From 3a43be3c328ff42327da0b141de360dc4587aab7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 15 Sep 2010 11:35:10 +0000 Subject: [PATCH] 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: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv6/sit.c | 64 ++++++++++++++++++++++++-------------------------- 1 file changed, 31 insertions(+), 33 deletions(-) diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 86618eb30335..6822481ff766 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -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) @@ -187,17 +185,20 @@ static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn) #endif } -static struct ip_tunnel * ipip6_tunnel_locate(struct net *net, +static struct ip_tunnel *ipip6_tunnel_locate(struct net *net, struct ip_tunnel_parm *parms, int create) { __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; -- 2.30.2