Home » Mailing list archives » linux-netdev » 2009 » March » 25

Re: [patch 1/3] ctnetlink: allocate right-sized ctnetlink skb

Previous thread: Re: Next March 25: staging/epl build break. by Randy Dunlap on Wednesday, March 25, 2009 - 9:04 am. (1 message)

Next thread: [patch 0/3] ctnetlink: allocation improvements by Holger Eitzenberger on Wednesday, March 25, 2009 - 1:34 pm. (1 message)
[view original message]
From: Holger Eitzenberger
Subject: [patch 1/3] ctnetlink: allocate right-sized ctnetlink skb
Date: Wednesday, March 25, 2009 - 1:34 pm

Try to allocate a Netlink skb roughly the size of the actual
message, with the help from the l3 and l4 protocol helpers.
This is all to prevent a reallocation in netlink_trim() later.

The overhead of allocating the right-sized skb is rather small, with
ctnetlink_alloc_skb() actually being inlined away on my x86_64 box.
The size of the per-proto space is determined at registration time of
the protocol helper.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>

Index: nf-next-2.6/net/netfilter/nf_conntrack_netlink.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/nf_conntrack_netlink.c
+++ nf-next-2.6/net/netfilter/nf_conntrack_netlink.c
@@ -404,6 +404,69 @@ nla_put_failure:
 }
 
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
+/*
+ * The general structure of a ctnetlink event is
+ *
+ *  CTA_TUPLE_ORIG
+ *    <l3/l4-proto-attributes>
+ *  CTA_TUPLE_REPLY
+ *    <l3/l4-proto-attributes>
+ *  CTA_ID
+ *  ...
+ *  CTA_PROTOINFO
+ *    <l4-proto-attributes>
+ *  CTA_TUPLE_MASTER
+ *    <l3/l4-proto-attributes>
+ *
+ * Therefore the formular is
+ *
+ *   size = sizeof(headers) + sizeof(generic_nlas) + 3 * sizeof(tuple_nlas)
+ *		+ sizeof(protoinfo_nlas)
+ */
+static struct sk_buff *
+ctnetlink_alloc_skb(const struct nf_conntrack_tuple *tuple, gfp_t gfp)
+{
+	struct nf_conntrack_l3proto *l3proto;
+	struct nf_conntrack_l4proto *l4proto;
+	int len;
+
+#define NLA_TYPE_SIZE(type)		nla_total_size(sizeof(type))
+
+	/* proto independant part */
+	len = NLMSG_SPACE(sizeof(struct nfgenmsg))
+		+ 3 * nla_total_size(0)		/* CTA_TUPLE_ORIG|REPL|MASTER */
+		+ 3 * nla_total_size(0)		/* CTA_TUPLE_IP */
+		+ 3 * nla_total_size(0)		/* CTA_TUPLE_PROTO */
+		+ 3 * NLA_TYPE_SIZE(u_int8_t)	/* CTA_PROTO_NUM */
+		+ NLA_TYPE_SIZE(u_int32_t)	/* CTA_ID */
+		+ NLA_TYPE_SIZE(u_int32_t)	/* CTA_STATUS */
+		+ 2 * nla_total_size(0)		/* CTA_COUNTERS_ORIG|REPL */
+		+ 2 * NLA_TYPE_SIZE(uint64_t)	/* CTA_COUNTERS_PACKETS */
+		+ 2 * ...
[ message continues ]
[view original message]
From: Patrick McHardy
Subject: Re: [patch 1/3] ctnetlink: allocate right-sized ctnetlink skb
Date: Wednesday, March 25, 2009 - 1:51 pm

Applied, thanks.
--


[ message continues ]
Previous thread: Re: Next March 25: staging/epl build break. by Randy Dunlap on Wednesday, March 25, 2009 - 9:04 am. (1 message)

Next thread: [patch 0/3] ctnetlink: allocation improvements by Holger Eitzenberger on Wednesday, March 25, 2009 - 1:34 pm. (1 message)