ipip: convert hash tables locking to RCU
IPIP tunnels use one rwlock to protect their hash tables.
This locking scheme can be converted to RCU for free, since netdevice
already must wait for a RCU grace period at dismantle time.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 6a55392..3bd6998 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -134,7 +134,13 @@
static void ipip_tunnel_init(struct net_device *dev);
static void ipip_tunnel_setup(struct net_device *dev);
-static DEFINE_RWLOCK(ipip_lock);
+/*
+ * Locking : hash tables are protected by RCU and a spinlock
+ */
+static DEFINE_SPINLOCK(ipip_lock);
+
+#define for_each_ip_tunnel_rcu(start) \
+ for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
static struct ip_tunnel * ipip_tunnel_lookup(struct net *net,
__be32 remote, __be32 local)
@@ -144,20 +150,21 @@
struct ip_tunnel *t;
struct ipip_net *ipn = net_generic(net, ipip_net_id);
- for (t = ipn->tunnels_r_l[h0^h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(ipn->tunnels_r_l[h0 ^ h1])
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
return t;
- }
- for (t = ipn->tunnels_r[h0]; t; t = t->next) {
+
+ for_each_ip_tunnel_rcu(ipn->tunnels_r[h0])
if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
return t;
- }
- for (t = ipn->tunnels_l[h1]; t; t = t->next) {
+
+ for_each_ip_tunnel_rcu(ipn->tunnels_l[h1])
if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
return t;
- }
- if ((t = ipn->tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
+
+ t = rcu_dereference(ipn->tunnels_wc[0]);
+ if (t && (t->dev->flags&IFF_UP))
return t;
return NULL;
}
@@ -193,9 +200,9 @@
for (tp = ipip_bucket(ipn, t); *tp; tp = &(*tp)->next) {
if (t == *tp) {
- write_lock_bh(&ipip_lock);
+ spin_lock_bh(&ipip_lock);
*tp = t->next;
- write_unlock_bh(&ipip_lock);
+ spin_unlock_bh(&ipip_lock);
break;
}
}
@@ -205,10 +212,10 @@
{
struct ip_tunnel **tp = ipip_bucket(ipn, t);
+ spin_lock_bh(&ipip_lock);
t->next = *tp;
- write_lock_bh(&ipip_lock);
- *tp = t;
- write_unlock_bh(&ipip_lock);
+ rcu_assign_pointer(*tp, t);
+ spin_unlock_bh(&ipip_lock);
}
static struct ip_tunnel * ipip_tunnel_locate(struct net *net,
@@ -267,9 +274,9 @@
struct ipip_net *ipn = net_generic(net, ipip_net_id);
if (dev == ipn->fb_tunnel_dev) {
- write_lock_bh(&ipip_lock);
+ spin_lock_bh(&ipip_lock);
ipn->tunnels_wc[0] = NULL;
- write_unlock_bh(&ipip_lock);
+ spin_unlock_bh(&ipip_lock);
} else
ipip_tunnel_unlink(ipn, netdev_priv(dev));
dev_put(dev);
@@ -318,7 +325,7 @@
err = -ENOENT;
- read_lock(&ipip_lock);
+ rcu_read_lock();
t = ipip_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr);
if (t == NULL || t->parms.iph.daddr == 0)
goto out;
@@ -333,7 +340,7 @@
t->err_count = 1;
t->err_time = jiffies;
out:
- read_unlock(&ipip_lock);
+ rcu_read_unlock();
return err;
}
@@ -351,11 +358,11 @@
struct ip_tunnel *tunnel;
const struct iphdr *iph = ip_hdr(skb);
- read_lock(&ipip_lock);
+ rcu_read_lock();
if ((tunnel = ipip_tunnel_lookup(dev_net(skb->dev),
iph->saddr, iph->daddr)) != NULL) {
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
- read_unlock(&ipip_lock);
+ rcu_read_unlock();
kfree_skb(skb);
return 0;
}
@@ -374,10 +381,10 @@
nf_reset(skb);
ipip_ecn_decapsulate(iph, skb);
netif_rx(skb);
- read_unlock(&ipip_lock);
+ rcu_read_unlock();
return 0;
}
- read_unlock(&ipip_lock);
+ rcu_read_unlock();
return -1;
}