[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, 41 insertions, 31 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index dad98e4a5043..e156be90df14 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -880,9 +880,11 @@ static struct open_request *tcp_v4_search_req(struct tcp_sock *tp,
         for (prev = &lopt->syn_table[tcp_v4_synq_hash(raddr, rport, lopt->hash_rnd)];
              (req = *prev) != NULL;
              prev = &req->dl_next) {
-                if (req->rmt_port == rport &&
-                    req->af.v4_req.rmt_addr == raddr &&
-                    req->af.v4_req.loc_addr == laddr &&
+                const struct inet_request_sock *ireq = inet_rsk(req);
+
+                if (ireq->rmt_port == rport &&
+                    ireq->rmt_addr == raddr &&
+                    ireq->loc_addr == laddr &&
                     TCP_INET_FAMILY(req->class->family)) {
                         BUG_TRAP(!req->sk);
                         *prevp = prev;
@@ -897,7 +899,7 @@ static void tcp_v4_synq_add(struct sock *sk, struct open_request *req)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct tcp_listen_opt *lopt = tp->listen_opt;
-        u32 h = tcp_v4_synq_hash(req->af.v4_req.rmt_addr, req->rmt_port, lopt->hash_rnd);
+        u32 h = tcp_v4_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port, lopt->hash_rnd);
 
         req->expires = jiffies + TCP_TIMEOUT_INIT;
         req->retrans = 0;
@@ -1065,7 +1067,7 @@ void tcp_v4_err(struct sk_buff *skb, u32 info)
                  */
                 BUG_TRAP(!req->sk);
 
-                if (seq != req->snt_isn) {
+                if (seq != tcp_rsk(req)->snt_isn) {
                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
                         goto out;
                 }
@@ -1256,7 +1258,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 
 static void tcp_v4_or_send_ack(struct sk_buff *skb, struct open_request *req)
 {
-        tcp_v4_send_ack(skb, req->snt_isn + 1, req->rcv_isn + 1, req->rcv_wnd,
+        tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
                         req->ts_recent);
 }
 
@@ -1264,18 +1266,19 @@ static struct dst_entry* tcp_v4_route_req(struct sock *sk,
                                           struct open_request *req)
 {
         struct rtable *rt;
-        struct ip_options *opt = req->af.v4_req.opt;
+        const struct inet_request_sock *ireq = inet_rsk(req);
+        struct ip_options *opt = inet_rsk(req)->opt;
         struct flowi fl = { .oif = sk->sk_bound_dev_if,
                             .nl_u = { .ip4_u =
                                       { .daddr = ((opt && opt->srr) ?
                                                   opt->faddr :
-                                                  req->af.v4_req.rmt_addr),
-                                        .saddr = req->af.v4_req.loc_addr,
+                                                  ireq->rmt_addr),
+                                        .saddr = ireq->loc_addr,
                                         .tos = RT_CONN_FLAGS(sk) } },
                             .proto = IPPROTO_TCP,
                             .uli_u = { .ports =
                                        { .sport = inet_sk(sk)->sport,
-                                         .dport = req->rmt_port } } };
+                                         .dport = ireq->rmt_port } } };
 
         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
@@ -1297,6 +1300,7 @@ static struct dst_entry* tcp_v4_route_req(struct sock *sk,
 static int tcp_v4_send_synack(struct sock *sk, struct open_request *req,
                               struct dst_entry *dst)
 {
+        const struct inet_request_sock *ireq = inet_rsk(req);
         int err = -1;
         struct sk_buff * skb;
 
@@ -1310,14 +1314,14 @@ static int tcp_v4_send_synack(struct sock *sk, struct open_request *req,
                 struct tcphdr *th = skb->h.th;
 
                 th->check = tcp_v4_check(th, skb->len,
-                                         req->af.v4_req.loc_addr,
-                                         req->af.v4_req.rmt_addr,
+                                         ireq->loc_addr,
+                                         ireq->rmt_addr,
                                          csum_partial((char *)th, skb->len,
                                                       skb->csum));
 
-                err = ip_build_and_send_pkt(skb, sk, req->af.v4_req.loc_addr,
-                                            req->af.v4_req.rmt_addr,
-                                            req->af.v4_req.opt);
+                err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
+                                            ireq->rmt_addr,
+                                            ireq->opt);
                 if (err == NET_XMIT_CN)
                         err = 0;
         }
@@ -1332,8 +1336,8 @@ out:
  */
 static void tcp_v4_or_free(struct open_request *req)
 {
-        if (req->af.v4_req.opt)
-                kfree(req->af.v4_req.opt);
+        if (inet_rsk(req)->opt)
+                kfree(inet_rsk(req)->opt);
 }
 
 static inline void syn_flood_warning(struct sk_buff *skb)
@@ -1387,6 +1391,7 @@ int sysctl_max_syn_backlog = 256;
 
 struct or_calltable or_ipv4 = {
         .family         =       PF_INET,
+        .obj_size       =       sizeof(struct tcp_request_sock),
         .rtx_syn_ack    =       tcp_v4_send_synack,
         .send_ack       =       tcp_v4_or_send_ack,
         .destructor     =       tcp_v4_or_free,
@@ -1395,6 +1400,7 @@ struct or_calltable or_ipv4 = {
 
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
+        struct inet_request_sock *ireq;
         struct tcp_options_received tmp_opt;
         struct open_request *req;
         __u32 saddr = skb->nh.iph->saddr;
@@ -1433,7 +1439,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
         if (sk_acceptq_is_full(sk) && tcp_synq_young(sk) > 1)
                 goto drop;
 
-        req = tcp_openreq_alloc();
+        req = tcp_openreq_alloc(&or_ipv4);
         if (!req)
                 goto drop;
 
@@ -1461,10 +1467,10 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 
         tcp_openreq_init(req, &tmp_opt, skb);
 
-        req->af.v4_req.loc_addr = daddr;
-        req->af.v4_req.rmt_addr = saddr;
-        req->af.v4_req.opt = tcp_v4_save_options(sk, skb);
-        req->class = &or_ipv4;
+        ireq = inet_rsk(req);
+        ireq->loc_addr = daddr;
+        ireq->rmt_addr = saddr;
+        ireq->opt = tcp_v4_save_options(sk, skb);
         if (!want_cookie)
                 TCP_ECN_create_request(req, skb->h.th);
 
@@ -1523,7 +1529,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 
                 isn = tcp_v4_init_sequence(sk, skb);
         }
-        req->snt_isn = isn;
+        tcp_rsk(req)->snt_isn = isn;
 
         if (tcp_v4_send_synack(sk, req, dst))
                 goto drop_and_free;
@@ -1551,6 +1557,7 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
                                   struct open_request *req,
                                   struct dst_entry *dst)
 {
+        struct inet_request_sock *ireq;
         struct inet_sock *newinet;
         struct tcp_sock *newtp;
         struct sock *newsk;
@@ -1570,11 +1577,12 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 
         newtp                 = tcp_sk(newsk);
         newinet               = inet_sk(newsk);
-        newinet->daddr        = req->af.v4_req.rmt_addr;
-        newinet->rcv_saddr    = req->af.v4_req.loc_addr;
-        newinet->saddr        = req->af.v4_req.loc_addr;
-        newinet->opt          = req->af.v4_req.opt;
-        req->af.v4_req.opt    = NULL;
+        ireq                  = inet_rsk(req);
+        newinet->daddr        = ireq->rmt_addr;
+        newinet->rcv_saddr    = ireq->loc_addr;
+        newinet->saddr        = ireq->loc_addr;
+        newinet->opt          = ireq->opt;
+        ireq->opt             = NULL;
         newinet->mc_index     = tcp_v4_iif(skb);
         newinet->mc_ttl       = skb->nh.iph->ttl;
         newtp->ext_header_len = 0;
@@ -2454,15 +2462,16 @@ void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
 static void get_openreq4(struct sock *sk, struct open_request *req,
                          char *tmpbuf, int i, int uid)
 {
+        const struct inet_request_sock *ireq = inet_rsk(req);
         int ttd = req->expires - jiffies;
 
         sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
                 i,
-                req->af.v4_req.loc_addr,
+                ireq->loc_addr,
                 ntohs(inet_sk(sk)->sport),
-                req->af.v4_req.rmt_addr,
-                ntohs(req->rmt_port),
+                ireq->rmt_addr,
+                ntohs(ireq->rmt_port),
                 TCP_SYN_RECV,
                 0, 0, /* could print option size, but that is af dependent. */
                 1,    /* timers active (only the expire timer) */
@@ -2618,6 +2627,7 @@ struct proto tcp_prot = {
         .sysctl_rmem            = sysctl_tcp_rmem,
         .max_header             = MAX_TCP_HEADER,
         .obj_size               = sizeof(struct tcp_sock),
+        .rsk_prot               = &or_ipv4,
 };