tunnel: eliminate recursion field
Eric Dumazet [Wed, 23 Sep 2009 10:28:33 +0000 (10:28 +0000)]
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>

include/net/ipip.h
net/ipv4/ip_gre.c
net/ipv4/ipip.c
net/ipv6/ip6_tunnel.c
net/ipv6/sit.c

index 5d3036f..76e3ea6 100644 (file)
@@ -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 */
 
index d9645c9..41ada99 100644 (file)
    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;
 }
 
index 62548cb..08ccd34 100644 (file)
@@ -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;
 }
 
index 7d25bbe..c595bbe 100644 (file)
@@ -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;
 }
 
index 0ae4f64..fcb5396 100644 (file)
@@ -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;
 }