From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yafang Shao Subject: [PATCH net-next] tcp: fix the calculation of sysctl_max_tw_buckets in tcp_sk_init() Date: Mon, 6 Aug 2018 19:47:00 +0800 Message-ID: <1533556020-20778-1-git-send-email-laoar.shao@gmail.com> Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao To: edumazet@google.com, davem@davemloft.net, yanhaishuang@cmss.chinamobile.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org tcp_hashinfo.ehash_mask is always an odd number, which is set in function alloc_large_system_hash(). See bellow, if (_hash_mask) *_hash_mask = (1 << log2qty) - 1; <<< always odd number Hence the local variable 'cnt' is a even number, as a result of that it is no difference to do the incrementation here. Maybe the compiler could also optimize it, but this code is a little ugly. Fix: fee83d09 ("ipv4: Namespaceify tcp_max_syn_backlog knob") Signed-off-by: Yafang Shao --- net/ipv4/tcp_ipv4.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 9e041fa..a9b7c4b 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2543,7 +2543,7 @@ static int __net_init tcp_sk_init(struct net *net) net->ipv4.sysctl_tcp_tw_reuse = 2; cnt = tcp_hashinfo.ehash_mask + 1; - net->ipv4.tcp_death_row.sysctl_max_tw_buckets = (cnt + 1) / 2; + net->ipv4.tcp_death_row.sysctl_max_tw_buckets = cnt / 2; net->ipv4.tcp_death_row.hashinfo = &tcp_hashinfo; net->ipv4.sysctl_max_syn_backlog = max(128, cnt / 256); -- 1.8.3.1