rhashtable: Move hash_rnd into bucket_table

Currently hash_rnd is a parameter that users can set.  However,
no existing users set this parameter.  It is also something that
people are unlikely to want to set directly since it's just a
random number.

In preparation for allowing the reseeding/rehashing of rhashtable,
this patch moves hash_rnd into bucket_table so that it's now an
internal state rather than a parameter.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 9 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index b5344ef4c684..ba15dceee27f 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -66,25 +66,28 @@ static u32 rht_bucket_index(const struct bucket_table *tbl, u32 hash)
         return hash & (tbl->size - 1);
 }
 
-static u32 obj_raw_hashfn(const struct rhashtable *ht, const void *ptr)
+static u32 obj_raw_hashfn(struct rhashtable *ht, const void *ptr)
 {
+        struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
         u32 hash;
 
         if (unlikely(!ht->p.key_len))
-                hash = ht->p.obj_hashfn(ptr, ht->p.hash_rnd);
+                hash = ht->p.obj_hashfn(ptr, tbl->hash_rnd);
         else
                 hash = ht->p.hashfn(ptr + ht->p.key_offset, ht->p.key_len,
-                                    ht->p.hash_rnd);
+                                    tbl->hash_rnd);
 
         return hash >> HASH_RESERVED_SPACE;
 }
 
 static u32 key_hashfn(struct rhashtable *ht, const void *key, u32 len)
 {
-        return ht->p.hashfn(key, len, ht->p.hash_rnd) >> HASH_RESERVED_SPACE;
+        struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
+
+        return ht->p.hashfn(key, len, tbl->hash_rnd) >> HASH_RESERVED_SPACE;
 }
 
-static u32 head_hashfn(const struct rhashtable *ht,
+static u32 head_hashfn(struct rhashtable *ht,
                        const struct bucket_table *tbl,
                        const struct rhash_head *he)
 {
@@ -92,7 +95,7 @@ static u32 head_hashfn(const struct rhashtable *ht,
 }
 
 #ifdef CONFIG_PROVE_LOCKING
-static void debug_dump_buckets(const struct rhashtable *ht,
+static void debug_dump_buckets(struct rhashtable *ht,
                                const struct bucket_table *tbl)
 {
         struct rhash_head *he;
@@ -385,6 +388,8 @@ int rhashtable_expand(struct rhashtable *ht)
         if (new_tbl == NULL)
                 return -ENOMEM;
 
+        new_tbl->hash_rnd = old_tbl->hash_rnd;
+
         atomic_inc(&ht->shift);
 
         /* Make insertions go into the new, empty table right away. Deletions
@@ -476,6 +481,8 @@ int rhashtable_shrink(struct rhashtable *ht)
         if (new_tbl == NULL)
                 return -ENOMEM;
 
+        new_tbl->hash_rnd = tbl->hash_rnd;
+
         rcu_assign_pointer(ht->future_tbl, new_tbl);
         synchronize_rcu();
 
@@ -1099,14 +1106,13 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
         if (tbl == NULL)
                 return -ENOMEM;
 
+        get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
+
         atomic_set(&ht->nelems, 0);
         atomic_set(&ht->shift, ilog2(tbl->size));
         RCU_INIT_POINTER(ht->tbl, tbl);
         RCU_INIT_POINTER(ht->future_tbl, tbl);
 
-        if (!ht->p.hash_rnd)
-                get_random_bytes(&ht->p.hash_rnd, sizeof(ht->p.hash_rnd));
-
         INIT_WORK(&ht->run_work, rht_deferred_worker);
 
         return 0;