Re: [PATCH v1 bpf-next 05/11] tcp: Migrate TCP_NEW_SYN_RECV requests.

This patch renames reuseport_select_sock() to __reuseport_select_sock() and
adds two wrapper function of it to pass the migration type defined in the
previous commit.

  reuseport_select_sock          : BPF_SK_REUSEPORT_MIGRATE_NO
  reuseport_select_migrated_sock : BPF_SK_REUSEPORT_MIGRATE_REQUEST

As mentioned before, we have to select a new listener for TCP_NEW_SYN_RECV
requests at receiving the final ACK or sending a SYN+ACK. Therefore, this
patch also changes the code to call reuseport_select_migrated_sock() even
if the listening socket is TCP_CLOSE. If we can pick out a listening socket
from the reuseport group, we rewrite request_sock.rsk_listener and resume
processing the request.

Reviewed-by: Benjamin Herrenschmidt <redacted>
Signed-off-by: Kuniyuki Iwashima <redacted>
---
 include/net/inet_connection_sock.h | 12 +++++++++++
 include/net/request_sock.h         | 13 ++++++++++++
 include/net/sock_reuseport.h       |  8 +++----
 net/core/sock_reuseport.c          | 34 ++++++++++++++++++++++++------
 net/ipv4/inet_connection_sock.c    | 13 ++++++++++--
 net/ipv4/tcp_ipv4.c                |  9 ++++++--
 net/ipv6/tcp_ipv6.c                |  9 ++++++--
 7 files changed, 81 insertions(+), 17 deletions(-)

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 2ea2d743f8fc..1e0958f5eb21 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h

@@ -272,6 +272,18 @@ static inline void inet_csk_reqsk_queue_added(struct sock *sk)
 	reqsk_queue_added(&inet_csk(sk)->icsk_accept_queue);
 }
 
+static inline void inet_csk_reqsk_queue_migrated(struct sock *sk,
+						 struct sock *nsk,
+						 struct request_sock *req)
+{
+	reqsk_queue_migrated(&inet_csk(sk)->icsk_accept_queue,
+			     &inet_csk(nsk)->icsk_accept_queue,
+			     req);
+	sock_put(sk);
+	sock_hold(nsk);