[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>

4 files changed, 96 insertions, 79 deletions

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
new file mode 100644
index 0000000..9502f55
--- /dev/null
+++ b/include/net/request_sock.h
@@ -0,0 +1,77 @@
+/*
+ * NET		Generic infrastructure for Network protocols.
+ *
+ *		Definitions for request_sock 
+ *
+ * Authors:	Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * 		From code originally in include/net/tcp.h
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+#ifndef _REQUEST_SOCK_H
+#define _REQUEST_SOCK_H
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <net/sock.h>
+
+struct open_request;
+struct sk_buff;
+struct dst_entry;
+struct proto;
+
+struct or_calltable {
+	int		family;
+	kmem_cache_t	*slab;
+	int		obj_size;
+	int		(*rtx_syn_ack)(struct sock *sk,
+				       struct open_request *req,
+				       struct dst_entry *dst);
+	void		(*send_ack)(struct sk_buff *skb,
+				    struct open_request *req);
+	void		(*send_reset)(struct sk_buff *skb);
+	void		(*destructor)(struct open_request *req);
+};
+
+/* struct open_request - mini sock to represent a connection request
+ */
+struct open_request {
+	struct open_request		*dl_next; /* Must be first member! */
+	u16				mss;
+	u8				retrans;
+	u8				__pad;
+	/* The following two fields can be easily recomputed I think -AK */
+	u32				window_clamp; /* window clamp at creation time */
+	u32				rcv_wnd;	  /* rcv_wnd offered first time */
+	u32				ts_recent;
+	unsigned long			expires;
+	struct or_calltable		*class;
+	struct sock			*sk;
+};
+
+static inline struct open_request *tcp_openreq_alloc(struct or_calltable *class)
+{
+	struct open_request *req = kmem_cache_alloc(class->slab, SLAB_ATOMIC);
+
+	if (req != NULL)
+		req->class = class;
+
+	return req;
+}
+
+static inline void tcp_openreq_fastfree(struct open_request *req)
+{
+	kmem_cache_free(req->class->slab, req);
+}
+
+static inline void tcp_openreq_free(struct open_request *req)
+{
+	req->class->destructor(req);
+	tcp_openreq_fastfree(req);
+}
+
+#endif /* _REQUEST_SOCK_H */
diff --git a/include/net/sock.h b/include/net/sock.h
index a9ef3a6..6919276 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -484,6 +484,8 @@ extern void sk_stream_kill_queues(struct sock *sk);
 
 extern int sk_wait_data(struct sock *sk, long *timeo);
 
+struct or_calltable;
+
 /* Networking protocol blocks we attach to sockets.
  * socket layer -> transport layer interface
  * transport -> network interface is defined by struct inet_proto
@@ -547,6 +549,8 @@ struct proto {
 	kmem_cache_t		*slab;
 	unsigned int		obj_size;
 
+	struct or_calltable	*rsk_prot;
+
 	struct module		*owner;
 
 	char			name[32];
diff --git a/include/net/tcp.h b/include/net/tcp.h
index e71f8ba..d438ba5 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -31,6 +31,7 @@
 #include <linux/cache.h>
 #include <linux/percpu.h>
 #include <net/checksum.h>
+#include <net/request_sock.h>
 #include <net/sock.h>
 #include <net/snmp.h>
 #include <net/ip.h>
@@ -613,74 +614,6 @@ extern atomic_t tcp_memory_allocated;
 extern atomic_t tcp_sockets_allocated;
 extern int tcp_memory_pressure;
 
-struct open_request;
-
-struct or_calltable {
-	int  family;
-	int  (*rtx_syn_ack)	(struct sock *sk, struct open_request *req, struct dst_entry*);
-	void (*send_ack)	(struct sk_buff *skb, struct open_request *req);
-	void (*destructor)	(struct open_request *req);
-	void (*send_reset)	(struct sk_buff *skb);
-};
-
-struct tcp_v4_open_req {
-	__u32			loc_addr;
-	__u32			rmt_addr;
-	struct ip_options	*opt;
-};
-
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-struct tcp_v6_open_req {
-	struct in6_addr		loc_addr;
-	struct in6_addr		rmt_addr;
-	struct sk_buff		*pktopts;
-	int			iif;
-};
-#endif
-
-/* this structure is too big */
-struct open_request {
-	struct open_request	*dl_next; /* Must be first member! */
-	__u32			rcv_isn;
-	__u32			snt_isn;
-	__u16			rmt_port;
-	__u16			mss;
-	__u8			retrans;
-	__u8			__pad;
-	__u16	snd_wscale : 4, 
-		rcv_wscale : 4, 
-		tstamp_ok : 1,
-		sack_ok : 1,
-		wscale_ok : 1,
-		ecn_ok : 1,
-		acked : 1;
-	/* The following two fields can be easily recomputed I think -AK */
-	__u32			window_clamp;	/* window clamp at creation time */
-	__u32			rcv_wnd;	/* rcv_wnd offered first time */
-	__u32			ts_recent;
-	unsigned long		expires;
-	struct or_calltable	*class;
-	struct sock		*sk;
-	union {
-		struct tcp_v4_open_req v4_req;
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-		struct tcp_v6_open_req v6_req;
-#endif
-	} af;
-};
-
-/* SLAB cache for open requests. */
-extern kmem_cache_t *tcp_openreq_cachep;
-
-#define tcp_openreq_alloc()		kmem_cache_alloc(tcp_openreq_cachep, SLAB_ATOMIC)
-#define tcp_openreq_fastfree(req)	kmem_cache_free(tcp_openreq_cachep, req)
-
-static inline void tcp_openreq_free(struct open_request *req)
-{
-	req->class->destructor(req);
-	tcp_openreq_fastfree(req);
-}
-
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 #define TCP_INET_FAMILY(fam) ((fam) == AF_INET)
 #else
@@ -1832,17 +1765,19 @@ static __inline__ void tcp_openreq_init(struct open_request *req,
 					struct tcp_options_received *rx_opt,
 					struct sk_buff *skb)
 {
+	struct inet_request_sock *ireq = inet_rsk(req);
+
 	req->rcv_wnd = 0;		/* So that tcp_send_synack() knows! */
-	req->rcv_isn = TCP_SKB_CB(skb)->seq;
+	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
 	req->mss = rx_opt->mss_clamp;
 	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
-	req->tstamp_ok = rx_opt->tstamp_ok;
-	req->sack_ok = rx_opt->sack_ok;
-	req->snd_wscale = rx_opt->snd_wscale;
-	req->wscale_ok = rx_opt->wscale_ok;
-	req->acked = 0;
-	req->ecn_ok = 0;
-	req->rmt_port = skb->h.th->source;
+	ireq->tstamp_ok = rx_opt->tstamp_ok;
+	ireq->sack_ok = rx_opt->sack_ok;
+	ireq->snd_wscale = rx_opt->snd_wscale;
+	ireq->wscale_ok = rx_opt->wscale_ok;
+	ireq->acked = 0;
+	ireq->ecn_ok = 0;
+	ireq->rmt_port = skb->h.th->source;
 }
 
 extern void tcp_enter_memory_pressure(void);
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