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Commit 94767632 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ip6tnl: get rid of ip6_tnl_lock 



As RTNL is held while doing tunnels inserts and deletes, we can remove
ip6_tnl_lock spinlock. My initial RCU conversion was conservative and
converted the rwlock to spinlock, with no RTNL requirement.

Use appropriate rcu annotations and modern lockdep checks as well.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent caeda9b9

net/ipv6/ip6_tunnel.c

+28 −30
Original line number Diff line number Diff line
@@ -83,15 +83,14 @@ struct ip6_tnl_net { 
	/* the IPv6 tunnel fallback device */

	struct net_device *fb_tnl_dev;

	/* lists for storing tunnels in use */

	struct ip6_tnl *tnls_r_l[HASH_SIZE];

	struct ip6_tnl *tnls_wc[1];

	struct ip6_tnl **tnls[2];

	struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];

	struct ip6_tnl __rcu *tnls_wc[1];

	struct ip6_tnl __rcu **tnls[2];

};



/*

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

 * Locking : hash tables are protected by RCU and RTNL

 */

static DEFINE_SPINLOCK(ip6_tnl_lock);



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

{
@@ -138,8 +137,8 @@ static inline void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst) 
static struct ip6_tnl *

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

{

	unsigned h0 = HASH(remote);

	unsigned h1 = HASH(local);

	unsigned int h0 = HASH(remote);

	unsigned int h1 = HASH(local);

	struct ip6_tnl *t;

	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
@@ -167,7 +166,7 @@ ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local) 
 * Return: head of IPv6 tunnel list

 **/



static struct ip6_tnl **

static struct ip6_tnl __rcu **

ip6_tnl_bucket(struct ip6_tnl_net *ip6n, struct ip6_tnl_parm *p)

{

	struct in6_addr *remote = &p->raddr;
@@ -190,12 +189,10 @@ ip6_tnl_bucket(struct ip6_tnl_net *ip6n, struct ip6_tnl_parm *p) 
static void

ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)

{

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

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



	spin_lock_bh(&ip6_tnl_lock);

	t->next = *tp;

	rcu_assign_pointer(t->next , rtnl_dereference(*tp));

	rcu_assign_pointer(*tp, t);

	spin_unlock_bh(&ip6_tnl_lock);

}



/**
@@ -206,13 +203,14 @@ ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t) 
static void

ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)

{

	struct ip6_tnl **tp;



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

		if (t == *tp) {

			spin_lock_bh(&ip6_tnl_lock);

			*tp = t->next;

			spin_unlock_bh(&ip6_tnl_lock);

	struct ip6_tnl __rcu **tp;

	struct ip6_tnl *iter;



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

	     (iter = rtnl_dereference(*tp)) != NULL;

	     tp = &iter->next) {

		if (t == iter) {

			rcu_assign_pointer(*tp, t->next);

			break;

		}

	}
@@ -290,10 +288,13 @@ static struct ip6_tnl *ip6_tnl_locate(struct net *net, 
{

	struct in6_addr *remote = &p->raddr;

	struct in6_addr *local = &p->laddr;

	struct ip6_tnl __rcu **tp;

	struct ip6_tnl *t;

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



	for (t = *ip6_tnl_bucket(ip6n, p); t; t = t->next) {

	for (tp = ip6_tnl_bucket(ip6n, p);

	     (t = rtnl_dereference(*tp)) != NULL;

	     tp = &t->next) {

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

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

			return t;
@@ -318,13 +319,10 @@ ip6_tnl_dev_uninit(struct net_device *dev) 
	struct net *net = dev_net(dev);

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



	if (dev == ip6n->fb_tnl_dev) {

		spin_lock_bh(&ip6_tnl_lock);

		ip6n->tnls_wc[0] = NULL;

		spin_unlock_bh(&ip6_tnl_lock);

	} else {

	if (dev == ip6n->fb_tnl_dev)

		rcu_assign_pointer(ip6n->tnls_wc[0], NULL);

	else

		ip6_tnl_unlink(ip6n, t);

	}

	ip6_tnl_dst_reset(t);

	dev_put(dev);

}
@@ -1369,7 +1367,7 @@ static void __net_init ip6_fb_tnl_dev_init(struct net_device *dev) 
	ip6_tnl_dev_init_gen(dev);

	t->parms.proto = IPPROTO_IPV6;

	dev_hold(dev);

	ip6n->tnls_wc[0] = t;

	rcu_assign_pointer(ip6n->tnls_wc[0], t);

}



static struct xfrm6_tunnel ip4ip6_handler __read_mostly = {
@@ -1391,14 +1389,14 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct ip6_tnl_net *ip6n) 
	LIST_HEAD(list);



	for (h = 0; h < HASH_SIZE; h++) {

		t = ip6n->tnls_r_l[h];

		t = rtnl_dereference(ip6n->tnls_r_l[h]);

		while (t != NULL) {

			unregister_netdevice_queue(t->dev, &list);

			t = t->next;

			t = rtnl_dereference(t->next);

		}

	}



	t = ip6n->tnls_wc[0];

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

	unregister_netdevice_queue(t->dev, &list);

	unregister_netdevice_many(&list);

}