From 8f95dd63a2ab6fe7243c4f0bd2c3266e3a5525ab Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 23 Oct 2009 05:42:02 +0000 Subject: [PATCH] ipip: convert hash tables locking to RCU IPIP tunnels use one rwlock to protect their hash tables. This locking scheme can be converted to RCU for free, since netdevice already must wait for a RCU grace period at dismantle time. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ipip.c | 49 ++++++++++++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 21 deletions(-) diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 6a5539236ab3..3bd69988bccf 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -134,7 +134,13 @@ static void ipip_fb_tunnel_init(struct net_device *dev); static void ipip_tunnel_init(struct net_device *dev); static void ipip_tunnel_setup(struct net_device *dev); -static DEFINE_RWLOCK(ipip_lock); +/* + * Locking : hash tables are protected by RCU and a spinlock + */ +static DEFINE_SPINLOCK(ipip_lock); + +#define for_each_ip_tunnel_rcu(start) \ + for (t = rcu_dereference(start); t; t = rcu_dereference(t->next)) static struct ip_tunnel * ipip_tunnel_lookup(struct net *net, __be32 remote, __be32 local) @@ -144,20 +150,21 @@ static struct ip_tunnel * ipip_tunnel_lookup(struct net *net, struct ip_tunnel *t; struct ipip_net *ipn = net_generic(net, ipip_net_id); - for (t = ipn->tunnels_r_l[h0^h1]; t; t = t->next) { + for_each_ip_tunnel_rcu(ipn->tunnels_r_l[h0 ^ h1]) if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP)) return t; - } - for (t = ipn->tunnels_r[h0]; t; t = t->next) { + + for_each_ip_tunnel_rcu(ipn->tunnels_r[h0]) if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP)) return t; - } - for (t = ipn->tunnels_l[h1]; t; t = t->next) { + + for_each_ip_tunnel_rcu(ipn->tunnels_l[h1]) if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP)) return t; - } - if ((t = ipn->tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP)) + + t = rcu_dereference(ipn->tunnels_wc[0]); + if (t && (t->dev->flags&IFF_UP)) return t; return NULL; } @@ -193,9 +200,9 @@ static void ipip_tunnel_unlink(struct ipip_net *ipn, struct ip_tunnel *t) for (tp = ipip_bucket(ipn, t); *tp; tp = &(*tp)->next) { if (t == *tp) { - write_lock_bh(&ipip_lock); + spin_lock_bh(&ipip_lock); *tp = t->next; - write_unlock_bh(&ipip_lock); + spin_unlock_bh(&ipip_lock); break; } } @@ -205,10 +212,10 @@ static void ipip_tunnel_link(struct ipip_net *ipn, struct ip_tunnel *t) { struct ip_tunnel **tp = ipip_bucket(ipn, t); + spin_lock_bh(&ipip_lock); t->next = *tp; - write_lock_bh(&ipip_lock); - *tp = t; - write_unlock_bh(&ipip_lock); + rcu_assign_pointer(*tp, t); + spin_unlock_bh(&ipip_lock); } static struct ip_tunnel * ipip_tunnel_locate(struct net *net, @@ -267,9 +274,9 @@ static void ipip_tunnel_uninit(struct net_device *dev) struct ipip_net *ipn = net_generic(net, ipip_net_id); if (dev == ipn->fb_tunnel_dev) { - write_lock_bh(&ipip_lock); + spin_lock_bh(&ipip_lock); ipn->tunnels_wc[0] = NULL; - write_unlock_bh(&ipip_lock); + spin_unlock_bh(&ipip_lock); } else ipip_tunnel_unlink(ipn, netdev_priv(dev)); dev_put(dev); @@ -318,7 +325,7 @@ static int ipip_err(struct sk_buff *skb, u32 info) err = -ENOENT; - read_lock(&ipip_lock); + rcu_read_lock(); t = ipip_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr); if (t == NULL || t->parms.iph.daddr == 0) goto out; @@ -333,7 +340,7 @@ static int ipip_err(struct sk_buff *skb, u32 info) t->err_count = 1; t->err_time = jiffies; out: - read_unlock(&ipip_lock); + rcu_read_unlock(); return err; } @@ -351,11 +358,11 @@ static int ipip_rcv(struct sk_buff *skb) struct ip_tunnel *tunnel; const struct iphdr *iph = ip_hdr(skb); - read_lock(&ipip_lock); + rcu_read_lock(); if ((tunnel = ipip_tunnel_lookup(dev_net(skb->dev), iph->saddr, iph->daddr)) != NULL) { if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { - read_unlock(&ipip_lock); + rcu_read_unlock(); kfree_skb(skb); return 0; } @@ -374,10 +381,10 @@ static int ipip_rcv(struct sk_buff *skb) nf_reset(skb); ipip_ecn_decapsulate(iph, skb); netif_rx(skb); - read_unlock(&ipip_lock); + rcu_read_unlock(); return 0; } - read_unlock(&ipip_lock); + rcu_read_unlock(); return -1; } -- 2.20.1