On Tue, 29 Aug 2006 19:28:16 +0400
Alexey Kuznetsov <[EMAIL PROTECTED]> wrote:
> Hello!
>
> > @@ -346,8 +354,8 @@ struct neighbour *neigh_lookup(struct ne
> >
> > NEIGH_CACHE_STAT_INC(tbl, lookups);
> >
> > - read_lock_bh(&tbl->lock);
> > - hlist_for_each_entry(n, tmp, &tbl->hash_buckets[hash_val], hlist) {
> > + rcu_read_lock();
> > + hlist_for_each_entry_rcu(n, tmp, &tbl->hash_buckets[hash_val], hlist) {
> > if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
> > neigh_hold(n);
> > NEIGH_CACHE_STAT_INC(tbl, hits);
>
> Sure? Seems, you cannot grab refcnt here, the entry can be already
> released.
>
> Probably, you should do atomic_inc_and_test() here and restart lookup,
> if it fails.
>
> Alexey
atomic_inc_and_test is true iff result is zero, so that won't work.
But the following should work:
hlist_for_each_entry_rcu(n, tmp, &tbl->hash_buckets[hash_val], hlist) {
if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
if (unlikely(&atomic_inc_return(&n->refcnt) == 1)) {
neigh_release(n);
continue;
}
NEIGH_CACHE_STAT_INC(tbl, hits);
I'll wrap the atomic_inc_return inside neigh_hold_return()
--
Stephen Hemminger <[EMAIL PROTECTED]>
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