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net: ip_rt_send_redirect() optimization

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While doing some forwarding benchmarks, I noticed
ip_rt_send_redirect() is rather expensive, even if send_redirects is
false for the device.

Fix is to avoid two atomic ops, we dont really need to take a
reference on in_dev

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 2009-08-28 23:52:01 -07:00 committed by David S. Miller
parent df19a62677
commit 30038fc61a
1 changed files with 11 additions and 9 deletions
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20
net/ipv4/route.c
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@ -1514,13 +1514,17 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
void ip_rt_send_redirect(struct sk_buff *skb) void ip_rt_send_redirect(struct sk_buff *skb)
{ {
struct rtable *rt = skb_rtable(skb); struct rtable *rt = skb_rtable(skb);
struct in_device *in_dev = in_dev_get(rt->u.dst.dev); struct in_device *in_dev;
int log_martians;
if (!in_dev) rcu_read_lock();
in_dev = __in_dev_get_rcu(rt->u.dst.dev);
if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
rcu_read_unlock();
return; return;
}
if (!IN_DEV_TX_REDIRECTS(in_dev)) log_martians = IN_DEV_LOG_MARTIANS(in_dev);
goto out; rcu_read_unlock();
/* No redirected packets during ip_rt_redirect_silence; /* No redirected packets during ip_rt_redirect_silence;
* reset the algorithm. * reset the algorithm.
@ -1533,7 +1537,7 @@ void ip_rt_send_redirect(struct sk_buff *skb)
*/ */
if (rt->u.dst.rate_tokens >= ip_rt_redirect_number) { if (rt->u.dst.rate_tokens >= ip_rt_redirect_number) {
rt->u.dst.rate_last = jiffies; rt->u.dst.rate_last = jiffies;
goto out; return;
} }
/* Check for load limit; set rate_last to the latest sent /* Check for load limit; set rate_last to the latest sent
@ -1547,7 +1551,7 @@ void ip_rt_send_redirect(struct sk_buff *skb)
rt->u.dst.rate_last = jiffies; rt->u.dst.rate_last = jiffies;
++rt->u.dst.rate_tokens; ++rt->u.dst.rate_tokens;
#ifdef CONFIG_IP_ROUTE_VERBOSE #ifdef CONFIG_IP_ROUTE_VERBOSE
if (IN_DEV_LOG_MARTIANS(in_dev) && if (log_martians &&
rt->u.dst.rate_tokens == ip_rt_redirect_number && rt->u.dst.rate_tokens == ip_rt_redirect_number &&
net_ratelimit()) net_ratelimit())
printk(KERN_WARNING "host %pI4/if%d ignores redirects for %pI4 to %pI4.\n", printk(KERN_WARNING "host %pI4/if%d ignores redirects for %pI4 to %pI4.\n",
@ -1555,8 +1559,6 @@ void ip_rt_send_redirect(struct sk_buff *skb)
&rt->rt_dst, &rt->rt_gateway); &rt->rt_dst, &rt->rt_gateway);
#endif #endif
} }
out:
in_dev_put(in_dev);
} }
static int ip_error(struct sk_buff *skb) static int ip_error(struct sk_buff *skb)