1 files changed, 23 insertions, 17 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 89ff9d5b1500..40f043915235 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -156,8 +156,13 @@ struct ipgre_net {
 #define tunnels_r       tunnels[2]
 #define tunnels_l       tunnels[1]
 #define tunnels_wc      tunnels[0]
+/*
+ * Locking : hash tables are protected by RCU and a spinlock
+ */
+static DEFINE_SPINLOCK(ipgre_lock);
 
-static DEFINE_RWLOCK(ipgre_lock);
+#define for_each_ip_tunnel_rcu(start) \
+        for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
 
 /* Given src, dst and key, find appropriate for input tunnel. */
 
@@ -175,7 +180,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
                        ARPHRD_ETHER : ARPHRD_IPGRE;
         int score, cand_score = 4;
 
-        for (t = ign->tunnels_r_l[h0^h1]; t; t = t->next) {
+        for_each_ip_tunnel_rcu(ign->tunnels_r_l[h0 ^ h1]) {
                 if (local != t->parms.iph.saddr ||
                     remote != t->parms.iph.daddr ||
                     key != t->parms.i_key ||
@@ -200,7 +205,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
                 }
         }
 
-        for (t = ign->tunnels_r[h0^h1]; t; t = t->next) {
+        for_each_ip_tunnel_rcu(ign->tunnels_r[h0 ^ h1]) {
                 if (remote != t->parms.iph.daddr ||
                     key != t->parms.i_key ||
                     !(t->dev->flags & IFF_UP))
@@ -224,7 +229,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
                 }
         }
 
-        for (t = ign->tunnels_l[h1]; t; t = t->next) {
+        for_each_ip_tunnel_rcu(ign->tunnels_l[h1]) {
                 if ((local != t->parms.iph.saddr &&
                      (local != t->parms.iph.daddr ||
                       !ipv4_is_multicast(local))) ||
@@ -250,7 +255,7 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
                 }
         }
 
-        for (t = ign->tunnels_wc[h1]; t; t = t->next) {
+        for_each_ip_tunnel_rcu(ign->tunnels_wc[h1]) {
                 if (t->parms.i_key != key ||
                     !(t->dev->flags & IFF_UP))
                         continue;
@@ -276,8 +281,9 @@ static struct ip_tunnel * ipgre_tunnel_lookup(struct net_device *dev,
         if (cand != NULL)
                 return cand;
 
-        if (ign->fb_tunnel_dev->flags & IFF_UP)
-                return netdev_priv(ign->fb_tunnel_dev);
+        dev = ign->fb_tunnel_dev;
+        if (dev->flags & IFF_UP)
+                return netdev_priv(dev);
 
         return NULL;
 }
@@ -311,10 +317,10 @@ static void ipgre_tunnel_link(struct ipgre_net *ign, struct ip_tunnel *t)
 {
         struct ip_tunnel **tp = ipgre_bucket(ign, t);
 
+        spin_lock_bh(&ipgre_lock);
         t->next = *tp;
-        write_lock_bh(&ipgre_lock);
-        *tp = t;
-        write_unlock_bh(&ipgre_lock);
+        rcu_assign_pointer(*tp, t);
+        spin_unlock_bh(&ipgre_lock);
 }
 
 static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
@@ -323,9 +329,9 @@ static void ipgre_tunnel_unlink(struct ipgre_net *ign, struct ip_tunnel *t)
 
         for (tp = ipgre_bucket(ign, t); *tp; tp = &(*tp)->next) {
                 if (t == *tp) {
-                        write_lock_bh(&ipgre_lock);
+                        spin_lock_bh(&ipgre_lock);
                         *tp = t->next;
-                        write_unlock_bh(&ipgre_lock);
+                        spin_unlock_bh(&ipgre_lock);
                         break;
                 }
         }
@@ -476,7 +482,7 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
                 break;
         }
 
-        read_lock(&ipgre_lock);
+        rcu_read_lock();
         t = ipgre_tunnel_lookup(skb->dev, iph->daddr, iph->saddr,
                                 flags & GRE_KEY ?
                                 *(((__be32 *)p) + (grehlen / 4) - 1) : 0,
@@ -494,7 +500,7 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
                 t->err_count = 1;
         t->err_time = jiffies;
 out:
-        read_unlock(&ipgre_lock);
+        rcu_read_unlock();
         return;
 }
 
@@ -573,7 +579,7 @@ static int ipgre_rcv(struct sk_buff *skb)
 
         gre_proto = *(__be16 *)(h + 2);
 
-        read_lock(&ipgre_lock);
+        rcu_read_lock();
         if ((tunnel = ipgre_tunnel_lookup(skb->dev,
                                           iph->saddr, iph->daddr, key,
                                           gre_proto))) {
@@ -647,13 +653,13 @@ static int ipgre_rcv(struct sk_buff *skb)
                 ipgre_ecn_decapsulate(iph, skb);
 
                 netif_rx(skb);
-                read_unlock(&ipgre_lock);
+                rcu_read_unlock();
                 return(0);
         }
         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
 drop:
-        read_unlock(&ipgre_lock);
+        rcu_read_unlock();
 drop_nolock:
         kfree_skb(skb);
         return(0);