t i = 0;
    int t;

    list_for_each_entry_rcu(pt, &ptype_all, list) {
        if (i == pos)
            return pt;
        ++i;
    }

    for (t = 0; t < PTYPE_HASH_SIZE; t++) {
        list_for_each_entry_rcu(pt, &ptype_base[t], list) {
            if (i == pos)
                return pt;
            ++i;
        }
    }
    return NULL;
}

static void *ptype_seq_start(struct seq_file *seq, loff_t *pos)
    __acquires(RCU)
{
    rcu_read_lock();
    return *pos ? ptype_get_idx(*pos - 1) : SEQ_START_TOKEN;
}

static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    struct packet_type *pt;
    struct list_head *nxt;
    int hash;

    ++*pos;
    if (v == SEQ_START_TOKEN)
        return ptype_get_idx(0);

    pt = v;
    nxt = pt->list.next;
    if (pt->type == htons(ETH_P_ALL)) {
        if (nxt != &ptype_all)
            goto found;
        hash = 0;
        nxt = ptype_base[0].next;
    } else
        hash = ntohs(pt->type) & PTYPE_HASH_MASK;

    while (nxt == &ptype_base[hash]) {
        if (++hash >= PTYPE_HASH_SIZE)
            return NULL;
        nxt = ptype_base[hash].next;
    }
found:
    return list_entry(nxt, struct packet_type, list);
}

static void ptype_seq_stop(struct seq_file *seq, void *v)
    __releases(RCU)
{
    rcu_read_unlock();
}

static int ptype_seq_show(struct seq_file *seq, void *v)
{
    struct packet_type *pt = v;

    if (v == SEQ_START_TOKEN)
        seq_puts(seq, "Type Device      Function\n");
    else if (pt->dev == NULL || dev_net(pt->dev) == seq_file_net(seq)) {
        if (pt->type == htons(ETH_P_ALL))
            seq_puts(seq, "ALL ");
        else
            seq_printf(seq, "%04x", ntohs(pt->type));

        seq_printf(seq, " %-8s %pF\n",
               pt->dev ? pt->dev->name : "", pt->func);
    }

    return 0;
}

static const struct seq_operations ptype_seq_ops = {
    .start = ptype_seq_start,
    .next  = ptype_seq_next,
    .stop  = ptype_seq_stop,
    .show  = ptype_seq_show,
};

static int ptype_seq_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &ptype_seq_ops,
            sizeof(struct seq_net_private));
}

static const struct file_operations ptype_seq_fops = {
    .owner   = THIS_MODULE,
    .open    = ptype_seq_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};


static int __net_init dev_proc_net_init(struct net *net)
{
    int rc = -ENOMEM;

    if (!proc_net_fops_create(net, "dev", S_IRUGO, &dev_seq_fops))
        goto out;
    if (!proc_net_fops_create(net, "softnet_stat", S_IRUGO, &softnet_seq_fops))
        goto out_dev;
    if (!proc_net_fops_create(net, "ptype", S_IRUGO, &ptype_seq_fops))
        goto out_softnet;

    if (wext_proc_init(net))
        goto out_ptype;
    rc = 0;
out:
    return rc;
out_ptype:
    proc_net_remove(net, "ptype");
out_softnet:
    proc_net_remove(net, "softnet_stat");
out_dev:
    proc_net_remove(net, "dev");
    goto out;
}

static void __net_exit dev_proc_net_exit(struct net *net)
{
    wext_proc_exit(net);

    proc_net_remove(net, "ptype");
    proc_net_remove(net, "softnet_stat");
    proc_net_remove(net, "dev");
}

static struct pernet_operations __net_initdata dev_proc_ops = {
    .init = dev_proc_net_init,
    .exit = dev_proc_net_exit,
};

static int __init dev_proc_init(void)
{
    return register_pernet_subsys(&dev_proc_ops);
}
#else
#define dev_proc_init() 0
#endif  /* CONFIG_PROC_FS */


int netdev_set_master(struct net_device *slave, struct net_device *master)
{
    struct net_device *old = slave->master;

    ASSERT_RTNL();

    if (master) {
        if (old)
            return -EBUSY;
        dev_hold(master);
    }

    slave->master = master;

    if (old)
        dev_put(old);
    return 0;
}
EXPORT_SYMBOL(netdev_set_master);

int netdev_set_bond_master(struct net_device *slave, struct net_device *master)
{
    int err;

    ASSERT_RTNL();

    err = netdev_set_master(slave, master);
    if (err)
        return err;
    if (master)
        slave->flags |= IFF_SLAVE;
    else
        slave->flags &= ~IFF_SLAVE;

    rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE);
    return 0;
}
EXPORT_SYMBOL(netdev_set_bond_master);

static void dev_change_rx_flags(struct net_device *dev, int flags)
{
    const struct net_device_ops *ops = dev->netdev_ops;

    if ((dev->flags & IFF_UP) && ops->ndo_change_rx_flags)
        ops->ndo_change_rx_flags(dev, flags);
}

static int __dev_set_promiscuity(struct net_device *dev, int inc)
{
    unsigned int old_flags = dev->flags;
    kuid_t uid;
    kgid_t gid;

    ASSERT_RTNL();

    dev->flags |= IFF_PROMISC;
    dev->promiscuity += inc;
    if (dev->promiscuity == 0) {
        /*
         * Avoid overflow.
         * If inc causes overflow, untouch promisc and return error.
         */
        if (inc < 0)
            dev->flags &= ~IFF_PROMISC;
        else {
            dev->promiscuity -= inc;
            pr_warn("%s: promiscuity touches roof, set promiscuity failed. promiscuity feature of device might be broken.\n",
                dev->name);
            return -EOVERFLOW;
        }
    }
    if (dev->flags != old_flags) {
        pr_info("device %s %s promiscuous mode\n",
            dev->name,
            dev->flags & IFF_PROMISC ? "entered" : "left");
        if (audit_enabled) {
            current_uid_gid(&uid, &gid);
            audit_log(current->audit_context, GFP_ATOMIC,
                AUDIT_ANOM_PROMISCUOUS,
                "dev=%s prom=%d old_prom=%d auid=%u uid=%u gid=%u ses=%u",
                dev->name, (dev->flags & IFF_PROMISC),
                (old_flags & IFF_PROMISC),
                from_kuid(&init_user_ns, audit_get_loginuid(current)),
                from_kuid(&init_user_ns, uid),
                from_kgid(&init_user_ns, gid),
                audit_get_sessionid(current));
        }

        dev_change_rx_flags(dev, IFF_PROMISC);
    }
    return 0;
}

int dev_set_promiscuity(struct net_device *dev, int inc)
{
    unsigned int old_flags = dev->flags;
    int err;

    err = __dev_set_promiscuity(dev, inc);
    if (err < 0)
        return err;
    if (dev->flags != old_flags)
        dev_set_rx_mode(dev);
    return err;
}
EXPORT_SYMBOL(dev_set_promiscuity);

int dev_set_allmulti(struct net_device *dev, int inc)
{
    unsigned int old_flags = dev->flags;

    ASSERT_RTNL();

    dev->flags |= IFF_ALLMULTI;
    dev->allmulti += inc;
    if (dev->allmulti == 0) {
        /*
         * Avoid overflow.
         * If inc causes overflow, untouch allmulti and return error.
         */
        if (inc < 0)
            dev->flags &= ~IFF_ALLMULTI;
        else {
            dev->allmulti -= inc;
            pr_warn("%s: allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n",
                dev->name);
            return -EOVERFLOW;
        }
    }
    if (dev->flags ^ old_flags) {
        dev_change_rx_flags(dev, IFF_ALLMULTI);
        dev_set_rx_mode(dev);
    }
    return 0;
}
EXPORT_SYMBOL(dev_set_allmulti);

/*
 *  Upload unicast and multicast address lists to device and
 *  configure RX filtering. When the device doesn't support unicast
 *  filtering it is put in promiscuous mode while unicast addresses
 *  are present.
 */
void __dev_set_rx_mode(struct net_device *dev)
{
    const struct net_device_ops *ops = dev->netdev_ops;

    /* dev_open will call this function so the list will stay sane. */
    if (!(dev->flags&IFF_UP))
        return;

    if (!netif_device_present(dev))
        return;

    if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
        /* Unicast addresses changes may only happen under the rtnl,
         * therefore calling __dev_set_promiscuity here is safe.
         */
        if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
            __dev_set_promiscuity(dev, 1);
            dev->uc_promisc = true;
        } else if (netdev_uc_empty(dev) && dev->uc_promisc) {
            __dev_set_promiscuity(dev, -1);
            dev->uc_promisc = false;
        }
    }

    if (ops->ndo_set_rx_mode)
        ops->ndo_set_rx_mode(dev);
}

void dev_set_rx_mode(struct net_device *dev)
{
    netif_addr_lock_bh(dev);
    __dev_set_rx_mode(dev);
    netif_addr_unlock_bh(dev);
}

unsigned int dev_get_flags(const struct net_device *dev)
{
    unsigned int flags;

    flags = (dev->flags & ~(IFF_PROMISC |
                IFF_ALLMULTI |
                IFF_RUNNING |
                IFF_LOWER_UP |
                IFF_DORMANT)) |
        (dev->gflags & (IFF_PROMISC |
                IFF_ALLMULTI));

    if (netif_running(dev)) {
        if (netif_oper_up(dev))
            flags |= IFF_RUNNING;
        if (netif_carrier_ok(dev))
            flags |= IFF_LOWER_UP;
        if (netif_dormant(dev))
            flags |= IFF_DORMANT;
    }

    return flags;
}
EXPORT_SYMBOL(dev_get_flags);

int __dev_change_flags(struct net_device *dev, unsigned int flags)
{
    unsigned int old_flags = dev->flags;
    int ret;

    ASSERT_RTNL();

    /*
     *  Set the flags on our device.
     */

    dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
                   IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
                   IFF_AUTOMEDIA)) |
             (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
                    IFF_ALLMULTI));

    /*
     *  Load in the correct multicast list now the flags have changed.
     */

    if ((old_flags ^ flags) & IFF_MULTICAST)
        dev_change_rx_flags(dev, IFF_MULTICAST);

    dev_set_rx_mode(dev);

    /*
     *  Have we downed the interface. We handle IFF_UP ourselves
     *  according to user attempts to set it, rather than blindly
     *  setting it.
     */

    ret = 0;
    if ((old_flags ^ flags) & IFF_UP) { /* Bit is different  ? */
        ret = ((old_flags & IFF_UP) ? __dev_close : __dev_open)(dev);

        if (!ret)
            dev_set_rx_mode(dev);
    }

    if ((flags ^ dev->gflags) & IFF_PROMISC) {
        int inc = (flags & IFF_PROMISC) ? 1 : -1;

        dev->gflags ^= IFF_PROMISC;
        dev_set_promiscuity(dev, inc);
    }

    /* NOTE: order of synchronization of IFF_PROMISC and IFF_ALLMULTI
       is important. Some (broken) drivers set IFF_PROMISC, when
       IFF_ALLMULTI is requested not asking us and not reporting.
     */
    if ((flags ^ dev->gflags) & IFF_ALLMULTI) {
        int inc = (flags & IFF_ALLMULTI) ? 1 : -1;

        dev->gflags ^= IFF_ALLMULTI;
        dev_set_allmulti(dev, inc);
    }

    return ret;
}

void __dev_notify_flags(struct net_device *dev, unsigned int old_flags)
{
    unsigned int changes = dev->flags ^ old_flags;

    if (changes & IFF_UP) {
        if (dev->flags & IFF_UP)
            call_netdevice_notifiers(NETDEV_UP, dev);
        else
            call_netdevice_notifiers(NETDEV_DOWN, dev);
    }

    if (dev->flags & IFF_UP &&
        (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE)))
        call_netdevice_notifiers(NETDEV_CHANGE, dev);
}

int dev_change_flags(struct net_device *dev, unsigned int flags)
{
    int ret;
    unsigned int changes, old_flags = dev->flags;

    ret = __dev_change_flags(dev, flags);
    if (ret < 0)
        return ret;

    changes = old_flags ^ dev->flags;
    if (changes)
        rtmsg_ifinfo(RTM_NEWLINK, dev, changes);

    __dev_notify_flags(dev, old_flags);
    return ret;
}
EXPORT_SYMBOL(dev_change_flags);

int dev_set_mtu(struct net_device *dev, int new_mtu)
{
    const struct net_device_ops *ops = dev->netdev_ops;
    int err;

    if (new_mtu == dev->mtu)
        return 0;

    /*  MTU must be positive.    */
    if (new_mtu < 0)
        return -EINVAL;

    if (!netif_device_present(dev))
        return -ENODEV;

    err = 0;
    if (ops->ndo_change_mtu)
        err = ops->ndo_change_mtu(dev, new_mtu);
    else
        dev->mtu = new_mtu;

    if (!err && dev->flags & IFF_UP)
        call_netdevice_notifiers(NETDEV_CHANGEMTU, dev);
    return err;
}
EXPORT_SYMBOL(dev_set_mtu);

void dev_set_group(struct net_device *dev, int new_group)
{
    dev->group = new_group;
}
EXPORT_SYMBOL(dev_set_group);

int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa)
{
    const struct net_device_ops *ops = dev->netdev_ops;
    int err;

    if (!ops->ndo_set_mac_address)
        return -EOPNOTSUPP;
    if (sa->sa_family != dev->type)
        return -EINVAL;
    if (!netif_device_present(dev))
        return -ENODEV;
    err = ops->ndo_set_mac_address(dev, sa);
    if (!err)
        call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
    add_device_randomness(dev->dev_addr, dev->addr_len);
    return err;
}
EXPORT_SYMBOL(dev_set_mac_address);

/*
 *  Perform the SIOCxIFxxx calls, inside rcu_read_lock()
 */
static int dev_ifsioc_locked(struct net *net, struct ifreq *ifr, unsigned int cmd)
{
    int err;
    struct net_device *dev = dev_get_by_name_rcu(net, ifr->ifr_name);

    if (!dev)
        return -ENODEV;

    switch (cmd) {
    case SIOCGIFFLAGS:  /* Get interface flags */
        ifr->ifr_flags = (short) dev_get_flags(dev);
        return 0;

    case SIOCGIFMETRIC: /* Get the metric on the interface
                   (currently unused) */
        ifr->ifr_metric = 0;
        return 0;

    case SIOCGIFMTU:    /* Get the MTU of a device */
        ifr->ifr_mtu = dev->mtu;
        return 0;

    case SIOCGIFHWADDR:
        if (!dev->addr_len)
            memset(ifr->ifr_hwaddr.sa_data, 0, sizeof ifr->ifr_hwaddr.sa_data);
        else
            memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr,
                   min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) dev->addr_len));
        ifr->ifr_hwaddr.sa_family = dev->type;
        return 0;

    case SIOCGIFSLAVE:
        err = -EINVAL;
        break;

    case SIOCGIFMAP:
        ifr->ifr_map.mem_start = dev->mem_start;
        ifr->ifr_map.mem_end   = dev->mem_end;
        ifr->ifr_map.base_addr = dev->base_addr;
        ifr->ifr_map.irq       = dev->irq;
        ifr->ifr_map.dma       = dev->dma;
        ifr->ifr_map.port      = dev->if_port;
        return 0;

    case SIOCGIFINDEX:
        ifr->ifr_ifindex = dev->ifindex;
        return 0;

    case SIOCGIFTXQLEN:
        ifr->ifr_qlen = dev->tx_queue_len;
        return 0;

    default:
        /* dev_ioctl() should ensure this case
         * is never reached
         */
        WARN_ON(1);
        err = -ENOTTY;
        break;

    }
    return err;
}

/*
 *  Perform the SIOCxIFxxx calls, inside rtnl_lock()
 */
static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
{
    int err;
    struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
    const struct net_device_ops *ops;

    if (!dev)
        return -ENODEV;

    ops = dev->netdev_ops;

    switch (cmd) {
    case SIOCSIFFLAGS:  /* Set interface flags */
        return dev_change_flags(dev, ifr->ifr_flags);

    case SIOCSIFMETRIC: /* Set the metric on the interface
                   (currently unused) */
        return -EOPNOTSUPP;

    case SIOCSIFMTU:    /* Set the MTU of a device */
        return dev_set_mtu(dev, ifr->ifr_mtu);

    case SIOCSIFHWADDR:
        return dev_set_mac_address(dev, &ifr->ifr_hwaddr);

    case SIOCSIFHWBROADCAST:
        if (ifr->ifr_hwaddr.sa_family != dev->type)
            return -EINVAL;
        memcpy(dev->broadcast, ifr->ifr_hwaddr.sa_data,
               min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) dev->addr_len));
        call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
        return 0;

    case SIOCSIFMAP:
        if (ops->ndo_set_config) {
            if (!netif_device_present(dev))
                return -ENODEV;
            return ops->ndo_set_config(dev, &ifr->ifr_map);
        }
        return -EOPNOTSUPP;

    case SIOCADDMULTI:
        if (!ops->ndo_set_rx_mode ||
            ifr->ifr_hwaddr.sa_family != AF_UNSPEC)
            return -EINVAL;
        if (!netif_device_present(dev))
            return -ENODEV;
        return dev_mc_add_global(dev, ifr->ifr_hwaddr.sa_data);

    case SIOCDELMULTI:
        if (!ops->ndo_set_rx_mode ||
            ifr->ifr_hwaddr.sa_family != AF_UNSPEC)
            return -EINVAL;
        if (!netif_device_present(dev))
            return -ENODEV;
        return dev_mc_del_global(dev, ifr->ifr_hwaddr.sa_data);

    case SIOCSIFTXQLEN:
        if (ifr->ifr_qlen < 0)
            return -EINVAL;
        dev->tx_queue_len = ifr->ifr_qlen;
        return 0;

    case SIOCSIFNAME:
        ifr->ifr_newname[IFNAMSIZ-1] = '\0';
        return dev_change_name(dev, ifr->ifr_newname);

    case SIOCSHWTSTAMP:
        err = net_hwtstamp_validate(ifr);
        if (err)
            return err;
        /* fall through */

    /*
     *  Unknown or private ioctl
     */
    default:
        if ((cmd >= SIOCDEVPRIVATE &&
            cmd <= SIOCDEVPRIVATE + 15) ||
            cmd == SIOCBONDENSLAVE ||
            cmd == SIOCBONDRELEASE ||
            cmd == SIOCBONDSETHWADDR ||
            cmd == SIOCBONDSLAVEINFOQUERY ||
            cmd == SIOCBONDINFOQUERY ||
            cmd == SIOCBONDCHANGEACTIVE ||
            cmd == SIOCGMIIPHY ||
            cmd == SIOCGMIIREG ||
            cmd == SIOCSMIIREG ||
            cmd == SIOCBRADDIF ||
            cmd == SIOCBRDELIF ||
            cmd == SIOCSHWTSTAMP ||
            cmd == SIOCWANDEV) {
            err = -EOPNOTSUPP;
            if (ops->ndo_do_ioctl) {
                if (netif_device_present(dev))
                    err = ops->ndo_do_ioctl(dev, ifr, cmd);
                else
                    err = -ENODEV;
            }
        } else
            err = -EINVAL;

    }
    return err;
}

/*
 *  This function handles all "interface"-type I/O control requests. The actual
 *  'doing' part of this is dev_ifsioc above.
 */

int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg)
{
    struct ifreq ifr;
    int ret;
    char *colon;

    /* One special case: SIOCGIFCONF takes ifconf argument
       and requires shared lock, because it sleeps writing
       to user space.
     */

    if (cmd == SIOCGIFCONF) {
        rtnl_lock();
        ret = dev_ifconf(net, (char __user *) arg);
        rtnl_unlock();
        return ret;
    }
    if (cmd == SIOCGIFNAME)
        return dev_ifname(net, (struct ifreq __user *)arg);

    if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
        return -EFAULT;

    ifr.ifr_name[IFNAMSIZ-1] = 0;

    colon = strchr(ifr.ifr_name, ':');
    if (colon)
        *colon = 0;

    /*
     *  See which interface the caller is talking about.
     */

    switch (cmd) {
    /*
     *  These ioctl calls:
     *  - can be done by all.
     *  - atomic and do not require locking.
     *  - return a value
     */
    case SIOCGIFFLAGS:
    case SIOCGIFMETRIC:
    case SIOCGIFMTU:
    case SIOCGIFHWADDR:
    case SIOCGIFSLAVE:
    case SIOCGIFMAP:
    case SIOCGIFINDEX:
    case SIOCGIFTXQLEN:
        dev_load(net, ifr.ifr_name);
        rcu_read_lock();
        ret = dev_ifsioc_locked(net, &ifr, cmd);
        rcu_read_unlock();
        if (!ret) {
            if (colon)
                *colon = ':';
            if (copy_to_user(arg, &ifr,
                     sizeof(struct ifreq)))
                ret = -EFAULT;
        }
        return ret;

    case SIOCETHTOOL:
        dev_load(net, ifr.ifr_name);
        rtnl_lock();
        ret = dev_ethtool(net, &ifr);
        rtnl_unlock();
        if (!ret) {
            if (colon)
                *colon = ':';
            if (copy_to_user(arg, &ifr,
                     sizeof(struct ifreq)))
                ret = -EFAULT;
        }
        return ret;

    /*
     *  These ioctl calls:
     *  - require superuser power.
     *  - require strict serialization.
     *  - return a value
     */
    case SIOCGMIIPHY:
    case SIOCGMIIREG:
    case SIOCSIFNAME:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        dev_load(net, ifr.ifr_name);
        rtnl_lock();
        ret = dev_ifsioc(net, &ifr, cmd);
        rtnl_unlock();
        if (!ret) {
            if (colon)
                *colon = ':';
            if (copy_to_user(arg, &ifr,
                     sizeof(struct ifreq)))
                ret = -EFAULT;
        }
        return ret;

    /*
     *  These ioctl calls:
     *  - require superuser power.
     *  - require strict serialization.
     *  - do not return a value
     */
    case SIOCSIFFLAGS:
    case SIOCSIFMETRIC:
    case SIOCSIFMTU:
    case SIOCSIFMAP:
    case SIOCSIFHWADDR:
    case SIOCSIFSLAVE:
    case SIOCADDMULTI:
    case SIOCDELMULTI:
    case SIOCSIFHWBROADCAST:
    case SIOCSIFTXQLEN:
    case SIOCSMIIREG:
    case SIOCBONDENSLAVE:
    case SIOCBONDRELEASE:
    case SIOCBONDSETHWADDR:
    case SIOCBONDCHANGEACTIVE:
    case SIOCBRADDIF:
    case SIOCBRDELIF:
    case SIOCSHWTSTAMP:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        /* fall through */
    case SIOCBONDSLAVEINFOQUERY:
    case SIOCBONDINFOQUERY:
        dev_load(net, ifr.ifr_name);
        rtnl_lock();
        ret = dev_ifsioc(net, &ifr, cmd);
        rtnl_unlock();
        return ret;

    case SIOCGIFMEM:
        /* Get the per device memory space. We can add this but
         * currently do not support it */
    case SIOCSIFMEM:
        /* Set the per device memory buffer space.
         * Not applicable in our case */
    case SIOCSIFLINK:
        return -ENOTTY;

    /*
     *  Unknown or private ioctl.
     */
    default:
        if (cmd == SIOCWANDEV ||
            (cmd >= SIOCDEVPRIVATE &&
             cmd <= SIOCDEVPRIVATE + 15)) {
            dev_load(net, ifr.ifr_name);
            rtnl_lock();
            ret = dev_ifsioc(net, &ifr, cmd);
            rtnl_unlock();
            if (!ret && copy_to_user(arg, &ifr,
                         sizeof(struct ifreq)))
                ret = -EFAULT;
            return ret;
        }
        /* Take care of Wireless Extensions */
        if (cmd >= SIOCIWFIRST && cmd <= SIOCIWLAST)
            return wext_handle_ioctl(net, &ifr, cmd, arg);
        return -ENOTTY;
    }
}


static int dev_new_index(struct net *net)
{
    int ifindex = net->ifindex;
    for (;;) {
        if (++ifindex <= 0)
            ifindex = 1;
        if (!__dev_get_by_index(net, ifindex))
            return net->ifindex = ifindex;
    }
}

/* Delayed registration/unregisteration */
static LIST_HEAD(net_todo_list);

static void net_set_todo(struct net_device *dev)
{
    list_add_tail(&dev->todo_list, &net_todo_list);
}

static void rollback_registered_many(struct list_head *head)
{
    struct net_device *dev, *tmp;

    BUG_ON(dev_boot_phase);
    ASSERT_RTNL();

    list_for_each_entry_safe(dev, tmp, head, unreg_list) {
        /* Some devices call without registering
         * for initialization unwind. Remove those
         * devices and proceed with the remaining.
         */
        if (dev->reg_state == NETREG_UNINITIALIZED) {
            pr_debug("unregister_netdevice: device %s/%p never was registered\n",
                 dev->name, dev);

            WARN_ON(1);
            list_del(&dev->unreg_list);
            continue;
        }
        dev->dismantle = true;
        BUG_ON(dev->reg_state != NETREG_REGISTERED);
    }

    /* If device is running, close it first. */
    dev_close_many(head);

    list_for_each_entry(dev, head, unreg_list) {
        /* And unlink it from device chain. */
        unlist_netdevice(dev);

        dev->reg_state = NETREG_UNREGISTERING;
    }

    synchronize_net();

    list_for_each_entry(dev, head, unreg_list) {
        /* Shutdown queueing discipline. */
        dev_shutdown(dev);


        /* Notify protocols, that we are about to destroy
           this device. They should clean all the things.
        */
        call_netdevice_notifiers(NETDEV_UNREGISTER, dev);

        if (!dev->rtnl_link_ops ||
            dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
            rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);

        /*
         *  Flush the unicast and multicast chains
         */
        dev_uc_flush(dev);
        dev_mc_flush(dev);

        if (dev->netdev_ops->ndo_uninit)
            dev->netdev_ops->ndo_uninit(dev);

        /* Notifier chain MUST detach us from master device. */
        WARN_ON(dev->master);

        /* Remove entries from kobject tree */
        netdev_unregister_kobject(dev);
    }

    synchronize_net();

    list_for_each_entry(dev, head, unreg_list)
        dev_put(dev);
}

static void rollback_registered(struct net_device *dev)
{
    LIST_HEAD(single);

    list_add(&dev->unreg_list, &single);
    rollback_registered_many(&single);
    list_del(&single);
}

static netdev_features_t netdev_fix_features(struct net_device *dev,
    netdev_features_t features)
{
    /* Fix illegal checksum combinations */
    if ((features & NETIF_F_HW_CSUM) &&
        (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
        netdev_warn(dev, "mixed HW and IP checksum settings.\n");
        features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
    }

    /* Fix illegal SG+CSUM combinations. */
    if ((features & NETIF_F_SG) &&
        !(features & NETIF_F_ALL_CSUM)) {
        netdev_dbg(dev,
            "Dropping NETIF_F_SG since no checksum feature.\n");
        features &= ~NETIF_F_SG;
    }

    /* TSO requires that SG is present as well. */
    if ((features & NETIF_F_ALL_TSO) && !(features & NETIF_F_SG)) {
        netdev_dbg(dev, "Dropping TSO features since no SG feature.\n");
        features &= ~NETIF_F_ALL_TSO;
    }

    /* TSO ECN requires that TSO is present as well. */
    if ((features & NETIF_F_ALL_TSO) == NETIF_F_TSO_ECN)
        features &= ~NETIF_F_TSO_ECN;

    /* Software GSO depends on SG. */
    if ((features & NETIF_F_GSO) && !(features & NETIF_F_SG)) {
        netdev_dbg(dev, "Dropping NETIF_F_GSO since no SG feature.\n");
        features &= ~NETIF_F_GSO;
    }

    /* UFO needs SG and checksumming */
    if (features & NETIF_F_UFO) {
        /* maybe split UFO into V4 and V6? */
        if (!((features & NETIF_F_GEN_CSUM) ||
            (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))
                == (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
            netdev_dbg(dev,
                "Dropping NETIF_F_UFO since no checksum offload features.\n");
            features &= ~NETIF_F_UFO;
        }

        if (!(features & NETIF_F_SG)) {
            netdev_dbg(dev,
                "Dropping NETIF_F_UFO since no NETIF_F_SG feature.\n");
            features &= ~NETIF_F_UFO;
        }
    }

    return features;
}

int __netdev_update_features(struct net_device *dev)
{
    netdev_features_t features;
    int err = 0;

    ASSERT_RTNL();

    features = netdev_get_wanted_features(dev);

    if (dev->netdev_ops->ndo_fix_features)
        features = dev->netdev_ops->ndo_fix_features(dev, features);

    /* driver might be less strict about feature dependencies */
    features = netdev_fix_features(dev, features);

    if (dev->features == features)
        return 0;

    netdev_dbg(dev, "Features changed: %pNF -> %pNF\n",
        &dev->features, &features);

    if (dev->netdev_ops->ndo_set_features)
        err = dev->netdev_ops->ndo_set_features(dev, features);

    if (unlikely(err < 0)) {
        netdev_err(dev,
            "set_features() failed (%d); wanted %pNF, left %pNF\n",
            err, &features, &dev->features);
        return -1;
    }

    if (!err)
        dev->features = features;

    return 1;
}

void netdev_update_features(struct net_device *dev)
{
    if (__netdev_update_features(dev))
        netdev_features_change(dev);
}
EXPORT_SYMBOL(netdev_update_features);

void netdev_change_features(struct net_device *dev)
{
    __netdev_update_features(dev);
    netdev_features_change(dev);
}
EXPORT_SYMBOL(netdev_change_features);

void netif_stacked_transfer_operstate(const struct net_device *rootdev,
                    struct net_device *dev)
{
    if (rootdev->operstate == IF_OPER_DORMANT)
        netif_dormant_on(dev);
    else
        netif_dormant_off(dev);

    if (netif_carrier_ok(rootdev)) {
        if (!netif_carrier_ok(dev))
            netif_carrier_on(dev);
    } else {
        if (netif_carrier_ok(dev))
            netif_carrier_off(dev);
    }
}
EXPORT_SYMBOL(netif_stacked_transfer_operstate);

#ifdef CONFIG_RPS
static int netif_alloc_rx_queues(struct net_device *dev)
{
    unsigned int i, count = dev->num_rx_queues;
    struct netdev_rx_queue *rx;

    BUG_ON(count < 1);

    rx = kcalloc(count, sizeof(struct netdev_rx_queue), GFP_KERNEL);
    if (!rx) {
        pr_err("netdev: Unable to allocate %u rx queues\n", count);
        return -ENOMEM;
    }
    dev->_rx = rx;

    for (i = 0; i < count; i++)
        rx[i].dev = dev;
    return 0;
}
#endif

static void netdev_init_one_queue(struct net_device *dev,
                  struct netdev_queue *queue, void *_unused)
{
    /* Initialize queue lock */
    spin_lock_init(&queue->_xmit_lock);
    netdev_set_xmit_lockdep_class(&queue->_xmit_lock, dev->type);
    queue->xmit_lock_owner = -1;
    netdev_queue_numa_node_write(queue, NUMA_NO_NODE);
    queue->dev = dev;
#ifdef CONFIG_BQL
    dql_init(&queue->dql, HZ);
#endif
}

static int netif_alloc_netdev_queues(struct net_device *dev)
{
    unsigned int count = dev->num_tx_queues;
    struct netdev_queue *tx;

    BUG_ON(count < 1);

    tx = kcalloc(count, sizeof(struct netdev_queue), GFP_KERNEL);
    if (!tx) {
        pr_err("netdev: Unable to allocate %u tx queues\n", count);
        return -ENOMEM;
    }
    dev->_tx = tx;

    netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
    spin_lock_init(&dev->tx_global_lock);

    return 0;
}

int register_netdevice(struct net_device *dev)
{
    int ret;
    struct net *net = dev_net(dev);

    BUG_ON(dev_boot_phase);
    ASSERT_RTNL();

    might_sleep();

    /* When net_device's are persistent, this will be fatal. */
    BUG_ON(dev->reg_state != NETREG_UNINITIALIZED);
    BUG_ON(!net);

    spin_lock_init(&dev->addr_list_lock);
    netdev_set_addr_lockdep_class(dev);

    dev->iflink = -1;

    ret = dev_get_valid_name(net, dev, dev->name);
    if (ret < 0)
        goto out;

    /* Init, if this function is available */
    if (dev->netdev_ops->ndo_init) {
        ret = dev->netdev_ops->ndo_init(dev);
        if (ret) {
            if (ret > 0)
                ret = -EIO;
            goto out;
        }
    }

    ret = -EBUSY;
    if (!dev->ifindex)
        dev->ifindex = dev_new_index(net);
    else if (__dev_get_by_index(net, dev->ifindex))
        goto err_uninit;

    if (dev->iflink == -1)
        dev->iflink = dev->ifindex;

    /* Transfer changeable features to wanted_features and enable
     * software offloads (GSO and GRO).
     */
    dev->hw_features |= NETIF_F_SOFT_FEATURES;
    dev->features |= NETIF_F_SOFT_FEATURES;
    dev->wanted_features = dev->features & dev->hw_features;

    /* Turn on no cache copy if HW is doing checksum */
    if (!(dev->flags & IFF_LOOPBACK)) {
        dev->hw_features |= NETIF_F_NOCACHE_COPY;
        if (dev->features & NETIF_F_ALL_CSUM) {
            dev->wanted_features |= NETIF_F_NOCACHE_COPY;
            dev->features |= NETIF_F_NOCACHE_COPY;
        }
    }

    /* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
     */
    dev->vlan_features |= NETIF_F_HIGHDMA;

    ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev);
    ret = notifier_to_errno(ret);
    if (ret)
        goto err_uninit;

    ret = netdev_register_kobject(dev);
    if (ret)
        goto err_uninit;
    dev->reg_state = NETREG_REGISTERED;

    __netdev_update_features(dev);

    /*
     *  Default initial state at registry is that the
     *  device is present.
     */

    set_bit(__LINK_STATE_PRESENT, &dev->state);

    linkwatch_init_dev(dev);

    dev_init_scheduler(dev);
    dev_hold(dev);
    list_netdevice(dev);
    add_device_randomness(dev->dev_addr, dev->addr_len);

    /* Notify protocols, that a new device appeared. */
    ret = call_netdevice_notifiers(NETDEV_REGISTER, dev);
    ret = notifier_to_errno(ret);
    if (ret) {
        rollback_registered(dev);
        dev->reg_state = NETREG_UNREGISTERED;
    }
    /*
     *  Prevent userspace races by waiting until the network
     *  device is fully setup before sending notifications.
     */
    if (!dev->rtnl_link_ops ||
        dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
        rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);

out:
    return ret;

err_uninit:
    if (dev->netdev_ops->ndo_uninit)
        dev->netdev_ops->ndo_uninit(dev);
    goto out;
}
EXPORT_SYMBOL(register_netdevice);

int init_dummy_netdev(struct net_device *dev)
{
    /* Clear everything. Note we don't initialize spinlocks
     * are they aren't supposed to be taken by any of the
     * NAPI code and this dummy netdev is supposed to be
     * only ever used for NAPI polls
     */
    memset(dev, 0, sizeof(struct net_device));

    /* make sure we BUG if trying to hit standard
     * register/unregister code path
     */
    dev->reg_state = NETREG_DUMMY;

    /* NAPI wants this */
    INIT_LIST_HEAD(&dev->napi_list);

    /* a dummy interface is started by default */
    set_bit(__LINK_STATE_PRESENT, &dev->state);
    set_bit(__LINK_STATE_START, &dev->state);

    /* Note : We dont allocate pcpu_refcnt for dummy devices,
     * because users of this 'device' dont need to change
     * its refcount.
     */

    return 0;
}
EXPORT_SYMBOL_GPL(init_dummy_netdev);


int register_netdev(struct net_device *dev)
{
    int err;

    rtnl_lock();
    err = register_netdevice(dev);
    rtnl_unlock();
    return err;
}
EXPORT_SYMBOL(register_netdev);

int netdev_refcnt_read(const struct net_device *dev)
{
    int i, refcnt = 0;

    for_each_possible_cpu(i)
        refcnt += *per_cpu_ptr(dev->pcpu_refcnt, i);
    return refcnt;
}
EXPORT_SYMBOL(netdev_refcnt_read);

static void netdev_wait_allrefs(struct net_device *dev)
{
    unsigned long rebroadcast_time, warning_time;
    int refcnt;

    linkwatch_forget_dev(dev);

    rebroadcast_time = warning_time = jiffies;
    refcnt = netdev_refcnt_read(dev);

    while (refcnt != 0) {
        if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
            rtnl_lock();

            /* Rebroadcast unregister notification */
            call_netdevice_notifiers(NETDEV_UNREGISTER, dev);

            __rtnl_unlock();
            rcu_barrier();
            rtnl_lock();

            call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
            if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
                     &dev->state)) {
                /* We must not have linkwatch events
                 * pending on unregister. If this
                 * happens, we simply run the queue
                 * unscheduled, resulting in a noop
                 * for this device.
                 */
                linkwatch_run_queue();
            }

            __rtnl_unlock();

            rebroadcast_time = jiffies;
        }

        msleep(250);

        refcnt = netdev_refcnt_read(dev);

        if (time_after(jiffies, warning_time + 10 * HZ)) {
            pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
                 dev->name, refcnt);
            warning_time = jiffies;
        }
    }
}

/* The sequence is:
 *
 *  rtnl_lock();
 *  ...
 *  register_netdevice(x1);
 *  register_netdevice(x2);
 *  ...
 *  unregister_netdevice(y1);
 *  unregister_netdevice(y2);
 *      ...
 *  rtnl_unlock();
 *  free_netdev(y1);
 *  free_netdev(y2);
 *
 * We are invoked by rtnl_unlock().
 * This allows us to deal with problems:
 * 1) We can delete sysfs objects which invoke hotplug
 *    without deadlocking with linkwatch via keventd.
 * 2) Since we run with the RTNL semaphore not held, we can sleep
 *    safely in order to wait for the netdev refcnt to drop to zero.
 *
 * We must not return until all unregister events added during
 * the interval the lock was held have been completed.
 */
void netdev_run_todo(void)
{
    struct list_head list;

    /* Snapshot list, allow later requests */
    list_replace_init(&net_todo_list, &list);

    __rtnl_unlock();


    /* Wait for rcu callbacks to finish before next phase */
    if (!list_empty(&list))
        rcu_barrier();

    while (!list_empty(&list)) {
        struct net_device *dev
            = list_first_entry(&list, struct net_device, todo_list);
        list_del(&dev->todo_list);

        rtnl_lock();
        call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
        __rtnl_unlock();

        if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
            pr_err("network todo '%s' but state %d\n",
                   dev->name, dev->reg_state);
            dump_stack();
            continue;
        }

        dev->reg_state = NETREG_UNREGISTERED;

        on_each_cpu(flush_backlog, dev, 1);

        netdev_wait_allrefs(dev);

        /* paranoia */
        BUG_ON(netdev_refcnt_read(dev));
        WARN_ON(rcu_access_pointer(dev->ip_ptr));
        WARN_ON(rcu_access_pointer(dev->ip6_ptr));
        WARN_ON(dev->dn_ptr);

        if (dev->destructor)
            dev->destructor(dev);

        /* Free network device */
        kobject_put(&dev->dev.kobj);
    }
}

/* Convert net_device_stats to rtnl_link_stats64.  They have the same
 * fields in the same order, with only the type differing.
 */
void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
                 const struct net_device_stats *netdev_stats)
{
#if BITS_PER_LONG == 64
    BUILD_BUG_ON(sizeof(*stats64) != sizeof(*netdev_stats));
    memcpy(stats64, netdev_stats, sizeof(*stats64));
#else
    size_t i, n = sizeof(*stats64) / sizeof(u64);
    const unsigned long *src = (const unsigned long *)netdev_stats;
    u64 *dst = (u64 *)stats64;

    BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=
             sizeof(*stats64) / sizeof(u64));
    for (i = 0; i < n; i++)
        dst[i] = src[i];
#endif
}
EXPORT_SYMBOL(netdev_stats_to_stats64);

struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
                    struct rtnl_link_stats64 *storage)
{
    const struct net_device_ops *ops = dev->netdev_ops;

    if (ops->ndo_get_stats64) {
        memset(storage, 0, sizeof(*storage));
        ops->ndo_get_stats64(dev, storage);
    } else if (ops->ndo_get_stats) {
        netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));
    } else {
        netdev_stats_to_stats64(storage, &dev->stats);
    }
    storage->rx_dropped += atomic_long_read(&dev->rx_dropped);
    return storage;
}
EXPORT_SYMBOL(dev_get_stats);

struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
{
    struct netdev_queue *queue = dev_ingress_queue(dev);

#ifdef CONFIG_NET_CLS_ACT
    if (queue)
        return queue;
    queue = kzalloc(sizeof(*queue), GFP_KERNEL);
    if (!queue)
        return NULL;
    netdev_init_one_queue(dev, queue, NULL);
    queue->qdisc = &noop_qdisc;
    queue->qdisc_sleeping = &noop_qdisc;
    rcu_assign_pointer(dev->ingress_queue, queue);
#endif
    return queue;
}

static const struct ethtool_ops default_ethtool_ops;

struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
        void (*setup)(struct net_device *),
        unsigned int txqs, unsigned int rxqs)
{
    struct net_device *dev;
    size_t alloc_size;
    struct net_device *p;

    BUG_ON(strlen(name) >= sizeof(dev->name));

    if (txqs < 1) {
        pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
        return NULL;
    }

#ifdef CONFIG_RPS
    if (rxqs < 1) {
        pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
        return NULL;
    }
#endif

    alloc_size = sizeof(struct net_device);
    if (sizeof_priv) {
        /* ensure 32-byte alignment of private area */
        alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
        alloc_size += sizeof_priv;
    }
    /* ensure 32-byte alignment of whole construct */
    alloc_size += NETDEV_ALIGN - 1;

    p = kzalloc(alloc_size, GFP_KERNEL);
    if (!p) {
        pr_err("alloc_netdev: Unable to allocate device\n");
        return NULL;
    }

    dev = PTR_ALIGN(p, NETDEV_ALIGN);
    dev->padded = (char *)dev - (char *)p;

    dev->pcpu_refcnt = alloc_percpu(int);
    if (!dev->pcpu_refcnt)
        goto free_p;

    if (dev_addr_init(dev))
        goto free_pcpu;

    dev_mc_init(dev);
    dev_uc_init(dev);

    dev_net_set(dev, &init_net);

    dev->gso_max_size = GSO_MAX_SIZE;
    dev->gso_max_segs = GSO_MAX_SEGS;

    INIT_LIST_HEAD(&dev->napi_list);
    INIT_LIST_HEAD(&dev->unreg_list);
    INIT_LIST_HEAD(&dev->link_watch_list);
    dev->priv_flags = IFF_XMIT_DST_RELEASE;
    setup(dev);

    dev->num_tx_queues = txqs;
    dev->real_num_tx_queues = txqs;
    if (netif_alloc_netdev_queues(dev))
        goto free_all;

#ifdef CONFIG_RPS
    dev->num_rx_queues = rxqs;
    dev->real_num_rx_queues = rxqs;
    if (netif_alloc_rx_queues(dev))
        goto free_all;
#endif

    strcpy(dev->name, name);
    dev->group = INIT_NETDEV_GROUP;
    if (!dev->ethtool_ops)
        dev->ethtool_ops = &default_ethtool_ops;
    return dev;

free_all:
    free_netdev(dev);
    return NULL;

free_pcpu:
    free_percpu(dev->pcpu_refcnt);
    kfree(dev->_tx);
#ifdef CONFIG_RPS
    kfree(dev->_rx);
#endif

free_p:
    kfree(p);
    return NULL;
}
EXPORT_SYMBOL(alloc_netdev_mqs);

void free_netdev(struct net_device *dev)
{
    struct napi_struct *p, *n;

    release_net(dev_net(dev));

    kfree(dev->_tx);
#ifdef CONFIG_RPS
    kfree(dev->_rx);
#endif

    kfree(rcu_dereference_protected(dev->ingress_queue, 1));

    /* Flush device addresses */
    dev_addr_flush(dev);

    list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
        netif_napi_del(p);

    free_percpu(dev->pcpu_refcnt);
    dev->pcpu_refcnt = NULL;

    /*  Compatibility with error handling in drivers */
    if (dev->reg_state == NETREG_UNINITIALIZED) {
        kfree((char *)dev - dev->padded);
        return;
    }

    BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
    dev->reg_state = NETREG_RELEASED;

    /* will free via device release */
    put_device(&dev->dev);
}
EXPORT_SYMBOL(free_netdev);

void synchronize_net(void)
{
    might_sleep();
    if (rtnl_is_locked())
        synchronize_rcu_expedited();
    else
        synchronize_rcu();
}
EXPORT_SYMBOL(synchronize_net);

void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
{
    ASSERT_RTNL();

    if (head) {
        list_move_tail(&dev->unreg_list, head);
    } else {
        rollback_registered(dev);
        /* Finish processing unregister after unlock */
        net_set_todo(dev);
    }
}
EXPORT_SYMBOL(unregister_netdevice_queue);

void unregister_netdevice_many(struct list_head *head)
{
    struct net_device *dev;

    if (!list_empty(head)) {
        rollback_registered_many(head);
        list_for_each_entry(dev, head, unreg_list)
            net_set_todo(dev);
    }
}
EXPORT_SYMBOL(unregister_netdevice_many);

void unregister_netdev(struct net_device *dev)
{
    rtnl_lock();
    unregister_netdevice(dev);
    rtnl_unlock();
}
EXPORT_SYMBOL(unregister_netdev);

int dev_change_net_namespace(struct net_device *dev, struct net *net, const char *pat)
{
    int err;

    ASSERT_RTNL();

    /* Don't allow namespace local devices to be moved. */
    err = -EINVAL;
    if (dev->features & NETIF_F_NETNS_LOCAL)
        goto out;

    /* Ensure the device has been registrered */
    err = -EINVAL;
    if (dev->reg_state != NETREG_REGISTERED)
        goto out;

    /* Get out if there is nothing todo */
    err = 0;
    if (net_eq(dev_net(dev), net))
        goto out;

    /* Pick the destination device name, and ensure
     * we can use it in the destination network namespace.
     */
    err = -EEXIST;
    if (__dev_get_by_name(net, dev->name)) {
        /* We get here if we can't use the current device name */
        if (!pat)
            goto out;
        if (dev_get_valid_name(net, dev, pat) < 0)
            goto out;
    }

    /*
     * And now a mini version of register_netdevice unregister_netdevice.
     */

    /* If device is running close it first. */
    dev_close(dev);

    /* And unlink it from device chain */
    err = -ENODEV;
    unlist_netdevice(dev);

    synchronize_net();

    /* Shutdown queueing discipline. */
    dev_shutdown(dev);

    /* Notify protocols, that we are about to destroy
       this device. They should clean all the things.

       Note that dev->reg_state stays at NETREG_REGISTERED.
       This is wanted because this way 8021q and macvlan know
       the device is just moving and can keep their slaves up.
    */
    call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
    rcu_barrier();
    call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
    rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);

    /*
     *  Flush the unicast and multicast chains
     */
    dev_uc_flush(dev);
    dev_mc_flush(dev);

    /* Actually switch the network namespace */
    dev_net_set(dev, net);

    /* If there is an ifindex conflict assign a new one */
    if (__dev_get_by_index(net, dev->ifindex)) {
        int iflink = (dev->iflink == dev->ifindex);
        dev->ifindex = dev_new_index(net);
        if (iflink)
            dev->iflink = dev->ifindex;
    }

    /* Fixup kobjects */
    err = device_rename(&dev->dev, dev->name);
    WARN_ON(err);

    /* Add the device back in the hashes */
    list_netdevice(dev);

    /* Notify protocols, that a new device appeared. */
    call_netdevice_notifiers(NETDEV_REGISTER, dev);

    /*
     *  Prevent userspace races by waiting until the network
     *  device is fully setup before sending notifications.
     */
    rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);

    synchronize_net();
    err = 0;
out:
    return err;
}
EXPORT_SYMBOL_GPL(dev_change_net_namespace);

static int dev_cpu_callback(struct notifier_block *nfb,
                unsigned long action,
                void *ocpu)
{
    struct sk_buff **list_skb;
    struct sk_buff *skb;
    unsigned int cpu, oldcpu = (unsigned long)ocpu;
    struct softnet_data *sd, *oldsd;

    if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
        return NOTIFY_OK;

    local_irq_disable();
    cpu = smp_processor_id();
    sd = &per_cpu(softnet_data, cpu);
    oldsd = &per_cpu(softnet_data, oldcpu);

    /* Find end of our completion_queue. */
    list_skb = &sd->completion_queue;
    while (*list_skb)
        list_skb = &(*list_skb)->next;
    /* Append completion queue from offline CPU. */
    *list_skb = oldsd->completion_queue;
    oldsd->completion_queue = NULL;

    /* Append output queue from offline CPU. */
    if (oldsd->output_queue) {
        *sd->output_queue_tailp = oldsd->output_queue;
        sd->output_queue_tailp = oldsd->output_queue_tailp;
        oldsd->output_queue = NULL;
        oldsd->output_queue_tailp = &oldsd->output_queue;
    }
    /* Append NAPI poll list from offline CPU. */
    if (!list_empty(&oldsd->poll_list)) {
        list_splice_init(&oldsd->poll_list, &sd->poll_list);
        raise_softirq_irqoff(NET_RX_SOFTIRQ);
    }

    raise_softirq_irqoff(NET_TX_SOFTIRQ);
    local_irq_enable();

    /* Process offline CPU's input_pkt_queue */
    while ((skb = __skb_dequeue(&oldsd->process_queue))) {
        netif_rx(skb);
        input_queue_head_incr(oldsd);
    }
    while ((skb = __skb_dequeue(&oldsd->input_pkt_queue))) {
        netif_rx(skb);
        input_queue_head_incr(oldsd);
    }

    return NOTIFY_OK;
}


netdev_features_t netdev_increment_features(netdev_features_t all,
    netdev_features_t one, netdev_features_t mask)
{
    if (mask & NETIF_F_GEN_CSUM)
        mask |= NETIF_F_ALL_CSUM;
    mask |= NETIF_F_VLAN_CHALLENGED;

    all |= one & (NETIF_F_ONE_FOR_ALL|NETIF_F_ALL_CSUM) & mask;
    all &= one | ~NETIF_F_ALL_FOR_ALL;

    /* If one device supports hw checksumming, set for all. */
    if (all & NETIF_F_GEN_CSUM)
        all &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);

    return all;
}
EXPORT_SYMBOL(netdev_increment_features);

static struct hlist_head *netdev_create_hash(void)
{
    int i;
    struct hlist_head *hash;

    hash = kmalloc(sizeof(*hash) * NETDEV_HASHENTRIES, GFP_KERNEL);
    if (hash != NULL)
        for (i = 0; i < NETDEV_HASHENTRIES; i++)
            INIT_HLIST_HEAD(&hash[i]);

    return hash;
}

/* Initialize per network namespace state */
static int __net_init netdev_init(struct net *net)
{
    if (net != &init_net)
        INIT_LIST_HEAD(&net->dev_base_head);

    net->dev_name_head = netdev_create_hash();
    if (net->dev_name_head == NULL)
        goto err_name;

    net->dev_index_head = netdev_create_hash();
    if (net->dev_index_head == NULL)
        goto err_idx;

    return 0;

err_idx:
    kfree(net->dev_name_head);
err_name:
    return -ENOMEM;
}

const char *netdev_drivername(const struct net_device *dev)
{
    const struct device_driver *driver;
    const struct device *parent;
    const char *empty = "";

    parent = dev->dev.parent;
    if (!parent)
        return empty;

    driver = parent->driver;
    if (driver && driver->name)
        return driver->name;
    return empty;
}

static int __netdev_printk(const char *level, const struct net_device *dev,
               struct va_format *vaf)
{
    int r;

    if (dev && dev->dev.parent) {
        r = dev_printk_emit(level[1] - '0',
                    dev->dev.parent,
                    "%s %s %s: %pV",
                    dev_driver_string(dev->dev.parent),
                    dev_name(dev->dev.parent),
                    netdev_name(dev), vaf);
    } else if (dev) {
        r = printk("%s%s: %pV", level, netdev_name(dev), vaf);
    } else {
        r = printk("%s(NULL net_device): %pV", level, vaf);
    }

    return r;
}

int netdev_printk(const char *level, const struct net_device *dev,
          const char *format, ...)
{
    struct va_format vaf;
    va_list args;
    int r;

    va_start(args, format);

    vaf.fmt = format;
    vaf.va = &args;

    r = __netdev_printk(level, dev, &vaf);

    va_end(args);

    return r;
}
EXPORT_SYMBOL(netdev_printk);

#define define_netdev_printk_level(func, level)         \
int func(const struct net_device *dev, const char *fmt, ...)    \
{                               \
    int r;                          \
    struct va_format vaf;                   \
    va_list args;                       \
                                \
    va_start(args, fmt);                    \
                                \
    vaf.fmt = fmt;                      \
    vaf.va = &args;                     \
                                \
    r = __netdev_printk(level, dev, &vaf);          \
                                \
    va_end(args);                       \
                                \
    return r;                       \
}                               \
EXPORT_SYMBOL(func);

define_netdev_printk_level(netdev_emerg, KERN_EMERG);
define_netdev_printk_level(netdev_alert, KERN_ALERT);
define_netdev_printk_level(netdev_crit, KERN_CRIT);
define_netdev_printk_level(netdev_err, KERN_ERR);
define_netdev_printk_level(netdev_warn, KERN_WARNING);
define_netdev_printk_level(netdev_notice, KERN_NOTICE);
define_netdev_printk_level(netdev_info, KERN_INFO);

static void __net_exit netdev_exit(struct net *net)
{
    kfree(net->dev_name_head);
    kfree(net->dev_index_head);
}

static struct pernet_operations __net_initdata netdev_net_ops = {
    .init = netdev_init,
    .exit = netdev_exit,
};

static void __net_exit default_device_exit(struct net *net)
{
    struct net_device *dev, *aux;
    /*
     * Push all migratable network devices back to the
     * initial network namespace
     */
    rtnl_lock();
    for_each_netdev_safe(net, dev, aux) {
        int err;
        char fb_name[IFNAMSIZ];

        /* Ignore unmoveable devices (i.e. loopback) */
        if (dev->features & NETIF_F_NETNS_LOCAL)
            continue;

        /* Leave virtual devices for the generic cleanup */
        if (dev->rtnl_link_ops)
            continue;

        /* Push remaining network devices to init_net */
        snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
        err = dev_change_net_namespace(dev, &init_net, fb_name);
        if (err) {
            pr_emerg("%s: failed to move %s to init_net: %d\n",
                 __func__, dev->name, err);
            BUG();
        }
    }
    rtnl_unlock();
}

static void __net_exit default_device_exit_batch(struct list_head *net_list)
{
    /* At exit all network devices most be removed from a network
     * namespace.  Do this in the reverse order of registration.
     * Do this across as many network namespaces as possible to
     * improve batching efficiency.
     */
    struct net_device *dev;
    struct net *net;
    LIST_HEAD(dev_kill_list);

    rtnl_lock();
    list_for_each_entry(net, net_list, exit_list) {
        for_each_netdev_reverse(net, dev) {
            if (dev->rtnl_link_ops)
                dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
            else
                unregister_netdevice_queue(dev, &dev_kill_list);
        }
    }
    unregister_netdevice_many(&dev_kill_list);
    list_del(&dev_kill_list);
    rtnl_unlock();
}

static struct pernet_operations __net_initdata default_device_ops = {
    .exit = default_device_exit,
    .exit_batch = default_device_exit_batch,
};

/*
 *  Initialize the DEV module. At boot time this walks the device list and
 *  unhooks any devices that fail to initialise (normally hardware not
 *  present) and leaves us with a valid list of present and active devices.
 *
 */

/*
 *       This is called single threaded during boot, so no need
 *       to take the rtnl semaphore.
 */
static int __init net_dev_init(void)
{
    int i, rc = -ENOMEM;

    BUG_ON(!dev_boot_phase);

    if (dev_proc_init())
        goto out;

    if (netdev_kobject_init())
        goto out;

    INIT_LIST_HEAD(&ptype_all);
    for (i = 0; i < PTYPE_HASH_SIZE; i++)
        INIT_LIST_HEAD(&ptype_base[i]);

    if (register_pernet_subsys(&netdev_net_ops))
        goto out;

    /*
     *  Initialise the packet receive queues.
     */

    for_each_possible_cpu(i) {
        struct softnet_data *sd = &per_cpu(softnet_data, i);

        memset(sd, 0, sizeof(*sd));
        skb_queue_head_init(&sd->input_pkt_queue);
        skb_queue_head_init(&sd->process_queue);
        sd->completion_queue = NULL;
        INIT_LIST_HEAD(&sd->poll_list);
        sd->output_queue = NULL;
        sd->output_queue_tailp = &sd->output_queue;
#ifdef CONFIG_RPS
        sd->csd.func = rps_trigger_softirq;
        sd->csd.info = sd;
        sd->csd.flags = 0;
        sd->cpu = i;
#endif

        sd->backlog.poll = process_backlog;
        sd->backlog.weight = weight_p;
        sd->backlog.gro_list = NULL;
        sd->backlog.gro_count = 0;
    }

    dev_boot_phase = 0;

    /* The loopback device is special if any other network devices
     * is present in a network namespace the loopback device must
     * be present. Since we now dynamically allocate and free the
     * loopback device ensure this invariant is maintained by
     * keeping the loopback device as the first device on the
     * list of network devices.  Ensuring the loopback devices
     * is the first device that appears and the last network device
     * that disappears.
     */
    if (register_pernet_device(&loopback_net_ops))
        goto out;

    if (register_pernet_device(&default_device_ops))
        goto out;

    open_softirq(NET_TX_SOFTIRQ, net_tx_action);
    open_softirq(NET_RX_SOFTIRQ, net_rx_action);

    hotcpu_notifier(dev_cpu_callback, 0);
    dst_init();
    dev_mcast_init();
    rc = 0;
out:
    return rc;
}

subsys_initcall(net_dev_init);

static int __init initialize_hashrnd(void)
{
    get_random_bytes(&hashrnd, sizeof(hashrnd));
    return 0;
}

late_initcall_sync(initialize_hashrnd);