[NET] generalise per protocol slab cache handling

With this patch we get two new slabcaches, for sctp socks, that previously
were being allocated on the default, that was tcp[6]_sock, i.e. wasting 288
bytes per sock in the IPv4 case and 256 bytes for the IPv6 version, this is in
preparation for DCCP (or any other new protocol :) ).

With this in place another nice side effect that is easier to achieve is to
get rid of struct sock sk->sk_slab, and instead use sk->sk_prot->slab, saving
sizeof(void *) on every struct sock instance, but this unfortunatly has to
wait for the conversion of all protocols that use per socket slabcaches to
use sk->sk_prot, AF_UNIX is the only one AFAIK, so I'll try to convert it to
use sk->sk_prot and then get rid of sk->sk_slab.

As for the protocols that don't use per socket slabcaches its just a matter
of defaulting to sk_cachep at sk_free time if sk->sk_prot is NULL.

[root@qemu ~]# modprobe sctp
[root@qemu ~]# grep _sock /proc/slabinfo
sctpv6_sock            9      9    864    9    2 : tunables   54   27    0 :
sctp_sock              0      0    736    5    1 : tunables   54   27    0 :
rawv6_sock             3      6    640    6    1 : tunables   54   27    0 :
udpv6_sock             0      0    608    6    1 : tunables   54   27    0 :
tcpv6_sock             1      7   1120    7    2 : tunables   24   12    0 :
unix_sock              6     10    384   10    1 : tunables   54   27    0 :
raw_sock               2      8    480    8    1 : tunables   54   27    0 :
udp_sock               0      0    512    7    1 : tunables   54   27    0 :
tcp_sock               0      0   1024    4    1 : tunables   54   27    0 :

Signed-off-by: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
Signed-off-by: David S. Miller <davem@redhat.com>

4 files changed, 17 insertions, 3 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index ccc084d370cd..55aba976aba6 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -282,6 +282,10 @@ static inline struct raw6_opt * raw6_sk(const struct sock *__sk)
 	return &((struct raw6_sock *)__sk)->raw6;
 }
 
+struct ipv6_sk_offset {
+	int	offset;
+};
+
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 #define __ipv6_only_sock(sk)	(inet6_sk(sk)->ipv6only)
 #define ipv6_only_sock(sk)	((sk)->sk_family == PF_INET6 && __ipv6_only_sock(sk))
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 17d0f9adce09..053a0ac270f9 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -505,6 +505,7 @@ for (pos = chunk->subh.fwdtsn_hdr->skip;\
 /* External references. */
 
 extern struct proto sctp_prot;
+extern struct proto sctpv6_prot;
 extern struct proc_dir_entry *proc_net_sctp;
 void sctp_put_port(struct sock *sk);
 
diff --git a/include/net/sock.h b/include/net/sock.h
index 0b94438d5403..e9a5eb5d1840 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -555,6 +555,10 @@ struct proto {
 	int			*sysctl_rmem;
 	int			max_header;
 
+	kmem_cache_t		*slab;
+	int			slab_obj_size;
+	void			*af_specific;
+
 	char			name[32];
 
 	struct {
@@ -563,6 +567,14 @@ struct proto {
 	} stats[NR_CPUS];
 };
 
+extern int sk_alloc_slab(struct proto *prot, char *name);
+extern void sk_free_slab(struct proto *prot);
+
+static inline void sk_alloc_slab_error(struct proto *proto)
+{
+	printk(KERN_CRIT "%s: Can't create sock SLAB cache!\n", proto->name);
+}
+
 static __inline__ void sk_set_owner(struct sock *sk, struct module *owner)
 {
 	/*
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1a8a317f2bd5..858a0b490378 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -153,9 +153,6 @@ extern struct tcp_hashinfo {
 #define tcp_lhash_wait	(tcp_hashinfo.__tcp_lhash_wait)
 #define tcp_portalloc_lock (tcp_hashinfo.__tcp_portalloc_lock)
 
-/* SLAB cache for TCP socks */
-extern kmem_cache_t *tcp_sk_cachep;
-
 extern kmem_cache_t *tcp_bucket_cachep;
 extern struct tcp_bind_bucket *tcp_bucket_create(struct tcp_bind_hashbucket *head,
 						 unsigned short snum);