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authorFlorian Westphal <fw@strlen.de>2017-09-06 14:39:51 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2017-09-08 18:55:50 +0200
commite1bf1687740ce1a3598a1c5e452b852ff2190682 (patch)
tree38df06856971c709b8becc0b505f7a1660764742 /include/net
parenta5d7a714569199f909cd60ff7074107bf15c7db4 (diff)
downloadlinux-e1bf1687740ce1a3598a1c5e452b852ff2190682.tar.bz2
netfilter: nat: Revert "netfilter: nat: convert nat bysrc hash to rhashtable"
This reverts commit 870190a9ec9075205c0fa795a09fa931694a3ff1. It was not a good idea. The custom hash table was a much better fit for this purpose. A fast lookup is not essential, in fact for most cases there is no lookup at all because original tuple is not taken and can be used as-is. What needs to be fast is insertion and deletion. rhlist removal however requires a rhlist walk. We can have thousands of entries in such a list if source port/addresses are reused for multiple flows, if this happens removal requests are so expensive that deletions of a few thousand flows can take several seconds(!). The advantages that we got from rhashtable are: 1) table auto-sizing 2) multiple locks 1) would be nice to have, but it is not essential as we have at most one lookup per new flow, so even a million flows in the bysource table are not a problem compared to current deletion cost. 2) is easy to add to custom hash table. I tried to add hlist_node to rhlist to speed up rhltable_remove but this isn't doable without changing semantics. rhltable_remove_fast will check that the to-be-deleted object is part of the table and that requires a list walk that we want to avoid. Furthermore, using hlist_node increases size of struct rhlist_head, which in turn increases nf_conn size. Link: https://bugzilla.kernel.org/show_bug.cgi?id=196821 Reported-by: Ivan Babrou <ibobrik@gmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/netfilter/nf_conntrack.h3
-rw-r--r--include/net/netfilter/nf_nat.h1
2 files changed, 1 insertions, 3 deletions
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index fdc9c64a1c94..8f3bd30511de 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -17,7 +17,6 @@
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/atomic.h>
-#include <linux/rhashtable.h>
#include <linux/netfilter/nf_conntrack_tcp.h>
#include <linux/netfilter/nf_conntrack_dccp.h>
@@ -77,7 +76,7 @@ struct nf_conn {
possible_net_t ct_net;
#if IS_ENABLED(CONFIG_NF_NAT)
- struct rhlist_head nat_bysource;
+ struct hlist_node nat_bysource;
#endif
/* all members below initialized via memset */
u8 __nfct_init_offset[0];
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 05c82a1a4267..b71701302e61 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -1,6 +1,5 @@
#ifndef _NF_NAT_H
#define _NF_NAT_H
-#include <linux/rhashtable.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/nf_nat.h>
#include <net/netfilter/nf_conntrack_tuple.h>