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 8ad73a8..a150ff5 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -724,6 +724,13 @@
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 @@
/* 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_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 2aef23e..6ad24e7 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1395,10 +1395,13 @@
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 5265eaa..ef48cc5 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -641,15 +641,26 @@
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 @@
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 603eb8a..3db7889 100644
--- 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 @@
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_dst = dest->dst_cache;
- dest->dst_cache = dst;
- dest->dst_cookie = dst_cookie;
- dst_release(old_dst);
+ 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);
+
+ 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 @@
{
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) {
- rt = do_output_route4(net, dest->addr.ip, rt_mode,
- &dest->dst_saddr.ip);
- 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;
}
- __ip_vs_dst_set(dest, dst_clone(&rt->dst), 0);
+ rt = do_output_route4(net, dest->addr.ip, rt_mode,
+ &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, 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 @@
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 @@
}
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 @@
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 @@
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 @@
}
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 @@
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 @@
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 @@
{
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
tx_error:
LeaveFunction(10);
kfree_skb(skb);
+ rcu_read_unlock();
return NF_STOLEN;
}
#endif
@@ -755,6 +827,7 @@
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_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_local_out(skb);
else if (ret == NF_DROP)
kfree_skb(skb);
+ rcu_read_unlock();
LeaveFunction(10);
@@ -825,6 +901,7 @@
tx_error:
kfree_skb(skb);
+ rcu_read_unlock();
LeaveFunction(10);
return NF_STOLEN;
}
@@ -844,6 +921,7 @@
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_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 @@
ip6_local_out(skb);
else if (ret == NF_DROP)
kfree_skb(skb);
+ rcu_read_unlock();
LeaveFunction(10);
@@ -908,6 +989,7 @@
tx_error:
kfree_skb(skb);
+ rcu_read_unlock();
LeaveFunction(10);
return NF_STOLEN;
}
@@ -926,14 +1008,17 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);