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Date: Thu, 16 Sep 2010 08:25:34 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next-2.6] ip6tnl: get rid of ip6_tnl_lock
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@...il.com>
---
net/ipv6/ip6_tunnel.c | 58 +++++++++++++++++++---------------------
1 files changed, 28 insertions(+), 30 deletions(-)
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 29f99dd..9289cec 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -83,15 +83,14 @@ struct ip6_tnl_net {
/* the IPv6 tunnel fallback device */
struct net_device *fb_tnl_dev;
/* lists for storing tunnels in use */
- struct ip6_tnl *tnls_r_l[HASH_SIZE];
- struct ip6_tnl *tnls_wc[1];
- struct ip6_tnl **tnls[2];
+ struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];
+ struct ip6_tnl __rcu *tnls_wc[1];
+ 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)
{
@@ -138,8 +137,8 @@ static inline void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst)
static struct ip6_tnl *
ip6_tnl_lookup(struct net *net, struct in6_addr *remote, struct in6_addr *local)
{
- unsigned h0 = HASH(remote);
- unsigned h1 = HASH(local);
+ unsigned int h0 = HASH(remote);
+ unsigned int h1 = HASH(local);
struct ip6_tnl *t;
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
**/
-static struct ip6_tnl **
+static struct ip6_tnl __rcu **
ip6_tnl_bucket(struct ip6_tnl_net *ip6n, struct ip6_tnl_parm *p)
{
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
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);
- t->next = *tp;
+ rcu_assign_pointer(t->next , rtnl_dereference(*tp));
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
ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
{
- struct ip6_tnl **tp;
-
- for (tp = ip6_tnl_bucket(ip6n, &t->parms); *tp; tp = &(*tp)->next) {
- if (t == *tp) {
- spin_lock_bh(&ip6_tnl_lock);
- *tp = t->next;
- spin_unlock_bh(&ip6_tnl_lock);
+ struct ip6_tnl __rcu **tp;
+ struct ip6_tnl *iter;
+
+ for (tp = ip6_tnl_bucket(ip6n, &t->parms);
+ (iter = rtnl_dereference(*tp)) != NULL;
+ tp = &iter->next) {
+ if (t == iter) {
+ rcu_assign_pointer(*tp, t->next);
break;
}
}
@@ -290,10 +288,13 @@ static struct ip6_tnl *ip6_tnl_locate(struct net *net,
{
struct in6_addr *remote = &p->raddr;
struct in6_addr *local = &p->laddr;
+ struct ip6_tnl __rcu **tp;
struct ip6_tnl *t;
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) &&
ipv6_addr_equal(remote, &t->parms.raddr))
return t;
@@ -318,13 +319,10 @@ ip6_tnl_dev_uninit(struct net_device *dev)
struct net *net = dev_net(dev);
struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
- if (dev == ip6n->fb_tnl_dev) {
- spin_lock_bh(&ip6_tnl_lock);
- ip6n->tnls_wc[0] = NULL;
- spin_unlock_bh(&ip6_tnl_lock);
- } else {
+ if (dev == ip6n->fb_tnl_dev)
+ rcu_assign_pointer(ip6n->tnls_wc[0], NULL);
+ else
ip6_tnl_unlink(ip6n, t);
- }
ip6_tnl_dst_reset(t);
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);
t->parms.proto = IPPROTO_IPV6;
dev_hold(dev);
- ip6n->tnls_wc[0] = t;
+ rcu_assign_pointer(ip6n->tnls_wc[0], t);
}
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);
for (h = 0; h < HASH_SIZE; h++) {
- t = ip6n->tnls_r_l[h];
+ t = rtnl_dereference(ip6n->tnls_r_l[h]);
while (t != NULL) {
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_many(&list);
}
--
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