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ip6tnl: get rid of ip6_tnl_lock

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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-15 20:25:34 +00:00 • committed by David S. Miller
commit 9476763262
1 changed files with 27 additions and 29 deletions
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56
net/ipv6/ip6_tunnel.c
View file

@ -83,15 +83,14 @@ struct ip6_tnl_net {
/* the IPv6 tunnel fallback device */ /* the IPv6 tunnel fallback device */
struct net_device *fb_tnl_dev; struct net_device *fb_tnl_dev;
/* lists for storing tunnels in use */ /* lists for storing tunnels in use */
struct ip6_tnl *tnls_r_l[HASH_SIZE]; struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];
struct ip6_tnl *tnls_wc[1]; struct ip6_tnl __rcu *tnls_wc[1];
struct ip6_tnl **tnls[2]; 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) 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 * static struct ip6_tnl *
ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local) ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local)
{ {
unsigned h0 = HASH(remote); unsigned int h0 = HASH(remote);
unsigned h1 = HASH(local); unsigned int h1 = HASH(local);
struct ip6_tnl *t; struct ip6_tnl *t;
struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id); 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 * 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) ip6_tnl_bucket(struct ip6_tnl_net *ip6n, struct ip6_tnl_parm *p)
{ {
struct in6_addr *remote = &p->raddr; 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 static void
ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t) 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); rcu_assign_pointer(t->next , rtnl_dereference(*tp));
t->next = *tp;
rcu_assign_pointer(*tp, t); 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 static void
ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t) ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
{ {
struct ip6_tnl **tp; struct ip6_tnl __rcu **tp;
struct ip6_tnl *iter;
for (tp = ip6_tnl_bucket(ip6n, &t->parms); *tp; tp = &(*tp)->next) { for (tp = ip6_tnl_bucket(ip6n, &t->parms);
if (t == *tp) { (iter = rtnl_dereference(*tp)) != NULL;
spin_lock_bh(&ip6_tnl_lock); tp = &iter->next) {
*tp = t->next; if (t == iter) {
spin_unlock_bh(&ip6_tnl_lock); rcu_assign_pointer(*tp, t->next);
break; break;
} }
} }
@ -290,10 +288,13 @@ static struct ip6_tnl *ip6_tnl_locate(struct net *net,
{ {
struct in6_addr *remote = &p->raddr; struct in6_addr *remote = &p->raddr;
struct in6_addr *local = &p->laddr; struct in6_addr *local = &p->laddr;
struct ip6_tnl __rcu **tp;
struct ip6_tnl *t; struct ip6_tnl *t;
struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id); 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) && if (ipv6_addr_equal(local, &t->parms.laddr) &&
ipv6_addr_equal(remote, &t->parms.raddr)) ipv6_addr_equal(remote, &t->parms.raddr))
return t; return t;
@ -318,13 +319,10 @@ ip6_tnl_dev_uninit(struct net_device *dev)
struct net *net = dev_net(dev); struct net *net = dev_net(dev);
struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id); struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
if (dev == ip6n->fb_tnl_dev) { if (dev == ip6n->fb_tnl_dev)
spin_lock_bh(&ip6_tnl_lock); rcu_assign_pointer(ip6n->tnls_wc[0], NULL);
ip6n->tnls_wc[0] = NULL; else
spin_unlock_bh(&ip6_tnl_lock);
} else {
ip6_tnl_unlink(ip6n, t); ip6_tnl_unlink(ip6n, t);
}
ip6_tnl_dst_reset(t); ip6_tnl_dst_reset(t);
dev_put(dev); 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); ip6_tnl_dev_init_gen(dev);
t->parms.proto = IPPROTO_IPV6; t->parms.proto = IPPROTO_IPV6;
dev_hold(dev); dev_hold(dev);
ip6n->tnls_wc[0] = t; rcu_assign_pointer(ip6n->tnls_wc[0], t);
} }
static struct xfrm6_tunnel ip4ip6_handler __read_mostly = { 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); LIST_HEAD(list);
for (h = 0; h < HASH_SIZE; h++) { for (h = 0; h < HASH_SIZE; h++) {
t = ip6n->tnls_r_l[h]; t = rtnl_dereference(ip6n->tnls_r_l[h]);
while (t != NULL) { while (t != NULL) {
unregister_netdevice_queue(t->dev, &list); 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_queue(t->dev, &list);
unregister_netdevice_many(&list); unregister_netdevice_many(&list);
} }