[RFC] relationship of struct atm_vcc with struct sock

[Arnaldo Carvalho de Melo <acme@conectiva.com.br>]

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Hi Chas,

	I'm working on a series of patches to make all protocol families
use private slab caches for its socks, this is needed to introduce struct
connection_sock, to move the connection specific members out of struct
sock and save bytes/cachelines in non connected protocols, such as UDP.

	Take a look at the attached patch that does this work on pfkey,
basically I need that struct atm_sock (now called atm_vcc) contains as
its first member a struct sock, so a pointer to an struct atm_sock is a
pointer to an struct sock.

	This approach eliminates the need for a struct sock backpointer
in atm_sock.

	The approach I'm using in ax25/netrom/rose is to make all functions
receive struct sock pointers, and from it, if needed, obtain the ax25_sock
pointer using ax25_sk(sk).

	I'm coordinating with Ralf Baechle, the ham radio protocols
maintainer, that is reviewing my changes.

	Do you have any mixed feelings about doing the same with atm?

Regards,

- Arnaldo

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===================================================================


ChangeSet@1.2347, 2005-01-18 04:41:35-02:00, acme@toy.ghostprotocols.net
  [PF_KEY] use a private slab cache for socks
  
  Required to get rid of sk_protinfo and to introduce struct connection_sock,
  also for consistency with other protocol families implementations.
  
  Signed-off-by: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  Signed-off-by: David S. Miller <davem@davemloft.net>


 af_key.c |   48 +++++++++++++++++++++++++++++-------------------
 1 files changed, 29 insertions(+), 19 deletions(-)


diff -Nru a/net/key/af_key.c b/net/key/af_key.c
--- a/net/key/af_key.c	2005-01-18 04:55:03 -02:00
+++ b/net/key/af_key.c	2005-01-18 04:55:03 -02:00
@@ -42,11 +42,19 @@
 
 static atomic_t pfkey_socks_nr = ATOMIC_INIT(0);
 
-struct pfkey_opt {
-	int	registered;
-	int	promisc;
+struct pfkey_sock {
+	/* struct sock must be the first member of struct pfkey_sock */
+	struct sock	sk;
+	int		registered;
+	int		promisc;
 };
-#define pfkey_sk(__sk) ((struct pfkey_opt *)(__sk)->sk_protinfo)
+
+static inline struct pfkey_sock *pfkey_sk(struct sock *sk)
+{
+	return (struct pfkey_sock *)sk;
+}
+
+static kmem_cache_t *pfkey_sk_slab;
 
 static void pfkey_sock_destruct(struct sock *sk)
 {
@@ -60,8 +68,6 @@
 	BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
 	BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
 
-	kfree(pfkey_sk(sk));
-
 	atomic_dec(&pfkey_socks_nr);
 }
 
@@ -128,7 +134,6 @@
 static int pfkey_create(struct socket *sock, int protocol)
 {
 	struct sock *sk;
-	struct pfkey_opt *pfk;
 	int err;
 
 	if (!capable(CAP_NET_ADMIN))
@@ -139,7 +144,8 @@
 		return -EPROTONOSUPPORT;
 
 	err = -ENOMEM;
-	sk = sk_alloc(PF_KEY, GFP_KERNEL, 1, NULL);
+	sk = sk_alloc(PF_KEY, GFP_KERNEL,
+		      sizeof(struct pfkey_sock), pfkey_sk_slab);
 	if (sk == NULL)
 		goto out;
 	
@@ -147,14 +153,6 @@
 	sock_init_data(sock, sk);
 	sk_set_owner(sk, THIS_MODULE);
 
-	err = -ENOMEM;
-	pfk = sk->sk_protinfo = kmalloc(sizeof(*pfk), GFP_KERNEL);
-	if (!pfk) {
-		sk_free(sk);
-		goto out;
-	}
-	memset(pfk, 0, sizeof(*pfk));
-
 	sk->sk_family = PF_KEY;
 	sk->sk_destruct = pfkey_sock_destruct;
 
@@ -233,7 +231,7 @@
 
 	pfkey_lock_table();
 	sk_for_each(sk, node, &pfkey_table) {
-		struct pfkey_opt *pfk = pfkey_sk(sk);
+		struct pfkey_sock *pfk = pfkey_sk(sk);
 		int err2;
 
 		/* Yes, it means that if you are meant to receive this
@@ -1418,7 +1416,7 @@
 
 static int pfkey_register(struct sock *sk, struct sk_buff *skb, struct sadb_msg *hdr, void **ext_hdrs)
 {
-	struct pfkey_opt *pfk = pfkey_sk(sk);
+	struct pfkey_sock *pfk = pfkey_sk(sk);
 	struct sk_buff *supp_skb;
 
 	if (hdr->sadb_msg_satype > SADB_SATYPE_MAX)
@@ -1514,7 +1512,7 @@
 
 static int pfkey_promisc(struct sock *sk, struct sk_buff *skb, struct sadb_msg *hdr, void **ext_hdrs)
 {
-	struct pfkey_opt *pfk = pfkey_sk(sk);
+	struct pfkey_sock *pfk = pfkey_sk(sk);
 	int satype = hdr->sadb_msg_satype;
 
 	if (hdr->sadb_msg_len == (sizeof(*hdr) / sizeof(uint64_t))) {
@@ -2863,10 +2861,22 @@
 	xfrm_unregister_km(&pfkeyv2_mgr);
 	remove_proc_entry("net/pfkey", NULL);
 	sock_unregister(PF_KEY);
+
+	if (pfkey_sk_slab != NULL) {
+		kmem_cache_destroy(pfkey_sk_slab);
+		pfkey_sk_slab = NULL;
+	}
 }
 
 static int __init ipsec_pfkey_init(void)
 {
+	pfkey_sk_slab = kmem_cache_create("pfkey_sock",
+					  sizeof(struct pfkey_sock), 0,
+					  SLAB_HWCACHE_ALIGN, NULL, NULL);
+
+	if (pfkey_sk_slab == NULL)
+		return -ENOMEM;
+
 	sock_register(&pfkey_family_ops);
 #ifdef CONFIG_PROC_FS
 	create_proc_read_entry("net/pfkey", 0, NULL, pfkey_read_proc, NULL);

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