netfilter: conntrack: remove packet hotpath stats

These counters sit in hot path and do show up in perf, this is especially
true for 'found' and 'searched' which get incremented for every packet
processed.

Information like

searched=212030105
new=623431
found=333613
delete=623327

does not seem too helpful nowadays:

- on busy systems found and searched will overflow every few hours
(these are 32bit integers), other more busy ones every few days.

- for debugging there are better methods, such as iptables' trace target,
the conntrack log sysctls.  Nowadays we also have perf tool.

This removes packet path stat counters except those that
are expected to be 0 (or close to 0) on a normal system, e.g.
'insert_failed' (race happened) or 'invalid' (proto tracker rejects).

The insert stat is retained for the ctnetlink case.
The found stat is retained for the tuple-is-taken check when NAT has to
determine if it needs to pick a different source address.

Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>

Author: Florian Westphal

include/linux/netfilter/nf_conntrack_common.h

@@ -4,13 +4,9 @@
 #include <uapi/linux/netfilter/nf_conntrack_common.h>
 
 struct ip_conntrack_stat {
-	unsigned int searched;
 	unsigned int found;
-	unsigned int new;
 	unsigned int invalid;
 	unsigned int ignore;
-	unsigned int delete;
-	unsigned int delete_list;
 	unsigned int insert;
 	unsigned int insert_failed;
 	unsigned int drop;

include/uapi/linux/netfilter/nfnetlink_conntrack.h

@@ -231,13 +231,13 @@ enum ctattr_secctx {
 
 enum ctattr_stats_cpu {
 	CTA_STATS_UNSPEC,
-	CTA_STATS_SEARCHED,
+	CTA_STATS_SEARCHED,	/* no longer used */
 	CTA_STATS_FOUND,
-	CTA_STATS_NEW,
+	CTA_STATS_NEW,		/* no longer used */
 	CTA_STATS_INVALID,
 	CTA_STATS_IGNORE,
-	CTA_STATS_DELETE,
-	CTA_STATS_DELETE_LIST,
+	CTA_STATS_DELETE,	/* no longer used */
+	CTA_STATS_DELETE_LIST,	/* no longer used */
 	CTA_STATS_INSERT,
 	CTA_STATS_INSERT_FAILED,
 	CTA_STATS_DROP,

net/netfilter/nf_conntrack_core.c

@@ -379,7 +379,6 @@ static void
 destroy_conntrack(struct nf_conntrack *nfct)
 {
 	struct nf_conn *ct = (struct nf_conn *)nfct;
-	struct net *net = nf_ct_net(ct);
 	struct nf_conntrack_l4proto *l4proto;
 
 	pr_debug("destroy_conntrack(%p)\n", ct);
@@ -406,7 +405,6 @@ destroy_conntrack(struct nf_conntrack *nfct)
 
 	nf_ct_del_from_dying_or_unconfirmed_list(ct);
 
-	NF_CT_STAT_INC(net, delete);
 	local_bh_enable();
 
 	if (ct->master)
@@ -438,7 +436,6 @@ static void nf_ct_delete_from_lists(struct nf_conn *ct)
 
 	nf_ct_add_to_dying_list(ct);
 
-	NF_CT_STAT_INC(net, delete_list);
 	local_bh_enable();
 }
 
@@ -529,11 +526,8 @@ ____nf_conntrack_find(struct net *net, const struct nf_conntrack_zone *zone,
 		if (nf_ct_is_dying(ct))
 			continue;
 
-		if (nf_ct_key_equal(h, tuple, zone, net)) {
-			NF_CT_STAT_INC_ATOMIC(net, found);
+		if (nf_ct_key_equal(h, tuple, zone, net))
 			return h;
-		}
-		NF_CT_STAT_INC_ATOMIC(net, searched);
 	}
 	/*
 	 * if the nulls value we got at the end of this lookup is
@@ -798,7 +792,6 @@ __nf_conntrack_confirm(struct sk_buff *skb)
 	 */
 	__nf_conntrack_hash_insert(ct, hash, reply_hash);
 	nf_conntrack_double_unlock(hash, reply_hash);
-	NF_CT_STAT_INC(net, insert);
 	local_bh_enable();
 
 	help = nfct_help(ct);
@@ -857,7 +850,6 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 			rcu_read_unlock();
 			return 1;
 		}
-		NF_CT_STAT_INC_ATOMIC(net, searched);
 	}
 
 	if (get_nulls_value(n) != hash) {
@@ -1177,10 +1169,8 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 		}
 		spin_unlock(&nf_conntrack_expect_lock);
 	}
-	if (!exp) {
+	if (!exp)
 		__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
-		NF_CT_STAT_INC(net, new);
-	}
 
 	/* Now it is inserted into the unconfirmed list, bump refcount */
 	nf_conntrack_get(&ct->ct_general);

net/netfilter/nf_conntrack_netlink.c

@@ -1984,13 +1984,9 @@ ctnetlink_ct_stat_cpu_fill_info(struct sk_buff *skb, u32 portid, u32 seq,
 	nfmsg->version      = NFNETLINK_V0;
 	nfmsg->res_id	    = htons(cpu);
 
-	if (nla_put_be32(skb, CTA_STATS_SEARCHED, htonl(st->searched)) ||
-	    nla_put_be32(skb, CTA_STATS_FOUND, htonl(st->found)) ||
-	    nla_put_be32(skb, CTA_STATS_NEW, htonl(st->new)) ||
+	if (nla_put_be32(skb, CTA_STATS_FOUND, htonl(st->found)) ||
 	    nla_put_be32(skb, CTA_STATS_INVALID, htonl(st->invalid)) ||
 	    nla_put_be32(skb, CTA_STATS_IGNORE, htonl(st->ignore)) ||
-	    nla_put_be32(skb, CTA_STATS_DELETE, htonl(st->delete)) ||
-	    nla_put_be32(skb, CTA_STATS_DELETE_LIST, htonl(st->delete_list)) ||
 	    nla_put_be32(skb, CTA_STATS_INSERT, htonl(st->insert)) ||
 	    nla_put_be32(skb, CTA_STATS_INSERT_FAILED,
 				htonl(st->insert_failed)) ||

net/netfilter/nf_conntrack_standalone.c

@@ -352,13 +352,13 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v)
 	seq_printf(seq, "%08x  %08x %08x %08x %08x %08x %08x %08x "
 			"%08x %08x %08x %08x %08x  %08x %08x %08x %08x\n",
 		   nr_conntracks,
-		   st->searched,
+		   0,
 		   st->found,
-		   st->new,
+		   0,
 		   st->invalid,
 		   st->ignore,
-		   st->delete,
-		   st->delete_list,
+		   0,
+		   0,
 		   st->insert,
 		   st->insert_failed,
 		   st->drop,