ipp_up_and_iff_running

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ipp_up_and_iff_running [2018/08/25 16:09] – [Flags] rpjdayipp_up_and_iff_running [2018/08/27 11:03] (current) – [net/core/dev_ioctl.c] rpjday
Line 8: Line 8:
  
 ===== Flags ===== ===== Flags =====
 +
 +Issues:
 +
 +  * Is ''IFF_LOWER_UP'' significant?
 +  * Can we use ''IFF_DEBUG''?
 +  * Understand actual meaning of "volatile".
  
 From ''include/uapi/linux/if.h'': From ''include/uapi/linux/if.h'':
  
 <code> <code>
 +/**
 + * enum net_device_flags - &struct net_device flags
 + *
 + * These are the &struct net_device flags, they can be set by drivers, the
 + * kernel and some can be triggered by userspace. Userspace can query and
 + * set these flags using userspace utilities but there is also a sysfs
 + * entry available for all dev flags which can be queried and set. These flags
 + * are shared for all types of net_devices. The sysfs entries are available
 + * via /sys/class/net/<dev>/flags. Flags which can be toggled through sysfs
 + * are annotated below, note that only a few flags can be toggled and some
 + * other flags are always preserved from the original net_device flags
 + * even if you try to set them via sysfs. Flags which are always preserved
 + * are kept under the flag grouping @IFF_VOLATILE. Flags which are volatile
 + * are annotated below as such.
 + *
 + * You should have a pretty good reason to be extending these flags.
 + *
 + * @IFF_UP: interface is up. Can be toggled through sysfs.
 + * @IFF_BROADCAST: broadcast address valid. Volatile.
 + * @IFF_DEBUG: turn on debugging. Can be toggled through sysfs.
 + * @IFF_LOOPBACK: is a loopback net. Volatile.
 + * @IFF_POINTOPOINT: interface is has p-p link. Volatile.
 + * @IFF_NOTRAILERS: avoid use of trailers. Can be toggled through sysfs.
 + *      Volatile.
 + * @IFF_RUNNING: interface RFC2863 OPER_UP. Volatile.
 + * @IFF_NOARP: no ARP protocol. Can be toggled through sysfs. Volatile.
 + * @IFF_PROMISC: receive all packets. Can be toggled through sysfs.
 + * @IFF_ALLMULTI: receive all multicast packets. Can be toggled through
 + *      sysfs.
 + * @IFF_MASTER: master of a load balancer. Volatile.
 + * @IFF_SLAVE: slave of a load balancer. Volatile.
 + * @IFF_MULTICAST: Supports multicast. Can be toggled through sysfs.
 + * @IFF_PORTSEL: can set media type. Can be toggled through sysfs.
 + * @IFF_AUTOMEDIA: auto media select active. Can be toggled through sysfs.
 + * @IFF_DYNAMIC: dialup device with changing addresses. Can be toggled
 + *      through sysfs.
 + * @IFF_LOWER_UP: driver signals L1 up. Volatile.
 + * @IFF_DORMANT: driver signals dormant. Volatile.
 + * @IFF_ECHO: echo sent packets. Volatile.
 + */
 +
 enum net_device_flags { enum net_device_flags {
 /* for compatibility with glibc net/if.h */ /* for compatibility with glibc net/if.h */
Line 41: Line 88:
  
 ===== operstates.txt ===== ===== operstates.txt =====
 +
 +Administrative versus operational state:
  
 <code> <code>
Line 60: Line 109:
 a RFC2863 compatible state that is derived from these flags, a policy, a RFC2863 compatible state that is derived from these flags, a policy,
 and changeable from userspace under certain rules. and changeable from userspace under certain rules.
 +</code>
 +
 +===== Flags =====
 +
 +==== Source ====
 +
 +''ifconfig'' is getting hex value from ''SIOCGIFFLAGS'' which does ''dev_get_flags(dev)''.
 +
 +==== Up and running ====
 +
 +4163:
 +
 +<code>
 +enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
 +        inet 192.168.0.15  netmask 255.255.255.0  broadcast 192.168.0.255
 +        inet6 fd00:f81d:f81:4062:2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x0<global>
 +        inet6 fe80::2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x20<link>
 +        ether 2c:56:dc:25:ad:47  txqueuelen 1000  (Ethernet)
 +        RX packets 81232  bytes 92092778 (87.8 MiB)
 +        RX errors 0  dropped 0  overruns 0  frame 0
 +        TX packets 36768  bytes 9024553 (8.6 MiB)
 +        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 +</code>
 +
 +==== Down ====
 +
 +4098:
 +
 +<code>
 +enp3s0: flags=4098<BROADCAST,MULTICAST>  mtu 1500
 +        inet 192.168.0.15  netmask 255.255.255.0  broadcast 192.168.0.255
 +        ether 2c:56:dc:25:ad:47  txqueuelen 1000  (Ethernet)
 +        RX packets 81290  bytes 92110209 (87.8 MiB)
 +        RX errors 0  dropped 0  overruns 0  frame 0
 +        TX packets 36836  bytes 9042100 (8.6 MiB)
 +        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 +</code>
 +
 +==== Up again ====
 +
 +UP, shortly followed by RUNNING:
 +
 +<code>
 +enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
 +        inet 192.168.0.15  netmask 255.255.255.0  broadcast 192.168.0.255
 +        inet6 fd00:f81d:f81:4062:2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x0<global>
 +        inet6 fe80::2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x20<link>
 +        ether 2c:56:dc:25:ad:47  txqueuelen 1000  (Ethernet)
 +        RX packets 1268514  bytes 1611028865 (1.5 GiB)
 +        RX errors 0  dropped 0  overruns 0  frame 0
 +        TX packets 396222  bytes 65965632 (62.9 MiB)
 +        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 +</code>
 +
 +==== Up, then disconnected ====
 +
 +4099:
 +
 +<code>
 +enp3s0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
 +        inet 192.168.0.15  netmask 255.255.255.0  broadcast 192.168.0.255
 +        inet6 fd00:f81d:f81:4062:2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x0<global>
 +        inet6 fe80::2e56:dcff:fe25:ad47  prefixlen 64  scopeid 0x20<link>
 +        ether 2c:56:dc:25:ad:47  txqueuelen 1000  (Ethernet)
 +        RX packets 81318  bytes 92115343 (87.8 MiB)
 +        RX errors 0  dropped 0  overruns 0  frame 0
 +        TX packets 36917  bytes 9052750 (8.6 MiB)
 +        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 +</code>
 +
 +===== dev_get_flags() =====
 +
 +==== net/core/dev_ioctl.c ====
 +
 +This is how ''ifconfig'' gets its info -- via ''dev_get_flags()'' and ioctl command ''SIOCGIFFLAGS'':
 +
 +<code>
 +/*
 + *      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;
 +</code>
 +
 +==== net/core/dev.c ====
 +
 +Volatile flags are supported via RFC2863 operstates.
 +
 +<code>
 +/**
 + * dev_get_flags - get flags reported to userspace
 + * @dev: device
 + *
 + * Get the combination of flag bits exported through APIs to userspace.
 + */
 +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);
 </code> </code>
  • ipp_up_and_iff_running.1535213379.txt.gz
  • Last modified: 2018/08/25 16:09
  • by rpjday