netdev - [PATCH 25/29] netfilter: nf_conntrack: ensure that CONNTRACK

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Date:   Sat,  2 Mar 2019 19:37:16 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 25/29] netfilter: nf_conntrack: ensure that CONNTRACK_LOCKS is power of 2

From: Li RongQing <lirongqing@...du.com>

CONNTRACK_LOCKS is divisor when computer array index, if it is power of
2, compiler will optimize modulo operation as bitwise AND, or else
modulo will lower performance.

Suggested-by: Florian Westphal <fw@...len.de>
Signed-off-by: Li RongQing <lirongqing@...du.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_conntrack_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index ff9313c579b4..82bfbeef46af 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2480,6 +2480,7 @@ int nf_conntrack_init_net(struct net *net)
 	int cpu;
 
 	BUILD_BUG_ON(IP_CT_UNTRACKED == IP_CT_NUMBER);
+	BUILD_BUG_ON_NOT_POWER_OF_2(CONNTRACK_LOCKS);
 	atomic_set(&net->ct.count, 0);
 
 	net->ct.pcpu_lists = alloc_percpu(struct ct_pcpu);
-- 
2.11.0