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Message-ID: <4AE279EE.8090007@gmail.com>
Date: Sat, 24 Oct 2009 05:52:14 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: "David S. Miller" <davem@...emloft.net>
CC: Linux Netdev List <netdev@...r.kernel.org>,
Yoshifuji Hideaki <yoshfuji@...ux-ipv6.org>
Subject: [PATCH 2/2 net-next-2.6] ipv6 sit: RCU conversion phase II
SIT 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@...il.com>
---
net/ipv6/sit.c | 45 +++++++++++++++++++++++++++------------------
1 files changed, 27 insertions(+), 18 deletions(-)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 8cdcc2a..b6b1626 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -77,8 +77,17 @@ struct sit_net {
struct net_device *fb_tunnel_dev;
};
-static DEFINE_RWLOCK(ipip6_lock);
+/*
+ * Locking : hash tables are protected by RCU and a spinlock
+ */
+static DEFINE_SPINLOCK(ipip6_lock);
+
+#define for_each_ip_tunnel_rcu(start) \
+ for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
+/*
+ * Must be invoked with rcu_read_lock
+ */
static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
struct net_device *dev, __be32 remote, __be32 local)
{
@@ -87,26 +96,26 @@ static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
struct ip_tunnel *t;
struct sit_net *sitn = net_generic(net, sit_net_id);
- for (t = sitn->tunnels_r_l[h0^h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(sitn->tunnels_r_l[h0 ^ h1]) {
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr &&
(!dev || !t->parms.link || dev->iflink == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
- for (t = sitn->tunnels_r[h0]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(sitn->tunnels_r[h0]) {
if (remote == t->parms.iph.daddr &&
(!dev || !t->parms.link || dev->iflink == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
- for (t = sitn->tunnels_l[h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(sitn->tunnels_l[h1]) {
if (local == t->parms.iph.saddr &&
(!dev || !t->parms.link || dev->iflink == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
- t = sitn->tunnels_wc[0];
+ t = rcu_dereference(sitn->tunnels_wc[0]);
if ((t != NULL) && (t->dev->flags & IFF_UP))
return t;
return NULL;
@@ -143,9 +152,9 @@ static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
if (t == *tp) {
- write_lock_bh(&ipip6_lock);
+ spin_lock_bh(&ipip6_lock);
*tp = t->next;
- write_unlock_bh(&ipip6_lock);
+ spin_unlock_bh(&ipip6_lock);
break;
}
}
@@ -155,10 +164,10 @@ static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
{
struct ip_tunnel **tp = ipip6_bucket(sitn, t);
+ spin_lock_bh(&ipip6_lock);
t->next = *tp;
- write_lock_bh(&ipip6_lock);
- *tp = t;
- write_unlock_bh(&ipip6_lock);
+ rcu_assign_pointer(*tp, t);
+ spin_unlock_bh(&ipip6_lock);
}
static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
@@ -447,9 +456,9 @@ static void ipip6_tunnel_uninit(struct net_device *dev)
struct sit_net *sitn = net_generic(net, sit_net_id);
if (dev == sitn->fb_tunnel_dev) {
- write_lock_bh(&ipip6_lock);
+ spin_lock_bh(&ipip6_lock);
sitn->tunnels_wc[0] = NULL;
- write_unlock_bh(&ipip6_lock);
+ spin_unlock_bh(&ipip6_lock);
dev_put(dev);
} else {
ipip6_tunnel_unlink(sitn, netdev_priv(dev));
@@ -502,7 +511,7 @@ static int ipip6_err(struct sk_buff *skb, u32 info)
err = -ENOENT;
- read_lock(&ipip6_lock);
+ rcu_read_lock();
t = ipip6_tunnel_lookup(dev_net(skb->dev),
skb->dev,
iph->daddr,
@@ -520,7 +529,7 @@ static int ipip6_err(struct sk_buff *skb, u32 info)
t->err_count = 1;
t->err_time = jiffies;
out:
- read_unlock(&ipip6_lock);
+ rcu_read_unlock();
return err;
}
@@ -540,7 +549,7 @@ static int ipip6_rcv(struct sk_buff *skb)
iph = ip_hdr(skb);
- read_lock(&ipip6_lock);
+ rcu_read_lock();
tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
iph->saddr, iph->daddr);
if (tunnel != NULL) {
@@ -554,7 +563,7 @@ static int ipip6_rcv(struct sk_buff *skb)
if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
!isatap_chksrc(skb, iph, tunnel)) {
tunnel->dev->stats.rx_errors++;
- read_unlock(&ipip6_lock);
+ rcu_read_unlock();
kfree_skb(skb);
return 0;
}
@@ -565,12 +574,12 @@ static int ipip6_rcv(struct sk_buff *skb)
nf_reset(skb);
ipip6_ecn_decapsulate(iph, skb);
netif_rx(skb);
- read_unlock(&ipip6_lock);
+ rcu_read_unlock();
return 0;
}
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
- read_unlock(&ipip6_lock);
+ rcu_read_unlock();
out:
kfree_skb(skb);
return 0;
--
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