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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index fafbe16..91867d3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1514,13 +1514,17 @@
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 @@
*/
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 @@
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 @@
&rt->rt_dst, &rt->rt_gateway);
#endif
}
-out:
- in_dev_put(in_dev);
}
static int ip_error(struct sk_buff *skb)