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Date: Wed, 15 Sep 2010 19:27:56 +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] 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 <eric.dumazet@...il.com>
---
Tested with CONFIG_PROVE_RCU=y
net/ipv4/ipip.c | 71 ++++++++++++++++++++++++----------------------
1 file changed, 38 insertions(+), 33 deletions(-)
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 3c6f8f3..7f0e216 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 = rcu_dereference_check(*tp, lockdep_rtnl_is_held())) != NULL;
+ tp = &iter->next) {
+ if (t == iter) {
+ rcu_assign_pointer(*tp, t->next);
break;
}
}
@@ -210,12 +210,12 @@ 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,
+ rcu_dereference_check(*tp,
+ lockdep_rtnl_is_held()));
rcu_assign_pointer(*tp, t);
- spin_unlock_bh(&ipip_lock);
}
static struct ip_tunnel * ipip_tunnel_locate(struct net *net,
@@ -223,12 +223,15 @@ 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 = rcu_dereference_check(*tp, lockdep_rtnl_is_held())) != NULL;
+ tp = &t->next) {
if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
return t;
}
@@ -268,16 +271,15 @@ 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 +743,7 @@ 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 +762,14 @@ 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 = rcu_dereference_check(ipn->tunnels[prio][h],
+ lockdep_rtnl_is_held());
while (t != NULL) {
unregister_netdevice_queue(t->dev, head);
- t = t->next;
+ t = rcu_dereference_check(t->next,
+ lockdep_rtnl_is_held());
}
}
}
--
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