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ipip: get rid of ipip_lock
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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>
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Eric Dumazet authored and David S. Miller committed Sep 16, 2010
1 parent 7dff59e commit b7285b7
Showing 1 changed file with 34 additions and 33 deletions.
67 changes: 34 additions & 33 deletions net/ipv4/ipip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
};
Expand All @@ -135,18 +135,17 @@ 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))

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);

Expand All @@ -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) {
Expand All @@ -188,47 +187,49 @@ 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);
}

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 = rtnl_dereference(*tp)) != NULL;
tp = &iter->next) {
if (t == iter) {
rcu_assign_pointer(*tp, t->next);
break;
}
}
}

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, rtnl_dereference(*tp));
rcu_assign_pointer(*tp, t);
spin_unlock_bh(&ipip_lock);
}

static struct ip_tunnel * ipip_tunnel_locate(struct net *net,
struct ip_tunnel_parm *parms, int create)
{
__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 = rtnl_dereference(*tp)) != NULL;
tp = &t->next) {
if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
return t;
}
Expand Down Expand Up @@ -268,16 +269,15 @@ static struct ip_tunnel * ipip_tunnel_locate(struct net *net,
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);
}
Expand Down Expand Up @@ -741,7 +741,7 @@ 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 = {
Expand All @@ -760,11 +760,12 @@ 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 = rtnl_dereference(ipn->tunnels[prio][h]);
while (t != NULL) {
unregister_netdevice_queue(t->dev, head);
t = t->next;
t = rtnl_dereference(t->next);
}
}
}
Expand Down

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