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sit: get rid of ipip6_lock
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As RTNL is held while doing tunnels inserts and deletes, we can remove
ipip6_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 1507850 commit 3a43be3
Showing 1 changed file with 31 additions and 33 deletions.
64 changes: 31 additions & 33 deletions net/ipv6/sit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,19 +68,18 @@ static void ipip6_tunnel_setup(struct net_device *dev);

static int sit_net_id __read_mostly;
struct sit_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;
};

/*
* Locking : hash tables are protected by RCU and a spinlock
* Locking : hash tables are protected by RCU and RTNL
*/
static DEFINE_SPINLOCK(ipip6_lock);

#define for_each_ip_tunnel_rcu(start) \
for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
Expand All @@ -91,8 +90,8 @@ static DEFINE_SPINLOCK(ipip6_lock);
static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
struct net_device *dev, __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 sit_net *sitn = net_generic(net, sit_net_id);

Expand Down Expand Up @@ -121,12 +120,12 @@ static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
return NULL;
}

static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
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 @@ -140,34 +139,33 @@ static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
return &sitn->tunnels[prio][h];
}

static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,
static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
struct ip_tunnel *t)
{
return __ipip6_bucket(sitn, &t->parms);
}

static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
{
struct ip_tunnel **tp;

for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
if (t == *tp) {
spin_lock_bh(&ipip6_lock);
*tp = t->next;
spin_unlock_bh(&ipip6_lock);
struct ip_tunnel __rcu **tp;
struct ip_tunnel *iter;

for (tp = ipip6_bucket(sitn, t);
(iter = rtnl_dereference(*tp)) != NULL;
tp = &iter->next) {
if (t == iter) {
rcu_assign_pointer(*tp, t->next);
break;
}
}
}

static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
{
struct ip_tunnel **tp = ipip6_bucket(sitn, t);
struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);

spin_lock_bh(&ipip6_lock);
t->next = *tp;
rcu_assign_pointer(t->next, rtnl_dereference(*tp));
rcu_assign_pointer(*tp, t);
spin_unlock_bh(&ipip6_lock);
}

static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
Expand All @@ -187,17 +185,20 @@ static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
#endif
}

static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
static struct ip_tunnel *ipip6_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 sit_net *sitn = net_generic(net, sit_net_id);

for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
for (tp = __ipip6_bucket(sitn, parms);
(t = rtnl_dereference(*tp)) != NULL;
tp = &t->next) {
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr &&
parms->link == t->parms.link) {
Expand Down Expand Up @@ -340,7 +341,7 @@ ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)

ASSERT_RTNL();

for (p = t->prl; p; p = p->next) {
for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
if (p->addr == a->addr) {
if (chg) {
p->flags = a->flags;
Expand Down Expand Up @@ -451,15 +452,12 @@ static void ipip6_tunnel_uninit(struct net_device *dev)
struct sit_net *sitn = net_generic(net, sit_net_id);

if (dev == sitn->fb_tunnel_dev) {
spin_lock_bh(&ipip6_lock);
sitn->tunnels_wc[0] = NULL;
spin_unlock_bh(&ipip6_lock);
dev_put(dev);
rcu_assign_pointer(sitn->tunnels_wc[0], NULL);
} else {
ipip6_tunnel_unlink(sitn, netdev_priv(dev));
ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
dev_put(dev);
}
dev_put(dev);
}


Expand Down Expand Up @@ -590,7 +588,7 @@ __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
#ifdef CONFIG_IPV6_SIT_6RD
if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
tunnel->ip6rd.prefixlen)) {
unsigned pbw0, pbi0;
unsigned int pbw0, pbi0;
int pbi1;
u32 d;

Expand Down

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