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Commit 2922bc8a authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ip6tnl: convert hash tables locking to RCU 



ip6_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 8f95dd63

net/ipv6/ip6_tunnel.c

+25 −19
Original line number Diff line number Diff line
@@ -88,8 +88,10 @@ struct ip6_tnl_net { 
	struct ip6_tnl **tnls[2];

};



/* lock for the tunnel lists */

static DEFINE_RWLOCK(ip6_tnl_lock);

/*

 * Locking : hash tables are protected by RCU and a spinlock

 */

static DEFINE_SPINLOCK(ip6_tnl_lock);



static inline struct dst_entry *ip6_tnl_dst_check(struct ip6_tnl *t)

{
@@ -130,6 +132,9 @@ static inline void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst) 
 *   else %NULL

 **/



#define for_each_ip6_tunnel_rcu(start) \

	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))



static struct ip6_tnl *

ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local)

{
@@ -138,13 +143,14 @@ ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local) 
	struct ip6_tnl *t;

	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);



	for (t = ip6n->tnls_r_l[h0 ^ h1]; t; t = t->next) {

	for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[h0 ^ h1]) {

		if (ipv6_addr_equal(local, &t->parms.laddr) &&

		    ipv6_addr_equal(remote, &t->parms.raddr) &&

		    (t->dev->flags & IFF_UP))

			return t;

	}

	if ((t = ip6n->tnls_wc[0]) != NULL && (t->dev->flags & IFF_UP))

	t = rcu_dereference(ip6n->tnls_wc[0]);

	if (t && (t->dev->flags & IFF_UP))

		return t;



	return NULL;
@@ -186,10 +192,10 @@ ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t) 
{

	struct ip6_tnl **tp = ip6_tnl_bucket(ip6n, &t->parms);



	spin_lock_bh(&ip6_tnl_lock);

	t->next = *tp;

	write_lock_bh(&ip6_tnl_lock);

	*tp = t;

	write_unlock_bh(&ip6_tnl_lock);

	rcu_assign_pointer(*tp, t);

	spin_unlock_bh(&ip6_tnl_lock);

}



/**
@@ -204,9 +210,9 @@ ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t) 


	for (tp = ip6_tnl_bucket(ip6n, &t->parms); *tp; tp = &(*tp)->next) {

		if (t == *tp) {

			write_lock_bh(&ip6_tnl_lock);

			spin_lock_bh(&ip6_tnl_lock);

			*tp = t->next;

			write_unlock_bh(&ip6_tnl_lock);

			spin_unlock_bh(&ip6_tnl_lock);

			break;

		}

	}
@@ -313,9 +319,9 @@ ip6_tnl_dev_uninit(struct net_device *dev) 
	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);



	if (dev == ip6n->fb_tnl_dev) {

		write_lock_bh(&ip6_tnl_lock);

		spin_lock_bh(&ip6_tnl_lock);

		ip6n->tnls_wc[0] = NULL;

		write_unlock_bh(&ip6_tnl_lock);

		spin_unlock_bh(&ip6_tnl_lock);

	} else {

		ip6_tnl_unlink(ip6n, t);

	}
@@ -409,7 +415,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt, 
	   in trouble since we might need the source address for further

	   processing of the error. */



	read_lock(&ip6_tnl_lock);

	rcu_read_lock();

	if ((t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->daddr,

					&ipv6h->saddr)) == NULL)

		goto out;
@@ -482,7 +488,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt, 
	*msg = rel_msg;



out:

	read_unlock(&ip6_tnl_lock);

	rcu_read_unlock();

	return err;

}
@@ -693,23 +699,23 @@ static int ip6_tnl_rcv(struct sk_buff *skb, __u16 protocol, 
	struct ip6_tnl *t;

	struct ipv6hdr *ipv6h = ipv6_hdr(skb);



	read_lock(&ip6_tnl_lock);

	rcu_read_lock();



	if ((t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr,

					&ipv6h->daddr)) != NULL) {

		if (t->parms.proto != ipproto && t->parms.proto != 0) {

			read_unlock(&ip6_tnl_lock);

			rcu_read_unlock();

			goto discard;

		}



		if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {

			read_unlock(&ip6_tnl_lock);

			rcu_read_unlock();

			goto discard;

		}



		if (!ip6_tnl_rcv_ctl(t)) {

			t->dev->stats.rx_dropped++;

			read_unlock(&ip6_tnl_lock);

			rcu_read_unlock();

			goto discard;

		}

		secpath_reset(skb);
@@ -727,10 +733,10 @@ static int ip6_tnl_rcv(struct sk_buff *skb, __u16 protocol, 
		t->dev->stats.rx_packets++;

		t->dev->stats.rx_bytes += skb->len;

		netif_rx(skb);

		read_unlock(&ip6_tnl_lock);

		rcu_read_unlock();

		return 0;

	}

	read_unlock(&ip6_tnl_lock);

	rcu_read_unlock();

	return 1;



discard: