[NET] Generalise TCP's struct open_request minisock infrastructure

Kept this first changeset minimal, without changing existing names to
ease peer review.

Basicaly tcp_openreq_alloc now receives the or_calltable, that in turn
has two new members:

->slab, that replaces tcp_openreq_cachep
->obj_size, to inform the size of the openreq descendant for
  a specific protocol

The protocol specific fields in struct open_request were moved to a
class hierarchy, with the things that are common to all connection
oriented PF_INET protocols in struct inet_request_sock, the TCP ones
in tcp_request_sock, that is an inet_request_sock, that is an
open_request.

I.e. this uses the same approach used for the struct sock class
hierarchy, with sk_prot indicating if the protocol wants to use the
open_request infrastructure by filling in sk_prot->rsk_prot with an
or_calltable.

Results? Performance is improved and TCP v4 now uses only 64 bytes per
open request minisock, down from 96 without this patch :-)

Next changeset will rename some of the structs, fields and functions
mentioned above, struct or_calltable is way unclear, better name it
struct request_sock_ops, s/struct open_request/struct request_sock/g,
etc.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/include/net/tcp_ecn.h b/include/net/tcp_ecn.h
index dc14563..94ad970 100644
--- a/include/net/tcp_ecn.h
+++ b/include/net/tcp_ecn.h
@@ -2,6 +2,7 @@
 #define _NET_TCP_ECN_H_ 1
 
 #include <net/inet_ecn.h>
+#include <net/request_sock.h>
 
 #define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
 
@@ -40,7 +41,7 @@ static inline void TCP_ECN_send_syn(struct sock *sk, struct tcp_sock *tp,
 static __inline__ void
 TCP_ECN_make_synack(struct open_request *req, struct tcphdr *th)
 {
-	if (req->ecn_ok)
+	if (inet_rsk(req)->ecn_ok)
 		th->ece = 1;
 }
 
@@ -113,14 +114,14 @@ static inline int TCP_ECN_rcv_ecn_echo(struct tcp_sock *tp, struct tcphdr *th)
 static inline void TCP_ECN_openreq_child(struct tcp_sock *tp,
 					 struct open_request *req)
 {
-	tp->ecn_flags = req->ecn_ok ? TCP_ECN_OK : 0;
+	tp->ecn_flags = inet_rsk(req)->ecn_ok ? TCP_ECN_OK : 0;
 }
 
 static __inline__ void
 TCP_ECN_create_request(struct open_request *req, struct tcphdr *th)
 {
 	if (sysctl_tcp_ecn && th->ece && th->cwr)
-		req->ecn_ok = 1;
+		inet_rsk(req)->ecn_ok = 1;
 }
 
 #endif