[PATCH net-next v3] ipvs: Fix reuse connection if RS weight is 0

[yangxingwu <xingwu.yang@xxxxxxxxx>]

We are changing expire_nodest_conn to work even for reused connections when
conn_reuse_mode=0 but without affecting the controlled and persistent
connections during the graceful termination period while server is with
weight=0.

Fixes: d752c3645717 ("ipvs: allow rescheduling of new connections when port
reuse is detected")
Co-developed-by: Chuanqi Liu <legend050709@xxxxxx>
Signed-off-by: Chuanqi Liu <legend050709@xxxxxx>
Signed-off-by: yangxingwu <xingwu.yang@xxxxxxxxx>
---
 Documentation/networking/ipvs-sysctl.rst |  3 +--
 net/netfilter/ipvs/ip_vs_core.c          | 12 ++++--------
 2 files changed, 5 insertions(+), 10 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..ce6ceb55822b 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1100,10 +1100,6 @@ static inline bool is_new_conn(const struct sk_buff *skb,
 static inline bool is_new_conn_expected(const struct ip_vs_conn *cp,
                                        int conn_reuse_mode)
 {
-       /* Controlled (FTP DATA or persistence)? */
-       if (cp->control)
-               return false;
-
        switch (cp->protocol) {
        case IPPROTO_TCP:
                return (cp->state == IP_VS_TCP_S_TIME_WAIT) ||
@@ -1964,7 +1960,6 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, int
        struct ip_vs_proto_data *pd;
        struct ip_vs_conn *cp;
        int ret, pkts;
-       int conn_reuse_mode;
        struct sock *sk;
 
        /* Already marked as IPVS request or reply? */
@@ -2041,15 +2036,16 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, int
        cp = INDIRECT_CALL_1(pp->conn_in_get, ip_vs_conn_in_get_proto,
                             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 && !cp->control) {
                bool old_ct = false, resched = false;
+               int conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);
 
                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