[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, 14 insertions, 11 deletions

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index 8faa8948f75c..700ff2413588 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -458,6 +458,7 @@ static int tcpdiag_fill_req(struct sk_buff *skb, struct sock *sk,
                             struct open_request *req,
                             u32 pid, u32 seq)
 {
+        const struct inet_request_sock *ireq = inet_rsk(req);
         struct inet_sock *inet = inet_sk(sk);
         unsigned char *b = skb->tail;
         struct tcpdiagmsg *r;
@@ -482,9 +483,9 @@ static int tcpdiag_fill_req(struct sk_buff *skb, struct sock *sk,
                 tmo = 0;
 
         r->id.tcpdiag_sport = inet->sport;
-        r->id.tcpdiag_dport = req->rmt_port;
-        r->id.tcpdiag_src[0] = req->af.v4_req.loc_addr;
-        r->id.tcpdiag_dst[0] = req->af.v4_req.rmt_addr;
+        r->id.tcpdiag_dport = ireq->rmt_port;
+        r->id.tcpdiag_src[0] = ireq->loc_addr;
+        r->id.tcpdiag_dst[0] = ireq->rmt_addr;
         r->tcpdiag_expires = jiffies_to_msecs(tmo),
         r->tcpdiag_rqueue = 0;
         r->tcpdiag_wqueue = 0;
@@ -493,9 +494,9 @@ static int tcpdiag_fill_req(struct sk_buff *skb, struct sock *sk,
 #ifdef CONFIG_IP_TCPDIAG_IPV6
         if (r->tcpdiag_family == AF_INET6) {
                 ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_src,
-                               &req->af.v6_req.loc_addr);
+                               &tcp6_rsk(req)->loc_addr);
                 ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_dst,
-                               &req->af.v6_req.rmt_addr);
+                               &tcp6_rsk(req)->rmt_addr);
         }
 #endif
         nlh->nlmsg_len = skb->tail - b;
@@ -545,9 +546,11 @@ static int tcpdiag_dump_reqs(struct sk_buff *skb, struct sock *sk,
 
                 reqnum = 0;
                 for (req = head; req; reqnum++, req = req->dl_next) {
+                        struct inet_request_sock *ireq = inet_rsk(req);
+
                         if (reqnum < s_reqnum)
                                 continue;
-                        if (r->id.tcpdiag_dport != req->rmt_port &&
+                        if (r->id.tcpdiag_dport != ireq->rmt_port &&
                             r->id.tcpdiag_dport)
                                 continue;
 
@@ -555,16 +558,16 @@ static int tcpdiag_dump_reqs(struct sk_buff *skb, struct sock *sk,
                                 entry.saddr =
 #ifdef CONFIG_IP_TCPDIAG_IPV6
                                         (entry.family == AF_INET6) ?
-                                        req->af.v6_req.loc_addr.s6_addr32 :
+                                        tcp6_rsk(req)->loc_addr.s6_addr32 :
 #endif
-                                        &req->af.v4_req.loc_addr;
+                                        &ireq->loc_addr;
                                 entry.daddr = 
 #ifdef CONFIG_IP_TCPDIAG_IPV6
                                         (entry.family == AF_INET6) ?
-                                        req->af.v6_req.rmt_addr.s6_addr32 :
+                                        tcp6_rsk(req)->rmt_addr.s6_addr32 :
 #endif
-                                        &req->af.v4_req.rmt_addr;
-                                entry.dport = ntohs(req->rmt_port);
+                                        &ireq->rmt_addr;
+                                entry.dport = ntohs(ireq->rmt_port);
 
                                 if (!tcpdiag_bc_run(RTA_DATA(bc),
                                                     RTA_PAYLOAD(bc), &entry))