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authorEric Dumazet <eric.dumazet@gmail.com>2009-10-23 06:14:38 +0000
committerDavid S. Miller <davem@davemloft.net>2009-10-24 06:07:59 -0700
commit8d5b2c084d2e71587e30a6ef528a8a8051e59dcd (patch)
treea66dd86d178eb5ce50a1704e085542ae3516e398 /net/ipv4
parent2922bc8aedfcd41ca6171cfe1a79ff111ad72019 (diff)
gre: convert hash tables locking to RCU
GRE 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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_gre.c40
1 files changed, 23 insertions, 17 deletions
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 89ff9d5b150..40f04391523 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -156,8 +156,13 @@ struct ipgre_net {
#define tunnels_r tunnels[2]
#define tunnels_l tunnels[1]
#define tunnels_wc tunnels[0]
+/*
+ * Locking : hash tables are protected by RCU and a spinlock
+ */
+static DEFINE_SPINLOCK(ipgre_lock);
-static DEFINE_RWLOCK(ipgre_lock);
+#define for_each_ip_tunnel_rcu(start) \
+ for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
/* Given src, dst and key, find appropriate for input tunnel. */
@@ -175,7 +180,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
ARPHRD_ETHER : ARPHRD_IPGRE;
int score, cand_score = 4;
- for (t = ign->tunnels_r_l[h0^h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(ign->tunnels_r_l[h0 ^ h1]) {
if (local != t->parms.iph.saddr ||
remote != t->parms.iph.daddr ||
key != t->parms.i_key ||
@@ -200,7 +205,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
}
}
- for (t = ign->tunnels_r[h0^h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(ign->tunnels_r[h0 ^ h1]) {
if (remote != t->parms.iph.daddr ||
key != t->parms.i_key ||
!(t->dev->flags & IFF_UP))
@@ -224,7 +229,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
}
}
- for (t = ign->tunnels_l[h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(ign->tunnels_l[h1]) {
if ((local != t->parms.iph.saddr &&
(local != t->parms.iph.daddr ||
!ipv4_is_multicast(local))) ||
@@ -250,7 +255,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
}
}
- for (t = ign->tunnels_wc[h1]; t; t = t->next) {
+ for_each_ip_tunnel_rcu(ign->tunnels_wc[h1]) {
if (t->parms.i_key != key ||
!(t->dev->flags & IFF_UP))
continue;
@@ -276,8 +281,9 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
if (cand != NULL)
return cand;
- if (ign->fb_tunnel_dev->flags & IFF_UP)
- return netdev_priv(ign->fb_tunnel_dev);
+ dev = ign->fb_tunnel_dev;
+ if (dev->flags & IFF_UP)
+ return netdev_priv(dev);
return NULL;
}
@@ -311,10 +317,10 @@ static void ipgre_tunnel_link(struct ipgre_net *ign, struct ip_tunnel *t)
{
struct ip_tunnel **tp = ipgre_bucket(ign, t);
+ spin_lock_bh(&ipgre_lock);
t->next = *tp;
- write_lock_bh(&ipgre_lock);
- *tp = t;
- write_unlock_bh(&ipgre_lock);
+ rcu_assign_pointer(*tp, t);
+ spin_unlock_bh(&ipgre_lock);
}
static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
@@ -323,9 +329,9 @@ static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
for (tp = ipgre_bucket(ign, t); *tp; tp = &(*tp)->next) {
if (t == *tp) {
- write_lock_bh(&ipgre_lock);
+ spin_lock_bh(&ipgre_lock);
*tp = t->next;
- write_unlock_bh(&ipgre_lock);
+ spin_unlock_bh(&ipgre_lock);
break;
}
}
@@ -476,7 +482,7 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
break;
}
- read_lock(&ipgre_lock);
+ rcu_read_lock();
t = ipgre_tunnel_lookup(skb->dev, iph->daddr, iph->saddr,
flags & GRE_KEY ?
*(((__be32 *)p) + (grehlen / 4) - 1) : 0,
@@ -494,7 +500,7 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
t->err_count = 1;
t->err_time = jiffies;
out:
- read_unlock(&ipgre_lock);
+ rcu_read_unlock();
return;
}
@@ -573,7 +579,7 @@ static int ipgre_rcv(struct sk_buff *skb)
gre_proto = *(__be16 *)(h + 2);
- read_lock(&ipgre_lock);
+ rcu_read_lock();
if ((tunnel = ipgre_tunnel_lookup(skb->dev,
iph->saddr, iph->daddr, key,
gre_proto))) {
@@ -647,13 +653,13 @@ static int ipgre_rcv(struct sk_buff *skb)
ipgre_ecn_decapsulate(iph, skb);
netif_rx(skb);
- read_unlock(&ipgre_lock);
+ rcu_read_unlock();
return(0);
}
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
drop:
- read_unlock(&ipgre_lock);
+ rcu_read_unlock();
drop_nolock:
kfree_skb(skb);
return(0);