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ipv4: RCU conversion of ip_route_input_slow/ip_route_input_mc

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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-06-02 19:21:31 +00:00 committed by David S. Miller
parent b5f7e75547
commit 96d362202b
1 changed files with 17 additions and 18 deletions
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35
net/ipv4/route.c
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@ -1843,13 +1843,14 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
rt->rt_type = res->type; 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, static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev, int our) u8 tos, struct net_device *dev, int our)
{ {
unsigned hash; unsigned int hash;
struct rtable *rth; struct rtable *rth;
__be32 spec_dst; __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; u32 itag = 0;
int err; int err;
@ -1914,18 +1915,14 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
#endif #endif
RT_CACHE_STAT_INC(in_slow_mc); RT_CACHE_STAT_INC(in_slow_mc);
in_dev_put(in_dev);
hash = rt_hash(daddr, saddr, dev->ifindex, rt_genid(dev_net(dev))); hash = rt_hash(daddr, saddr, dev->ifindex, rt_genid(dev_net(dev)));
return rt_intern_hash(hash, rth, NULL, skb, dev->ifindex); return rt_intern_hash(hash, rth, NULL, skb, dev->ifindex);
e_nobufs: e_nobufs:
in_dev_put(in_dev);
return -ENOBUFS; return -ENOBUFS;
e_inval: e_inval:
err = -EINVAL; return -EINVAL;
e_err: e_err:
in_dev_put(in_dev);
return err; 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) u8 tos, struct net_device *dev)
{ {
struct fib_result res; 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 = struct flowi fl = { .nl_u = { .ip4_u =
{ .daddr = daddr, { .daddr = daddr,
.saddr = saddr, .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); err = ip_mkroute_input(skb, &res, &fl, in_dev, daddr, saddr, tos);
done: done:
in_dev_put(in_dev);
if (free_res) if (free_res)
fib_res_put(&res); fib_res_put(&res);
out: return err; out: return err;
@ -2288,16 +2284,18 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
unsigned hash; unsigned hash;
int iif = dev->ifindex; int iif = dev->ifindex;
struct net *net; struct net *net;
int res;
net = dev_net(dev); net = dev_net(dev);
rcu_read_lock();
if (!rt_caching(net)) if (!rt_caching(net))
goto skip_cache; goto skip_cache;
tos &= IPTOS_RT_MASK; tos &= IPTOS_RT_MASK;
hash = rt_hash(daddr, saddr, iif, rt_genid(net)); hash = rt_hash(daddr, saddr, iif, rt_genid(net));
rcu_read_lock();
for (rth = rcu_dereference(rt_hash_table[hash].chain); rth; for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
rth = rcu_dereference(rth->u.dst.rt_next)) { rth = rcu_dereference(rth->u.dst.rt_next)) {
if ((((__force u32)rth->fl.fl4_dst ^ (__force u32)daddr) | 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); RT_CACHE_STAT_INC(in_hlist_search);
} }
rcu_read_unlock();
skip_cache: skip_cache:
/* Multicast recognition logic is moved from route cache to here. /* Multicast recognition logic is moved from route cache to here.
@ -2336,12 +2333,11 @@ skip_cache:
route cache entry is created eventually. route cache entry is created eventually.
*/ */
if (ipv4_is_multicast(daddr)) { 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) {
if ((in_dev = __in_dev_get_rcu(dev)) != NULL) {
int our = ip_check_mc(in_dev, daddr, saddr, int our = ip_check_mc(in_dev, daddr, saddr,
ip_hdr(skb)->protocol); ip_hdr(skb)->protocol);
if (our if (our
#ifdef CONFIG_IP_MROUTE #ifdef CONFIG_IP_MROUTE
|| ||
@ -2349,15 +2345,18 @@ skip_cache:
IN_DEV_MFORWARD(in_dev)) IN_DEV_MFORWARD(in_dev))
#endif #endif
) { ) {
int res = ip_route_input_mc(skb, daddr, saddr,
tos, dev, our);
rcu_read_unlock(); rcu_read_unlock();
return ip_route_input_mc(skb, daddr, saddr, return res;
tos, dev, our);
} }
} }
rcu_read_unlock(); rcu_read_unlock();
return -EINVAL; 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); EXPORT_SYMBOL(ip_route_input_common);