From a23349bb9f1283e6262c096e7b805168772dd8ca Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 6 Sep 2017 14:39:51 +0200 Subject: netfilter: nat: Revert "netfilter: nat: convert nat bysrc hash to rhashtable" commit e1bf1687740ce1a3598a1c5e452b852ff2190682 upstream. 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 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- include/net/netfilter/nf_conntrack.h | 3 +-- include/net/netfilter/nf_nat.h | 1 - 2 files changed, 1 insertion(+), 3 deletions(-) (limited to 'include') diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index d9d52c020a70..9ae819e27940 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -17,7 +17,6 @@ #include #include #include -#include #include #include @@ -101,7 +100,7 @@ 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 c327a431a6f3..02515f7ed4cc 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 #include #include #include -- cgit v1.2.3