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tunnel: eliminate recursion field

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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>
This commit is contained in:
Eric Dumazet
2009-09-23 10:28:33 +00:00
committed by David S. Miller
parent edf42a27e8
commit a43912ab19
5 changed files with 1 additions and 36 deletions
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13
net/ipv4/ip_gre.c
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@@ -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;
}