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Date: Thu, 03 Jun 2010 07:21:31 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next-2.6] ipv4: RCU conversion of
ip_route_input_slow/ip_route_input_mc
David
Following patch on net-next-2.6 if previous patch touching
net/ipv4/route.c is applied before.
(ipv4: add LINUX_MIB_IPRPFILTER snmp counter)
Thanks
[PATCH] ipv4: rcu conversion of ip_route_input_slow/ip_route_input_mc
Avoid two atomic ops on struct in_device refcount per incoming packet,
if slow path taken, (or route cache disabled)
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/ipv4/route.c | 35 +++++++++++++++++------------------
1 file changed, 17 insertions(+), 18 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d377b45..1cfe0d1 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1843,13 +1843,14 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
rt->rt_type = res->type;
}
+/* called in rcu_read_lock() section */
static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev, int our)
{
- unsigned hash;
+ unsigned int hash;
struct rtable *rth;
__be32 spec_dst;
- struct in_device *in_dev = in_dev_get(dev);
+ struct in_device *in_dev = __in_dev_get_rcu(dev);
u32 itag = 0;
int err;
@@ -1914,18 +1915,14 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
#endif
RT_CACHE_STAT_INC(in_slow_mc);
- in_dev_put(in_dev);
hash = rt_hash(daddr, saddr, dev->ifindex, rt_genid(dev_net(dev)));
return rt_intern_hash(hash, rth, NULL, skb, dev->ifindex);
e_nobufs:
- in_dev_put(in_dev);
return -ENOBUFS;
-
e_inval:
- err = -EINVAL;
+ return -EINVAL;
e_err:
- in_dev_put(in_dev);
return err;
}
@@ -2101,7 +2098,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev)
{
struct fib_result res;
- struct in_device *in_dev = in_dev_get(dev);
+ struct in_device *in_dev = __in_dev_get_rcu(dev);
struct flowi fl = { .nl_u = { .ip4_u =
{ .daddr = daddr,
.saddr = saddr,
@@ -2179,7 +2176,6 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
err = ip_mkroute_input(skb, &res, &fl, in_dev, daddr, saddr, tos);
done:
- in_dev_put(in_dev);
if (free_res)
fib_res_put(&res);
out: return err;
@@ -2288,16 +2284,18 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
unsigned hash;
int iif = dev->ifindex;
struct net *net;
+ int res;
net = dev_net(dev);
+ rcu_read_lock();
+
if (!rt_caching(net))
goto skip_cache;
tos &= IPTOS_RT_MASK;
hash = rt_hash(daddr, saddr, iif, rt_genid(net));
- rcu_read_lock();
for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
rth = rcu_dereference(rth->u.dst.rt_next)) {
if ((((__force u32)rth->fl.fl4_dst ^ (__force u32)daddr) |
@@ -2321,7 +2319,6 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
}
RT_CACHE_STAT_INC(in_hlist_search);
}
- rcu_read_unlock();
skip_cache:
/* Multicast recognition logic is moved from route cache to here.
@@ -2336,12 +2333,11 @@ skip_cache:
route cache entry is created eventually.
*/
if (ipv4_is_multicast(daddr)) {
- struct in_device *in_dev;
+ struct in_device *in_dev = __in_dev_get_rcu(dev);
- rcu_read_lock();
- if ((in_dev = __in_dev_get_rcu(dev)) != NULL) {
+ if (in_dev) {
int our = ip_check_mc(in_dev, daddr, saddr,
- ip_hdr(skb)->protocol);
+ ip_hdr(skb)->protocol);
if (our
#ifdef CONFIG_IP_MROUTE
||
@@ -2349,15 +2345,18 @@ skip_cache:
IN_DEV_MFORWARD(in_dev))
#endif
) {
+ int res = ip_route_input_mc(skb, daddr, saddr,
+ tos, dev, our);
rcu_read_unlock();
- return ip_route_input_mc(skb, daddr, saddr,
- tos, dev, our);
+ return res;
}
}
rcu_read_unlock();
return -EINVAL;
}
- return ip_route_input_slow(skb, daddr, saddr, tos, dev);
+ res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
+ rcu_read_unlock();
+ return res;
}
EXPORT_SYMBOL(ip_route_input_common);
--
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