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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-15 11:07:53 +00:00 committed by David S. Miller
parent b7285b7912
commit 1507850b40
1 changed files with 31 additions and 28 deletions
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59
net/ipv4/ip_gre.c
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@ -129,7 +129,7 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev);
static int ipgre_net_id __read_mostly; static int ipgre_net_id __read_mostly;
struct ipgre_net { struct ipgre_net {
struct ip_tunnel *tunnels[4][HASH_SIZE]; struct ip_tunnel __rcu *tunnels[4][HASH_SIZE];
struct net_device *fb_tunnel_dev; struct net_device *fb_tunnel_dev;
}; };
@ -159,9 +159,8 @@ struct ipgre_net {
#define tunnels_l tunnels[1] #define tunnels_l tunnels[1]
#define tunnels_wc tunnels[0] #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) \ #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))
@ -174,8 +173,8 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
{ {
struct net *net = dev_net(dev); struct net *net = dev_net(dev);
int link = dev->ifindex; int link = dev->ifindex;
unsigned h0 = HASH(remote); unsigned int h0 = HASH(remote);
unsigned h1 = HASH(key); unsigned int h1 = HASH(key);
struct ip_tunnel *t, *cand = NULL; struct ip_tunnel *t, *cand = NULL;
struct ipgre_net *ign = net_generic(net, ipgre_net_id); struct ipgre_net *ign = net_generic(net, ipgre_net_id);
int dev_type = (gre_proto == htons(ETH_P_TEB)) ? 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; 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) 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;
__be32 key = parms->i_key; __be32 key = parms->i_key;
unsigned h = HASH(key); unsigned int h = HASH(key);
int prio = 0; int prio = 0;
if (local) if (local)
@ -309,7 +308,7 @@ static struct ip_tunnel **__ipgre_bucket(struct ipgre_net *ign,
return &ign->tunnels[prio][h]; 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) struct ip_tunnel *t)
{ {
return __ipgre_bucket(ign, &t->parms); 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) 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); rcu_assign_pointer(t->next, rtnl_dereference(*tp));
t->next = *tp;
rcu_assign_pointer(*tp, t); rcu_assign_pointer(*tp, t);
spin_unlock_bh(&ipgre_lock);
} }
static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t) static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
{ {
struct ip_tunnel **tp; struct ip_tunnel __rcu **tp;
struct ip_tunnel *iter;
for (tp = ipgre_bucket(ign, t); *tp; tp = &(*tp)->next) { for (tp = ipgre_bucket(ign, t);
if (t == *tp) { (iter = rtnl_dereference(*tp)) != NULL;
spin_lock_bh(&ipgre_lock); tp = &iter->next) {
*tp = t->next; if (t == iter) {
spin_unlock_bh(&ipgre_lock); rcu_assign_pointer(*tp, t->next);
break; break;
} }
} }
@ -347,10 +345,13 @@ static struct ip_tunnel *ipgre_tunnel_find(struct net *net,
__be32 local = parms->iph.saddr; __be32 local = parms->iph.saddr;
__be32 key = parms->i_key; __be32 key = parms->i_key;
int link = parms->link; 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); 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 && if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr && remote == t->parms.iph.daddr &&
key == t->parms.i_key && key == t->parms.i_key &&
@ -361,7 +362,7 @@ static struct ip_tunnel *ipgre_tunnel_find(struct net *net,
return t; 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_parm *parms, int create)
{ {
struct ip_tunnel *t, *nt; 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; u8 tos;
__be16 df; __be16 df;
struct rtable *rt; /* Route to the other host */ 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 */ struct iphdr *iph; /* Our new IP header */
unsigned int max_headroom; /* The extra header space needed */ unsigned int max_headroom; /* The extra header space needed */
int gre_hlen; int gre_hlen;
@ -1013,7 +1014,7 @@ ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
break; break;
} }
} else { } else {
unsigned nflags = 0; unsigned int nflags = 0;
t = netdev_priv(dev); 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, static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type, 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 ip_tunnel *t = netdev_priv(dev);
struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen); 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; tunnel->hlen = sizeof(struct iphdr) + 4;
dev_hold(dev); 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++) { for (prio = 0; 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 = ign->tunnels[prio][h]; struct ip_tunnel *t;
t = rtnl_dereference(ign->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);
} }
} }
} }
@ -1522,7 +1525,7 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
t = nt; t = nt;
if (dev->type != ARPHRD_ETHER) { if (dev->type != ARPHRD_ETHER) {
unsigned nflags = 0; unsigned int nflags = 0;
if (ipv4_is_multicast(p.iph.daddr)) if (ipv4_is_multicast(p.iph.daddr))
nflags = IFF_BROADCAST; nflags = IFF_BROADCAST;