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Message-ID: <20150316112628.GA1373@gondor.apana.org.au>
Date: Mon, 16 Mar 2015 22:26:28 +1100
From: Herbert Xu <herbert@...dor.apana.org.au>
To: David Miller <davem@...emloft.net>
Cc: tgraf@...g.ch, netdev@...r.kernel.org, eric.dumazet@...il.com,
Patrick McHardy <kaber@...sh.net>
Subject: Re: [v1 PATCH 0/14] rhashtable: Kill shift/Key netlink
namespace/Merge jhash
On Mon, Mar 16, 2015 at 12:40:17AM -0400, David Miller wrote:
>
> Patrick McHardy had mentioned to me his consternation about this issue
> offhand the other week, and I've just failed to get around to bringing
> it up :-)
How about something like this? Compile tested only but at least
it does inline correctly.
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index c5104aa..79df647 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -42,6 +42,9 @@
#define RHT_HASH_BITS 27
#define RHT_BASE_SHIFT RHT_HASH_BITS
+/* Base bits plus 1 bit for nulls marker */
+#define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1)
+
struct rhash_head {
struct rhash_head __rcu *next;
};
@@ -172,6 +175,24 @@ static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr)
return ((unsigned long) ptr) >> 1;
}
+static void *rht_obj(const struct rhashtable *ht, const struct rhash_head *he)
+{
+ return (void *) he - ht->p.head_offset;
+}
+
+static inline u32 rht_bucket_index(const struct bucket_table *tbl, u32 hash)
+{
+ return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1);
+}
+
+static inline u32 rht_key_hashfn(const struct bucket_table *tbl,
+ const void *key,
+ unsigned int key_len,
+ rht_hashfn_t hashfn)
+{
+ return rht_bucket_index(tbl, hashfn(key, key_len, tbl->hash_rnd));
+}
+
#ifdef CONFIG_PROVE_LOCKING
int lockdep_rht_mutex_is_held(struct rhashtable *ht);
int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
@@ -197,6 +218,7 @@ int rhashtable_expand(struct rhashtable *ht);
int rhashtable_shrink(struct rhashtable *ht);
void *rhashtable_lookup(struct rhashtable *ht, const void *key);
+void *rhashtable_lookup_slow(struct rhashtable *ht, const void *key);
int rhashtable_lookup_insert(struct rhashtable *ht, struct rhash_head *obj);
int rhashtable_lookup_insert_key(struct rhashtable *ht,
@@ -358,4 +380,30 @@ void rhashtable_destroy(struct rhashtable *ht);
rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\
tbl, hash, member)
+static inline void *rhashtable_lookup_fast(struct rhashtable *ht,
+ const void *key,
+ unsigned int key_len,
+ rht_hashfn_t hashfn,
+ rht_obj_cmpfn_t obj_cmpfn)
+{
+ const struct bucket_table *tbl;
+ struct rhash_head *he;
+ u32 hash;
+
+ rcu_read_lock();
+
+ tbl = rht_dereference_rcu(ht->tbl, ht);
+ hash = rht_key_hashfn(tbl, key, key_len, hashfn);
+ rht_for_each_rcu(he, tbl, hash) {
+ if (!obj_cmpfn(key, rht_obj(ht, he)))
+ continue;
+ rcu_read_unlock();
+ return rht_obj(ht, he);
+ }
+
+ rcu_read_unlock();
+
+ return rhashtable_lookup(ht, key);
+}
+
#endif /* _LINUX_RHASHTABLE_H */
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index d22da74..7486e6a 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -33,9 +33,6 @@
#define HASH_MIN_SIZE 4U
#define BUCKET_LOCKS_PER_CPU 128UL
-/* Base bits plus 1 bit for nulls marker */
-#define HASH_RESERVED_SPACE (RHT_BASE_BITS + 1)
-
/* The bucket lock is selected based on the hash and protects mutations
* on a group of hash buckets.
*
@@ -54,21 +51,10 @@ static spinlock_t *bucket_lock(const struct bucket_table *tbl, u32 hash)
return &tbl->locks[hash & tbl->locks_mask];
}
-static void *rht_obj(const struct rhashtable *ht, const struct rhash_head *he)
-{
- return (void *) he - ht->p.head_offset;
-}
-
-static u32 rht_bucket_index(const struct bucket_table *tbl, u32 hash)
-{
- return (hash >> HASH_RESERVED_SPACE) & (tbl->size - 1);
-}
-
static u32 key_hashfn(struct rhashtable *ht, const struct bucket_table *tbl,
const void *key)
{
- return rht_bucket_index(tbl, ht->p.hashfn(key, ht->hashfn_key_len,
- tbl->hash_rnd));
+ return rht_key_hashfn(tbl, key, ht->p.key_len, ht->p.hashfn);
}
static u32 head_hashfn(struct rhashtable *ht,
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index f521f35..4f225c7 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1000,7 +1000,7 @@ static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
struct netlink_compare_arg arg;
netlink_compare_arg_init(&arg, net, portid);
- return rhashtable_lookup(&table->hash, &arg);
+ return rhashtable_lookup_fast(&table->hash, &arg, netlink_compare_arg_len, jhash2, netlink_compare);
}
static int __netlink_insert(struct netlink_table *table, struct sock *sk)
Cheers,
--
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
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