From 96d362202bfc0e5da78ee59b1645296fbca515f4 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Jun 2010 19:21:31 +0000 Subject: [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 Signed-off-by: David S. Miller --- 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); -- 2.7.4