ipvs: optimize dst usage for real server

Currently when forwarding requests to real servers
we use dst_lock and atomic operations when cloning the
dst_cache value. As the dst_cache value does not change
most of the time it is better to use RCU and to lock
dst_lock only when we need to replace the obsoleted dst.
For this to work we keep dst_cache in new structure protected
by RCU. For packets to remote real servers we will use noref
version of dst_cache, it will be valid while we are in RCU
read-side critical section because now dst_release for replaced
dsts will be invoked after the grace period. Packets to
local real servers that are passed to local stack with
NF_ACCEPT need a dst clone.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 8ad73a83465581df3c52c7cce163dbb43ca24d61..a150ff5d838cf2858fa4a25c7a83839ac135e083 100644 (file)
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -724,6 +724,13 @@ struct ip_vs_service {
        struct ip_vs_pe         *pe;
 };
 
+/* Information for cached dst */
+struct ip_vs_dest_dst {
+       struct dst_entry        *dst_cache;     /* destination cache entry */
+       u32                     dst_cookie;
+       union nf_inet_addr      dst_saddr;
+       struct rcu_head         rcu_head;
+};
 
 /*
  *     The real server destination forwarding entry
@@ -752,9 +759,7 @@ struct ip_vs_dest {
 
        /* for destination cache */
        spinlock_t              dst_lock;       /* lock of dst_cache */
-       struct dst_entry        *dst_cache;     /* destination cache entry */
-       u32                     dst_cookie;
-       union nf_inet_addr      dst_saddr;
+       struct ip_vs_dest_dst __rcu *dest_dst;  /* cached dst info */
 
        /* for virtual service */
        struct ip_vs_service    *svc;           /* service it belongs to */
@@ -1427,6 +1432,7 @@ extern int ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 extern int ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
                           struct ip_vs_protocol *pp, int offset,
                           unsigned int hooknum, struct ip_vs_iphdr *iph);
+extern void ip_vs_dest_dst_rcu_free(struct rcu_head *head);
 
 #ifdef CONFIG_IP_VS_IPV6
 extern int ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 2aef23ed748b098e807db39736c74f36aa46f213..6ad24e7ef44002ecb241f7052f7b1286df8660f2 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1395,10 +1395,13 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum)
                                goto ignore_ipip;
                        /* Prefer the resulting PMTU */
                        if (dest) {
-                               spin_lock(&dest->dst_lock);
-                               if (dest->dst_cache)
-                                       mtu = dst_mtu(dest->dst_cache);
-                               spin_unlock(&dest->dst_lock);
+                               struct ip_vs_dest_dst *dest_dst;
+
+                               rcu_read_lock();
+                               dest_dst = rcu_dereference(dest->dest_dst);
+                               if (dest_dst)
+                                       mtu = dst_mtu(dest_dst->dst_cache);
+                               rcu_read_unlock();
                        }
                        if (mtu > 68 + sizeof(struct iphdr))
                                mtu -= sizeof(struct iphdr);

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 5265eaa7b42b35564523ff38fe379ecea0de75de..ef48cc55f7758ea31de1dfe14d930ec505f084a4 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -641,15 +641,26 @@ struct ip_vs_dest *ip_vs_find_dest(struct net  *net, int af,
        return dest;
 }
 
-/* Release dst_cache for dest in user context */
+void ip_vs_dest_dst_rcu_free(struct rcu_head *head)
+{
+       struct ip_vs_dest_dst *dest_dst = container_of(head,
+                                                      struct ip_vs_dest_dst,
+                                                      rcu_head);
+
+       dst_release(dest_dst->dst_cache);
+       kfree(dest_dst);
+}
+
+/* Release dest_dst and dst_cache for dest in user context */
 static void __ip_vs_dst_cache_reset(struct ip_vs_dest *dest)
 {
-       struct dst_entry *old_dst;
+       struct ip_vs_dest_dst *old;
 
-       old_dst = dest->dst_cache;
-       dest->dst_cache = NULL;
-       dst_release(old_dst);
-       dest->dst_saddr.ip = 0;
+       old = rcu_dereference_protected(dest->dest_dst, 1);
+       if (old) {
+               RCU_INIT_POINTER(dest->dest_dst, NULL);
+               call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free);
+       }
 }
 
 /*
@@ -1513,7 +1524,7 @@ static inline void
 ip_vs_forget_dev(struct ip_vs_dest *dest, struct net_device *dev)
 {
        spin_lock_bh(&dest->dst_lock);
-       if (dest->dst_cache && dest->dst_cache->dev == dev) {
+       if (dest->dest_dst && dest->dest_dst->dst_cache->dev == dev) {
                IP_VS_DBG_BUF(3, "Reset dev:%s dest %s:%u ,dest->refcnt=%d\n",
                              dev->name,
                              IP_VS_DBG_ADDR(dest->af, &dest->addr),

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 603eb8a50e190c6854ba847c70dee6e1b9e9bfdb..3db7889edefc7ae193a0cd5c70a204345a2e9a74 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -17,6 +17,8 @@
  * - not all connections have destination server, for example,
  * connections in backup server when fwmark is used
  * - bypass connections use daddr from packet
+ * - we can use dst without ref while sending in RCU section, we use
+ * ref when returning NF_ACCEPT for NAT-ed packet via loopback
  * LOCAL_OUT rules:
  * - skb->dev is NULL, skb->protocol is not set (both are set in POST_ROUTING)
  * - skb->pkt_type is not set yet
@@ -54,34 +56,51 @@ enum {
        IP_VS_RT_MODE_TUNNEL    = 32,/* Tunnel mode */
 };
 
+static inline struct ip_vs_dest_dst *ip_vs_dest_dst_alloc(void)
+{
+       return kmalloc(sizeof(struct ip_vs_dest_dst), GFP_ATOMIC);
+}
+
+static inline void ip_vs_dest_dst_free(struct ip_vs_dest_dst *dest_dst)
+{
+       kfree(dest_dst);
+}
+
 /*
  *      Destination cache to speed up outgoing route lookup
  */
 static inline void
-__ip_vs_dst_set(struct ip_vs_dest *dest, struct dst_entry *dst, u32 dst_cookie)
+__ip_vs_dst_set(struct ip_vs_dest *dest, struct ip_vs_dest_dst *dest_dst,
+               struct dst_entry *dst, u32 dst_cookie)
 {
-       struct dst_entry *old_dst;
+       struct ip_vs_dest_dst *old;
+
+       old = rcu_dereference_protected(dest->dest_dst,
+                                       lockdep_is_held(&dest->dst_lock));
+
+       if (dest_dst) {
+               dest_dst->dst_cache = dst;
+               dest_dst->dst_cookie = dst_cookie;
+       }
+       rcu_assign_pointer(dest->dest_dst, dest_dst);
 
-       old_dst = dest->dst_cache;
-       dest->dst_cache = dst;
-       dest->dst_cookie = dst_cookie;
-       dst_release(old_dst);
+       if (old)
+               call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free);
 }
 
-static inline struct dst_entry *
+static inline struct ip_vs_dest_dst *
 __ip_vs_dst_check(struct ip_vs_dest *dest)
 {
-       struct dst_entry *dst = dest->dst_cache;
+       struct ip_vs_dest_dst *dest_dst = rcu_dereference(dest->dest_dst);
+       struct dst_entry *dst;
 
-       if (!dst)
+       if (!dest_dst)
                return NULL;
-       if (dst->obsolete && dst->ops->check(dst, dest->dst_cookie) == NULL) {
-               dest->dst_cache = NULL;
-               dst_release(dst);
+       dst = dest_dst->dst_cache;
+       if (dst->obsolete &&
+           dst->ops->check(dst, dest_dst->dst_cookie) == NULL)
                return NULL;
-       }
-       dst_hold(dst);
-       return dst;
+       return dest_dst;
 }
 
 static inline bool
@@ -144,35 +163,48 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest,
 {
        struct net *net = dev_net(skb_dst(skb)->dev);
        struct netns_ipvs *ipvs = net_ipvs(net);
+       struct ip_vs_dest_dst *dest_dst;
        struct rtable *rt;                      /* Route to the other host */
        struct rtable *ort;                     /* Original route */
        struct iphdr *iph;
        __be16 df;
        int mtu;
-       int local;
+       int local, noref = 1;
 
        if (dest) {
-               spin_lock(&dest->dst_lock);
-               rt = (struct rtable *) __ip_vs_dst_check(dest);
-               if (!rt) {
+               dest_dst = __ip_vs_dst_check(dest);
+               if (likely(dest_dst))
+                       rt = (struct rtable *) dest_dst->dst_cache;
+               else {
+                       dest_dst = ip_vs_dest_dst_alloc();
+                       spin_lock(&dest->dst_lock);
+                       if (!dest_dst) {
+                               __ip_vs_dst_set(dest, NULL, NULL, 0);
+                               spin_unlock(&dest->dst_lock);
+                               goto err_unreach;
+                       }
                        rt = do_output_route4(net, dest->addr.ip, rt_mode,
-                                             &dest->dst_saddr.ip);
+                                             &dest_dst->dst_saddr.ip);
                        if (!rt) {
+                               __ip_vs_dst_set(dest, NULL, NULL, 0);
                                spin_unlock(&dest->dst_lock);
+                               ip_vs_dest_dst_free(dest_dst);
                                goto err_unreach;
                        }
-                       __ip_vs_dst_set(dest, dst_clone(&rt->dst), 0);
+                       __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0);
+                       spin_unlock(&dest->dst_lock);
                        IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n",
-                                 &dest->addr.ip, &dest->dst_saddr.ip,
+                                 &dest->addr.ip, &dest_dst->dst_saddr.ip,
                                  atomic_read(&rt->dst.__refcnt));
                }
                daddr = dest->addr.ip;
                if (ret_saddr)
-                       *ret_saddr = dest->dst_saddr.ip;
-               spin_unlock(&dest->dst_lock);
+                       *ret_saddr = dest_dst->dst_saddr.ip;
        } else {
                __be32 saddr = htonl(INADDR_ANY);
 
+               noref = 0;
+
                /* For such unconfigured boxes avoid many route lookups
                 * for performance reasons because we do not remember saddr
                 */
@@ -210,7 +242,8 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest,
                        goto err_put;
                }
                /* skb to local stack, preserve old route */
-               ip_rt_put(rt);
+               if (!noref)
+                       ip_rt_put(rt);
                return local;
        }
 
@@ -240,12 +273,19 @@ __ip_vs_get_out_rt(struct sk_buff *skb, struct ip_vs_dest *dest,
        }
 
        skb_dst_drop(skb);
-       skb_dst_set(skb, &rt->dst);
+       if (noref) {
+               if (!local)
+                       skb_dst_set_noref_force(skb, &rt->dst);
+               else
+                       skb_dst_set(skb, dst_clone(&rt->dst));
+       } else
+               skb_dst_set(skb, &rt->dst);
 
        return local;
 
 err_put:
-       ip_rt_put(rt);
+       if (!noref)
+               ip_rt_put(rt);
        return -1;
 
 err_unreach:
@@ -303,36 +343,48 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest,
                      struct ip_vs_iphdr *ipvsh, int do_xfrm, int rt_mode)
 {
        struct net *net = dev_net(skb_dst(skb)->dev);
+       struct ip_vs_dest_dst *dest_dst;
        struct rt6_info *rt;                    /* Route to the other host */
        struct rt6_info *ort;                   /* Original route */
        struct dst_entry *dst;
        int mtu;
-       int local;
+       int local, noref = 1;
 
        if (dest) {
-               spin_lock(&dest->dst_lock);
-               rt = (struct rt6_info *)__ip_vs_dst_check(dest);
-               if (!rt) {
+               dest_dst = __ip_vs_dst_check(dest);
+               if (likely(dest_dst))
+                       rt = (struct rt6_info *) dest_dst->dst_cache;
+               else {
                        u32 cookie;
 
+                       dest_dst = ip_vs_dest_dst_alloc();
+                       spin_lock(&dest->dst_lock);
+                       if (!dest_dst) {
+                               __ip_vs_dst_set(dest, NULL, NULL, 0);
+                               spin_unlock(&dest->dst_lock);
+                               goto err_unreach;
+                       }
                        dst = __ip_vs_route_output_v6(net, &dest->addr.in6,
-                                                     &dest->dst_saddr.in6,
+                                                     &dest_dst->dst_saddr.in6,
                                                      do_xfrm);
                        if (!dst) {
+                               __ip_vs_dst_set(dest, NULL, NULL, 0);
                                spin_unlock(&dest->dst_lock);
+                               ip_vs_dest_dst_free(dest_dst);
                                goto err_unreach;
                        }
                        rt = (struct rt6_info *) dst;
                        cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
-                       __ip_vs_dst_set(dest, dst_clone(&rt->dst), cookie);
+                       __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
+                       spin_unlock(&dest->dst_lock);
                        IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n",
-                                 &dest->addr.in6, &dest->dst_saddr.in6,
+                                 &dest->addr.in6, &dest_dst->dst_saddr.in6,
                                  atomic_read(&rt->dst.__refcnt));
                }
                if (ret_saddr)
-                       *ret_saddr = dest->dst_saddr.in6;
-               spin_unlock(&dest->dst_lock);
+                       *ret_saddr = dest_dst->dst_saddr.in6;
        } else {
+               noref = 0;
                dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm);
                if (!dst)
                        goto err_unreach;
@@ -367,7 +419,8 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest,
                        goto err_put;
                }
                /* skb to local stack, preserve old route */
-               dst_release(&rt->dst);
+               if (!noref)
+                       dst_release(&rt->dst);
                return local;
        }
 
@@ -399,12 +452,19 @@ __ip_vs_get_out_rt_v6(struct sk_buff *skb, struct ip_vs_dest *dest,
        }
 
        skb_dst_drop(skb);
-       skb_dst_set(skb, &rt->dst);
+       if (noref) {
+               if (!local)
+                       skb_dst_set_noref_force(skb, &rt->dst);
+               else
+                       skb_dst_set(skb, dst_clone(&rt->dst));
+       } else
+               skb_dst_set(skb, &rt->dst);
 
        return local;
 
 err_put:
-       dst_release(&rt->dst);
+       if (!noref)
+               dst_release(&rt->dst);
        return -1;
 
 err_unreach:
@@ -494,6 +554,7 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        if (__ip_vs_get_out_rt(skb, NULL, iph->daddr, IP_VS_RT_MODE_NON_LOCAL,
                               NULL) < 0)
                goto tx_error;
@@ -504,12 +565,14 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return NF_STOLEN;
 
  tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -521,6 +584,7 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 {
        EnterFunction(10);
 
+       rcu_read_lock();
        if (__ip_vs_get_out_rt_v6(skb, NULL, &ipvsh->daddr.in6, NULL,
                                  ipvsh, 0, IP_VS_RT_MODE_NON_LOCAL) < 0)
                goto tx_error;
@@ -529,12 +593,14 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return NF_STOLEN;
 
  tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -553,6 +619,7 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        /* check if it is a connection of no-client-port */
        if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
                __be16 _pt, *p;
@@ -620,12 +687,14 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return rc;
 
   tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -640,6 +709,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        /* check if it is a connection of no-client-port */
        if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT && !ipvsh->fragoffs)) {
                __be16 _pt, *p;
@@ -707,6 +777,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return rc;
@@ -714,6 +785,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 tx_error:
        LeaveFunction(10);
        kfree_skb(skb);
+       rcu_read_unlock();
        return NF_STOLEN;
 }
 #endif
@@ -755,6 +827,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip,
                                   IP_VS_RT_MODE_LOCAL |
                                   IP_VS_RT_MODE_NON_LOCAL |
@@ -762,8 +835,10 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
                                   IP_VS_RT_MODE_TUNNEL, &saddr);
        if (local < 0)
                goto tx_error;
-       if (local)
+       if (local) {
+               rcu_read_unlock();
                return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
+       }
 
        rt = skb_rtable(skb);
        tdev = rt->dst.dev;
@@ -818,6 +893,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
                ip_local_out(skb);
        else if (ret == NF_DROP)
                kfree_skb(skb);
+       rcu_read_unlock();
 
        LeaveFunction(10);
 
@@ -825,6 +901,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
   tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -844,6 +921,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6,
                                      &saddr, ipvsh, 1,
                                      IP_VS_RT_MODE_LOCAL |
@@ -851,8 +929,10 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
                                      IP_VS_RT_MODE_TUNNEL);
        if (local < 0)
                goto tx_error;
-       if (local)
+       if (local) {
+               rcu_read_unlock();
                return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1);
+       }
 
        rt = (struct rt6_info *) skb_dst(skb);
        tdev = rt->dst.dev;
@@ -901,6 +981,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
                ip6_local_out(skb);
        else if (ret == NF_DROP)
                kfree_skb(skb);
+       rcu_read_unlock();
 
        LeaveFunction(10);
 
@@ -908,6 +989,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -926,14 +1008,17 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip,
                                   IP_VS_RT_MODE_LOCAL |
                                   IP_VS_RT_MODE_NON_LOCAL |
                                   IP_VS_RT_MODE_KNOWN_NH, NULL);
        if (local < 0)
                goto tx_error;
-       if (local)
+       if (local) {
+               rcu_read_unlock();
                return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
+       }
 
        ip_send_check(ip_hdr(skb));
 
@@ -941,12 +1026,14 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return NF_STOLEN;
 
   tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -960,25 +1047,30 @@ ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        EnterFunction(10);
 
+       rcu_read_lock();
        local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
                                      ipvsh, 0,
                                      IP_VS_RT_MODE_LOCAL |
                                      IP_VS_RT_MODE_NON_LOCAL);
        if (local < 0)
                goto tx_error;
-       if (local)
+       if (local) {
+               rcu_read_unlock();
                return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1);
+       }
 
        /* Another hack: avoid icmp_send in ip_fragment */
        skb->local_df = 1;
 
        ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0);
+       rcu_read_unlock();
 
        LeaveFunction(10);
        return NF_STOLEN;
 
 tx_error:
        kfree_skb(skb);
+       rcu_read_unlock();
        LeaveFunction(10);
        return NF_STOLEN;
 }
@@ -1023,6 +1115,7 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        rt_mode = (hooknum != NF_INET_FORWARD) ?
                  IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL |
                  IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
+       rcu_read_lock();
        local = __ip_vs_get_out_rt(skb, cp->dest, cp->daddr.ip, rt_mode, NULL);
        if (local < 0)
                goto tx_error;
@@ -1067,10 +1160,12 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local);
+       rcu_read_unlock();
        goto out;
 
   tx_error:
-       dev_kfree_skb(skb);
+       kfree_skb(skb);
+       rcu_read_unlock();
        rc = NF_STOLEN;
   out:
        LeaveFunction(10);
@@ -1111,6 +1206,7 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
        rt_mode = (hooknum != NF_INET_FORWARD) ?
                  IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL |
                  IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
+       rcu_read_lock();
        local = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
                                      ipvsh, 0, rt_mode);
        if (local < 0)
@@ -1156,10 +1252,12 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
        skb->local_df = 1;
 
        rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local);
+       rcu_read_unlock();
        goto out;
 
 tx_error:
-       dev_kfree_skb(skb);
+       kfree_skb(skb);
+       rcu_read_unlock();
        rc = NF_STOLEN;
 out:
        LeaveFunction(10);