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Commit 3a43be3c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

sit: get rid of ipip6_lock 



As RTNL is held while doing tunnels inserts and deletes, we can remove
ipip6_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 1507850b

net/ipv6/sit.c

+31 −33
Original line number Diff line number Diff line
@@ -68,19 +68,18 @@ static void ipip6_tunnel_setup(struct net_device *dev); 


static int sit_net_id __read_mostly;

struct sit_net {

	struct ip_tunnel *tunnels_r_l[HASH_SIZE];

	struct ip_tunnel *tunnels_r[HASH_SIZE];

	struct ip_tunnel *tunnels_l[HASH_SIZE];

	struct ip_tunnel *tunnels_wc[1];

	struct ip_tunnel **tunnels[4];

	struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];

	struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];

	struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];

	struct ip_tunnel __rcu *tunnels_wc[1];

	struct ip_tunnel __rcu **tunnels[4];



	struct net_device *fb_tunnel_dev;

};



/*

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

 * Locking : hash tables are protected by RCU and RTNL

 */

static DEFINE_SPINLOCK(ipip6_lock);



#define for_each_ip_tunnel_rcu(start) \

	for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
@@ -91,8 +90,8 @@ static DEFINE_SPINLOCK(ipip6_lock); 
static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,

		struct net_device *dev, __be32 remote, __be32 local)

{

	unsigned h0 = HASH(remote);

	unsigned h1 = HASH(local);

	unsigned int h0 = HASH(remote);

	unsigned int h1 = HASH(local);

	struct ip_tunnel *t;

	struct sit_net *sitn = net_generic(net, sit_net_id);
@@ -121,12 +120,12 @@ static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net, 
	return NULL;

}



static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,

static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,

		struct ip_tunnel_parm *parms)

{

	__be32 remote = parms->iph.daddr;

	__be32 local = parms->iph.saddr;

	unsigned h = 0;

	unsigned int h = 0;

	int prio = 0;



	if (remote) {
@@ -140,7 +139,7 @@ static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn, 
	return &sitn->tunnels[prio][h];

}



static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,

static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,

		struct ip_tunnel *t)

{

	return __ipip6_bucket(sitn, &t->parms);
@@ -148,13 +147,14 @@ static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn, 


static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)

{

	struct ip_tunnel **tp;



	for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {

		if (t == *tp) {

			spin_lock_bh(&ipip6_lock);

			*tp = t->next;

			spin_unlock_bh(&ipip6_lock);

	struct ip_tunnel __rcu **tp;

	struct ip_tunnel *iter;



	for (tp = ipip6_bucket(sitn, t);

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

	     tp = &iter->next) {

		if (t == iter) {

			rcu_assign_pointer(*tp, t->next);

			break;

		}

	}
@@ -162,12 +162,10 @@ static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t) 


static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)

{

	struct ip_tunnel **tp = ipip6_bucket(sitn, t);

	struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);



	spin_lock_bh(&ipip6_lock);

	t->next = *tp;

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

	rcu_assign_pointer(*tp, t);

	spin_unlock_bh(&ipip6_lock);

}



static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
@@ -192,12 +190,15 @@ static struct ip_tunnel * ipip6_tunnel_locate(struct net *net, 
{

	__be32 remote = parms->iph.daddr;

	__be32 local = parms->iph.saddr;

	struct ip_tunnel *t, **tp, *nt;

	struct ip_tunnel *t, *nt;

	struct ip_tunnel __rcu **tp;

	struct net_device *dev;

	char name[IFNAMSIZ];

	struct sit_net *sitn = net_generic(net, sit_net_id);



	for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {

	for (tp = __ipip6_bucket(sitn, parms);

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

	     tp = &t->next) {

		if (local == t->parms.iph.saddr &&

		    remote == t->parms.iph.daddr &&

		    parms->link == t->parms.link) {
@@ -340,7 +341,7 @@ ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg) 


	ASSERT_RTNL();



	for (p = t->prl; p; p = p->next) {

	for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {

		if (p->addr == a->addr) {

			if (chg) {

				p->flags = a->flags;
@@ -451,15 +452,12 @@ 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) {

		spin_lock_bh(&ipip6_lock);

		sitn->tunnels_wc[0] = NULL;

		spin_unlock_bh(&ipip6_lock);

		dev_put(dev);

		rcu_assign_pointer(sitn->tunnels_wc[0], NULL);

	} else {

		ipip6_tunnel_unlink(sitn, netdev_priv(dev));

		ipip6_tunnel_del_prl(netdev_priv(dev), NULL);

		dev_put(dev);

	}

	dev_put(dev);

}
@@ -590,7 +588,7 @@ __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel) 
#ifdef CONFIG_IPV6_SIT_6RD

	if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,

			      tunnel->ip6rd.prefixlen)) {

		unsigned pbw0, pbi0;

		unsigned int pbw0, pbi0;

		int pbi1;

		u32 d;