From: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx>
Since Commit 64b87639c9cb ("netfilter: conntrack: fix race between
nf_conntrack proc read and hash resize") introdue the
nf_conntrack_get_ht, so there's no need to check nf_conntrack_generation
again and again to get the hash table and hash size.
But keep ____nf_conntrack_find unchanged, because it is performance
critical path, increase the overhead of the function call is not so
good.
Suggested-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx>
---
V2: remove "inline void" declared to nf_conntrack_get_ht, and keep
____nf_conntrack_find unchanged suggested by Florian.
net/netfilter/nf_conntrack_core.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 2d46225..23c6db0 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -801,18 +801,15 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_head *ct_hash;
- unsigned int hash, sequence;
+ unsigned int hash, hsize;
struct hlist_nulls_node *n;
struct nf_conn *ct;
zone = nf_ct_zone(ignored_conntrack);
rcu_read_lock();
- do {
- sequence = read_seqcount_begin(&nf_conntrack_generation);
- hash = hash_conntrack(net, tuple);
- ct_hash = nf_conntrack_hash;
- } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
+ nf_conntrack_get_ht(&ct_hash, &hsize);
+ hash = __hash_conntrack(net, tuple, hsize);
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[hash], hnnode) {
ct = nf_ct_tuplehash_to_ctrack(h);
@@ -878,14 +875,11 @@ static noinline int early_drop(struct net *net, unsigned int _hash)
for (i = 0; i < NF_CT_EVICTION_RANGE; i++) {
struct hlist_nulls_head *ct_hash;
- unsigned hash, sequence, drops;
+ unsigned int hash, hsize, drops;
rcu_read_lock();
- do {
- sequence = read_seqcount_begin(&nf_conntrack_generation);
- hash = scale_hash(_hash++);
- ct_hash = nf_conntrack_hash;
- } while (read_seqcount_retry(&nf_conntrack_generation, sequence));
+ nf_conntrack_get_ht(&ct_hash, &hsize);
+ hash = reciprocal_scale(_hash++, hsize);
drops = early_drop_list(net, &ct_hash[hash]);
rcu_read_unlock();
--
2.5.5
--
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