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Date: Wed, 15 Sep 2010 23:07:53 +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 3/3] gre: get rid of ipgre_lock
As RTNL is held while doing tunnels inserts and deletes, we can remove
ipgre_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/ip_gre.c | 61 +++++++++++++++++++++++---------------------
1 files changed, 32 insertions(+), 29 deletions(-)
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 8517689..fc20e68 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -129,7 +129,7 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev);
static int ipgre_net_id __read_mostly;
struct ipgre_net {
- struct ip_tunnel *tunnels[4][HASH_SIZE];
+ struct ip_tunnel __rcu *tunnels[4][HASH_SIZE];
struct net_device *fb_tunnel_dev;
};
@@ -159,9 +159,8 @@ struct ipgre_net {
#define tunnels_l tunnels[1]
#define tunnels_wc tunnels[0]
/*
- * Locking : hash tables are protected by RCU and a spinlock
+ * Locking : hash tables are protected by RCU and RTNL
*/
-static DEFINE_SPINLOCK(ipgre_lock);
#define for_each_ip_tunnel_rcu(start) \
for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
@@ -174,8 +173,8 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
{
struct net *net = dev_net(dev);
int link = dev->ifindex;
- unsigned h0 = HASH(remote);
- unsigned h1 = HASH(key);
+ unsigned int h0 = HASH(remote);
+ unsigned int h1 = HASH(key);
struct ip_tunnel *t, *cand = NULL;
struct ipgre_net *ign = net_generic(net, ipgre_net_id);
int dev_type = (gre_proto == htons(ETH_P_TEB)) ?
@@ -290,13 +289,13 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
return NULL;
}
-static struct ip_tunnel **__ipgre_bucket(struct ipgre_net *ign,
+static struct ip_tunnel __rcu **__ipgre_bucket(struct ipgre_net *ign,
struct ip_tunnel_parm *parms)
{
__be32 remote = parms->iph.daddr;
__be32 local = parms->iph.saddr;
__be32 key = parms->i_key;
- unsigned h = HASH(key);
+ unsigned int h = HASH(key);
int prio = 0;
if (local)
@@ -309,7 +308,7 @@ static struct ip_tunnel **__ipgre_bucket(struct ipgre_net *ign,
return &ign->tunnels[prio][h];
}
-static inline struct ip_tunnel **ipgre_bucket(struct ipgre_net *ign,
+static inline struct ip_tunnel __rcu **ipgre_bucket(struct ipgre_net *ign,
struct ip_tunnel *t)
{
return __ipgre_bucket(ign, &t->parms);
@@ -317,23 +316,22 @@ static inline struct ip_tunnel **ipgre_bucket(struct ipgre_net *ign,
static void ipgre_tunnel_link(struct ipgre_net *ign, struct ip_tunnel *t)
{
- struct ip_tunnel **tp = ipgre_bucket(ign, t);
+ struct ip_tunnel __rcu **tp = ipgre_bucket(ign, t);
- spin_lock_bh(&ipgre_lock);
- t->next = *tp;
+ rcu_assign_pointer(t->next, rtnl_dereference(*tp));
rcu_assign_pointer(*tp, t);
- spin_unlock_bh(&ipgre_lock);
}
static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
{
- struct ip_tunnel **tp;
-
- for (tp = ipgre_bucket(ign, t); *tp; tp = &(*tp)->next) {
- if (t == *tp) {
- spin_lock_bh(&ipgre_lock);
- *tp = t->next;
- spin_unlock_bh(&ipgre_lock);
+ struct ip_tunnel __rcu **tp;
+ struct ip_tunnel *iter;
+
+ for (tp = ipgre_bucket(ign, t);
+ (iter = rtnl_dereference(*tp)) != NULL;
+ tp = &iter->next) {
+ if (t == iter) {
+ rcu_assign_pointer(*tp, t->next);
break;
}
}
@@ -347,10 +345,13 @@ static struct ip_tunnel *ipgre_tunnel_find(struct net *net,
__be32 local = parms->iph.saddr;
__be32 key = parms->i_key;
int link = parms->link;
- struct ip_tunnel *t, **tp;
+ struct ip_tunnel *t;
+ struct ip_tunnel __rcu **tp;
struct ipgre_net *ign = net_generic(net, ipgre_net_id);
- for (tp = __ipgre_bucket(ign, parms); (t = *tp) != NULL; tp = &t->next)
+ for (tp = __ipgre_bucket(ign, parms);
+ (t = rtnl_dereference(*tp)) != NULL;
+ tp = &t->next)
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr &&
key == t->parms.i_key &&
@@ -361,7 +362,7 @@ static struct ip_tunnel *ipgre_tunnel_find(struct net *net,
return t;
}
-static struct ip_tunnel * ipgre_tunnel_locate(struct net *net,
+static struct ip_tunnel *ipgre_tunnel_locate(struct net *net,
struct ip_tunnel_parm *parms, int create)
{
struct ip_tunnel *t, *nt;
@@ -669,7 +670,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
u8 tos;
__be16 df;
struct rtable *rt; /* Route to the other host */
- struct net_device *tdev; /* Device to other host */
+ struct net_device *tdev; /* Device to other host */
struct iphdr *iph; /* Our new IP header */
unsigned int max_headroom; /* The extra header space needed */
int gre_hlen;
@@ -1013,7 +1014,7 @@ ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
break;
}
} else {
- unsigned nflags = 0;
+ unsigned int nflags = 0;
t = netdev_priv(dev);
@@ -1126,7 +1127,7 @@ static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type,
- const void *daddr, const void *saddr, unsigned len)
+ const void *daddr, const void *saddr, unsigned int len)
{
struct ip_tunnel *t = netdev_priv(dev);
struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
@@ -1275,7 +1276,7 @@ static void ipgre_fb_tunnel_init(struct net_device *dev)
tunnel->hlen = sizeof(struct iphdr) + 4;
dev_hold(dev);
- ign->tunnels_wc[0] = tunnel;
+ rcu_assign_pointer(ign->tunnels_wc[0], tunnel);
}
@@ -1291,11 +1292,13 @@ static void ipgre_destroy_tunnels(struct ipgre_net *ign, struct list_head *head)
for (prio = 0; prio < 4; prio++) {
int h;
for (h = 0; h < HASH_SIZE; h++) {
- struct ip_tunnel *t = ign->tunnels[prio][h];
+ struct ip_tunnel *t;
+
+ t = rtnl_dereference(ign->tunnels[prio][h]);
while (t != NULL) {
unregister_netdevice_queue(t->dev, head);
- t = t->next;
+ t = rtnl_dereference(t->next);
}
}
}
@@ -1522,7 +1525,7 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
t = nt;
if (dev->type != ARPHRD_ETHER) {
- unsigned nflags = 0;
+ unsigned int nflags = 0;
if (ipv4_is_multicast(p.iph.daddr))
nflags = IFF_BROADCAST;
--
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