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Commit 30038fc6 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: ip_rt_send_redirect() optimization 



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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent df19a626

net/ipv4/route.c

+11 −9
Original line number Diff line number Diff line
@@ -1514,13 +1514,17 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst) 
void ip_rt_send_redirect(struct sk_buff *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;



	if (!IN_DEV_TX_REDIRECTS(in_dev))

		goto out;

	}

	log_martians = IN_DEV_LOG_MARTIANS(in_dev);

	rcu_read_unlock();



	/* No redirected packets during ip_rt_redirect_silence;

	 * 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) {

		rt->u.dst.rate_last = jiffies;

		goto out;

		return;

	}



	/* 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_tokens;

#ifdef CONFIG_IP_ROUTE_VERBOSE

		if (IN_DEV_LOG_MARTIANS(in_dev) &&

		if (log_martians &&

		    rt->u.dst.rate_tokens == ip_rt_redirect_number &&

		    net_ratelimit())

			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);

#endif

	}

out:

	in_dev_put(in_dev);

}



static int ip_error(struct sk_buff *skb)