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Date: Tue, 03 Jul 2012 02:45:51 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: netdev@...r.kernel.org
Subject: [PATCH 01/19] ipv4: Make neigh lookups directly in output packet
path.
Do not use the dst cached neigh, we'll be getting rid of that.
Signed-off-by: David S. Miller <davem@...emloft.net>
---
include/net/arp.h | 28 +++++++++++++++++++---------
include/net/neighbour.h | 11 +++++++++--
net/core/neighbour.c | 12 +++++++-----
net/ipv4/ip_output.c | 12 ++++++++----
net/ipv4/route.c | 6 +-----
5 files changed, 44 insertions(+), 25 deletions(-)
diff --git a/include/net/arp.h b/include/net/arp.h
index 4a1f3fb..4617d98 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -15,24 +15,34 @@ static inline u32 arp_hashfn(u32 key, const struct net_device *dev, u32 hash_rnd
return val * hash_rnd;
}
-static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key)
+static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key)
{
- struct neigh_hash_table *nht;
+ struct neigh_hash_table *nht = rcu_dereference_bh(arp_tbl.nht);
struct neighbour *n;
u32 hash_val;
- rcu_read_lock_bh();
- nht = rcu_dereference_bh(arp_tbl.nht);
+ if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
+ key = 0;
+
hash_val = arp_hashfn(key, dev, nht->hash_rnd[0]) >> (32 - nht->hash_shift);
for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
n != NULL;
n = rcu_dereference_bh(n->next)) {
- if (n->dev == dev && *(u32 *)n->primary_key == key) {
- if (!atomic_inc_not_zero(&n->refcnt))
- n = NULL;
- break;
- }
+ if (n->dev == dev && *(u32 *)n->primary_key == key)
+ return n;
}
+
+ return NULL;
+}
+
+static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key)
+{
+ struct neighbour *n;
+
+ rcu_read_lock_bh();
+ n = __ipv4_neigh_lookup_noref(dev, key);
+ if (n && !atomic_inc_not_zero(&n->refcnt))
+ n = NULL;
rcu_read_unlock_bh();
return n;
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 6cdfeed..e1d18bd 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -202,9 +202,16 @@ extern struct neighbour * neigh_lookup(struct neigh_table *tbl,
extern struct neighbour * neigh_lookup_nodev(struct neigh_table *tbl,
struct net *net,
const void *pkey);
-extern struct neighbour * neigh_create(struct neigh_table *tbl,
+extern struct neighbour * __neigh_create(struct neigh_table *tbl,
+ const void *pkey,
+ struct net_device *dev,
+ bool want_ref);
+static inline struct neighbour *neigh_create(struct neigh_table *tbl,
const void *pkey,
- struct net_device *dev);
+ struct net_device *dev)
+{
+ return __neigh_create(tbl, pkey, dev, true);
+}
extern void neigh_destroy(struct neighbour *neigh);
extern int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
extern int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index d81d026..a793af9 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -474,8 +474,8 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
}
EXPORT_SYMBOL(neigh_lookup_nodev);
-struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
- struct net_device *dev)
+struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
+ struct net_device *dev, bool want_ref)
{
u32 hash_val;
int key_len = tbl->key_len;
@@ -535,14 +535,16 @@ struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
n1 = rcu_dereference_protected(n1->next,
lockdep_is_held(&tbl->lock))) {
if (dev == n1->dev && !memcmp(n1->primary_key, pkey, key_len)) {
- neigh_hold(n1);
+ if (want_ref)
+ neigh_hold(n1);
rc = n1;
goto out_tbl_unlock;
}
}
n->dead = 0;
- neigh_hold(n);
+ if (want_ref)
+ neigh_hold(n);
rcu_assign_pointer(n->next,
rcu_dereference_protected(nht->hash_buckets[hash_val],
lockdep_is_held(&tbl->lock)));
@@ -558,7 +560,7 @@ out_neigh_release:
neigh_release(n);
goto out;
}
-EXPORT_SYMBOL(neigh_create);
+EXPORT_SYMBOL(__neigh_create);
static u32 pneigh_hash(const void *pkey, int key_len)
{
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 2630900..6e9a266 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -170,6 +170,7 @@ static inline int ip_finish_output2(struct sk_buff *skb)
struct net_device *dev = dst->dev;
unsigned int hh_len = LL_RESERVED_SPACE(dev);
struct neighbour *neigh;
+ u32 nexthop;
if (rt->rt_type == RTN_MULTICAST) {
IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
@@ -191,15 +192,18 @@ static inline int ip_finish_output2(struct sk_buff *skb)
skb = skb2;
}
- rcu_read_lock();
- neigh = dst_get_neighbour_noref(dst);
+ rcu_read_lock_bh();
+ nexthop = rt->rt_gateway ? rt->rt_gateway : ip_hdr(skb)->daddr;
+ neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
+ if (unlikely(!neigh))
+ neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
if (neigh) {
int res = neigh_output(neigh, skb);
- rcu_read_unlock();
+ rcu_read_unlock_bh();
return res;
}
- rcu_read_unlock();
+ rcu_read_unlock_bh();
net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
__func__);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 6a5afc7..2f40363 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1098,17 +1098,13 @@ static int slow_chain_length(const struct rtable *head)
static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, const void *daddr)
{
- static const __be32 inaddr_any = 0;
struct net_device *dev = dst->dev;
const __be32 *pkey = daddr;
const struct rtable *rt;
struct neighbour *n;
rt = (const struct rtable *) dst;
-
- if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
- pkey = &inaddr_any;
- else if (rt->rt_gateway)
+ if (rt->rt_gateway)
pkey = (const __be32 *) &rt->rt_gateway;
n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
--
1.7.10
--
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