From: Menglong Dong <imagedong@tencent.com>

Seems now the reasons of skb drop in TCP layer are almost supported,
except the path of connect requesting. So let's just finish it.

The TCP connect requesting is processed by
'inet_csk(sk)->icsk_af_ops->conn_request()'. Yeah, it's a function
pointer, so it's not easy to add function param to it. Luckily, it's
return value can be reused. For now, 0 means a call of 'consume_skb()'
and -1 means 'kfree_skb()', with a RESET be send. Therefore, we can
free skb with 'kfree_skb_reason()' in 'conn_request()' and return 1.
While 1 is returned, we do nothing outside. This work is done in the
1th patch.

And in the 2th patch, skb drop reasons are added to route_req() in
struct tcp_request_sock_ops by adding a function param to it.

Following new skb drop reasons are added:

  SKB_DROP_REASON_LISTENOVERFLOWS
  SKB_DROP_REASON_TCP_REQQFULLDROP
  SKB_DROP_REASON_SECURITY

Menglong Dong (2):
  net: add skb drop reasons to inet connect request
  net: tcp: add skb drop reasons to route_req()

 include/linux/skbuff.h     |  5 +++++
 include/net/tcp.h          |  3 ++-
 include/trace/events/skb.h |  3 +++
 net/dccp/input.c           | 12 +++++-------
 net/ipv4/tcp_input.c       | 23 ++++++++++++++---------
 net/ipv4/tcp_ipv4.c        | 17 +++++++++++++----
 net/ipv6/tcp_ipv6.c        | 14 +++++++++++---
 net/mptcp/subflow.c        | 10 ++++++----
 8 files changed, 59 insertions(+), 28 deletions(-)

-- 
2.36.0