From b7285b7912776a4492744949c747c88d539006fa Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 15 Sep 2010 11:07:24 +0000 Subject: [PATCH] ipip: get rid of ipip_lock As RTNL is held while doing tunnels inserts and deletes, we can remove ipip_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/ipv4/ipip.c | 67 +++++++++++++++++++++++++------------------------ 1 file changed, 34 insertions(+), 33 deletions(-) diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 3c6f8f3968a..8de8888dc95 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -122,11 +122,11 @@ static int ipip_net_id __read_mostly; struct ipip_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; }; @@ -135,9 +135,8 @@ static void ipip_tunnel_init(struct net_device *dev); static void ipip_tunnel_setup(struct net_device *dev); /* - * Locking : hash tables are protected by RCU and a spinlock + * Locking : hash tables are protected by RCU and RTNL */ -static DEFINE_SPINLOCK(ipip_lock); #define for_each_ip_tunnel_rcu(start) \ for (t = rcu_dereference(start); t; t = rcu_dereference(t->next)) @@ -145,8 +144,8 @@ static DEFINE_SPINLOCK(ipip_lock); static struct ip_tunnel * ipip_tunnel_lookup(struct net *net, __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 ipip_net *ipn = net_generic(net, ipip_net_id); @@ -169,12 +168,12 @@ static struct ip_tunnel * ipip_tunnel_lookup(struct net *net, return NULL; } -static struct ip_tunnel **__ipip_bucket(struct ipip_net *ipn, +static struct ip_tunnel __rcu **__ipip_bucket(struct ipip_net *ipn, 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) { @@ -188,7 +187,7 @@ static struct ip_tunnel **__ipip_bucket(struct ipip_net *ipn, return &ipn->tunnels[prio][h]; } -static inline struct ip_tunnel **ipip_bucket(struct ipip_net *ipn, +static inline struct ip_tunnel __rcu **ipip_bucket(struct ipip_net *ipn, struct ip_tunnel *t) { return __ipip_bucket(ipn, &t->parms); @@ -196,13 +195,14 @@ static inline struct ip_tunnel **ipip_bucket(struct ipip_net *ipn, static void ipip_tunnel_unlink(struct ipip_net *ipn, struct ip_tunnel *t) { - struct ip_tunnel **tp; - - for (tp = ipip_bucket(ipn, t); *tp; tp = &(*tp)->next) { - if (t == *tp) { - spin_lock_bh(&ipip_lock); - *tp = t->next; - spin_unlock_bh(&ipip_lock); + struct ip_tunnel __rcu **tp; + struct ip_tunnel *iter; + + for (tp = ipip_bucket(ipn, t); + (iter = rtnl_dereference(*tp)) != NULL; + tp = &iter->next) { + if (t == iter) { + rcu_assign_pointer(*tp, t->next); break; } } @@ -210,12 +210,10 @@ static void ipip_tunnel_unlink(struct ipip_net *ipn, struct ip_tunnel *t) static void ipip_tunnel_link(struct ipip_net *ipn, struct ip_tunnel *t) { - struct ip_tunnel **tp = ipip_bucket(ipn, t); + struct ip_tunnel __rcu **tp = ipip_bucket(ipn, t); - spin_lock_bh(&ipip_lock); - t->next = *tp; + rcu_assign_pointer(t->next, rtnl_dereference(*tp)); rcu_assign_pointer(*tp, t); - spin_unlock_bh(&ipip_lock); } static struct ip_tunnel * ipip_tunnel_locate(struct net *net, @@ -223,12 +221,15 @@ static struct ip_tunnel * ipip_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 ipip_net *ipn = net_generic(net, ipip_net_id); - for (tp = __ipip_bucket(ipn, parms); (t = *tp) != NULL; tp = &t->next) { + for (tp = __ipip_bucket(ipn, parms); + (t = rtnl_dereference(*tp)) != NULL; + tp = &t->next) { if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) return t; } @@ -268,16 +269,15 @@ failed_free: return NULL; } +/* called with RTNL */ static void ipip_tunnel_uninit(struct net_device *dev) { struct net *net = dev_net(dev); struct ipip_net *ipn = net_generic(net, ipip_net_id); - if (dev == ipn->fb_tunnel_dev) { - spin_lock_bh(&ipip_lock); - ipn->tunnels_wc[0] = NULL; - spin_unlock_bh(&ipip_lock); - } else + if (dev == ipn->fb_tunnel_dev) + rcu_assign_pointer(ipn->tunnels_wc[0], NULL); + else ipip_tunnel_unlink(ipn, netdev_priv(dev)); dev_put(dev); } @@ -741,7 +741,7 @@ static void __net_init ipip_fb_tunnel_init(struct net_device *dev) iph->ihl = 5; dev_hold(dev); - ipn->tunnels_wc[0] = tunnel; + rcu_assign_pointer(ipn->tunnels_wc[0], tunnel); } static struct xfrm_tunnel ipip_handler __read_mostly = { @@ -760,11 +760,12 @@ static void ipip_destroy_tunnels(struct ipip_net *ipn, struct list_head *head) for (prio = 1; prio < 4; prio++) { int h; for (h = 0; h < HASH_SIZE; h++) { - struct ip_tunnel *t = ipn->tunnels[prio][h]; + struct ip_tunnel *t; + t = rtnl_dereference(ipn->tunnels[prio][h]); while (t != NULL) { unregister_netdevice_queue(t->dev, head); - t = t->next; + t = rtnl_dereference(t->next); } } } -- 2.20.1