netdev - [PATCH] ipvs: Fix reuse connection if RS weight is 0

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Message-Id: <20211025115910.2595-1-xingwu.yang@gmail.com>
Date:   Mon, 25 Oct 2021 19:59:10 +0800
From:   yangxingwu <xingwu.yang@...il.com>
To:     horms@...ge.net.au
Cc:     ja@....bg, pablo@...filter.org, kadlec@...filter.org, fw@...len.de,
        davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        lvs-devel@...r.kernel.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, corbet@....net, xingwu.yang@...il.com
Subject: [PATCH] ipvs: Fix reuse connection if RS weight is 0

Since commit dc7b3eb900aa ("ipvs: Fix reuse connection if real server is
dead"), new connections to dead servers are redistributed immediately to
new servers.

Then commit d752c3645717 ("ipvs: allow rescheduling of new connections when
port reuse is detected") disable expire_nodest_conn if conn_reuse_mode is
0. And new connection may be distributed to a real server with weight 0.

Signed-off-by: yangxingwu <xingwu.yang@...il.com>
---
 Documentation/networking/ipvs-sysctl.rst | 3 +--
 net/netfilter/ipvs/ip_vs_core.c          | 5 +++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/networking/ipvs-sysctl.rst b/Documentation/networking/ipvs-sysctl.rst
index 2afccc63856e..1cfbf1add2fc 100644
--- a/Documentation/networking/ipvs-sysctl.rst
+++ b/Documentation/networking/ipvs-sysctl.rst
@@ -37,8 +37,7 @@ conn_reuse_mode - INTEGER
 
 	0: disable any special handling on port reuse. The new
 	connection will be delivered to the same real server that was
-	servicing the previous connection. This will effectively
-	disable expire_nodest_conn.
+	servicing the previous connection.
 
 	bit 1: enable rescheduling of new connections when it is safe.
 	That is, whenever expire_nodest_conn and for TCP sockets, when
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 128690c512df..9279aed69e23 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -2042,14 +2042,15 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int
 			     ipvs, af, skb, &iph);
 
 	conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);
-	if (conn_reuse_mode && !iph.fragoffs && is_new_conn(skb, &iph) && cp) {
+	if (!iph.fragoffs && is_new_conn(skb, &iph) && cp) {
 		bool old_ct = false, resched = false;
 
 		if (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest &&
 		    unlikely(!atomic_read(&cp->dest->weight))) {
 			resched = true;
 			old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
-		} else if (is_new_conn_expected(cp, conn_reuse_mode)) {
+		} else if (conn_reuse_mode &&
+			   is_new_conn_expected(cp, conn_reuse_mode)) {
 			old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
 			if (!atomic_read(&cp->n_control)) {
 				resched = true;
-- 
2.30.2