[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, 25 insertions, 23 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index eea1a17a9ac2..1037401c7cc8 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -692,6 +692,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
         struct sock *newsk = sk_alloc(PF_INET, GFP_ATOMIC, sk->sk_prot, 0);
 
         if(newsk != NULL) {
+                struct inet_request_sock *ireq = inet_rsk(req);
+                struct tcp_request_sock *treq = tcp_rsk(req);
                 struct tcp_sock *newtp;
                 struct sk_filter *filter;
 
@@ -703,7 +705,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
                 tcp_sk(newsk)->bind_hash = NULL;
 
                 /* Clone the TCP header template */
-                inet_sk(newsk)->dport = req->rmt_port;
+                inet_sk(newsk)->dport = ireq->rmt_port;
 
                 sock_lock_init(newsk);
                 bh_lock_sock(newsk);
@@ -739,14 +741,14 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
                 /* Now setup tcp_sock */
                 newtp = tcp_sk(newsk);
                 newtp->pred_flags = 0;
-                newtp->rcv_nxt = req->rcv_isn + 1;
-                newtp->snd_nxt = req->snt_isn + 1;
-                newtp->snd_una = req->snt_isn + 1;
-                newtp->snd_sml = req->snt_isn + 1;
+                newtp->rcv_nxt = treq->rcv_isn + 1;
+                newtp->snd_nxt = treq->snt_isn + 1;
+                newtp->snd_una = treq->snt_isn + 1;
+                newtp->snd_sml = treq->snt_isn + 1;
 
                 tcp_prequeue_init(newtp);
 
-                tcp_init_wl(newtp, req->snt_isn, req->rcv_isn);
+                tcp_init_wl(newtp, treq->snt_isn, treq->rcv_isn);
 
                 newtp->retransmits = 0;
                 newtp->backoff = 0;
@@ -775,10 +777,10 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
                 tcp_set_ca_state(newtp, TCP_CA_Open);
                 tcp_init_xmit_timers(newsk);
                 skb_queue_head_init(&newtp->out_of_order_queue);
-                newtp->rcv_wup = req->rcv_isn + 1;
-                newtp->write_seq = req->snt_isn + 1;
+                newtp->rcv_wup = treq->rcv_isn + 1;
+                newtp->write_seq = treq->snt_isn + 1;
                 newtp->pushed_seq = newtp->write_seq;
-                newtp->copied_seq = req->rcv_isn + 1;
+                newtp->copied_seq = treq->rcv_isn + 1;
 
                 newtp->rx_opt.saw_tstamp = 0;
 
@@ -808,18 +810,18 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
                 newsk->sk_socket = NULL;
                 newsk->sk_sleep = NULL;
 
-                newtp->rx_opt.tstamp_ok = req->tstamp_ok;
-                if((newtp->rx_opt.sack_ok = req->sack_ok) != 0) {
+                newtp->rx_opt.tstamp_ok = ireq->tstamp_ok;
+                if((newtp->rx_opt.sack_ok = ireq->sack_ok) != 0) {
                         if (sysctl_tcp_fack)
                                 newtp->rx_opt.sack_ok |= 2;
                 }
                 newtp->window_clamp = req->window_clamp;
                 newtp->rcv_ssthresh = req->rcv_wnd;
                 newtp->rcv_wnd = req->rcv_wnd;
-                newtp->rx_opt.wscale_ok = req->wscale_ok;
+                newtp->rx_opt.wscale_ok = ireq->wscale_ok;
                 if (newtp->rx_opt.wscale_ok) {
-                        newtp->rx_opt.snd_wscale = req->snd_wscale;
-                        newtp->rx_opt.rcv_wscale = req->rcv_wscale;
+                        newtp->rx_opt.snd_wscale = ireq->snd_wscale;
+                        newtp->rx_opt.rcv_wscale = ireq->rcv_wscale;
                 } else {
                         newtp->rx_opt.snd_wscale = newtp->rx_opt.rcv_wscale = 0;
                         newtp->window_clamp = min(newtp->window_clamp, 65535U);
@@ -881,7 +883,7 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
         }
 
         /* Check for pure retransmitted SYN. */
-        if (TCP_SKB_CB(skb)->seq == req->rcv_isn &&
+        if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn &&
             flg == TCP_FLAG_SYN &&
             !paws_reject) {
                 /*
@@ -959,7 +961,7 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
          * Invalid ACK: reset will be sent by listening socket
          */
         if ((flg & TCP_FLAG_ACK) &&
-            (TCP_SKB_CB(skb)->ack_seq != req->snt_isn+1))
+            (TCP_SKB_CB(skb)->ack_seq != tcp_rsk(req)->snt_isn + 1))
                 return sk;
 
         /* Also, it would be not so bad idea to check rcv_tsecr, which
@@ -970,7 +972,7 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
         /* RFC793: "first check sequence number". */
 
         if (paws_reject || !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-                                          req->rcv_isn+1, req->rcv_isn+1+req->rcv_wnd)) {
+                                          tcp_rsk(req)->rcv_isn + 1, tcp_rsk(req)->rcv_isn + 1 + req->rcv_wnd)) {
                 /* Out of window: send ACK and drop. */
                 if (!(flg & TCP_FLAG_RST))
                         req->class->send_ack(skb, req);
@@ -981,12 +983,12 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
 
         /* In sequence, PAWS is OK. */
 
-        if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, req->rcv_isn+1))
+        if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_isn + 1))
                         req->ts_recent = tmp_opt.rcv_tsval;
 
-                if (TCP_SKB_CB(skb)->seq == req->rcv_isn) {
+                if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) {
                         /* Truncate SYN, it is out of window starting
-                           at req->rcv_isn+1. */
+                           at tcp_rsk(req)->rcv_isn + 1. */
                         flg &= ~TCP_FLAG_SYN;
                 }
 
@@ -1003,8 +1005,8 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
                         return NULL;
 
                 /* If TCP_DEFER_ACCEPT is set, drop bare ACK. */
-                if (tp->defer_accept && TCP_SKB_CB(skb)->end_seq == req->rcv_isn+1) {
-                        req->acked = 1;
+                if (tp->defer_accept && TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
+                        inet_rsk(req)->acked = 1;
                         return NULL;
                 }
 
@@ -1026,7 +1028,7 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
 
         listen_overflow:
                 if (!sysctl_tcp_abort_on_overflow) {
-                        req->acked = 1;
+                        inet_rsk(req)->acked = 1;
                         return NULL;
                 }