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net: Embed hh_cache inside of struct neighbour.

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Now that there is a one-to-one correspondance between neighbour
and hh_cache entries, we no longer need:

1) dynamic allocation
2) attachment to dst->hh
3) refcounting

Initialization of the hh_cache entry is indicated by hh_len
being non-zero, and such initialization is always done with
the neighbour's lock held as a writer.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2011-07-14 07:53:20 -07:00
parent 390fd0b388
commit f6b72b6217
9 changed files with 59 additions and 105 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
net/core/neighbour.c
View File

@@ -297,6 +297,7 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl)
n->updated = n->used = now;
n->nud_state = NUD_NONE;
n->output = neigh_blackhole;
seqlock_init(&n->hh.hh_lock);
n->parms = neigh_parms_clone(&tbl->parms);
setup_timer(&n->timer, neigh_timer_handler, (unsigned long)n);
@@ -702,14 +703,11 @@ void neigh_destroy(struct neighbour *neigh)
if (neigh_del_timer(neigh))
printk(KERN_WARNING "Impossible event.\n");
hh = neigh->hh;
if (hh) {
neigh->hh = NULL;
hh = &neigh->hh;
if (hh->hh_len) {
write_seqlock_bh(&hh->hh_lock);
hh->hh_output = neigh_blackhole;
write_sequnlock_bh(&hh->hh_lock);
hh_cache_put(hh);
}
skb_queue_purge(&neigh->arp_queue);
@@ -737,8 +735,8 @@ static void neigh_suspect(struct neighbour *neigh)
neigh->output = neigh->ops->output;
hh = neigh->hh;
if (hh)
hh = &neigh->hh;
if (hh->hh_len)
hh->hh_output = neigh->ops->output;
}
@@ -755,8 +753,8 @@ static void neigh_connect(struct neighbour *neigh)
neigh->output = neigh->ops->connected_output;
hh = neigh->hh;
if (hh)
hh = &neigh->hh;
if (hh->hh_len)
hh->hh_output = neigh->ops->hh_output;
}
@@ -1017,7 +1015,7 @@ out_unlock_bh:
}
EXPORT_SYMBOL(__neigh_event_send);
static void neigh_update_hhs(const struct neighbour *neigh)
static void neigh_update_hhs(struct neighbour *neigh)
{
struct hh_cache *hh;
void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)
@@ -1027,8 +1025,8 @@ static void neigh_update_hhs(const struct neighbour *neigh)
update = neigh->dev->header_ops->cache_update;
if (update) {
hh = neigh->hh;
if (hh) {
hh = &neigh->hh;
if (hh->hh_len) {
write_seqlock_bh(&hh->hh_lock);
update(hh, neigh->dev, neigh->ha);
write_sequnlock_bh(&hh->hh_lock);
@@ -1214,62 +1212,29 @@ struct neighbour *neigh_event_ns(struct neigh_table *tbl,
}
EXPORT_SYMBOL(neigh_event_ns);
static inline bool neigh_hh_lookup(struct neighbour *n, struct dst_entry *dst)
{
struct hh_cache *hh;
smp_rmb(); /* paired with smp_wmb() in neigh_hh_init() */
hh = n->hh;
if (hh) {
atomic_inc(&hh->hh_refcnt);
if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL))
hh_cache_put(hh);
return true;
}
return false;
}
/* called with read_lock_bh(&n->lock); */
static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
__be16 protocol)
static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst)
{
struct hh_cache *hh;
struct net_device *dev = dst->dev;
if (likely(neigh_hh_lookup(n, dst)))
return;
/* slow path */
hh = kzalloc(sizeof(*hh), GFP_ATOMIC);
if (!hh)
return;
seqlock_init(&hh->hh_lock);
atomic_set(&hh->hh_refcnt, 2);
if (dev->header_ops->cache(n, hh, protocol)) {
kfree(hh);
return;
}
__be16 prot = dst->ops->protocol;
struct hh_cache *hh = &n->hh;
write_lock_bh(&n->lock);
/* must check if another thread already did the insert */
if (neigh_hh_lookup(n, dst)) {
kfree(hh);
/* Only one thread can come in here and initialize the
* hh_cache entry.
*/
if (hh->hh_len)
goto end;
if (dev->header_ops->cache(n, hh, prot))
goto end;
}
if (n->nud_state & NUD_CONNECTED)
hh->hh_output = n->ops->hh_output;
else
hh->hh_output = n->ops->output;
smp_wmb(); /* paired with smp_rmb() in neigh_hh_lookup() */
n->hh = hh;
if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL))
hh_cache_put(hh);
end:
write_unlock_bh(&n->lock);
}
@@ -1312,10 +1277,8 @@ int neigh_resolve_output(struct sk_buff *skb)
struct net_device *dev = neigh->dev;
unsigned int seq;
if (dev->header_ops->cache &&
!dst->hh &&
!(dst->flags & DST_NOCACHE))
neigh_hh_init(neigh, dst, dst->ops->protocol);
if (dev->header_ops->cache && !neigh->hh.hh_len)
neigh_hh_init(neigh, dst);
do {
seq = read_seqbegin(&neigh->ha_lock);