[PATCH 18/34] ipvs: add ip_vs_dest_hold and ip_vs_dest_put

[Simon Horman <horms@xxxxxxxxxxxx>]

From: Julian Anastasov <ja@xxxxxx>

ip_vs_dest_hold will be used under RCU lock
while ip_vs_dest_put can be called even after dest
is removed from service, as it happens for conns and
some schedulers.

Signed-off-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
---
 include/net/ip_vs.h             |   10 ++++++++++
 net/netfilter/ipvs/ip_vs_conn.c |    9 ++-------
 net/netfilter/ipvs/ip_vs_ctl.c  |    4 ++--
 net/netfilter/ipvs/ip_vs_sync.c |    4 ++--
 4 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index d91385c..7d3027f 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -1427,6 +1427,16 @@ ip_vs_find_dest(struct net *net, int af, const union 
nf_inet_addr *daddr,
                __u16 protocol, __u32 fwmark, __u32 flags);
 extern struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp);
 
+static inline void ip_vs_dest_hold(struct ip_vs_dest *dest)
+{
+       atomic_inc(&dest->refcnt);
+}
+
+static inline void ip_vs_dest_put(struct ip_vs_dest *dest)
+{
+       smp_mb__before_atomic_dec();
+       atomic_dec(&dest->refcnt);
+}
 
 /*
  *      IPVS sync daemon data and function prototypes
diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index e3e2b4d..1b29e4a 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -554,7 +554,7 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest 
*dest)
                return;
 
        /* Increase the refcnt counter of the dest */
-       atomic_inc(&dest->refcnt);
+       ip_vs_dest_hold(dest);
 
        conn_flags = atomic_read(&dest->conn_flags);
        if (cp->protocol != IPPROTO_UDP)
@@ -700,12 +700,7 @@ static inline void ip_vs_unbind_dest(struct ip_vs_conn *cp)
                        dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
        }
 
-       /*
-        * Simply decrease the refcnt of the dest, because the
-        * dest will be either in service's destination list
-        * or in the trash.
-        */
-       atomic_dec(&dest->refcnt);
+       ip_vs_dest_put(dest);
 }
 
 static int expire_quiescent_template(struct netns_ipvs *ipvs,
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index d64f800..a4f6388 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -616,7 +616,7 @@ struct ip_vs_dest *ip_vs_find_dest(struct net  *net, int af,
        if (!dest)
                dest = ip_vs_lookup_dest(svc, daddr, port ^ dport);
        if (dest)
-               atomic_inc(&dest->refcnt);
+               ip_vs_dest_hold(dest);
        ip_vs_service_put(svc);
        return dest;
 }
@@ -1056,7 +1056,7 @@ static void __ip_vs_del_dest(struct net *net, struct 
ip_vs_dest *dest)
                              ntohs(dest->port),
                              atomic_read(&dest->refcnt));
                list_add(&dest->n_list, &ipvs->dest_trash);
-               atomic_inc(&dest->refcnt);
+               ip_vs_dest_hold(dest);
        }
 }
 
diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index 44fd10c..6cc3e52 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -861,7 +861,7 @@ static void ip_vs_proc_conn(struct net *net, struct 
ip_vs_conn_param *param,
                if (!dest) {
                        dest = ip_vs_try_bind_dest(cp);
                        if (dest)
-                               atomic_dec(&dest->refcnt);
+                               ip_vs_dest_put(dest);
                }
        } else {
                /*
@@ -874,7 +874,7 @@ static void ip_vs_proc_conn(struct net *net, struct 
ip_vs_conn_param *param,
 
                cp = ip_vs_conn_new(param, daddr, dport, flags, dest, fwmark);
                if (dest)
-                       atomic_dec(&dest->refcnt);
+                       ip_vs_dest_put(dest);
                if (!cp) {
                        if (param->pe_data)
                                kfree(param->pe_data);
-- 
1.7.10.4

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