[PATCHv5 net-next 0/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

[Hangbin Liu <liuhangbin@gmail.com>]

Netlink messages are used for communicating between user and kernel space.
When user space configures the kernel with netlink messages, it can set the
NLM_F_ECHO flag to request the kernel to send the applied configuration back
to the caller. This allows user space to retrieve configuration information
that are filled by the kernel (either because these parameters can only be
set by the kernel or because user space let the kernel choose a default
value).

The kernel has support this feature in some places like RTM_{NEW, DEL}ADDR,
RTM_{NEW, DEL}ROUTE. This patch set handles NLM_F_ECHO flag and send link
info back after rtnl_{new, del}link.

v5:
1) make rtnl_configure_link_notify static, reported by kernel test robot

v4:
1) Add rtnl_configure_link_notify() helper so rtnl_newlink_create could
   use it instead of creating new notify function.
2) Add unregister_netdevice_many_notify() helper so rtnl_delete_link()
   could use it instead of creating new notify function
3) Split the previous patch to 4 small patches for easier reviewing.

v3:
1) Fix group parameter in rtnl_notify.
2) Use helper rtmsg_ifinfo_build_skb() instead re-write a new one.

v2:
1) Rename rtnl_echo_link_info() to rtnl_link_notify().
2) Remove IFLA_LINK_NETNSID and IFLA_EXT_MASK, which do not fit here.
3) Add NLM_F_ECHO in rtnl_dellink. But we can't re-use the rtnl_link_notify()
   helper as we need to get the link info before rtnl_delete_link().

Hangbin Liu (4):
  rtnetlink: add new helper rtnl_configure_link_notify()
  net: add new helper unregister_netdevice_many_notify
  rtnetlink: Honour NLM_F_ECHO flag in rtnl_newlink_create
  rtnetlink: Honour NLM_F_ECHO flag in rtnl_delete_link

 include/linux/netdevice.h      |  4 ++-
 include/linux/rtnetlink.h      |  6 ++--
 include/net/rtnetlink.h        |  2 +-
 net/core/dev.c                 | 26 +++++++++++-----
 net/core/rtnetlink.c           | 56 ++++++++++++++++++++++------------
 net/openvswitch/vport-geneve.c |  2 +-
 net/openvswitch/vport-gre.c    |  2 +-
 net/openvswitch/vport-netdev.c |  2 +-
 net/openvswitch/vport-vxlan.c  |  2 +-
 9 files changed, 67 insertions(+), 35 deletions(-)

-- 
2.37.2