tunnel: eliminate recursion field

It seems recursion field from "struct ip_tunnel" is not anymore needed.
recursion prevention is done at the upper level (in dev_queue_xmit()),
since we use HARD_TX_LOCK protection for tunnels.

This avoids a cache line ping pong on "struct ip_tunnel" : This structure
should be now mostly read on xmit and receive paths.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 1 insertions, 36 deletions

diff --git a/include/net/ipip.h b/include/net/ipip.h
index 5d3036fa1511..76e3ea6e2fe5 100644
--- a/include/net/ipip.h
+++ b/include/net/ipip.h
@@ -12,7 +12,6 @@ struct ip_tunnel
         struct ip_tunnel        *next;
         struct net_device       *dev;
 
-        int                     recursion;      /* Depth of hard_start_xmit recursion */
         int                     err_count;      /* Number of arrived ICMP errors */
         unsigned long           err_time;       /* Time when the last ICMP error arrived */
 
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index d9645c94a067..41ada9904d31 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -66,10 +66,7 @@
    solution, but it supposes maintaing new variable in ALL
    skb, even if no tunneling is used.
 
-   Current solution: t->recursion lock breaks dead loops. It looks
-   like dev->tbusy flag, but I preferred new variable, because
-   the semantics is different. One day, when hard_start_xmit
-   will be multithreaded we will have to use skb->encapsulation.
+   Current solution: HARD_TX_LOCK lock breaks dead loops.
 
 
 
@@ -678,11 +675,6 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         __be32 dst;
         int    mtu;
 
-        if (tunnel->recursion++) {
-                stats->collisions++;
-                goto tx_error;
-        }
-
         if (dev->type == ARPHRD_ETHER)
                 IPCB(skb)->flags = 0;
 
@@ -820,7 +812,6 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
                         ip_rt_put(rt);
                         stats->tx_dropped++;
                         dev_kfree_skb(skb);
-                        tunnel->recursion--;
                         return NETDEV_TX_OK;
                 }
                 if (skb->sk)
@@ -888,7 +879,6 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         nf_reset(skb);
 
         IPTUNNEL_XMIT();
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 
 tx_error_icmp:
@@ -897,7 +887,6 @@ tx_error_icmp:
 tx_error:
         stats->tx_errors++;
         dev_kfree_skb(skb);
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 }
 
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 62548cb0923c..08ccd344de7a 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -402,11 +402,6 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
         __be32 dst = tiph->daddr;
         int    mtu;
 
-        if (tunnel->recursion++) {
-                stats->collisions++;
-                goto tx_error;
-        }
-
         if (skb->protocol != htons(ETH_P_IP))
                 goto tx_error;
 
@@ -485,7 +480,6 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
                         ip_rt_put(rt);
                         stats->tx_dropped++;
                         dev_kfree_skb(skb);
-                        tunnel->recursion--;
                         return NETDEV_TX_OK;
                 }
                 if (skb->sk)
@@ -523,7 +517,6 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
         nf_reset(skb);
 
         IPTUNNEL_XMIT();
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 
 tx_error_icmp:
@@ -531,7 +524,6 @@ tx_error_icmp:
 tx_error:
         stats->tx_errors++;
         dev_kfree_skb(skb);
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 }
 
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 7d25bbe32110..c595bbe1ed99 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1043,11 +1043,6 @@ ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
         struct net_device_stats *stats = &t->dev->stats;
         int ret;
 
-        if (t->recursion++) {
-                stats->collisions++;
-                goto tx_err;
-        }
-
         switch (skb->protocol) {
         case htons(ETH_P_IP):
                 ret = ip4ip6_tnl_xmit(skb, dev);
@@ -1062,14 +1057,12 @@ ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
         if (ret < 0)
                 goto tx_err;
 
-        t->recursion--;
         return NETDEV_TX_OK;
 
 tx_err:
         stats->tx_errors++;
         stats->tx_dropped++;
         kfree_skb(skb);
-        t->recursion--;
         return NETDEV_TX_OK;
 }
 
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 0ae4f6448187..fcb539628847 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -626,11 +626,6 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
         struct in6_addr *addr6;
         int addr_type;
 
-        if (tunnel->recursion++) {
-                stats->collisions++;
-                goto tx_error;
-        }
-
         if (skb->protocol != htons(ETH_P_IPV6))
                 goto tx_error;
 
@@ -753,7 +748,6 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                         ip_rt_put(rt);
                         stats->tx_dropped++;
                         dev_kfree_skb(skb);
-                        tunnel->recursion--;
                         return NETDEV_TX_OK;
                 }
                 if (skb->sk)
@@ -794,7 +788,6 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
         nf_reset(skb);
 
         IPTUNNEL_XMIT();
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 
 tx_error_icmp:
@@ -802,7 +795,6 @@ tx_error_icmp:
 tx_error:
         stats->tx_errors++;
         dev_kfree_skb(skb);
-        tunnel->recursion--;
         return NETDEV_TX_OK;
 }