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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-15 11:07:24 +00:00 committed by David S. Miller
parent 7dff59efbb
commit b7285b7912
1 changed files with 33 additions and 32 deletions
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65
net/ipv4/ipip.c
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@ -122,11 +122,11 @@
static int ipip_net_id __read_mostly; static int ipip_net_id __read_mostly;
struct ipip_net { struct ipip_net {
struct ip_tunnel *tunnels_r_l[HASH_SIZE]; struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
struct ip_tunnel *tunnels_r[HASH_SIZE]; struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
struct ip_tunnel *tunnels_l[HASH_SIZE]; struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
struct ip_tunnel *tunnels_wc[1]; struct ip_tunnel __rcu *tunnels_wc[1];
struct ip_tunnel **tunnels[4]; struct ip_tunnel __rcu **tunnels[4];
struct net_device *fb_tunnel_dev; 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); 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) \ #define for_each_ip_tunnel_rcu(start) \
for (t = rcu_dereference(start); t; t = rcu_dereference(t->next)) 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, static struct ip_tunnel * ipip_tunnel_lookup(struct net *net,
__be32 remote, __be32 local) __be32 remote, __be32 local)
{ {
unsigned h0 = HASH(remote); unsigned int h0 = HASH(remote);
unsigned h1 = HASH(local); unsigned int h1 = HASH(local);
struct ip_tunnel *t; struct ip_tunnel *t;
struct ipip_net *ipn = net_generic(net, ipip_net_id); 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; 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) struct ip_tunnel_parm *parms)
{ {
__be32 remote = parms->iph.daddr; __be32 remote = parms->iph.daddr;
__be32 local = parms->iph.saddr; __be32 local = parms->iph.saddr;
unsigned h = 0; unsigned int h = 0;
int prio = 0; int prio = 0;
if (remote) { if (remote) {
@ -188,7 +187,7 @@ static struct ip_tunnel **__ipip_bucket(struct ipip_net *ipn,
return &ipn->tunnels[prio][h]; 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) struct ip_tunnel *t)
{ {
return __ipip_bucket(ipn, &t->parms); 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) static void ipip_tunnel_unlink(struct ipip_net *ipn, struct ip_tunnel *t)
{ {
struct ip_tunnel **tp; struct ip_tunnel __rcu **tp;
struct ip_tunnel *iter;
for (tp = ipip_bucket(ipn, t); *tp; tp = &(*tp)->next) { for (tp = ipip_bucket(ipn, t);
if (t == *tp) { (iter = rtnl_dereference(*tp)) != NULL;
spin_lock_bh(&ipip_lock); tp = &iter->next) {
*tp = t->next; if (t == iter) {
spin_unlock_bh(&ipip_lock); rcu_assign_pointer(*tp, t->next);
break; 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) 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); rcu_assign_pointer(t->next, rtnl_dereference(*tp));
t->next = *tp;
rcu_assign_pointer(*tp, t); rcu_assign_pointer(*tp, t);
spin_unlock_bh(&ipip_lock);
} }
static struct ip_tunnel * ipip_tunnel_locate(struct net *net, 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 remote = parms->iph.daddr;
__be32 local = parms->iph.saddr; __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; struct net_device *dev;
char name[IFNAMSIZ]; char name[IFNAMSIZ];
struct ipip_net *ipn = net_generic(net, ipip_net_id); 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) if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
return t; return t;
} }
@ -268,16 +269,15 @@ failed_free:
return NULL; return NULL;
} }
/* called with RTNL */
static void ipip_tunnel_uninit(struct net_device *dev) static void ipip_tunnel_uninit(struct net_device *dev)
{ {
struct net *net = dev_net(dev); struct net *net = dev_net(dev);
struct ipip_net *ipn = net_generic(net, ipip_net_id); struct ipip_net *ipn = net_generic(net, ipip_net_id);
if (dev == ipn->fb_tunnel_dev) { if (dev == ipn->fb_tunnel_dev)
spin_lock_bh(&ipip_lock); rcu_assign_pointer(ipn->tunnels_wc[0], NULL);
ipn->tunnels_wc[0] = NULL; else
spin_unlock_bh(&ipip_lock);
} else
ipip_tunnel_unlink(ipn, netdev_priv(dev)); ipip_tunnel_unlink(ipn, netdev_priv(dev));
dev_put(dev); dev_put(dev);
} }
@ -741,7 +741,7 @@ static void __net_init ipip_fb_tunnel_init(struct net_device *dev)
iph->ihl = 5; iph->ihl = 5;
dev_hold(dev); dev_hold(dev);
ipn->tunnels_wc[0] = tunnel; rcu_assign_pointer(ipn->tunnels_wc[0], tunnel);
} }
static struct xfrm_tunnel ipip_handler __read_mostly = { 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++) { for (prio = 1; prio < 4; prio++) {
int h; int h;
for (h = 0; h < HASH_SIZE; 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) { while (t != NULL) {
unregister_netdevice_queue(t->dev, head); unregister_netdevice_queue(t->dev, head);
t = t->next; t = rtnl_dereference(t->next);
} }
} }
} }