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Commit 4543c10d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ef9a9d11

net/ipv6/sit.c

+27 −18
Original line number Diff line number Diff line
@@ -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;