[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, 0 insertions, 9 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0d9a4fd5f1a..a3cabfa2022 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -271,7 +271,6 @@ int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
 
 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics);
 
-kmem_cache_t *tcp_openreq_cachep;
 kmem_cache_t *tcp_bucket_cachep;
 kmem_cache_t *tcp_timewait_cachep;
 
@@ -2271,13 +2270,6 @@ void __init tcp_init(void)
 		__skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
 					   sizeof(skb->cb));
 
-	tcp_openreq_cachep = kmem_cache_create("tcp_open_request",
-						   sizeof(struct open_request),
-					       0, SLAB_HWCACHE_ALIGN,
-					       NULL, NULL);
-	if (!tcp_openreq_cachep)
-		panic("tcp_init: Cannot alloc open_request cache.");
-
 	tcp_bucket_cachep = kmem_cache_create("tcp_bind_bucket",
 					      sizeof(struct tcp_bind_bucket),
 					      0, SLAB_HWCACHE_ALIGN,
@@ -2374,7 +2366,6 @@ EXPORT_SYMBOL(tcp_destroy_sock);
 EXPORT_SYMBOL(tcp_disconnect);
 EXPORT_SYMBOL(tcp_getsockopt);
 EXPORT_SYMBOL(tcp_ioctl);
-EXPORT_SYMBOL(tcp_openreq_cachep);
 EXPORT_SYMBOL(tcp_poll);
 EXPORT_SYMBOL(tcp_read_sock);
 EXPORT_SYMBOL(tcp_recvmsg);